Java tutorial
/* * Copyright (C) 2013 The Android Open Source Project * * 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.linsq.androiddemo.refresh2; import android.content.Context; import android.content.res.Resources; import android.content.res.TypedArray; import android.graphics.Canvas; import android.support.v4.view.MotionEventCompat; import android.support.v4.view.ViewCompat; import android.util.AttributeSet; import android.util.DisplayMetrics; import android.view.MotionEvent; import android.view.View; import android.view.ViewConfiguration; import android.view.ViewGroup; import android.view.animation.AccelerateInterpolator; import android.view.animation.Animation; import android.view.animation.Animation.AnimationListener; import android.view.animation.DecelerateInterpolator; import android.view.animation.Transformation; import android.widget.AbsListView; import com.linsq.androiddemo.util.Logger; /** * The SwipeRefreshLayout should be used whenever the user can refresh the * contents of a view via a vertical swipe gesture. The activity that * instantiates this view should add an OnRefreshListener to be notified * whenever the swipe to refresh gesture is completed. The SwipeRefreshLayout * will notify the listener each and every time the gesture is completed again; * the listener is responsible for correctly determining when to actually * initiate a refresh of its content. If the listener determines there should * not be a refresh, it must call setRefreshing(false) to cancel any visual * indication of a refresh. If an activity wishes to show just the progress * animation, it should call setRefreshing(true). To disable the gesture and * progress animation, call setEnabled(false) on the view. * * <p> * This layout should be made the parent of the view that will be refreshed as a * result of the gesture and can only support one direct child. This view will * also be made the target of the gesture and will be forced to match both the * width and the height supplied in this layout. The SwipeRefreshLayout does not * provide accessibility events; instead, a menu item must be provided to allow * refresh of the content wherever this gesture is used. * </p> */ public class SwipeRefreshLayout extends ViewGroup { private static final String Logger_TAG = SwipeRefreshLayout.class.getSimpleName(); private static final long RETURN_TO_ORIGINAL_POSITION_TIMEOUT = 300;// ? private static final float MAX_SWIPE_DISTANCE_FACTOR = .6f;// view?120dpmDistanceToTriggerSync=view0.6? private static final int REFRESH_TRIGGER_DISTANCE = 200;// view120dpmDistanceToTriggerSync=120dp private float mDistanceToTriggerSync = -1;// ?? // private static final int INVALID_POINTER = -1; private View mTarget; // ?viewViewGroup???View private int mOriginalOffsetTop;// ??view?=mTarget.getTop+viewgorup.paddingTop. private int mCurrentTargetOffsetTop;// ?view??=mTarget.getTop // private OnRefreshListener mListener;// private boolean mRefreshing = false;// ?? private int mTouchSlop;// ?? // private boolean mReturningToStart;// ? private final DecelerateInterpolator mDecelerateInterpolator;// ?- private final AccelerateInterpolator mAccelerateInterpolator;// ?-- private int mMediumAnimationDuration;// ?view&? // private SwipeProgressBar mProgressBar; private int mProgressBarHeight;// ? private boolean mIsBeingDragged;// ? private static final int[] LAYOUT_ATTRS = new int[] { android.R.attr.enabled }; // ------------------------------------------------------------ private float mFromPercentage = 0;// progressbar private float mCurrPercentage = 0;// ?? // ?view?progressbar private final Runnable mCancel = new Runnable() { @Override public void run() { mReturningToStart = true; if (mProgressBar != null) { // // Logger.e("mCurrPercentage=" + mCurrPercentage); mShrinkTrigger.reset(); mFromPercentage = mCurrPercentage; mShrinkTrigger.setDuration(mMediumAnimationDuration); mShrinkTrigger.setAnimationListener(mShrinkAnimationListener); mShrinkTrigger.setInterpolator(mDecelerateInterpolator); startAnimation(mShrinkTrigger); } animateOffsetToStartPosition(mCurrentTargetOffsetTop + getPaddingTop(), mReturnToStartPositionListener); } }; private Animation mShrinkTrigger = new Animation() { // @Override public void applyTransformation(float interpolatedTime, Transformation t) { float percent = mFromPercentage + ((0 - mFromPercentage) * interpolatedTime); Logger.e("percent=" + percent); mProgressBar.setTriggerPercentage(percent); } }; private final AnimationListener mShrinkAnimationListener = new BaseAnimationListener() { @Override public void onAnimationEnd(Animation animation) { mCurrPercentage = 0; } }; // --------------------------------------------------------------------------------- // ?view?runnable private final Runnable mReturnToStartPosition = new Runnable() { @Override public void run() { mReturningToStart = true; animateOffsetToStartPosition(mCurrentTargetOffsetTop + getPaddingTop(), mReturnToStartPositionListener); } }; // ?view?? private void animateOffsetToStartPosition(int from, AnimationListener listener) { // Logger.e("mFrom=" + mFrom); mFrom = from; mAnimateToStartPosition.reset(); mAnimateToStartPosition.setDuration(mMediumAnimationDuration); mAnimateToStartPosition.setAnimationListener(listener); mAnimateToStartPosition.setInterpolator(mDecelerateInterpolator); mTarget.startAnimation(mAnimateToStartPosition); } private int mFrom;// ?view? // view?? private final Animation mAnimateToStartPosition = new Animation() { @Override public void applyTransformation(float interpolatedTime, Transformation t) { // interpolatedTime0~1? int targetTop = 0; if (mFrom != mOriginalOffsetTop) { targetTop = (mFrom + (int) ((mOriginalOffsetTop - mFrom) * interpolatedTime));// ? } // Logger.e("---------"+mTarget.getTop()+"="+mCurrentTargetOffsetTop); int offset = targetTop - mTarget.getTop();// mCurrentTargetOffsetTop; final int currentTop = mTarget.getTop();// mCurrentTargetOffsetTop if (offset + currentTop < 0) { offset = 0 - currentTop; } setTargetOffsetTopAndBottom(offset); } }; private final AnimationListener mReturnToStartPositionListener = new BaseAnimationListener() { // ? @Override public void onAnimationEnd(Animation animation) { mCurrentTargetOffsetTop = 0; } }; // -------------------------------------------------------------------------- public SwipeRefreshLayout(Context context) { this(context, null); } public SwipeRefreshLayout(Context context, AttributeSet attrs) { super(context, attrs); mTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop(); // mMediumAnimationDuration = getResources().getInteger(android.R.integer.config_mediumAnimTime); setWillNotDraw(false);// view??true??false mProgressBar = new SwipeProgressBar(this); final DisplayMetrics metrics = getResources().getDisplayMetrics(); mProgressBarHeight = (int) (metrics.density * 4);// ? mDecelerateInterpolator = new DecelerateInterpolator(2f); mAccelerateInterpolator = new AccelerateInterpolator(1.5f); final TypedArray a = context.obtainStyledAttributes(attrs, LAYOUT_ATTRS); setEnabled(a.getBoolean(0, true)); a.recycle(); } @Override public void onAttachedToWindow() { super.onAttachedToWindow(); removeCallbacks(mCancel); removeCallbacks(mReturnToStartPosition); } @Override public void onDetachedFromWindow() { super.onDetachedFromWindow(); removeCallbacks(mReturnToStartPosition); removeCallbacks(mCancel); } /** * @deprecated Use {@link #setColorSchemeResources(int, int, int, int)} */ @Deprecated public void setColorScheme(int colorRes1, int colorRes2, int colorRes3, int colorRes4) { setColorSchemeResources(colorRes1, colorRes2, colorRes3, colorRes4); } /** * Set the four colors used in the progress animation from color resources. * The first color will also be the color of the bar that grows in response * to a user swipe gesture. */ public void setColorSchemeResources(int colorRes1, int colorRes2, int colorRes3, int colorRes4) { final Resources res = getResources(); setColorSchemeColors(res.getColor(colorRes1), res.getColor(colorRes2), res.getColor(colorRes3), res.getColor(colorRes4)); } /** * Set the four colors used in the progress animation. The first color will * also be the color of the bar that grows in response to a user swipe * gesture. */ public void