Java tutorial
/* * Copyright 2015 Hippo Seven * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.hippo.widget; import android.content.Context; import android.content.res.TypedArray; import android.graphics.Canvas; import android.graphics.Rect; import android.os.Build; import android.os.Bundle; import android.os.Parcelable; import android.support.v4.view.ViewCompat; import android.util.AttributeSet; import android.util.Log; import android.util.TypedValue; import android.view.FocusFinder; import android.view.InputDevice; import android.view.KeyEvent; import android.view.MotionEvent; import android.view.VelocityTracker; import android.view.View; import android.view.ViewConfiguration; import android.view.ViewGroup; import android.view.ViewParent; import android.view.animation.AnimationUtils; import android.widget.EdgeEffect; import android.widget.FrameLayout; import android.widget.ScrollView; import com.hippo.nimingban.R; import java.util.List; public class BothScrollView extends FrameLayout { private static final String TAG = BothScrollView.class.getSimpleName(); private static final String KEY_SUPER = "super"; private static final String KEY_SCROLL_X = "scroll_x"; private static final String KEY_SCROLL_Y = "scroll_y"; private static final int ANIMATED_SCROLL_GAP = 250; private static final float MAX_SCROLL_FACTOR = 0.5f; private long mLastScroll; private final Rect mTempRect = new Rect(); private SmoothOverScroller mScroller; private EdgeEffect mEdgeGlowLeft; private EdgeEffect mEdgeGlowRight; private EdgeEffect mEdgeGlowTop; private EdgeEffect mEdgeGlowBottom; /** * Whether arrow scrolling is animated. */ private boolean mSmoothScrollingEnabled = true; private int mTouchSlop; private int mMinimumVelocity; private int mMaximumVelocity; private int mOverscrollDistance; private int mOverflingDistance; /** * Position of the last motion event x. */ private int mLastMotionX; /** * Position of the last motion event y. */ private int mLastMotionY; /** * True when the layout has changed but the traversal has not come through yet. * Ideally the view hierarchy would keep track of this for us. */ private boolean mIsLayoutDirty = true; /** * The child to give focus to in the event that a child has requested focus while the * layout is dirty. This prevents the scroll from being wrong if the child has not been * laid out before requesting focus. */ private View mChildToScrollTo = null; /** * True if the user is currently dragging this ScrollView around. This is * not the same as 'is being flinged', which can be checked by * mScroller.isFinished() (flinging begins when the user lifts his finger). */ private boolean mIsBeingDragged = false; /** * Determines speed during touch scrolling */ private VelocityTracker mVelocityTracker; /** * When set to true, the scroll view measure its child to make it fill the currently * visible area. */ private boolean mFillViewport; /** * ID of the active pointer. This is used to retain consistency during * drags/flings if multiple pointers are used. */ private int mActivePointerId = INVALID_POINTER; /** * Sentinel value for no current active pointer. * Used by {@link #mActivePointerId}. */ private static final int INVALID_POINTER = -1; private Bundle mSavedState; /** * Vertical scroll factor cached by {@link #getVerticalScrollFactor}. */ private float mVerticalScrollFactor; /** * true if this view has been through at least one layout since it * was last attached to or detached from a window. */ private boolean mLaidOut; public BothScrollView(Context context) { super(context); init(context, null, 0, 0); } public BothScrollView(Context context, AttributeSet attrs) { super(context, attrs); init(context, attrs, 0, 0); } public BothScrollView(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); init(context, attrs, defStyleAttr, 0); } private void init(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) { initBothScrollView(context); final TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.BothScrollView, defStyleAttr, defStyleRes); setFillViewport(a.getBoolean(R.styleable.BothScrollView_fillViewport, false)); a.recycle(); } private void initBothScrollView(Context context) { mScroller = new SmoothOverScroller(context); setFocusable(true); setDescendantFocusability(FOCUS_AFTER_DESCENDANTS); setWillNotDraw(false); final ViewConfiguration configuration = ViewConfiguration.get(context); mTouchSlop = configuration.getScaledTouchSlop(); mMinimumVelocity = configuration.getScaledMinimumFlingVelocity(); mMaximumVelocity = configuration.getScaledMaximumFlingVelocity(); mOverscrollDistance = configuration.getScaledOverscrollDistance(); mOverflingDistance = configuration.getScaledOverflingDistance(); } @Override protected float getLeftFadingEdgeStrength() { if (getChildCount() == 0) { return 0.0f; } final int length = getHorizontalFadingEdgeLength(); final int scrollX = getScrollX(); if (scrollX < length) { return scrollX / (float) length; } return 1.0f; } @Override protected float getRightFadingEdgeStrength() { if (getChildCount() == 0) { return 0.0f; } final int length = getHorizontalFadingEdgeLength(); final int rightEdge = getWidth() - getPaddingRight(); final int span = getChildAt(0).getRight() - getScrollX() - rightEdge; if (span < length) { return span / (float) length; } return 1.0f; } @Override protected float getTopFadingEdgeStrength() { if (getChildCount() == 0) { return 0.0f; } final int length = getVerticalFadingEdgeLength(); final int scrollY = getScrollY(); if (scrollY < length) { return scrollY / (float) length; } return 1.0f; } @Override protected float getBottomFadingEdgeStrength() { if (getChildCount() == 0) { return 0.0f; } final int length = getVerticalFadingEdgeLength(); final int bottomEdge = getHeight() - getPaddingBottom(); final int span = getChildAt(0).getBottom() - getScrollY() - bottomEdge; if (span < length) { return span / (float) length; } return 1.0f; } /** * @return The horizontal maximum amount this scroll view will scroll in response to * an arrow event. */ public int getHorizontalMaxScrollAmount() { return (int) (MAX_SCROLL_FACTOR * (getRight() - getLeft())); } /** * @return The vertical maximum amount this scroll view will scroll in response to * an arrow event. */ public int getVerticalMaxScrollAmount() { return (int) (MAX_SCROLL_FACTOR * (getBottom() - getTop())); } @Override public void addView(View child) { if (getChildCount() > 0) { throw new IllegalStateException("BothScrollView can host only one direct child"); } super.addView(child); } @Override public void addView(View child, int index) { if (getChildCount() > 0) { throw new IllegalStateException("BothScrollView can host only one direct child"); } super.addView(child, index); } @Override public void addView(View child, ViewGroup.LayoutParams params) { if (getChildCount() > 0) { throw new IllegalStateException("BothScrollView can host only one direct child"); } super.addView(child, params); } @Override public void addView(View child, int index, ViewGroup.LayoutParams params) { if (getChildCount() > 0) { throw new IllegalStateException("BothScrollView can host only one direct child"); } super.addView(child, index, params); } /** * @return Returns true this BothScrollView can be scrolled horizontally */ private boolean canScrollHorizontally() { View child = getChildAt(0); if (child != null) { int childWidth = child.getWidth(); return getWidth() < childWidth + getPaddingLeft() + getPaddingRight(); } return false; } /** * @return Returns true this BothScrollView can be scrolled vertically */ private boolean canScrollVertically() { View child = getChildAt(0); if (child != null) { int childHeight = child.getHeight(); return