android仿QQ滑动效果的实现

package com.gallerytest.main; import android.app.Activity; import android.content.Context; import android.graphics.Rect; import android.os.Handler; import android.os.Handler.Callback; import android.os.Message; import android.util.AttributeSet; import android.util.DisplayMetrics; import android.view.GestureDetector; import android.view.GestureDetector.OnGestureListener; import android.view.MotionEvent; import android.view.View; import android.widget.HorizontalScrollView; import android.widget.LinearLayout; public class ViewGallery extends HorizontalScrollView implements OnGestureListener { private GestureDetector gd; private LinearLayout root; private int ScreenWidth, ScreenHeight; private int distance; private Rect r; private int tab = 1; private boolean scrollable = true; private boolean leftScrollable = true, rightScrollable = true; private boolean hasFlinged = false; private boolean auto = false; private boolean scrolling = false; private boolean verticalScrolling = false; private static final int MIN_FLING_VELOCITY = 1200; private static final int MIN_FLING_DISTANCE = 80; public interface OnTabChangedListener { public void onTabChanged(int tab, View v); } private OnTabChangedListener onTabChangedListener; public ViewGallery(Context context) { super(context); } public ViewGallery(Context context, AttributeSet attrs) { super(context, attrs); Activity ac = (Activity) context; DisplayMetrics dm = new DisplayMetrics(); ac.getWindowManager().getDefaultDisplay().getMetrics(dm); ScreenWidth = dm.widthPixels; ScreenHeight = dm.heightPixels; gd = new GestureDetector(this); root = new LinearLayout(context); addView(root, new LayoutParams(ScreenWidth, ScreenHeight)); setHorizontalScrollBarEnabled(false); Rect r = new Rect(); root.getLocalVisibleRect(r); root.scrollBy(ScreenWidth - r.left, 0); } @Override public boolean onTouchEvent(MotionEvent ev) { int action = ev.getAction(); if (action == MotionEvent.ACTION_UP) { verticalScrolling = false; if (scrolling) { // do something scrollable = true; scrolling = false; if (Math.abs(distance) > ScreenWidth / 2) { // move left to the first item if (distance > 0) { tab--; moveToTab(tab, true); } else { tab++; moveToTab(tab, true); } } else { moveToTab(tab, false); } } } return true; } @Override protected void onLayout(boolean changed, int l, int t, int r, int b) { super.onLayout(changed, l, t, r, b); } @Override public boolean dispatchTouchEvent(MotionEvent ev) { auto = false; r = new Rect(); root.getLocalVisibleRect(r); // 判断当前页试图是否有子试图 View current = root.getChildAt(tab); // if (current instanceof ViewGroup) { // ViewGroup group = (ViewGroup) current; // int childCount = group.getChildCount(); // if (childCount > 0) { // // 如果有，则让触摸到的子试图响应触摸事件 // for (int j = 0; j < group.getChildCount(); j++) { // View child = group.getChildAt(j); // Rect rect = new Rect(); // child.getLocalVisibleRect(rect); // if (rect.contains((int) ev.getX(), (int) ev.getY())) { // child.dispatchTouchEvent(ev); // if (child instanceof SeekBar) { // focusChild = true; // touchedChild = child; // return true; // } // } // } // } // } if (!scrolling) { current.dispatchTouchEvent(ev); } gd.onTouchEvent(ev); if (!hasFlinged) { onTouchEvent(ev); } hasFlinged = false; return true; } @Override public boolean onInterceptTouchEvent(MotionEvent ev) { return super.onInterceptTouchEvent(ev); } public void addItem(View v) { LayoutParams params = new LayoutParams(ScreenWidth, ScreenHeight); v.setLayoutParams(params); root.addView(v); } @Override protected void onAttachedToWindow() { super.onAttachedToWindow(); } @Override public boolean onDown(MotionEvent e) { return false; } @Override public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) { int distanceX = (int) (e2.getX() - e1.getX()); if (Math.abs(distanceX) >= MIN_FLING_DISTANCE && Math.abs(velocityX) >= MIN_FLING_VELOCITY) { // startFling if (distanceX > 0) { // rightFling if (rightScrollable) { --tab; moveToTab(tab, true); } } else { // leftFling if (leftScrollable) { ++tab; moveToTab(tab, true); } } hasFlinged = true; } return false; } private void moveToTab(int tab, boolean changed) { if (tab >= 0 && tab < root.getChildCount()) { int flipping = tab * ScreenWidth - r.left; this.tab = tab; new ViewFlippingThread(flipping, changed).start(); } else { this.tab = tab < 0 ? 0 : root.getChildCount() - 1; } } @Override public void onLongPress(MotionEvent e) { } @Override public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) { if (!scrolling && !verticalScrolling) { scrolling = Math.abs(distanceX) > Math.abs(distanceY); verticalScrolling = !scrolling; } if (scrolling) { scrolling = true; verticalScrolling = false; distance = (int) (e2.getX() - e1.getX()); if (scrollable) { int leftBorder = 0; int rightBorder = (root.getChildCount() - 1) * ScreenWidth; int newBorder = (int) (r.left + distanceX); if (distanceX > 0) { if (leftScrollable) { if (newBorder <= rightBorder) { root.scrollBy((int) distanceX, 0); } else { root.scrollBy(rightBorder - r.left, 0); leftScrollable = false; } rightScrollable = true; } } else { if (rightScrollable) { if (newBorder >= leftBorder) { root.scrollBy((int) distanceX, 0); } else { root.scrollBy(leftBorder - r.left, 0); rightScrollable = false; } leftScrollable = true; } } } } else { verticalScrolling = true; } return false; } @Override public void onShowPress(MotionEvent e) { } @Override public boolean onSingleTapUp(MotionEvent e) { return false; } class ViewFlippingThread extends Thread { private int flipping; private boolean changed; private int interval = 1; public ViewFlippingThread(int flipping, boolean changed) { this.flipping = flipping; this.changed = changed; auto = true; } @Override public void run() { if (flipping >= 0) { for (int i = 0; i < flipping; i += 2) { if (auto) { int offset = i == flipping - 1 ? 1 : 2; handler.sendMessage(handler.obtainMessage(0, offset, 0)); try { int remain = flipping - i; interval = ScreenWidth / 2 / remain - 1; interval = Math.max(1, interval); Thread.sleep(interval); } catch (InterruptedException e) { e.printStackTrace(); } } else { break; } } } else { for (int i = 0; i > flipping; i += -2) { if (auto) { int offset = i == flipping + 1 ? -1 : -2; handler.sendMessage(handler.obtainMessage(0, offset, 0)); try { int remain = Math.abs(flipping - i); interval = ScreenWidth / 2 / remain - 1; interval = Math.max(1, interval); Thread.sleep(interval); } catch (InterruptedException e) { e.printStackTrace(); } } else { break; } } } handler.sendMessage(handler.obtainMessage(1, 0, 0, changed)); super.run(); } } private Handler handler = new Handler(new Callback() { @Override public boolean handleMessage(Message msg) { if (msg.what == 0) { root.scrollBy(msg.arg1, 0); } else if (msg.what == 1) { if (tab == 0) { leftScrollable = true; rightScrollable = false;