setColorSchemeColors(int color1, int color2, int color3, int color4) { ensureTarget(); mProgressBar.setColorScheme(color1, color2, color3, color4); } // ?view? private void ensureTarget() { // ???? if (mTarget == null) { if (getChildCount() > 1 && !isInEditMode()) { // ???View throw new IllegalStateException("SwipeRefreshLayout can host only one direct child"); } mTarget = getChildAt(0); mOriginalOffsetTop = mTarget.getTop() + getPaddingTop(); } if (mDistanceToTriggerSync == -1) { if (getParent() != null && ((View) getParent()).getHeight() > 0) { final DisplayMetrics metrics = getResources().getDisplayMetrics(); mDistanceToTriggerSync = (int) Math.min( ((View) getParent()).getHeight() * MAX_SWIPE_DISTANCE_FACTOR, REFRESH_TRIGGER_DISTANCE * metrics.density); } } } @Override public void draw(Canvas canvas) { super.draw(canvas); mProgressBar.draw(canvas); } @Override protected void onLayout(boolean changed, int left, int top, int right, int bottom) { final int width = getMeasuredWidth(); final int height = getMeasuredHeight(); mProgressBar.setBounds(0, 0, width, mProgressBarHeight); if (getChildCount() == 0) { return; } final View child = getChildAt(0); final int childLeft = getPaddingLeft(); final int childTop = mCurrentTargetOffsetTop + getPaddingTop(); final int childWidth = width - getPaddingLeft() - getPaddingRight(); final int childHeight = height - getPaddingTop() - getPaddingBottom(); child.layout(childLeft, childTop, childLeft + childWidth, childTop + childHeight); } @Override public void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); if (getChildCount() > 1 && !isInEditMode()) { throw new IllegalStateException("SwipeRefreshLayout can host only one direct child"); } if (getChildCount() > 0) { // super???view getChildAt(0).measure( MeasureSpec.makeMeasureSpec(getMeasuredWidth() - getPaddingLeft() - getPaddingRight(), MeasureSpec.EXACTLY), MeasureSpec.makeMeasureSpec(getMeasuredHeight() - getPaddingTop() - getPaddingBottom(), MeasureSpec.EXACTLY)); } } // ?view???? public boolean canChildScrollUp() { if (android.os.Build.VERSION.SDK_INT < 14) { if (mTarget instanceof AbsListView) { final AbsListView absListView = (AbsListView) mTarget; Logger.e("absListView.getChildAt(0).getTop()=" + absListView.getChildAt(0).getTop()); return absListView.getChildCount() > 0 && (absListView.getFirstVisiblePosition() > 0 || absListView.getChildAt(0).getTop() < absListView.getPaddingTop()); } else { return mTarget.getScrollY() > 0; } } else { return ViewCompat.canScrollVertically(mTarget, -1); } } private float mLastMotionY;// ?y??? private float mInitialMotionY;// downy??? private int mActivePointerId = INVALID_POINTER;// Action_DOWND @Override public boolean onInterceptTouchEvent(MotionEvent ev) { ensureTarget(); final int action = MotionEventCompat.getActionMasked(ev);// if (mReturningToStart && action == MotionEvent.ACTION_DOWN) { // ???? mReturningToStart = false; } if (!isEnabled() || mReturningToStart || canChildScrollUp()) { // viewGroup????view??? // ?view return false; } // switch (action) { case MotionEvent.ACTION_DOWN: mLastMotionY = mInitialMotionY = ev.getY(); mActivePointerId = MotionEventCompat.getPointerId(ev, 0);// Action_DOWND mIsBeingDragged = false; mCurrPercentage = 0; break; // ---------------------------------------------------- case MotionEvent.ACTION_MOVE: if (mActivePointerId == INVALID_POINTER) { // Logger.e("Got ACTION_MOVE event but don't have an active pointer id."); return false; } final int pointerIndex = MotionEventCompat.findPointerIndex(ev, mActivePointerId); if (pointerIndex < 0) { // ??? Logger.e("Got ACTION_MOVE event but have an invalid active pointer id."); return false; } final float y = MotionEventCompat.getY(ev, pointerIndex); final float yDiff = y - mInitialMotionY;// y? if (yDiff > mTouchSlop) {// mLastMotionY = y; mIsBeingDragged = true; } break; case MotionEventCompat.ACTION_POINTER_UP: onSecondaryPointerUp(ev);// ? break; case MotionEvent.ACTION_UP: case MotionEvent.ACTION_CANCEL: mIsBeingDragged = false; mCurrPercentage = 0; mActivePointerId = INVALID_POINTER; break; } // true?onTouchEventmoveup? // false?view?moveup? return