getHeight() < childHeight + getPaddingTop() + getPaddingBottom(); } return false; } /** * Indicates whether this BothScrollView's content is stretched to * fill the viewport. * * @return True if the content fills the viewport, false otherwise. */ public boolean isFillViewport() { return mFillViewport; } /** * Indicates this BothScrollView whether it should stretch its content width and height * to fill the viewport or not. * * @param fillViewport True to stretch the content's width and height to the viewport's * boundaries, false otherwise. */ public void setFillViewport(boolean fillViewport) { if (fillViewport != mFillViewport) { mFillViewport = fillViewport; requestLayout(); } } /** * @return Whether arrow scrolling will animate its transition. */ public boolean isSmoothScrollingEnabled() { return mSmoothScrollingEnabled; } /** * Set whether arrow scrolling will animate its transition. * @param smoothScrollingEnabled whether arrow scrolling will animate its transition */ public void setSmoothScrollingEnabled(boolean smoothScrollingEnabled) { mSmoothScrollingEnabled = smoothScrollingEnabled; } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); // TODO HorizontalFillViewport VerticalFillViewport if (!mFillViewport) { return; } final int widthMode = MeasureSpec.getMode(widthMeasureSpec); if (widthMode == MeasureSpec.UNSPECIFIED) { return; } final int heightMode = MeasureSpec.getMode(heightMeasureSpec); if (heightMode == MeasureSpec.UNSPECIFIED) { return; } if (getChildCount() > 0) { int childWidthMeasureSpec; int childHeightMeasureSpec; final View child = getChildAt(0); final FrameLayout.LayoutParams lp = (LayoutParams) child.getLayoutParams(); int width = getMeasuredWidth(); int paddingLeft = getPaddingLeft(); int paddingRight = getPaddingRight(); if (child.getMeasuredWidth() < width) { childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(width - paddingLeft - paddingRight, MeasureSpec.EXACTLY); } else { childWidthMeasureSpec = getChildMeasureSpec(widthMeasureSpec, paddingLeft + paddingRight, lp.width); } int height = getMeasuredHeight(); int paddingTop = getPaddingTop(); int paddingBottom = getPaddingBottom(); if (child.getMeasuredHeight() < height) { childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(height - paddingTop - paddingBottom, MeasureSpec.EXACTLY); } else { childHeightMeasureSpec = getChildMeasureSpec(heightMeasureSpec, paddingTop + paddingBottom, lp.height); } child.measure(childWidthMeasureSpec, childHeightMeasureSpec); } } @Override public boolean dispatchKeyEvent(KeyEvent event) { // Let the focused view and/or our descendants get the key first return super.dispatchKeyEvent(event) || executeKeyEvent(event); } /** * You can call this function yourself to have the scroll view perform * scrolling from a key event, just as if the event had been dispatched to * it by the view hierarchy. * * @param event The key event to execute. * @return Return true if the event was handled, else false. */ public boolean executeKeyEvent(KeyEvent event) { mTempRect.setEmpty(); if (!canScrollHorizontally()) { if (isFocused() && event.getKeyCode() != KeyEvent.KEYCODE_BACK) { View currentFocused = findFocus(); if (currentFocused == this) { currentFocused = null; } View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, View.FOCUS_RIGHT); return nextFocused != null && nextFocused != this && nextFocused.requestFocus(View.FOCUS_RIGHT); } return false; } if (!canScrollVertically()) { if (isFocused() && event.getKeyCode() != KeyEvent.KEYCODE_BACK) { View currentFocused = findFocus(); if (currentFocused == this) { currentFocused = null; } View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, View.FOCUS_DOWN); return nextFocused != null && nextFocused != this && nextFocused.requestFocus(View.FOCUS_DOWN); } return false; } boolean handled = false; if (event.getAction() == KeyEvent.ACTION_DOWN) { switch (event.getKeyCode()) { case KeyEvent.KEYCODE_DPAD_LEFT: if (!event.isAltPressed()) { handled = arrowScrollHorizontally(View.FOCUS_LEFT); } else { handled = fullScroll(View.FOCUS_LEFT); } break; case KeyEvent.KEYCODE_DPAD_RIGHT: if (!event.isAltPressed()) { handled = arrowScrollHorizontally(View.FOCUS_RIGHT); } else { handled = fullScroll(View.FOCUS_RIGHT); } break; case KeyEvent.KEYCODE_DPAD_UP: if (!event.isAltPressed()) { handled = arrowScrollVertically(View.FOCUS_UP); } else { handled = fullScroll(View.FOCUS_UP); } break; case KeyEvent.KEYCODE_DPAD_DOWN: if (!event.isAltPressed()) { handled = arrowScrollVertically(View.FOCUS_DOWN); } else { handled = fullScroll(View.FOCUS_DOWN); } break; case KeyEvent.KEYCODE_SPACE: if (event.isCtrlPressed()) { pageScroll(event.isShiftPressed() ? View.FOCUS_LEFT : View.FOCUS_RIGHT); } else { pageScroll(event.isShiftPressed() ? View.FOCUS_UP : View.FOCUS_DOWN); } break; } } return handled; } private boolean inChild(int x, int y) { if (getChildCount() > 0) { final int scrollX = getScrollX(); final int scrollY = getScrollY(); final View child = getChildAt(0); return !(y < child.getTop() - scrollY || y >= child.getBottom() - scrollY || x < child.getLeft() - scrollX || x >= child.getRight() - scrollX); } return false; } private void initOrResetVelocityTracker() { if (mVelocityTracker == null) { mVelocityTracker = VelocityTracker.obtain(); } else { mVelocityTracker.clear(); } } private void initVelocityTrackerIfNotExists() { if (mVelocityTracker == null) { mVelocityTracker = VelocityTracker.obtain(); } } private void recycleVelocityTracker() { if (mVelocityTracker != null) { mVelocityTracker.recycle(); mVelocityTracker = null; } } @Override public void requestDisallowInterceptTouchEvent(boolean disallowIntercept) { if (disallowIntercept) { recycleVelocityTracker(); } super.requestDisallowInterceptTouchEvent(disallowIntercept); } @Override public boolean onInterceptTouchEvent(MotionEvent ev) { /* * This method JUST determines whether we want to intercept the motion. * If we return true, onMotionEvent will be called and we do the actual * scrolling there. */ /* * Shortcut the most recurring case: the user is in the dragging * state and he is moving his finger. We want to intercept this * motion. */ final int action = ev.getAction(); if ((action == MotionEvent.ACTION_MOVE) && (mIsBeingDragged)) { return true; } /* * Don't try to intercept touch if we can't scroll anyway. */ if (getScrollX() == 0 && !canScrollHorizontally(1) && getScrollY() == 0 && !canScrollVertically(1)) { return false; } switch (action & MotionEvent.ACTION_MASK) { case MotionEvent.ACTION_MOVE: { /* * mIsBeingDragged == false, otherwise the shortcut would have caught it. Check * whether the user has moved far enough from his original down touch. */ /* * Locally do absolute value. mLastMotionY is set to the y value * of the down event. */ final int activePointerId = mActivePointerId; if (activePointerId == INVALID_POINTER) { // If we don't have a valid id, the touch down wasn't on content. break; } final int pointerIndex = ev.findPointerIndex(activePointerId); if (pointerIndex == -1) { Log.e(TAG, "Invalid pointerId=" + activePointerId + " in onInterceptTouchEvent"); break; } final int x = (int) ev.getX(pointerIndex); final int y = (int) ev.getY(pointerIndex); final int xDiff = Math.abs(x - mLastMotionX); final int yDiff = Math.abs(y - mLastMotionY); if (xDiff > mTouchSlop || yDiff > mTouchSlop) { mIsBeingDragged = true; mLastMotionX = x; mLastMotionY = y; initVelocityTrackerIfNotExists(); mVelocityTracker.addMovement(ev); final ViewParent parent = getParent(); if (parent != null) { parent.requestDisallowInterceptTouchEvent(true); } } break; } case MotionEvent.ACTION_DOWN: { final int x = (int) ev.getX(); final int y = (int) ev.getY(); if (!inChild(x, y)) { mIsBeingDragged = false; recycleVelocityTracker(); break; } /* * Remember location of down touch. * ACTION_DOWN always refers to pointer index 0. */ mLastMotionX = x; mLastMotionY = y; mActivePointerId = ev.getPointerId(0); initOrResetVelocityTracker(); mVelocityTracker.addMovement(ev); /* * If being flinged and user touches the screen, initiate drag; * otherwise don't. mScroller.isFinished should be false when * being flinged. */ mIsBeingDragged = !mScroller.isFinished(); break; } case MotionEvent.ACTION_CANCEL: case MotionEvent.ACTION_UP: /* Release the drag */ mIsBeingDragged = false; mActivePointerId = INVALID_POINTER; if (mScroller.springBack(getScrollX(), getScrollY(), 0, getHorizontalScrollRange(), 0, getVerticalScrollRange())) { ViewCompat.postInvalidateOnAnimation(this); } break; case MotionEvent.ACTION_POINTER_DOWN: { final int index = ev.getActionIndex(); mLastMotionX = (int) ev.getX(index); mLastMotionY = (int) ev.getY(index); mActivePointerId = ev.getPointerId(index); break; } case MotionEvent.ACTION_POINTER_UP: onSecondaryPointerUp(ev); final int index = ev.findPointerIndex(mActivePointerId); mLastMotionX = (int) ev.getX(index); mLastMotionY = (int) ev.getY(index); break; } /* * The only time we want to intercept motion events is if we are in the * drag mode. */ return mIsBeingDragged; } @Override public boolean onTouchEvent(MotionEvent ev) { initVelocityTrackerIfNotExists(); mVelocityTracker.addMovement(ev); final int action = ev.getAction(); switch (action & MotionEvent.ACTION_MASK) { case MotionEvent.ACTION_DOWN: { if (getChildCount() == 0) { return false; } if ((mIsBeingDragged = !mScroller.isFinished())) { final ViewParent parent = getParent(); if (parent != null) { parent.requestDisallowInterceptTouchEvent(true); } } /* * If being flinged and user touches, stop the fling. isFinished * will be false if being flinged. */ if (!mScroller.isFinished()) { mScroller.abortAnimation(); } // Remember where the motion event started mLastMotionX = (int) ev.getX(); mLastMotionY = (int) ev.getY(); mActivePointerId = ev.getPointerId(0); break; } case MotionEvent.ACTION_MOVE: final int activePointerIndex = ev.findPointerIndex(mActivePointerId); if (activePointerIndex == -1) { Log.e(TAG, "Invalid pointerId=" + mActivePointerId + " in onTouchEvent"); break; } final int x = (int) ev.getX(activePointerIndex); final int y = (int) ev.getY(activePointerIndex); int deltaX = mLastMotionX - x; int deltaY = mLastMotionY - y; if (!mIsBeingDragged && (Math.abs(deltaX) > mTouchSlop || Math.abs(deltaY) > mTouchSlop)) { final ViewParent parent = getParent(); if (parent != null) { parent.requestDisallowInterceptTouchEvent(true); } mIsBeingDragged = true; if (deltaX > 0) { deltaX -= mTouchSlop; deltaX = Math.max(0, deltaX); } else { deltaX += mTouchSlop; deltaX = Math.min(0, deltaX); } if (deltaY > 0) { deltaY -= mTouchSlop; deltaY = Math.max(0, deltaY); } else { deltaY += mTouchSlop; deltaY = Math.min(0, deltaY); } } if (mIsBeingDragged) { // Scroll to follow the motion event mLastMotionX = x; mLastMotionY = y; final int oldX = getScrollX(); final int oldY = getScrollY(); final int horizontalRange = getHorizontalScrollRange(); final int verticalRange = getVerticalScrollRange(); final int overscrollMode = getOverScrollMode(); final boolean canOverscroll = overscrollMode == OVER_SCROLL_ALWAYS || (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && (horizontalRange > 0 || verticalRange > 0)); // Calling overScrollBy will call onOverScrolled, which // calls onScrollChanged if applicable. overScrollBy(deltaX, deltaY, oldX, oldY, horizontalRange, verticalRange, mOverscrollDistance, mOverscrollDistance, true); if (canOverscroll) { final int pulledToX = oldX + deltaX; final int pulledToY = oldY + deltaY; if (pulledToX < 0) { mEdgeGlowLeft.onPull((float) deltaX / getWidth()); if (!mEdgeGlowRight.isFinished()) { mEdgeGlowRight.onRelease(); } } else if (pulledToX > horizontalRange) { mEdgeGlowRight.onPull((float) deltaX / getWidth()); if (!mEdgeGlowLeft.isFinished()) { mEdgeGlowLeft.onRelease(); } } if (pulledToY < 0) { mEdgeGlowTop.onPull((float) deltaY / getHeight()); if (!mEdgeGlowBottom.isFinished()) { mEdgeGlowBottom.onRelease(); } } else if (pulledToY > verticalRange) { mEdgeGlowBottom.onPull((float) deltaY / getHeight()); if (!mEdgeGlowTop.isFinished()) { mEdgeGlowTop.onRelease(); } } if (mEdgeGlowLeft != null && (!mEdgeGlowLeft.isFinished() || !mEdgeGlowRight.isFinished() || !mEdgeGlowTop.isFinished() || !mEdgeGlowBottom.isFinished())) { ViewCompat.postInvalidateOnAnimation(this); } } } break; case MotionEvent.ACTION_UP: if (mIsBeingDragged) { final VelocityTracker velocityTracker = mVelocityTracker; velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); int initialVelocityX = (int) velocityTracker.getXVelocity(mActivePointerId); int initialVelocityY = (int) velocityTracker.getYVelocity(mActivePointerId); if (getChildCount() > 0) { if (Math.abs(initialVelocityX) > mMinimumVelocity || Math.abs(initialVelocityY) > mMinimumVelocity) { fling(-initialVelocityX, -initialVelocityY); } else { if (mScroller.springBack(getScrollX(), getScrollY(), 0, getHorizontalScrollRange(), 0, getVerticalScrollRange())) { ViewCompat.postInvalidateOnAnimation(this); } } } mActivePointerId = INVALID_POINTER; endDrag(); } break; case MotionEvent.ACTION_CANCEL: if (mIsBeingDragged && getChildCount() > 0) { if (mScroller.springBack(getScrollX(), getScrollY(), 0, getHorizontalScrollRange(), 0, getVerticalScrollRange())) { ViewCompat.postInvalidateOnAnimation(this); } mActivePointerId = INVALID_POINTER; endDrag(); } break; case MotionEvent.ACTION_POINTER_DOWN: { final int index = ev.getActionIndex(); mLastMotionX = (int) ev.getX(index); mLastMotionY = (int) ev.getY(index); mActivePointerId = ev.getPointerId(index); break; } case MotionEvent.ACTION_POINTER_UP: onSecondaryPointerUp(ev); final int index = ev.findPointerIndex(mActivePointerId); mLastMotionX = (int) ev.getX(index); mLastMotionY = (int) ev.getY(index); break; } return true; } private void onSecondaryPointerUp(MotionEvent ev) { final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK) >> MotionEvent.ACTION_POINTER_INDEX_SHIFT; final int pointerId = ev.getPointerId(pointerIndex); if (pointerId == mActivePointerId) { // This was our active pointer going up. Choose a new // active pointer and adjust accordingly. // TODO: Make this decision more intelligent. final int newPointerIndex = pointerIndex == 0 ? 1 : 0; mLastMotionX = (int) ev.getY(newPointerIndex); mLastMotionY = (int) ev.getY(newPointerIndex); mActivePointerId = ev.getPointerId(newPointerIndex); if (mVelocityTracker != null) { mVelocityTracker.clear(); } } } /** * Gets a scale factor that determines the distance the view should scroll * vertically in response to {@link MotionEvent#ACTION_SCROLL}. * @return The vertical scroll scale factor. */ protected float getVerticalScrollFactor() { if (mVerticalScrollFactor == 0) { Context context = getContext(); TypedValue outValue = new TypedValue(); if (!context.getTheme().resolveAttribute(16842829, outValue, true)) { // listPreferredItemHeight throw new IllegalStateException("Expected theme to define listPreferredItemHeight."); } mVerticalScrollFactor = outValue.getDimension(context.getResources().getDisplayMetrics()); } return mVerticalScrollFactor; } /** * Gets a scale factor that determines the distance the view should scroll * horizontally in response to {@link MotionEvent#ACTION_SCROLL}. * @return The horizontal scroll scale factor. */ protected float getHorizontalScrollFactor() { // TODO: Should use something else. return getVerticalScrollFactor(); } @Override