Java tutorial
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We also recommend that a * file or class name and description of purpose be included on the * same "printed page" as the copyright notice for easier * identification within third-party archives. * * Copyright 2016 Alibaba Group * * 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.taobao.weex.ui.view.listview; import android.content.Context; import android.support.v4.view.GestureDetectorCompat; import android.util.AttributeSet; import android.view.GestureDetector; import android.view.MotionEvent; import android.view.View; import android.view.ViewConfiguration; import android.view.ViewGroup; import android.widget.Scroller; public abstract class BaseBounceView<T extends View> extends ViewGroup { private static final float FRICTION = 2.0f; private static final int DEFAULT_DURATION = 250; private int mTouchSlop; private boolean mIsBeingDragged; private float mLastMotionY; private float mLastMotionX; private Mode mMode; protected Scroller mScroller; private T mView; private IRefreshLayout mRefreshLayout; private IRefreshLayout mLoadMoreLayout; //scrollValue, for scroll padding use, ??? private int mScrollValue = 0; private int mMaxPadding = 0; private GestureDetectorCompat mGestureDetector; private boolean mBounceable = true; enum Mode { PULL_FROM_TOP, PULL_FROM_BOTTOM } public BaseBounceView(Context context) { this(context, null); } public BaseBounceView(Context context, AttributeSet attrs) { super(context, attrs); init(context); } private void init(Context context) { ViewConfiguration config = ViewConfiguration.get(getContext()); mTouchSlop = config.getScaledTouchSlop(); mScroller = new Scroller(context); mView = createBounceView(context); addView(mView, LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT); mRefreshLayout = createBounceHeaderView(context); if (mRefreshLayout != null) { addView(mRefreshLayout.getView(), LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT); } mLoadMoreLayout = createBounceFooterView(context); if (mLoadMoreLayout != null) { addView(mLoadMoreLayout.getView(), LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT); } } public final T getBounceView() { return mView; } @Override public boolean onInterceptTouchEvent(MotionEvent ev) { final int action = ev.getAction(); if (action != MotionEvent.ACTION_DOWN && mIsBeingDragged) { return true; } switch (action) { case MotionEvent.ACTION_DOWN: { mLastMotionY = ev.getRawY(); mLastMotionX = ev.getRawX(); //listview??listview.setPadding()getPaddingTop()scrollValue?? mScrollValue = -getPaddingTop(); break; } case MotionEvent.ACTION_MOVE: { float x = ev.getRawX(); float y = ev.getRawY(); float deltaX = ev.getRawX() - mLastMotionX; float deltaY = ev.getRawY() - mLastMotionY; float degree = Math.abs(deltaY) / Math.abs(deltaX); //Log.v(getClass().getSimpleName(), "onInterceptTouchEvent move"); if (Math.abs(deltaY) > mTouchSlop && degree >= 1.7f && mBounceable) { if (deltaY > 0 && isReadyForPullFromTop()) { mLastMotionX = x; mLastMotionY = y; mIsBeingDragged = true; mMode = Mode.PULL_FROM_TOP; } else if (deltaY < 0 && isReadyForPullFromBottom()) { mLastMotionX = x; mLastMotionY = y; mIsBeingDragged = true; mMode = Mode.PULL_FROM_BOTTOM; } } break; } case MotionEvent.ACTION_CANCEL: case MotionEvent.ACTION_UP: { mIsBeingDragged = false; } } return mIsBeingDragged; } @Override public boolean onTouchEvent(MotionEvent ev) { if (mGestureDetector != null) { mGestureDetector.onTouchEvent(ev); } switch (ev.getAction()) { case MotionEvent.ACTION_DOWN: { if (ev.getEdgeFlags() != 0) { return false; } mLastMotionX = ev.getRawX(); mLastMotionY = ev.getRawY(); mScrollValue = -getPaddingTop(); return mIsBeingDragged; } case MotionEvent.ACTION_MOVE: { if (mIsBeingDragged) { float y = ev.getRawY(); startPull(y); return true; } break; } case MotionEvent.ACTION_CANCEL: case MotionEvent.ACTION_UP: { if (mIsBeingDragged) { this.mScrollValue = -getPaddingTop(); mIsBeingDragged = false; onTouchActionUp(); if (mMaxPadding > 0) { /** * 1.listview?paddingTop?0????0deltaY?paddingTop < 0 * 2.listview??PADDING????PADDINGdeltaY(-PADDING - getPaddingTop()) > 0 * bug: * listview item?2?listview??pull * fix * listview?? */ if (getPaddingTop() > 0/*|| getPaddingTop() < -mMaxPadding*/) { mScrollValue = getPaddingTop() > 0 ? 