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package net.comfreeze.lib.views; // ww w.j ava 2 s . com import android.content.Context; import android.util.AttributeSet; import android.view.MotionEvent; import android.view.VelocityTracker; import android.view.View; import android.view.ViewConfiguration; import android.view.ViewGroup; import android.view.animation.AnimationUtils; import android.widget.FrameLayout; import android.widget.LinearLayout; import android.widget.Scroller; import android.widget.TextView; /** * Layout container for a view hierarchy that can be scrolled by the user, * allowing it to be larger than the physical display. A BiScrollView * is a {@link FrameLayout}, meaning you should place one child in it * containing the entire contents to scroll; this child may itself be a layout * manager with a complex hierarchy of objects. A child that is often used * is a {@link LinearLayout} in a vertical orientation, presenting a vertical * array of top-level items that the user can scroll through. * <p/> * <p>The {@link TextView} class also * takes care of its own scrolling, so does not require a BiScrollView, but * using the two together is possible to achieve the effect of a text view * within a larger container. * <p/> * <p>BiScrollView only supports vertical scrolling. */ public class BiScrollView extends FrameLayout { static final int ANIMATED_SCROLL_GAP = 250; static final float MAX_SCROLL_FACTOR = 0.5f; private long mLastScroll; private Scroller mScroller; /** * Position of the last motion event. */ private float mLastMotionY; private float mLastMotionX; /** * True if the user is currently dragging this BiScrollView 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; /** * Whether arrow scrolling is animated. */ private int mTouchSlop; private int mMinimumVelocity; //private int mMaximumVelocity; public BiScrollView(Context context) { super(context); initBiScrollView(); } public BiScrollView(Context context, AttributeSet attrs) { super(context, attrs); initBiScrollView(); } public BiScrollView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); initBiScrollView(); } @Override protected float getTopFadingEdgeStrength() { if (getChildCount() == 0) { return 0.0f; } final int length = getVerticalFadingEdgeLength(); if (getScrollY() < length) { return getScrollY() / (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; } @Override protected float getLeftFadingEdgeStrength() { if (getChildCount() == 0) { return 0.0f; } final int length = getHorizontalFadingEdgeLength(); if (getScrollX() < length) { return getScrollX() / (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; } private void initBiScrollView() { mScroller = new Scroller(getContext()); setFocusable(true); setDescendantFocusability(FOCUS_AFTER_DESCENDANTS); setWillNotDraw(false); final ViewConfiguration configuration = ViewConfiguration.get(getContext()); mTouchSlop = configuration.getScaledTouchSlop(); mMinimumVelocity = configuration.getScaledMinimumFlingVelocity(); //mMaximumVelocity = mMinimumVelocity * 5;//configuration.getScaledMaximumFlingVelocity(); } @Override public void addView(View child) { if (getChildCount() > 0) { throw new IllegalStateException("BiScrollView can host only one direct child"); } super.addView(child); } @Override public void addView(View child, int index) { if (getChildCount() > 0) { throw new IllegalStateException("BiScrollView 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("BiScrollView 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("BiScrollView can host only one direct child"); } super.addView(child, index, params); } /** * @return Returns true this BiScrollView can be scrolled */ private boolean canScroll() { View child = getChildAt(0); if (child != null) { int childHeight = child.getHeight(); int childWidth = child.getWidth(); return (getHeight() < childHeight + getPaddingTop() + getPaddingBottom()) || (getWidth() < childWidth + getPaddingLeft() + getPaddingRight()); } return false; } @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; } if (!canScroll()) { mIsBeingDragged = false; return false; } final float y = ev.getY(); final float x = ev.getX(); switch (action) { 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 yDiff = (int) Math.abs(y - mLastMotionY); final int xDiff = (int) Math.abs(x - mLastMotionX); if (yDiff > mTouchSlop || xDiff > mTouchSlop) { mIsBeingDragged = true; } break; case MotionEvent.ACTION_DOWN: /* Remember location of down touch */ mLastMotionY = y; mLastMotionX = x; /* * 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; 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) { if (ev.getAction() == MotionEvent.ACTION_DOWN && ev.getEdgeFlags() != 0) { // Don't handle edge touches immediately -- they may actually belong to one of our // descendants. return false; } if (!canScroll()) { return false; } if (mVelocityTracker == null) { mVelocityTracker = VelocityTracker.obtain(); } mVelocityTracker.addMovement(ev); final int action = ev.getAction(); final float y = ev.getY(); final float x = ev.getX(); switch (action) { case MotionEvent.ACTION_DOWN: /* * 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 mLastMotionY = y; mLastMotionX = x; break; case MotionEvent.ACTION_MOVE: // Scroll to follow the motion event int deltaX = (int) (mLastMotionX - x); int deltaY = (int) (mLastMotionY - y); mLastMotionX = x; mLastMotionY = y; if (deltaX < 0) { if (getScrollX() < 0) { deltaX = 0; } } else if (deltaX > 0) { final int rightEdge = getWidth() - getPaddingRight(); final int availableToScroll = getChildAt(0).getRight() - getScrollX() - rightEdge; if (availableToScroll > 0) { deltaX = Math.min(availableToScroll, deltaX); } else { deltaX = 0; } } if (deltaY < 0) { if (getScrollY() < 0) { deltaY = 0; } } else if (deltaY > 0) { final int bottomEdge = getHeight() - getPaddingBottom(); final int availableToScroll = getChildAt(0).getBottom() - getScrollY() - bottomEdge; if (availableToScroll > 0) { deltaY = Math.min(availableToScroll, deltaY); } else { deltaY = 0; } } if (deltaY != 0 || deltaX != 0) scrollBy(deltaX, deltaY); break; case MotionEvent.ACTION_UP: final VelocityTracker velocityTracker = mVelocityTracker; velocityTracker.computeCurrentVelocity(1000); //velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); int initialXVelocity = (int) velocityTracker.getXVelocity(); int initialYVelocity = (int) velocityTracker.getYVelocity(); if ((Math.abs(initialXVelocity) + Math.abs(initialYVelocity) > mMinimumVelocity) && getChildCount() > 0) { fling(-initialXVelocity, -initialYVelocity); } if (mVelocityTracker != null) { mVelocityTracker.recycle(); mVelocityTracker = null; } } return true; } /** * <p>Handles scrolling in response to a "home/end" shortcut press.</p> * * @param direction the scroll direction: {@link android.view.View#FOCUS_UP} * to go the top of the view or * {@link android.view.View#FOCUS_DOWN} to go the bottom * @return true if the key event is consumed by this method, false otherwise */ public boolean fullScroll(int direction_vert, int direction_horz) { int scrollAmountY = 0, scrollAmountX = 0; // vertical switch (direction_vert) { case View.FOCUS_UP: scrollAmountY = -getScrollY(); break; case View.FOCUS_DOWN: int count = getChildCount(); if (count > 0) { View view = getChildAt(count - 1); scrollAmountY = (view.getBottom() - getHeight()) - getScrollY(); } break; } // horizontal switch (direction_horz) { case View.FOCUS_LEFT: scrollAmountX = -getScrollX(); break; case View.FOCUS_RIGHT: int count = getChildCount(); if (count > 0) { View view = getChildAt(count - 1); scrollAmountX = (view.getRight() - getWidth()) - getScrollX(); } break; } boolean handled = (scrollAmountX != 0) || (scrollAmountY != 0); if (handled) doScroll(scrollAmountX, scrollAmountY); return handled; } /** * Smooth scroll by a Y delta * * @param delta the number of pixels to scroll by on the Y axis */ private void doScroll(int deltaX, int deltaY) { if (deltaX != 0 || deltaY != 0) { smoothScrollBy(deltaX, deltaY); } } /** * 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) { long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll; if (duration > ANIMATED_SCROLL_GAP) { mScroller.startScroll(getScrollX(), getScrollY(), dx, dy); //awakenScrollBars(mScroller.getDuration()); invalidate(); } 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 height of all of its * children.</p> */ @Override protected int computeVerticalScrollRange() { int count = getChildCount(); return count == 0 ? getHeight() : (getChildAt(0)).getBottom(); } @Override protected int computeHorizontalScrollRange() { int count = getChildCount(); return count == 0 ? getWidth() : (getChildAt(0)).getRight(); } @Override protected void measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec) { ViewGroup.LayoutParams lp = child.getLayoutParams(); int childWidthMeasureSpec; int childHeightMeasureSpec; childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec, getPaddingLeft() + getPaddingRight(), lp.width); childHeightMeasureSpec = 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 childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec, getPaddingLeft() + getPaddingRight() + lp.leftMargin + lp.rightMargin + widthUsed, lp.width); final int childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(lp.topMargin + lp.bottomMargin, 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 (getChildCount() > 0) { View child = getChildAt(0); scrollTo(clamp(x, getWidth() - getPaddingRight() - getPaddingLeft(), child.getWidth()), clamp(y, getHeight() - getPaddingBottom() - getPaddingTop(), child.getHeight())); } else { scrollTo(x, y); } if (oldX != getScrollX() || oldY != getScrollY()) { onScrollChanged(getScrollX(), getScrollY(), oldX, oldY); } // Keep on drawing until the animation has finished. postInvalidate(); } } @Override protected void onLayout(boolean changed, int l, int t, int r, int b) { super.onLayout(changed, l, t, r, b); // Calling this with the present values causes it to re-clam them scrollTo(getScrollX(), getScrollY()); } /** * Fling the scroll view * * @param velocityY The initial velocity in the Y direction. Positive * numbers mean that the finger/curor 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 height = getHeight() - getPaddingBottom() - getPaddingTop(); int bottom = getChildAt(0).getHeight(); int width = getWidth() - getPaddingRight() - getPaddingLeft(); int right = getChildAt(0).getWidth(); mScroller.fling(getScrollX(), getScrollY(), velocityX, velocityY, 0, right - width, 0, bottom - height); //awakenScrollBars(mScroller.getDuration()); invalidate(); } } /** * {@inheritDoc} * <p/> * <p>This version also clamps the scrolling to the bounds of our child. */ 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() - getPaddingRight() - getPaddingLeft(), child.getWidth()); y = clamp(y, getHeight() - getPaddingBottom() - getPaddingTop(), child.getHeight()); if (x != getScrollX() || y != getScrollY()) { super.scrollTo(x, y); } } } private int clamp(int n, int my, int child) { if (my >= child || n < 0) { /* my >= child is this case: * |--------------- me ---------------| * |------ child ------| * or * |--------------- me ---------------| * |------ child ------| * or * |--------------- me ---------------| * |------ child ------| * * n < 0 is this case: * |------ me ------| * |-------- child --------| * |-- mScrollX --| */ return 0; } if ((my + n) > child) { /* this case: * |------ me ------| * |------ child ------| * |-- mScrollX --| */ return child - my; } return n; } }