public boolean onGenericMotionEvent(MotionEvent event) { if ((event.getSource() & InputDevice.SOURCE_CLASS_POINTER) != 0) { switch (event.getAction()) { case MotionEvent.ACTION_SCROLL: { if (!mIsBeingDragged) { if ((event.getMetaState() & KeyEvent.META_SHIFT_ON) != 0) { final float hscroll = event.getAxisValue(MotionEvent.AXIS_VSCROLL); if (hscroll != 0) { final int delta = (int) (hscroll * getHorizontalScrollFactor()); final int range = getHorizontalScrollRange(); int oldScrollX = getScrollX(); int newScrollX = oldScrollX + delta; if (newScrollX < 0) { newScrollX = 0; } else if (newScrollX > range) { newScrollX = range; } if (newScrollX != oldScrollX) { super.scrollTo(newScrollX, getScrollY()); return true; } } } else { final float vscroll = event.getAxisValue(MotionEvent.AXIS_VSCROLL); if (vscroll != 0) { final int delta = (int) (vscroll * getVerticalScrollFactor()); final int range = getVerticalScrollRange(); int oldScrollY = getScrollY(); int newScrollY = oldScrollY - delta; if (newScrollY < 0) { newScrollY = 0; } else if (newScrollY > range) { newScrollY = range; } if (newScrollY != oldScrollY) { super.scrollTo(getScrollX(), newScrollY); return true; } } } } } } } return super.onGenericMotionEvent(event); } @Override public boolean shouldDelayChildPressedState() { return true; } @Override protected void onOverScrolled(int scrollX, int scrollY, boolean clampedX, boolean clampedY) { if (clampedX && clampedY && mVelocityTracker != null) { mVelocityTracker.clear(); } // Treat animating scrolls differently; see #computeScroll() for why. if (!mScroller.isFinished()) { setScrollX(scrollX); setScrollY(scrollY); if (clampedX) { mScroller.springBackX(scrollX, 0, getHorizontalScrollRange()); } if (clampedY) { mScroller.springBackY(scrollY, 0, getVerticalScrollRange()); } } else { super.scrollTo(scrollX, scrollY); } awakenScrollBars(); } @Override public CharSequence getAccessibilityClassName() { return ScrollView.class.getName(); } private int getHorizontalScrollRange() { int scrollRange = 0; if (getChildCount() > 0) { View child = getChildAt(0); scrollRange = Math.max(0, child.getWidth() - (getWidth() - getPaddingLeft() - getPaddingRight())); } return scrollRange; } private int getVerticalScrollRange() { int scrollRange = 0; if (getChildCount() > 0) { View child = getChildAt(0); scrollRange = Math.max(0, child.getHeight() - (getHeight() - getPaddingTop() - getPaddingBottom())); } return scrollRange; } /** * <p> * Finds the next focusable component that fits in this View's bounds * (excluding fading edges) pretending that this View's left is located at * the parameter left. * </p> * * @param leftFocus look for a candidate is the one at the left of the bounds * if leftFocus is true, or at the right of the bounds if leftFocus * is false * @param left the left offset of the bounds in which a focusable must be * found (the fading edge is assumed to start at this position) * @param preferredFocusable the View that has highest priority and will be * returned if it is within my bounds (null is valid) * @return the next focusable component in the bounds or null if none can be found */ private View findFocusableViewInMyBoundsHorizontally(final boolean leftFocus, final int left, View preferredFocusable) { /* * The fading edge's transparent side should be considered for focus * since it's mostly visible, so we divide the actual fading edge length * by 2. */ final int fadingEdgeLength = getHorizontalFadingEdgeLength() / 2; final int leftWithoutFadingEdge = left + fadingEdgeLength; final int rightWithoutFadingEdge = left + getWidth() - fadingEdgeLength; if ((preferredFocusable != null) && (preferredFocusable.getLeft() < rightWithoutFadingEdge) && (preferredFocusable.getRight() > leftWithoutFadingEdge)) { return preferredFocusable; } return findFocusableViewInBoundsHorizontally(leftFocus, leftWithoutFadingEdge, rightWithoutFadingEdge); } /** * <p> * Finds the next focusable component that fits in the specified bounds. * </p> * * @param leftFocus look for a candidate is the one at the left of the bounds * if leftFocus is true, or at the right of the bounds if * leftFocus is false * @param left the left offset of the bounds in which a focusable must be * found * @param right the right offset of the bounds in which a focusable must * be found * @return the next focusable component in the bounds or null if none can * be found */ private View findFocusableViewInBoundsHorizontally(boolean leftFocus, int left, int right) { List<View> focusables = getFocusables(View.FOCUS_FORWARD); View focusCandidate = null; /* * A fully contained focusable is one where its left is below the bound's * left, and its right is above the bound's right. A partially * contained focusable is one where some part of it is within the * bounds, but it also has some part that is not within bounds. A fully contained * focusable is preferred to a partially contained focusable. */ boolean foundFullyContainedFocusable = false; int count = focusables.size(); for (int i = 0; i < count; i++) { View view = focusables.get(i); int viewLeft = view.getLeft(); int viewRight = view.getRight(); if (left < viewRight && viewLeft < right) { /* * the focusable is in the target area, it is a candidate for * focusing */ final boolean viewIsFullyContained = (left < viewLeft) && (viewRight < right); if (focusCandidate == null) { /* No candidate, take this one */ focusCandidate = view; foundFullyContainedFocusable = viewIsFullyContained; } else { final boolean viewIsCloserToBoundary = (leftFocus && viewLeft < focusCandidate.getLeft()) || (!leftFocus && viewRight > focusCandidate.getRight()); if (foundFullyContainedFocusable) { if (viewIsFullyContained && viewIsCloserToBoundary) { /* * We're dealing with only fully contained views, so * it has to be closer to the boundary to beat our * candidate */ focusCandidate = view; } } else { if (viewIsFullyContained) { /* Any fully contained view beats a partially contained view */ focusCandidate = view; foundFullyContainedFocusable = true; } else if (viewIsCloserToBoundary) { /* * Partially contained view beats another partially * contained view if it's closer */ focusCandidate = view; } } } } } return focusCandidate; } /** * <p> * Finds the next focusable component that fits in the specified bounds. * </p> * * @param topFocus look for a candidate is the one at the top of the bounds * if topFocus is true, or at the bottom of the bounds if topFocus is * false * @param top the top offset of the bounds in which a focusable must be * found * @param bottom the bottom offset of the bounds in which a focusable must * be found * @return the next focusable component in the bounds or null if none can * be found */ private View findFocusableViewInBoundsVertically(boolean topFocus, int top, int bottom) { List<View> focusables = getFocusables(View.FOCUS_FORWARD); View focusCandidate = null; /* * A fully contained focusable is one where its top is below the bound's * top, and its bottom is above the bound's bottom. A partially * contained focusable is one where some part of it is within the * bounds, but it also has some part that is not within bounds. A fully contained * focusable is preferred to a partially contained focusable. */ boolean foundFullyContainedFocusable = false; int count = focusables.size(); for (int i = 0; i < count; i++) { View view = focusables.get(i); int viewTop = view.getTop(); int viewBottom = view.getBottom(); if (top < viewBottom && viewTop < bottom) { /* * the focusable is in the target area, it is a candidate for * focusing */ final boolean viewIsFullyContained = (top < viewTop) && (viewBottom < bottom); if (focusCandidate == null) { /* No candidate, take this one */ focusCandidate = view; foundFullyContainedFocusable = viewIsFullyContained; } else { final boolean viewIsCloserToBoundary = (topFocus && viewTop < focusCandidate.getTop()) || (!topFocus && viewBottom > focusCandidate.getBottom()); if (foundFullyContainedFocusable) { if (viewIsFullyContained && viewIsCloserToBoundary) { /* * We're dealing with only fully contained views, so * it has to be closer to the boundary to beat our * candidate */ focusCandidate = view; } } else { if (viewIsFullyContained) { /* Any fully contained view beats a partially contained view */ focusCandidate = view; foundFullyContainedFocusable = true; } else if (viewIsCloserToBoundary) { /* * Partially contained view beats another partially * contained view if it's closer */ focusCandidate = view; } } } } } return focusCandidate; } /** * <p>Handles scrolling in response to a "page up/down" shortcut press. This * method will scroll the view by one page left or right and give the focus * to the leftmost/rightmost component in the new visible area. If no * component is a good candidate for focus, this scrollview reclaims the * focus.