mIsBeingDragged; } @Override public boolean onTouchEvent(MotionEvent ev) { final int action = MotionEventCompat.getActionMasked(ev);// ? if (mReturningToStart && action == MotionEvent.ACTION_DOWN) { // ??? mReturningToStart = false; } if (!isEnabled() || mReturningToStart || canChildScrollUp()) { // viewGroup????view?? // view return false; } switch (action) { case MotionEvent.ACTION_DOWN: mLastMotionY = mInitialMotionY = ev.getY(); mActivePointerId = MotionEventCompat.getPointerId(ev, 0); mIsBeingDragged = false; mCurrPercentage = 0; break; case MotionEvent.ACTION_MOVE: final int pointerIndex = MotionEventCompat.findPointerIndex(ev, mActivePointerId); if (pointerIndex < 0) { // ??? Logger.e("Got ACTION_MOVE event but have an invalid active pointer id."); return false; } final float y = MotionEventCompat.getY(ev, pointerIndex); final float yDiff = y - mInitialMotionY;// down?? if (!mIsBeingDragged && yDiff > mTouchSlop) { mIsBeingDragged = true; } if (mIsBeingDragged) { if (yDiff > mDistanceToTriggerSync) { // ????starRefresh startRefresh(); } else { // ???? // ? setTriggerPercentage(mAccelerateInterpolator.getInterpolation(yDiff / mDistanceToTriggerSync)); updateContentOffsetTop((int) (yDiff));// view?? if (mLastMotionY > y && mTarget.getTop() == getPaddingTop()) { // ????? removeCallbacks(mCancel); } else { updatePositionTimeout(); } } mLastMotionY = y; } break; case MotionEventCompat.ACTION_POINTER_DOWN: {// ???? final int index = MotionEventCompat.getActionIndex(ev); mLastMotionY = MotionEventCompat.getY(ev, index); mActivePointerId = MotionEventCompat.getPointerId(ev, index); break; } case MotionEventCompat.ACTION_POINTER_UP: onSecondaryPointerUp(ev);// ? break; case MotionEvent.ACTION_UP: case MotionEvent.ACTION_CANCEL: mIsBeingDragged = false; mActivePointerId = INVALID_POINTER; return false; } return true; } // ? private void onSecondaryPointerUp(MotionEvent ev) { // ?ACTION_UP? final int pointerIndex = MotionEventCompat.getActionIndex(ev);// ???? final int pointerId = MotionEventCompat.getPointerId(ev, pointerIndex);// ???? if (pointerId == mActivePointerId) { // ==ACTION_DOWN? final int newPointerIndex = pointerIndex == 0 ? 1 : 0; mLastMotionY = MotionEventCompat.getY(ev, newPointerIndex); mActivePointerId = MotionEventCompat.getPointerId(ev, newPointerIndex); } } // ? private void setTriggerPercentage(float percent) { if (percent == 0f) { mCurrPercentage = 0; return; } mCurrPercentage = percent; mProgressBar.setTriggerPercentage(percent); } // ?View? private void updateContentOffsetTop(int targetTop) { // targetTopdown?? final int currentTop = mTarget.getTop();// ?view?? if (targetTop > mDistanceToTriggerSync) { // ?? targetTop = (int) mDistanceToTriggerSync; } else if (targetTop < 0) { // 0 targetTop = 0; } setTargetOffsetTopAndBottom(targetTop - currentTop); } // ?viewy? private void setTargetOffsetTopAndBottom(int offset) { // offset?view? mTarget.offsetTopAndBottom(offset); mCurrentTargetOffsetTop = mTarget.getTop(); } // ????viewrunnable? private void startRefresh() { removeCallbacks(mCancel);// ?? mReturnToStartPosition.run();// ?view setRefreshing(true);// ? mListener.onRefresh();// } // ?? public void setRefreshing(boolean refreshing) { if (mRefreshing != refreshing) { ensureTarget();// ?view? mCurrPercentage = 0; mRefreshing = refreshing; if (mRefreshing) { mProgressBar.start(); } else { mProgressBar.stop(); } } } // ????? private void updatePositionTimeout() { removeCallbacks(mCancel); postDelayed(mCancel, RETURN_TO_ORIGINAL_POSITION_TIMEOUT); } public boolean isRefreshing() { return mRefreshing; } @Override public void requestDisallowInterceptTouchEvent(boolean b) { // ?viewGroup // Nope. } public void setOnRefreshListener(OnRefreshListener listener) { mListener = listener; } // ? public interface OnRefreshListener { public void onRefresh(); } // ? private class BaseAnimationListener implements AnimationListener { @Override public void onAnimationStart(Animation animation) { } @Override public void onAnimationEnd(Animation animation) { } @Override public void onAnimationRepeat(Animation animation) { } } }