Java tutorial
/** * Copyright 2015 Pengyuan-Jiang * <p/> * 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 * <p/> * http://www.apache.org/licenses/LICENSE-2.0 * <p/> * 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. * <p/> * AuthorYbao on 2015/11/5 ?17:49 * <p/> * QQ: 392579823 * <p/> * Email392579823@qq.com */ package jiajun.threelevelistview.layout; import android.content.Context; import android.support.v4.view.NestedScrollingChild; import android.support.v4.view.NestedScrollingChildHelper; import android.support.v4.view.NestedScrollingParent; import android.support.v4.view.NestedScrollingParentHelper; import android.support.v4.view.ViewCompat; import android.util.AttributeSet; import android.util.Log; import android.view.MotionEvent; import android.view.View; import android.view.ViewConfiguration; import android.view.ViewGroup; import android.view.animation.DecelerateInterpolator; import android.widget.FrameLayout; import android.widget.Scroller; import jiajun.threelevelistview.layout.support.impl.Pullable; import jiajun.threelevelistview.layout.support.utils.CanPullUtil; public class FlingLayout extends FrameLayout implements NestedScrollingChild, NestedScrollingParent { private NestedScrollingParentHelper mParentHelper; private NestedScrollingChildHelper mChildHelper; public final static int SCROLL_STATE_IDLE = 0; public final static int SCROLL_STATE_TOUCH_SCROLL = 1; public final static int SCROLL_STATE_FLING = 2; private int stateType = SCROLL_STATE_IDLE; private int tempStateType = SCROLL_STATE_IDLE; protected Pullable pullable; protected View mPullView; private int mTouchSlop; private Scroller mScroller; protected float downY, downX; private boolean isScrolling = false; protected float tepmX; protected float tepmY; private static final int MAX_DURATION = 300; private boolean canPullUp = true; private boolean canPullDown = true; protected OnScrollListener mOnScrollListener; protected int maxDistance = 0; protected int version; int mPointerId; protected int MAXDISTANCE = 0; float moveY = 0; public View getPullView() { return mPullView; } public FlingLayout(Context context) { this(context, null); } public FlingLayout(Context context, AttributeSet attrs) { this(context, attrs, 0); } public FlingLayout(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); init(context); } public void init(Context context) { version = android.os.Build.VERSION.SDK_INT; mTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop(); mScroller = new Scroller(context, new DecelerateInterpolator()); mParentHelper = new NestedScrollingParentHelper(this); mChildHelper = new NestedScrollingChildHelper(this); } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); MAXDISTANCE = getMeasuredHeight() * 3 / 5; } @Override public void computeScroll() { if (!mScroller.isFinished()) { if (mScroller.computeScrollOffset()) { moveTo(mScroller.getCurrY()); ViewCompat.postInvalidateOnAnimation(this); } else if (stateType == SCROLL_STATE_FLING) { setScrollState(SCROLL_STATE_IDLE); } } else if (stateType == SCROLL_STATE_FLING) { setScrollState(SCROLL_STATE_IDLE); } super.computeScroll(); } private boolean canPullUp() { if (mPullView != null) { return canPullUp && pullable.isGetBottom(); } return canPullUp; } private boolean canPullDown() { if (mPullView != null) { return canPullDown && pullable.isGetTop(); } return canPullDown; } private void moveTo(float y) { setMoveY(y); setScrollState(tempStateType); Log.i("flingLayout", "moveY:" + y); boolean intercept = onScroll(y); if (mOnScrollListener != null) { mOnScrollListener.onScroll(this, y); } if (!intercept) { setViewTranslationY(mPullView, y); } } private void setScrollState(int stateType) { if (this.stateType != stateType) { this.stateType = stateType; this.tempStateType = stateType; Log.i("flingLayout", "onScrollChange:" + stateType); onScrollChange(stateType); if (mOnScrollListener != null) { mOnScrollListener.onScrollChange(this, stateType); } } } private void moveBy(float dy) { moveTo(getMoveY() + dy); } protected static void setViewTranslationY(View view, float value) { if (view == null) { return; } ViewCompat.setTranslationY(view, value); } private void setMoveY(float moveY) { this.moveY = moveY; } public float getMoveY() { return