</p> * * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} * to go one page left or {@link android.view.View#FOCUS_RIGHT} * to go one page right * @return true if the key event is consumed by this method, false otherwise */ public boolean pageScroll(int direction) { int width = getWidth(); int height = getHeight(); if (direction == View.FOCUS_UP) { mTempRect.top = getScrollY() - height; if (mTempRect.top < 0) { mTempRect.top = 0; } mTempRect.bottom = mTempRect.top + height; return scrollAndFocusVertically(direction, mTempRect.top, mTempRect.bottom); } else if (direction == View.FOCUS_DOWN) { mTempRect.top = getScrollY() + height; int count = getChildCount(); if (count > 0) { View view = getChildAt(count - 1); if (mTempRect.top + height > view.getBottom()) { mTempRect.top = view.getBottom() - height; } } mTempRect.bottom = mTempRect.top + height; return scrollAndFocusVertically(direction, mTempRect.top, mTempRect.bottom); } else if (direction == View.FOCUS_LEFT) { mTempRect.left = getScrollX() - width; if (mTempRect.left < 0) { mTempRect.left = 0; } mTempRect.right = mTempRect.left + width; return scrollAndFocusHorizontally(direction, mTempRect.left, mTempRect.right); } else { mTempRect.left = getScrollX() + width; int count = getChildCount(); if (count > 0) { View view = getChildAt(0); if (mTempRect.left + width > view.getRight()) { mTempRect.left = view.getRight() - width; } } mTempRect.right = mTempRect.left + width; return scrollAndFocusHorizontally(direction, mTempRect.left, mTempRect.right); } } /** * <p>Handles scrolling in response to a "home/end" shortcut press. This * method will scroll the view to the left or right and give the focus * to the leftmost/rightmost component in the new visible area. If no * component is a good candidate for focus, this scrollview reclaims the * focus.</p> * * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} * to go the left of the view or {@link android.view.View#FOCUS_RIGHT} * to go the right * @return true if the key event is consumed by this method, false otherwise */ public boolean fullScroll(int direction) { if (direction == View.FOCUS_LEFT || direction == View.FOCUS_RIGHT) { boolean right = direction == View.FOCUS_RIGHT; int width = getWidth(); mTempRect.left = 0; mTempRect.right = width; if (right) { int count = getChildCount(); if (count > 0) { View view = getChildAt(0); mTempRect.right = view.getRight() + getPaddingRight(); mTempRect.left = mTempRect.right - width; } } return scrollAndFocusHorizontally(direction, mTempRect.left, mTempRect.right); } else { boolean down = direction == View.FOCUS_DOWN; int height = getHeight(); mTempRect.top = 0; mTempRect.bottom = height; if (down) { int count = getChildCount(); if (count > 0) { View view = getChildAt(count - 1); mTempRect.bottom = view.getBottom() + getPaddingBottom(); mTempRect.top = mTempRect.bottom - height; } } return scrollAndFocusVertically(direction, mTempRect.top, mTempRect.bottom); } } /** * <p>Scrolls the view to make the area defined by <code>left</code> and * <code>right</code> visible. This method attempts to give the focus * to a component visible in this area. If no component can be focused in * the new visible area, the focus is reclaimed by this scrollview.</p> * * @param direction the scroll direction: {@link android.view.View#FOCUS_LEFT} * to go left {@link android.view.View#FOCUS_RIGHT} to right * @param left the left offset of the new area to be made visible * @param right the right offset of the new area to be made visible * @return true if the key event is consumed by this method, false otherwise */ private boolean scrollAndFocusHorizontally(int direction, int left, int right) { boolean handled = true; int width = getWidth(); int containerLeft = getScrollX(); int containerRight = containerLeft + width; boolean goLeft = direction == View.FOCUS_LEFT; View newFocused = findFocusableViewInBoundsHorizontally(goLeft, left, right); if (newFocused == null) { newFocused = this; } if (left >= containerLeft && right <= containerRight) { handled = false; } else { int delta = goLeft ? (left - containerLeft) : (right - containerRight); doScrollX(delta); } if (newFocused != findFocus()) newFocused.requestFocus(direction); return handled; } /** * <p>Scrolls the view to make the area defined by <code>top</code> and * <code>bottom</code> visible. This method attempts to give the focus * to a component visible in this area. If no component can be focused in * the new visible area, the focus is reclaimed by this ScrollView.</p> * * @param direction the scroll direction: {@link android.view.View#FOCUS_UP} * to go upward, {@link android.view.View#FOCUS_DOWN} to downward * @param top the top offset of the new area to be made visible * @param bottom the bottom offset of the new area to be made visible * @return true if the key event is consumed by this method, false otherwise */ private boolean scrollAndFocusVertically(int direction, int top, int bottom) { boolean handled = true; int height = getHeight(); int containerTop = getScrollY(); int containerBottom = containerTop + height; boolean up = direction == View.FOCUS_UP; View newFocused = findFocusableViewInBoundsVertically(up, top, bottom); if (newFocused == null) { newFocused = this; } if (top >= containerTop && bottom <= containerBottom) { handled = false; } else { int delta = up ? (top - containerTop) : (bottom - containerBottom); doScrollY(delta); } if (newFocused != findFocus()) newFocused.requestFocus(direction); return handled; } /** * Handle scrolling in response to a left or right arrow click. * * @param direction The direction corresponding to the arrow key that was * pressed * @return True if we consumed the event, false otherwise */ public boolean arrowScrollHorizontally(int direction) { View currentFocused = findFocus(); if (currentFocused == this) currentFocused = null; View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction); final int maxJump = getHorizontalMaxScrollAmount(); if (nextFocused != null && isWithinDeltaOfScreen(nextFocused, maxJump, getWidth(), getHeight())) { nextFocused.getDrawingRect(mTempRect); offsetDescendantRectToMyCoords(nextFocused, mTempRect); int scrollDelta = computeScrollXDeltaToGetChildRectOnScreen(mTempRect); doScrollX(scrollDelta); nextFocused.requestFocus(direction); } else { // no new focus int scrollDelta = maxJump; if (direction == View.FOCUS_LEFT && getScrollX() < scrollDelta) { scrollDelta = getScrollX(); } else if (direction == View.FOCUS_RIGHT && getChildCount() > 0) { int daRight = getChildAt(0).getRight(); int