0 : -mMaxPadding; backToInitPos(getPaddingTop(), getPaddingTop() > 0 ? -getPaddingTop() : (-mMaxPadding - getPaddingTop())); } } else { backToInitPos(getScrollY(), -getScrollY()); } mMode = null; return true; } break; } } return false; } @Override public void computeScroll() { super.computeScroll(); if (mScroller.computeScrollOffset()) { int x = mScroller.getCurrX(); int y = mScroller.getCurrY(); //Helper.logv("compute scroll y:" + y); if (mMaxPadding > 0) { this.mScrollValue = -y;//?scroll.fling() y?PADDING ?0 setPadding(x, y, 0, 0); } else { scrollTo(x, y); } invalidate(); } } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); //Helper.logv("BaseBounceView onMeasure"); View child0 = getChildAt(0); int w = 0; if (child0 != null) { child0.measure(widthMeasureSpec, heightMeasureSpec); w = child0.getMeasuredWidth(); } View child1 = getChildAt(1); if (child1 != null) { LayoutParams lp = child1.getLayoutParams(); child1.measure(MeasureSpec.makeMeasureSpec(w, MeasureSpec.EXACTLY), MeasureSpec .makeMeasureSpec(lp.height, lp.height > 0 ? MeasureSpec.EXACTLY : MeasureSpec.AT_MOST)); } View child2 = getChildAt(2); if (child2 != null) { LayoutParams lp = child2.getLayoutParams(); child2.measure(MeasureSpec.makeMeasureSpec(w, MeasureSpec.EXACTLY), MeasureSpec .makeMeasureSpec(lp.height, lp.height > 0 ? MeasureSpec.EXACTLY : MeasureSpec.AT_MOST)); } } @Override protected void onLayout(boolean changed, int l, int t, int r, int b) { View child0 = getChildAt(0); int paddingLeft, paddingTop, childRight; paddingLeft = getPaddingLeft(); paddingTop = getPaddingTop(); childRight = r - l - getPaddingRight(); if (child0 != null) { child0.layout(paddingLeft, paddingTop, childRight, b - t - paddingTop); } View child1 = getChildAt(1); if (child1 != null) { int h = child1.getMeasuredHeight(); child1.layout(paddingLeft, -h, childRight, 0); } View child2 = getChildAt(2); if (child2 != null) { int h = child2.getMeasuredHeight(); child2.layout(paddingLeft, b, childRight, b + h); } } protected void smoothScroll(int value) { mScroller.startScroll(0, getScrollY(), 0, value); invalidate(); } public void setBounceable(boolean bounceable) { mBounceable = bounceable; } public void setEffectMaxHeight(int padding) { this.mMaxPadding = padding; if (mGestureDetector == null) { mGestureDetector = new GestureDetectorCompat(getContext(), mGestureListener); } } private void startPull(float y) { int scrollValue = 0; final float lastY; lastY = mLastMotionY; switch (mMode) { case PULL_FROM_TOP: { scrollValue = Math.round(Math.min(lastY - y, 0) / FRICTION); break; } case PULL_FROM_BOTTOM: { scrollValue = Math.round(Math.max(lastY - y, 0) / FRICTION); break; } } //Helper.logv("start pull scrollvalue:" + scrollValue + ", y:" + y + ", allScroll:" + (this.mScrollValue + scrollValue)); pullScrollTo(this.mScrollValue + scrollValue); } private void pullScrollTo(int scrollValue) { int maxScroll = getMaximumPullScroll(); scrollValue = Math.min(maxScroll, Math.max(-maxScroll, scrollValue)); //scrollTo(0, scrollValue); if (mMaxPadding > 0) { setPadding(0, -scrollValue <= -mMaxPadding ? -mMaxPadding : -scrollValue, 0, 0); } else { scrollTo(0, scrollValue); } onPull(scrollValue); } private void onPull(int scrollValue) { IRefreshLayout pullLayout = null; switch (mMode) { case PULL_FROM_TOP: pullLayout = mRefreshLayout; break; case PULL_FROM_BOTTOM: pullLayout = mLoadMoreLayout; break; } if ((mMode == Mode.PULL_FROM_TOP || mMode == Mode.PULL_FROM_BOTTOM) && pullLayout != null) { final int itemDimension = pullLayout.getView().getHeight(); float scaleOfLayout = Math.abs(scrollValue) / (float) itemDimension; float angle = scaleOfLayout * 90f; pullLayout.onPull(angle); onPullStateChanged(itemDimension, scrollValue); } } private void backToInitPos(int startY, int deltaY) { int duration = DEFAULT_DURATION; if (mRefreshLayout != null) { int scrollLen = Math.abs(getScrollY()); int limit = mRefreshLayout.getView().getHeight(); if (scrollLen < limit) { duration = DEFAULT_DURATION; } else { duration = (scrollLen - limit) * DEFAULT_DURATION / (getMaximumPullScroll() - limit); } } mScroller.startScroll(0, startY, 0, deltaY/*-getPaddingTop()*/, duration); invalidate(); } private int getMaximumPullScroll() { return Math.round(getResources().getDisplayMetrics().heightPixels / (FRICTION)); } protected IRefreshLayout getBounceHeaderView() { return mRefreshLayout; } protected IRefreshLayout getBounceFooterView() { return mLoadMoreLayout; } public void setBounceHeaderView(IRefreshLayout layout) { mRefreshLayout = layout; if (mRefreshLayout != null && getChildCount() > 1) { removeViewAt(1); addView(mRefreshLayout.getView(), 1); } } public void setBounceFooterView(IRefreshLayout layout) { mLoadMoreLayout = layout; if (mLoadMoreLayout != null && getChildCount() > 2) { removeViewAt(2); addView(mLoadMoreLayout.getView(), 2); } } public abstract boolean isReadyForPullFromTop(); public abstract boolean isReadyForPullFromBottom(); public abstract T createBounceView(Context context); public abstract IRefreshLayout createBounceHeaderView(Context context); public IRefreshLayout createBounceFooterView(Context context) { return null; } protected void onPullStateChanged(int itemDimension, int scrollValue) { } protected void onTouchActionUp() { } private final GestureDetector.SimpleOnGestureListener mGestureListener = new GestureDetector.SimpleOnGestureListener() { @Override public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) { mScroller.fling(getPaddingLeft(), getPaddingTop(), 0, (int) velocityY, 0, 0, -mMaxPadding, 0); invalidate(); return true; } }; }