moveY; } public int startMoveBy(float startY, float dy) { setScrollState(SCROLL_STATE_FLING); int duration = (int) Math.abs(dy); int time = duration > MAX_DURATION ? MAX_DURATION : duration; mScroller.startScroll(0, (int) startY, 0, (int) dy, time); invalidate(); return time; } public int startMoveTo(float startY, float endY) { return startMoveBy(startY, endY - startY); } private void startFling() { float nowY = getMoveY(); if (nowY != 0) { if (!onStartFling(nowY)) { startMoveTo(nowY, 0); } } else { setScrollState(SCROLL_STATE_IDLE); } } @Override public void addView(View child, int index, ViewGroup.LayoutParams params) { if (mPullView == null && (pullable = CanPullUtil.getPullAble(child)) != null) { mPullView = child; } super.addView(child, index, params); } public void setMaxDistance(int maxDistance) { this.maxDistance = maxDistance; } public void setCanPullDown(boolean canPullDown) { this.canPullDown = canPullDown; if (!canPullDown && getMoveY() > 0) { moveTo(0); } } public void setCanPullUp(boolean canPullUp) { this.canPullUp = canPullUp; if (!canPullUp && getMoveY() < 0) { moveTo(0); } } /******************************************************************/ @Override public boolean dispatchTouchEvent(MotionEvent ev) { if (mPullView != null && !ViewCompat.isNestedScrollingEnabled(mPullView)) { float moveY = getMoveY(); int pointerCount = ev.getPointerCount(); int pointerIndex = ev.getActionIndex(); if (!mScroller.isFinished()) { mScroller.abortAnimation(); } switch (ev.getActionMasked()) { case MotionEvent.ACTION_DOWN: mPointerId = ev.getPointerId(pointerIndex); float x = ev.getX(pointerIndex); float y = ev.getY(pointerIndex); tepmY = downY = y; tepmX = downX = x; tempStateType = SCROLL_STATE_TOUCH_SCROLL; if (moveY != 0) { return true; } break; case MotionEvent.ACTION_POINTER_DOWN: mPointerId = ev.getPointerId(pointerIndex); tepmX = ev.getX(pointerIndex); tepmY = ev.getY(pointerIndex); break; case MotionEvent.ACTION_MOVE: pointerIndex = ev.findPointerIndex(mPointerId); float mx; float my; if (pointerCount > pointerIndex && pointerIndex >= 0) { mx = ev.getX(pointerIndex); my = ev.getY(pointerIndex); } else { mx = ev.getX(); my = ev.getY(); } //????? int dataX = (int) (mx - tepmX); int dataY = (int) (my - tepmY); tepmX = mx; tepmY = my; if (isScrolling || (Math.abs(dataY) > Math.abs(dataX))) { isScrolling = true; if (moveY == 0) { // 0,0 //?? if ((dataY < 0 && canPullUp()) || (dataY > 0 && canPullDown())) { moveBy(dataY); return true; } } else { //?0,0 ev.setAction(MotionEvent.ACTION_CANCEL);//? if ((moveY < 0 && moveY + dataY >= 0) || (moveY > 0 && moveY + dataY <= 0)) { //0,0 ev.setAction(MotionEvent.ACTION_DOWN); moveTo(0); } else if ((moveY > 0 && dataY > 0) || (moveY < 0 && dataY < 0)) { //?? if (maxDistance == 0 || Math.abs(moveY) < maxDistance) { int ps = 0; int hDataY = dataY / 2; if (maxDistance == 0) { ps = (int) (-hDataY * Math.abs(moveY) / (float) MAXDISTANCE) - hDataY; } else { ps = (int) (-hDataY * Math.abs(moveY) / (float) maxDistance) - hDataY; } moveBy(ps + dataY); } else if (moveY > maxDistance) { moveTo(maxDistance); } else if (moveY < -maxDistance) { moveTo(-maxDistance); } } else { moveBy(dataY); } } } else { ev.setLocation(mx, downY); } break; case MotionEvent.ACTION_CANCEL: case MotionEvent.ACTION_UP: startFling(); isScrolling = false; break; case MotionEvent.ACTION_POINTER_UP: // ?? int pointerIdLeave = ev.getPointerId(pointerIndex); if (mPointerId == pointerIdLeave) { // ??????VelocityTracker int reIndex = pointerIndex == 0 ? 1 : 0; mPointerId = ev.getPointerId(reIndex); // ? tepmY = ev.getY(reIndex); } } return super.dispatchTouchEvent(ev) || isScrolling; } else { return super.dispatchTouchEvent(ev); } } @Override public boolean onTouchEvent(MotionEvent event) { if (mPullView != null && !ViewCompat.isNestedScrollingEnabled(mPullView)) { switch (event.getAction()) { case MotionEvent.ACTION_DOWN: return true; } } return super.onTouchEvent(event); } /******************************************************************/ /******************************************************************/ @Override public boolean onStartNestedScroll(View child, View target, int nestedScrollAxes) { if (!isNestedScrollingEnabled()) { setNestedScrollingEnabled(true); } return (nestedScrollAxes & ViewCompat.SCROLL_AXIS_VERTICAL) != 0; } @Override public void onNestedScrollAccepted(View child, View target, int nestedScrollAxes) { mParentHelper.onNestedScrollAccepted(child, target, nestedScrollAxes); startNestedScroll(ViewCompat.SCROLL_AXIS_VERTICAL); } @Override public void onStopNestedScroll(View target) { startFling(); stopNestedScroll(); } @Override public void onNestedScroll(View target, int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed) { int[] offsetInWindow = new int[2]; dispatchNestedScroll(0, dyConsumed, 0, dyUnconsumed, offsetInWindow); moveBy(-dyUnconsumed - offsetInWindow[1]); } @Override public void onNestedPreScroll(View target, int dx, int dy, int[] consumed) { this.tempStateType = SCROLL_STATE_TOUCH_SCROLL; float moveY = getMoveY(); if (mPullView == null || moveY == 0) { dispatchNestedPreScroll(0, dy, consumed, null); } else { consumed[0] = 0; stopNestedScroll(); int dataY = -dy; if ((moveY < 0 && moveY + dataY >= 0) || (moveY > 0 && moveY + dataY <= 0)) { moveTo(0); startNestedScroll(ViewCompat.SCROLL_AXIS_VERTICAL); consumed[1] = (int) (moveY - 0); int[] pconsumed = new int[2]; dispatchNestedPreScroll(0, dy - consumed[1], pconsumed, null); consumed[1] += pconsumed[1]; } else if ((moveY > 0 && dataY > 0) || (moveY < 0 && dataY < 0)) { //?? if (maxDistance == 0 || Math.abs(moveY) < maxDistance) { int ps = 0; int hDataY = dataY / 2; if (maxDistance == 0) { ps = (int) (-hDataY * Math.abs(moveY) / (float) MAXDISTANCE) - hDataY; } else { ps = (int) (-hDataY * Math.abs(moveY) / (float) maxDistance) - hDataY; } moveBy(ps + dataY); } else if (moveY > maxDistance) { moveTo(maxDistance); } else if (moveY < -maxDistance) { moveTo(-maxDistance); } consumed[1] = dy; } else { moveBy(dataY); consumed[1] = dy; } } } @Override public boolean onNestedFling(View target, float velocityX, float velocityY, boolean consumed) { return dispatchNestedFling(velocityX, velocityY, consumed); } @Override public boolean onNestedPreFling(View target, float velocityX, float velocityY) { boolean consumed = dispatchNestedPreFling(velocityX, velocityY); if (consumed) { return true; } Pullable pullable = CanPullUtil.getPullAble(target); if (pullable != null) { if (pullable.isGetBottom() && velocityY < 0) { return true; } else if (pullable.isGetTop() && velocityY > 0) { return true; } } return false; } @Override public int getNestedScrollAxes() { return mParentHelper.getNestedScrollAxes(); } @Override public void setNestedScrollingEnabled(boolean enabled) { mChildHelper.setNestedScrollingEnabled(enabled); } @Override public boolean isNestedScrollingEnabled() { return mChildHelper.isNestedScrollingEnabled(); } @Override public boolean startNestedScroll(int axes) { return mChildHelper.startNestedScroll(axes); } @Override public void stopNestedScroll() { mChildHelper.stopNestedScroll(); } @Override public boolean dispatchNestedScroll(int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed, int[] offsetInWindow) { return mChildHelper.dispatchNestedScroll(dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed, offsetInWindow); } @Override public boolean dispatchNestedPreScroll(int dx, int dy, int[] consumed, int[] offsetInWindow) { return mChildHelper.dispatchNestedPreScroll(dx, dy, consumed, offsetInWindow); } @Override public boolean dispatchNestedFling(float velocityX, float velocityY, boolean consumed) { return mChildHelper.dispatchNestedFling(velocityX, velocityY, consumed); } @Override public boolean dispatchNestedPreFling(float velocityX, float velocityY) { return mChildHelper.dispatchNestedPreFling(velocityX, velocityY); } @Override public void onDetachedFromWindow() { super.onDetachedFromWindow(); mChildHelper.onDetachedFromWindow(); } /******************************************************************/ protected boolean onScroll(float y) { return false; } protected boolean onStartFling(float nowY) { return false; } protected void onScrollChange(int stateType) { } public interface OnScrollListener { public void onScroll(FlingLayout flingLayout, float y); public void onScrollChange(FlingLayout flingLayout, int state); } public void setOnScrollListener(OnScrollListener mOnScrollListener) { this.mOnScrollListener = mOnScrollListener; } }