screenRight = getScrollX() + getWidth() - getPaddingRight(); if (daRight - screenRight < maxJump) { scrollDelta = daRight - screenRight; } } if (scrollDelta == 0) { return false; } doScrollX(direction == View.FOCUS_RIGHT ? scrollDelta : -scrollDelta); } if (currentFocused != null && currentFocused.isFocused() && isOffScreen(currentFocused)) { // previously focused item still has focus and is off screen, give // it up (take it back to ourselves) // (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are // sure to // get it) final int descendantFocusability = getDescendantFocusability(); // save setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS); requestFocus(); setDescendantFocusability(descendantFocusability); // restore } return true; } /** * Handle scrolling in response to an up or down arrow click. * * @param direction The direction corresponding to the arrow key that was * pressed * @return True if we consumed the event, false otherwise */ public boolean arrowScrollVertically(int direction) { View currentFocused = findFocus(); if (currentFocused == this) currentFocused = null; View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction); final int maxJump = getVerticalMaxScrollAmount(); if (nextFocused != null && isWithinDeltaOfScreen(nextFocused, maxJump, getWidth(), getHeight())) { nextFocused.getDrawingRect(mTempRect); offsetDescendantRectToMyCoords(nextFocused, mTempRect); int scrollDelta = computeScrollYDeltaToGetChildRectOnScreen(mTempRect); doScrollY(scrollDelta); nextFocused.requestFocus(direction); } else { // no new focus int scrollDelta = maxJump; if (direction == View.FOCUS_UP && getScrollY() < scrollDelta) { scrollDelta = getScrollY(); } else if (direction == View.FOCUS_DOWN) { if (getChildCount() > 0) { int daBottom = getChildAt(0).getBottom(); int screenBottom = getScrollY() + getHeight() - getPaddingBottom(); if (daBottom - screenBottom < maxJump) { scrollDelta = daBottom - screenBottom; } } } if (scrollDelta == 0) { return false; } doScrollY(direction == View.FOCUS_DOWN ? scrollDelta : -scrollDelta); } if (currentFocused != null && currentFocused.isFocused() && isOffScreen(currentFocused)) { // previously focused item still has focus and is off screen, give // it up (take it back to ourselves) // (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are // sure to // get it) final int descendantFocusability = getDescendantFocusability(); // save setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS); requestFocus(); setDescendantFocusability(descendantFocusability); // restore } return true; } /** * @return whether the descendant of this scroll view is scrolled off * screen. */ private boolean isOffScreen(View descendant) { return !isWithinDeltaOfScreen(descendant, 0, getWidth(), getHeight()); } /** * @return whether the descendant of this scroll view is within delta * pixels of being on the screen. */ private boolean isWithinDeltaOfScreen(View descendant, int delta, int width, int height) { descendant.getDrawingRect(mTempRect); offsetDescendantRectToMyCoords(descendant, mTempRect); return (mTempRect.right + delta) >= getScrollX() && (mTempRect.left - delta) <= (getScrollX() + width) && (mTempRect.bottom + delta) >= getScrollY() && (mTempRect.top - delta) <= (getScrollY() + height); } /** * Smooth scroll by a X delta * * @param delta the number of pixels to scroll by on the X axis */ private void doScrollX(int delta) { if (delta != 0) { if (mSmoothScrollingEnabled) { smoothScrollBy(delta, 0); } else { scrollBy(delta, 0); } } } /** * Smooth scroll by a Y delta * * @param delta the number of pixels to scroll by on the Y axis */ private void doScrollY(int delta) { if (delta != 0) { if (mSmoothScrollingEnabled) { smoothScrollBy(0, delta); } else { scrollBy(0, delta); } } } /** * Like {@link View#scrollBy}, but scroll smoothly instead of immediately. * * @param dx the number of pixels to scroll by on the X axis * @param dy the number of pixels to scroll by on the Y axis */ public final void smoothScrollBy(int dx, int dy) { if (getChildCount() == 0) { // Nothing to do. return; } long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll; if (duration > ANIMATED_SCROLL_GAP) { final int width = getWidth() - getPaddingRight() - getPaddingLeft(); final int height = getHeight() - getPaddingBottom() - getPaddingTop(); final int right = getChildAt(0).getWidth(); final int bottom = getChildAt(0).getHeight(); final int maxX = Math.max(0, right - width); final int maxY = Math.max(0, bottom - height); final int scrollX = getScrollX(); final int scrollY = getScrollY(); dx = Math.max(0, Math.min(scrollX + dx, maxX)) - scrollX; dy = Math.max(0, Math.min(scrollY + dy, maxY)) - scrollY; mScroller.startScroll(scrollX, scrollY, dx, dy); ViewCompat.postInvalidateOnAnimation(this); } else { if (!mScroller.isFinished()) { mScroller.abortAnimation(); } scrollBy(dx, dy); } mLastScroll = AnimationUtils.currentAnimationTimeMillis(); } /** * Like {@link #scrollTo}, but scroll smoothly instead of immediately. * * @param x the position where to scroll on the X axis * @param y the position where to scroll on the Y axis */ public final void smoothScrollTo(int x, int y) { smoothScrollBy(x - getScrollX(), y - getScrollY()); } /** * <p>The scroll range of a scroll view is the overall width of all of its * children.</p> */ @Override protected int computeHorizontalScrollRange() { final int count = getChildCount(); final int contentWidth = getWidth() - getPaddingLeft() - getPaddingRight(); if (count == 0) { return contentWidth; } int scrollRange = getChildAt(0).getRight(); final int scrollX = getScrollX(); final int overscrollRight = Math.max(0, scrollRange - contentWidth); if (scrollX < 0) { scrollRange -= scrollX; } else if (scrollX > overscrollRight) { scrollRange += scrollX - overscrollRight; } return scrollRange; } /** * <p>The scroll range of a scroll view is the overall height of all of its * children.</p> */ @Override protected int computeVerticalScrollRange() { final int count = getChildCount(); final int contentHeight = getHeight() - getPaddingTop() - getPaddingBottom(); if (count == 0) { return contentHeight; } int scrollRange = getChildAt(0).getBottom(); final int scrollY = getScrollY(); final int overscrollBottom = Math.max(0, scrollRange - contentHeight); if (scrollY < 0) { scrollRange -= scrollY; } else if (scrollY > overscrollBottom) { scrollRange += scrollY - overscrollBottom; } return scrollRange; } @Override protected void measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec) { ViewGroup.LayoutParams lp = child.getLayoutParams(); int childWidthMeasureSpec; int childHeightMeasureSpec; childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); child.measure(childWidthMeasureSpec, childHeightMeasureSpec); } @Override protected void measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed, int parentHeightMeasureSpec, int heightUsed) { final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams(); final int childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(lp.topMargin + lp.bottomMargin, MeasureSpec.UNSPECIFIED); final int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(lp.leftMargin + lp.rightMargin, MeasureSpec.UNSPECIFIED); child.measure(childWidthMeasureSpec, childHeightMeasureSpec); } @Override public void computeScroll() { if (mScroller.computeScrollOffset()) { // This is called at drawing time by ViewGroup. We don't want to // re-show the scrollbars at this point, which scrollTo will do, // so we replicate most of scrollTo here. // // It's a little odd to call onScrollChanged from inside the drawing. // // It is, except when you remember that computeScroll() is