Android ListView实现仿iPhone实现左滑删除按钮

@Override
public boolean onTouchEvent(MotionEvent ev) {
switch (ev.getAction()) {
case MotionEvent.ACTION_DOWN:
// 获取按下的条目视图（child view）
int childCount = getChildCount();
int[] listViewCoords = new int[2];
getLocationOnScreen(listViewCoords);
int x = (int) ev.getRawX() - listViewCoords[0];
int y = (int) ev.getRawY() - listViewCoords[1];
for (int i = 0; i < childCount; i++) {
downChild = getChildAt(i); //
Rect rect = new Rect();
assert downChild != null;
downChild.getHitRect(rect); int childPosition = getPositionForView(downChild); if (rect.contains(x, y)) {
downX = ev.getRawX();
int downPosition = childPosition; velocityTracker = VelocityTracker.obtain();
assert velocityTracker != null;
velocityTracker.addMovement(ev);
break;
}
}
isSwipe = false;
break;
case MotionEvent.ACTION_MOVE:
velocityTracker.addMovement(ev);
// 计算水平和垂直方向移动速度
velocityTracker.computeCurrentVelocity(1000);
float velocityX = Math.abs(velocityTracker.getXVelocity());
float velocityY = Math.abs(velocityTracker.getYVelocity());

// 水平移动距离
float deltaX = ev.getRawX() - downX;
float deltaMode = Math.abs(deltaX);
if (deltaX > 150) {// right swipe（右滑）
isSwipeToLeft = false;
} else if (deltaX < -150) {// left swipe（左滑）
isSwipeToLeft = true;
}
// 如果水平滑动距离大于零，并且水平滑动速率比垂直大，说明是水平滑动
if (deltaMode > 0 && velocityY < velocityX) {
// 这里的FloatDelButtonLayout是自定义的LinearLayout。
((FloatDelButtonLayout) downChild).showDelButton(ev, isSwipeToLeft);
isSwipe = true;
}
break;
case MotionEvent.ACTION_CANCEL:
case MotionEvent.ACTION_UP:
downChild.setSelected(false);
if (isSwipe) {
isSwipe = false;
return true;
}
break;
}
return super.onTouchEvent(ev);
}

public class FloatDelButtonLayout extends LinearLayout {

// 提供删除按钮的接口
private OnDelListener delListener;

// 当前视图在列表中的索引，在delListener中使用
private int index;

// 右滑 还是 左滑？
    private boolean isSwipeToLeft;
public void setOnDelListener(OnDelListener listener, int i) {
delListener = listener;
index = i;
} public FloatDelButtonLayout(Context context) {
super(context, null);
} public FloatDelButtonLayout(Context context, AttributeSet attrs) {
super(context, attrs, 0);
} public FloatDelButtonLayout(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}

// 用来显示或者隐藏删除按钮。
public void showDelButton(MotionEvent ev, boolean isSwipeToLeft) {
this.isSwipeToLeft = isSwipeToLeft;
onTouchEvent(ev);
} private OnClickListener clickDel = new OnClickListener() {
@Override
public void onClick(View v) {
delListener.onDel(index);
}
};

/**
* 这里的event是我们显示的从FloatDelListView的onTouchEvent里面传进来的，
*/
@Override
public boolean onTouchEvent(MotionEvent event) {
switch (MotionEventCompat.getActionMasked(event)) {
case MotionEvent.ACTION_MOVE:
// 获取删除按钮对象，视图layout中必须要有id为del_button的Button标签
Button view = (Button) findViewById(R.id.del_button);
view.setText(R.string.del);
// 设置Button的MarginLayoutParams，当然可以做成各种动作，比如渐隐之类的显示出来。
MarginLayoutParams layoutParams = (MarginLayoutParams) view.getLayoutParams();
assert layoutParams != null;
if (isSwipeToLeft) {
view.setVisibility(View.VISIBLE);
view.setOnClickListener(clickDel);
layoutParams.leftMargin = -200;
} else {
view.setVisibility(View.GONE);
layoutParams.leftMargin = 0;
}
view.setLayoutParams(layoutParams);
invalidate();
break;
}
return super.onTouchEvent(event);
} public interface OnDelListener {
void onDel(int i);
}
}