Android滑动菜单 - 实现手动、自动滚动视图

package loveworld.slidingmenu; import android.content.Context; import android.graphics.RectF; import android.util.AttributeSet; import android.view.MotionEvent; import android.view.View; import android.view.ViewGroup; import android.widget.Scroller; public class SlidingMenu extends ViewGroup { // =========================================================== // Constants // =========================================================== // =========================================================== // Fields // =========================================================== private View mRightView; private View mLeftView; private ScrollRunnable mScrollRunnable; /** * 记录一次移动位置，用于计算移动偏移量 */ private int mLastX; /** * 按下时记录，用于判断当前滚动时向左还是向右 */ private int mMotionX; // =========================================================== // Constructors // =========================================================== public SlidingMenu(Context context) { super(context); } public SlidingMenu(Context context, AttributeSet attrs) { super(context, attrs); } public SlidingMenu(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); } // =========================================================== // Public Methods // =========================================================== public void addLeftView(View leftView) { mLeftView = leftView; addView(leftView); } /** * 提供右侧显示视图 * * @param rightView */ public void addRightView(View rightView) { mRightView = rightView; addView(rightView); } // =========================================================== // Methods for/from SuperClass/Interfaces // =========================================================== @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { measureChildren(widthMeasureSpec, heightMeasureSpec); int widthSize = MeasureSpec.getSize(widthMeasureSpec); int heightSize = MeasureSpec.getSize(heightMeasureSpec); setMeasuredDimension(widthSize, heightSize); } @Override protected void onLayout(boolean changed, int l, int t, int r, int b) { int childCount = getChildCount(); for (int i = 0; i < childCount; i++) { View childView = getChildAt(i); int measuredWidth = childView.getMeasuredWidth(); int measuredHeight = childView.getMeasuredHeight(); childView.layout(l, 0, l + measuredWidth, measuredHeight); } } @Override public boolean onTouchEvent(MotionEvent event) { final int x = (int) event.getX(); switch (event.getAction()) { case MotionEvent.ACTION_DOWN: mLastX = x; mMotionX = x; if (mScrollRunnable != null) { mScrollRunnable.endScroll(); mScrollRunnable = null; } boolean inRegion = canSliding(event); return inRegion; case MotionEvent.ACTION_MOVE: scrollIfNeed(x); return true; case MotionEvent.ACTION_UP: autoScrollIfNeed(x); break; } return true; } // =========================================================== // Private Methods // =========================================================== /** * 只有右侧视图可以移动 * * @param event * @return true 可以滚动 */ private boolean canSliding(MotionEvent event) { int[] location = new int[2]; // 获取右侧视图相对于屏幕坐标值 mRightView.getLocationOnScreen(location); RectF region = new RectF(); region.set(location[0] , location[1] , location[0] + mRightView.getWidth(), location[1] + mRightView.getHeight()); // 当前手指点击位置是否在右侧视图区域内 boolean inRegion = region.contains(event.getRawX(), event.getRawY()); return inRegion; } private void scrollIfNeed(final int x) { // 计算与上次的偏移量 int deltaX = x - mLastX; // 减少移动次数 if (x != mLastX) { int l = mRightView.getLeft(); int t = mRightView.getTop(); int b = mRightView.getBottom(); // 右侧视图的滑动区域，只能在左侧视图范围内滑动 int rightViewLeft = Math.max(mLeftView.getLeft(), l + deltaX); rightViewLeft = Math.min(mLeftView.getRight(), rightViewLeft); // 控制随手指滑动 mRightView.layout(rightViewLeft, t, rightViewLeft + mRightView.getWidth(), b); } // 记录当前值供下次计算 mLastX = x; } private void autoScrollIfNeed(final int x) { mScrollRunnable = new ScrollRunnable(); // 用于判断滑动方向 final int deltaX = x - mMotionX; // x轴向右是依次递增与手指落下点差值，小于0说明是手指向左滑动 boolean moveLeft = deltaX <= 0; // 滑动距离超过左侧视图一半，才会沿着手指方向滚动 final int distance = Math.abs(deltaX); if (distance < mLeftView.getWidth() / 2) { // 从哪来回哪去 moveLeft = !moveLeft; } // 启动自动滚动 mScrollRunnable.startScroll(moveLeft); } // =========================================================== // Inner and Anonymous Classes // =========================================================== private class ScrollRunnable implements Runnable { // 滚动辅助类，提供起始位置，移动偏移，移动总时间，可以获取每次滚动距离 private Scroller mScroller = new Scroller(getContext()); @Override public void run() { final Scroller scroller = mScroller; // 计算滚动偏移，返回是否可以接着滚动 boolean more = scroller.computeScrollOffset(); // 计算后获取需要滚动到的位置 final int x = scroller.getCurrX(); if (more) { // 与手动滚动调用的方法相同 scrollIfNeed(x); // 当前子线程已经执行完，但是需要接着滚动 // 所以把当前Runnable再次添加到消息队列中 post(this); } else { // 不需要滚动 endScroll(); } } private void startScroll(boolean moveLeft) { // 滚动前设置初始值 mLastX = mRightView.getLeft(); int dx = 0; // 计算移动总距离 if (moveLeft) { // 当前到左视图左侧边界距离 dx = mLeftView.getLeft() - mRightView.getLeft(); } else { // 到右侧边界 dx = mLeftView.getRight() - mRightView.getLeft(); } // 开始滚动 mScroller.startScroll(mRightView.getLeft(), 0, dx, 0, 300); // 把当前Runnable添加到消息队列中 post(this); } private void endScroll() { // 从消息队列中把当前Runnable删除，即停止滚动 removeCallbacks(this); } } }