used to // animate scrolling. So unless we want to defer the onScrollChanged() // until the end of the animated scrolling, we don't really have a // choice here. // // I agree. The alternative, which I think would be worse, is to post // something and tell the subclasses later. This is bad because there // will be a window where mScrollX/Y is different from what the app // thinks it is. // int oldX = getScrollX(); int oldY = getScrollY(); int x = mScroller.getCurrX(); int y = mScroller.getCurrY(); if (oldX != x || oldY != y) { final int horizontalRange = getHorizontalScrollRange(); final int verticalRange = getVerticalScrollRange(); final int overscrollMode = getOverScrollMode(); final boolean canOverscroll = overscrollMode == OVER_SCROLL_ALWAYS || (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && (horizontalRange > 0 || verticalRange > 0)); overScrollBy(x - oldX, y - oldY, oldX, oldY, horizontalRange, verticalRange, mOverflingDistance, 0, false); onScrollChanged(getScrollX(), getScrollY(), oldX, oldY); if (canOverscroll) { if (x < 0 && oldX >= 0) { mEdgeGlowLeft.onAbsorb((int) mScroller.getCurrVelocity()); } else if (x > horizontalRange && oldX <= horizontalRange) { mEdgeGlowRight.onAbsorb((int) mScroller.getCurrVelocity()); } if (y < 0 && oldY >= 0) { mEdgeGlowTop.onAbsorb((int) mScroller.getCurrVelocity()); } else if (y > verticalRange && oldY <= verticalRange) { mEdgeGlowBottom.onAbsorb((int) mScroller.getCurrVelocity()); } } } if (!awakenScrollBars()) { ViewCompat.postInvalidateOnAnimation(this); } } } /** * Scrolls the view to the given child. * * @param child the View to scroll to */ private void scrollToChild(View child) { child.getDrawingRect(mTempRect); /* Offset from child's local coordinates to ScrollView coordinates */ offsetDescendantRectToMyCoords(child, mTempRect); int scrollXDelta = computeScrollXDeltaToGetChildRectOnScreen(mTempRect); int scrollYDelta = computeScrollYDeltaToGetChildRectOnScreen(mTempRect); if (scrollXDelta != 0 && scrollYDelta != 0) { scrollBy(scrollXDelta, scrollYDelta); } } /** * If rect is off screen, scroll just enough to get it (or at least the * first screen size chunk of it) on screen. * * @param rect The rectangle. * @param immediate True to scroll immediately without animation * @return true if scrolling was performed */ private boolean scrollToChildRect(Rect rect, boolean immediate) { final int deltaX = computeScrollXDeltaToGetChildRectOnScreen(rect); final int deltaY = computeScrollYDeltaToGetChildRectOnScreen(rect); final boolean scroll = deltaX != 0 && deltaY != 0; if (scroll) { if (immediate) { scrollBy(deltaX, deltaY); } else { smoothScrollBy(deltaX, deltaY); } } return scroll; } /** * Compute the amount to scroll in the X direction in order to get * a rectangle completely on the screen (or, if taller than the screen, * at least the first screen size chunk of it). * * @param rect The rect. * @return The scroll delta. */ protected int computeScrollXDeltaToGetChildRectOnScreen(Rect rect) { if (getChildCount() == 0) return 0; int width = getWidth(); int screenLeft = getScrollX(); int screenRight = screenLeft + width; int fadingEdge = getHorizontalFadingEdgeLength(); // leave room for left fading edge as long as rect isn't at very left if (rect.left > 0) { screenLeft += fadingEdge; } // leave room for right fading edge as long as rect isn't at very right if (rect.right < getChildAt(0).getWidth()) { screenRight -= fadingEdge; } int scrollXDelta = 0; if (rect.right > screenRight && rect.left > screenLeft) { // need to move right to get it in view: move right just enough so // that the entire rectangle is in view (or at least the first // screen size chunk). if (rect.width() > width) { // just enough to get screen size chunk on scrollXDelta += (rect.left - screenLeft); } else { // get entire rect at right of screen scrollXDelta += (rect.right - screenRight); } // make sure we aren't scrolling beyond the end of our content int right = getChildAt(0).getRight(); int distanceToRight = right - screenRight; scrollXDelta = Math.min(scrollXDelta, distanceToRight); } else if (rect.left < screenLeft && rect.right < screenRight) { // need to move right to get it in view: move right just enough so that // entire rectangle is in view (or at least the first screen // size chunk of it). if (rect.width() > width) { // screen size chunk scrollXDelta -= (screenRight - rect.right); } else { // entire rect at left scrollXDelta -= (screenLeft - rect.left); } // make sure we aren't scrolling any further than the left our content scrollXDelta = Math.max(scrollXDelta, -getScrollX()); } return scrollXDelta; } /** * Compute the amount to scroll in the Y direction in order to get * a rectangle completely on the screen (or, if taller than the screen, * at least the first screen size chunk of it). * * @param rect The rect. * @return The scroll delta. */ protected int computeScrollYDeltaToGetChildRectOnScreen(Rect rect) { if (getChildCount() == 0) return 0; int height = getHeight(); int screenTop = getScrollY(); int screenBottom = screenTop + height; int fadingEdge = getVerticalFadingEdgeLength(); // leave room for top fading edge as long as rect isn't at very top if (rect.top > 0) { screenTop += fadingEdge; } // leave room for bottom fading edge as long as rect isn't at very bottom if (rect.bottom < getChildAt(0).getHeight()) { screenBottom -= fadingEdge; } int scrollYDelta = 0; if (rect.bottom > screenBottom && rect.top > screenTop) { // need to move down to get it in view: move down just enough so // that the entire rectangle is in view (or at least the first // screen size chunk). if (rect.height() > height) { // just enough to get screen size chunk on scrollYDelta += (rect.top - screenTop); } else { // get entire rect at bottom of screen scrollYDelta += (rect.bottom - screenBottom); } // make sure we aren't scrolling beyond the end of our content int bottom = getChildAt(0).getBottom(); int distanceToBottom = bottom - screenBottom; scrollYDelta = Math.min(scrollYDelta, distanceToBottom); } else if (rect.top < screenTop && rect.bottom < screenBottom) { // need to move up to get it in view: move up just enough so that // entire rectangle is in view (or at least the first screen // size chunk of it). if (rect.height() > height) { // screen size chunk scrollYDelta -= (screenBottom - rect.bottom); } else { // entire rect at top scrollYDelta -= (screenTop - rect.top); } // make sure we aren't scrolling any further than the top our content scrollYDelta = Math.max(scrollYDelta, -getScrollY()); } return scrollYDelta; } @Override public void requestChildFocus(View child, View focused) { if (!mIsLayoutDirty) { scrollToChild(focused); } else { // The child may not be laid out yet, we can't compute the scroll yet mChildToScrollTo = focused; } super.requestChildFocus(child, focused); } /** * When looking for focus in children of a scroll view, need to be a little * more careful not to give focus to something that is scrolled off screen. * * This is more expensive than the default {@link android.view.ViewGroup} * implementation, otherwise this behavior might have been made the default. */ @Override protected boolean onRequestFocusInDescendants(int direction, Rect previouslyFocusedRect) { // convert from forward / backward notation to up / down / left / right // (ugh). if (direction == View.FOCUS_FORWARD) { direction = View.FOCUS_RIGHT; } else if (direction == View.FOCUS_BACKWARD) { direction = View.FOCUS_LEFT; } final View nextFocus = previouslyFocusedRect == null ? FocusFinder.getInstance().findNextFocus(this, null, direction) : FocusFinder.getInstance().findNextFocusFromRect(this, previouslyFocusedRect, direction); if (nextFocus == null) { return false; } if (isOffScreen(nextFocus)) { return false; } return nextFocus.requestFocus(direction, previouslyFocusedRect); } @Override public boolean requestChildRectangleOnScreen(View child, Rect rectangle, boolean immediate) { // offset into coordinate space of this scroll view rectangle.offset(child.getLeft() - child.getScrollX(), child.getTop() - child.getScrollY()); return scrollToChildRect(rectangle, immediate); } @Override public void requestLayout() { mIsLayoutDirty = true; super.requestLayout(); } @Override protected void onAttachedToWindow() { super.onAttachedToWindow(); mLaidOut = false; } @Override protected void onDetachedFromWindow() { super.onDetachedFromWindow(); mLaidOut = false; } @Override protected void onLayout(boolean changed, int l, int t, int r, int b) { super.onLayout(changed, l, t, r, b); mIsLayoutDirty = false; // Give a child focus if it needs it if (mChildToScrollTo != null && isViewDescendantOf(mChildToScrollTo, this)) { scrollToChild(mChildToScrollTo); } mChildToScrollTo = null; if (!mLaidOut) { int scrollX = 0; int scrollY = 0; if (mSavedState != null) { scrollX = mSavedState.getInt(KEY_SCROLL_X, 0); scrollY = mSavedState.getInt(KEY_SCROLL_Y, 0); mSavedState = null; } // scrollX and scrollY default value is "0" final int childWidth = (getChildCount() > 0) ? getChildAt(0).getMeasuredWidth() : 0; final int childHeight = (getChildCount() > 0) ? getChildAt(0).getMeasuredHeight() : 0; final int scrollRangeX = Math.max(0, childWidth - (r - l - getPaddingLeft() - getPaddingRight())); final int scrollRangeY = Math.max(0, childHeight - (b - t - getPaddingTop() - getPaddingBottom())); // Don't forget to clamp if (scrollX > scrollRangeX) { scrollX = scrollRangeX; } else if (scrollX < 0) { scrollX = 0; } if (scrollY > scrollRangeY) { scrollY = scrollRangeY; } else if (scrollX < 0) { scrollY = 0; } // Calling this with the present values causes it to re-claim them scrollTo(scrollX, scrollY); } mLaidOut = true; } @Override protected void onSizeChanged(int w, int h, int oldw, int oldh) { super.onSizeChanged(w, h, oldw, oldh); View currentFocused = findFocus(); if (null == currentFocused || this == currentFocused) return; final int maxJump = getRight() - getLeft(); if (isWithinDeltaOfScreen(currentFocused, maxJump, w, h)) { currentFocused.getDrawingRect(mTempRect); offsetDescendantRectToMyCoords(currentFocused, mTempRect); int scrollXDelta = computeScrollXDeltaToGetChildRectOnScreen(mTempRect); int scrollYDelta = computeScrollYDeltaToGetChildRectOnScreen(mTempRect); doScrollX(scrollXDelta); doScrollY(scrollYDelta); } } /** * Return true if child is a descendant of parent, (or equal to the parent). */ private static boolean isViewDescendantOf(View child, View parent) { if (child == parent) { return true; } final ViewParent theParent = child.getParent(); return (theParent instanceof ViewGroup) && isViewDescendantOf((View) theParent, parent); } /** * Fling the scroll view * * @param velocityX The initial velocity in the X direction. Positive * numbers mean that the finger/cursor is moving down the screen, * which means we want to scroll towards the left. * @param velocityY The initial velocity in the Y direction. Positive * numbers mean that the finger/cursor is moving down the screen, * which means we want to scroll towards the top. */ public void fling(int velocityX, int velocityY) { if (getChildCount() > 0) { int width = getWidth() - getPaddingLeft() - getPaddingRight(); int height = getHeight() - getPaddingTop() - getPaddingBottom(); int right = getChildAt(0).getWidth(); int bottom = getChildAt(0).getHeight(); mScroller.fling(getScrollX(), getScrollY(), velocityX, velocityY, 0, Math.max(0, right - width), 0, Math.max(0, bottom - height), width / 2, height / 2); ViewCompat.postInvalidateOnAnimation(this); } } private void endDrag() { mIsBeingDragged = false; recycleVelocityTracker(); if (mEdgeGlowLeft != null) { mEdgeGlowLeft.onRelease(); mEdgeGlowRight.onRelease(); mEdgeGlowTop.onRelease(); mEdgeGlowBottom.onRelease(); } } /** * {@inheritDoc} * * <p>This version also clamps the scrolling to the bounds of our child. */ @Override public void scrollTo(int x, int y) { // we rely on the fact the View.scrollBy calls scrollTo. if (getChildCount() > 0) { View child = getChildAt(0); x = clamp(x, getWidth() - getPaddingLeft() - getPaddingRight(), child.getWidth()); y = clamp(y, getHeight() - getPaddingTop() - getPaddingBottom(), child.getHeight()); if (x != getScrollX() || y != getScrollY()) { super.scrollTo(x, y); } } } @Override public void setOverScrollMode(int mode) { if (mode != OVER_SCROLL_NEVER) { if (mEdgeGlowLeft == null) { Context context = getContext(); mEdgeGlowLeft = new EdgeEffect(context); mEdgeGlowRight = new EdgeEffect(context); mEdgeGlowTop = new EdgeEffect(context); mEdgeGlowBottom = new EdgeEffect(context); } } else { mEdgeGlowLeft = null; mEdgeGlowRight = null; mEdgeGlowTop = null; mEdgeGlowBottom = null; } super.setOverScrollMode(mode); } @SuppressWarnings("SuspiciousNameCombination") @Override public void draw(Canvas canvas) { super.draw(canvas); if (mEdgeGlowLeft != null) { final int scrollX = getScrollX(); final int scrollY = getScrollY(); final int width = getWidth(); final int height = getHeight(); if (!mEdgeGlowLeft.isFinished()) { final int restoreCount = canvas.save(); canvas.rotate(270); canvas.translate(-height - scrollY, Math.min(0, scrollX)); mEdgeGlowLeft.setSize(height, width); if (mEdgeGlowLeft.draw(canvas)) { ViewCompat.postInvalidateOnAnimation(this); } canvas.restoreToCount(restoreCount); } if (!mEdgeGlowRight.isFinished()) { final int restoreCount = canvas.save(); canvas.rotate(90); canvas.translate(scrollY, -(Math.max(getHorizontalScrollRange(), scrollX) + width)); mEdgeGlowRight.setSize(height, width); if (mEdgeGlowRight.draw(canvas)) { ViewCompat.postInvalidateOnAnimation(this); } canvas.restoreToCount(restoreCount); } if (!mEdgeGlowTop.isFinished()) { final int restoreCount = canvas.save(); canvas.translate(scrollX, Math.min(0, scrollY)); mEdgeGlowTop.setSize(width, height); if (mEdgeGlowTop.draw(canvas)) { ViewCompat.postInvalidateOnAnimation(this); } canvas.restoreToCount(restoreCount); } if (!mEdgeGlowBottom.isFinished()) { final int restoreCount = canvas.save(); canvas.translate(-width + scrollX, Math.max(getVerticalScrollRange(), scrollY) + height); canvas.rotate(180, width, 0); mEdgeGlowBottom.setSize(width, height); if (mEdgeGlowBottom.draw(canvas)) { ViewCompat.postInvalidateOnAnimation(this); } canvas.restoreToCount(restoreCount); } } } @Override protected void onRestoreInstanceState(Parcelable state) { if (getContext().getApplicationInfo().targetSdkVersion <= Build.VERSION_CODES.JELLY_BEAN_MR2) { // Some old apps reused IDs in ways they shouldn't have. // Don't break them, but they don't get scroll state restoration. super.onRestoreInstanceState(state); return; } Bundle saved = (Bundle) state; super.onRestoreInstanceState(saved.getParcelable(KEY_SUPER)); mSavedState = saved; requestLayout(); } @Override protected Parcelable onSaveInstanceState() { if (getContext().getApplicationInfo().targetSdkVersion <= Build.VERSION_CODES.JELLY_BEAN_MR2) { // Some old apps reused IDs in ways they shouldn't have. // Don't break them, but they don't get scroll state restoration. return super.onSaveInstanceState(); } Bundle saved = new Bundle(); saved.putParcelable(KEY_SUPER, super.onSaveInstanceState()); saved.putInt(KEY_SCROLL_X, getScrollX()); saved.putInt(KEY_SCROLL_X, getScrollY()); return saved; } private static int clamp(int n, int my, int child) { if (my >= child || n < 0) { return 0; } if ((my + n) > child) { return child - my; } return n; } }