Android TouchListener实现拖拽删实例代码
如果为一个控件设置了该触摸监听， 控件会随着用户的拖动而移动， 如果拖动的距离大过设置的临界值， 那么当松开手指时会有回调onDragComplete, 用户可在该方法中将该控件从父布局中删除， 或这进行其他操作。 如果用户拖拽的距离小于临界值， 那么当用户松开手指时控件会回谈到原来的初始位置。这时会触发onDragRebound回调。 如果用户触摸控件之后没有拖拽而是直接松开手指， 会触发onClick回调， 这样用户就不用为该控件设置onClick监听。
源码如下：
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
public class DragTouchListener implements View.onTouchListener {
public static final int DIRECTION_UP = 0;
public static final int DIRECTION_DOWN = 1;
public static final int DIRECTION_LEFT = 2;
public static final int DIRECTION_RIGHT = 3;
private int mDragDirection = -1;
private int mDragDistance = -1;
private ViewGroup.MarginLayoutParams mParams;
private ViewGroup.MarginLayoutParams mOriginParams;
private int viewOriginMargin = -1000;
private float mStartY = 0;
private float mStartX = 0;
private boolean isTouched = false;
public DragTouchListener(int dragDirection, int dragDistance){
mDragDirection = dragDirection;
mDragDistance = dragDistance;
}
protected void onClick(View view){
}
protected void onDragComplete(View view){
}
protected void onDragRebound(View view){
}
@Override
public boolean onTouch(View view, MotionEvent motionEvent) {
if (viewOriginMargin == -1000){
mParams = (ViewGroup.MarginLayoutParams)view.getLayoutParams();
if (mDragDirection == DIRECTION_UP) {
viewOriginMargin = mParams.bottomMargin;
}else if (mDragDirection == DIRECTION_DOWN){
viewOriginMargin = mParams.topMargin;
}else if (mDragDirection == DIRECTION_LEFT){
viewOriginMargin = mParams.rightMargin;
}else if (mDragDirection == DIRECTION_RIGHT){
viewOriginMargin = mParams.leftMargin;
}
}
int action = motionEvent.getAction();
switch (action){
case MotionEvent.ACTION_DOWN:
isTouched = true;
mStartY = motionEvent.getY();
mStartX = motionEvent.getX();
return true;
case MotionEvent.ACTION_MOVE:
float y = motionEvent.getY();
float x = motionEvent.getX();
if (mDragDirection == DIRECTION_UP){
if(y < mStartY){
mParams.bottomMargin = viewOriginMargin +(int) (mStartY - y);
}
}else if (mDragDirection == DIRECTION_DOWN){
if (y > mStartY){
mParams.topMargin = viewOriginMargin + (int) (y - mStartY);
}
}else if (mDragDirection == DIRECTION_LEFT){
if (x < mStartX){
mParams.rightMargin = viewOriginMargin + (int) (mStartX - x);
}
}else if (mDragDirection == DIRECTION_RIGHT){
if (x > mStartX){
mParams.leftMargin = viewOriginMargin + (int) (x - mStartX);
}
}
view.setLayoutParams(mParams);
break;
case MotionEvent.ACTION_UP:
float nowY = motionEvent.getY();
float nowX = motionEvent.getX();
int deltaX = (int)nowX - (int)mStartX;
int deltaY = (int)nowY - (int)mStartY;
if (isTouched && Math.abs(deltaX) < 5 && Math.abs(deltaY) < 5){
onClick(view);
break;
}
if (mDragDirection == DIRECTION_UP){
if (isTouched && mStartY - nowY > mDragDistance){
// Log.i("test-drag", "direction up , startY = " + mStartY + ", nowY = " + nowY +
// ", startY - nowY = " + (mStartY - nowY) + ", dragDistance : " + mDragDistance);
onDragComplete(view);
}else if (mStartY - nowY > 0 && mStartY - nowY < mDragDistance ){
mParams.bottomMargin = viewOriginMargin;
view.setLayoutParams(mParams);
onDragRebound(view);
}
}else if (mDragDirection == DIRECTION_DOWN){
if (isTouched && nowY - mStartY > mDragDistance){
onDragComplete(view);
}else if ( nowY - mStartY > 0 && nowY - mStartY < mDragDistance ){
mParams.topMargin = viewOriginMargin;
view.setLayoutParams(mParams);
onDragRebound(view);
}
}else if (mDragDirection == DIRECTION_LEFT){
if (isTouched && mStartX - nowX > mDragDistance){
onDragComplete(view);
}else if ( mStartX - nowX > 0 && mStartX - nowX < mDragDistance ){
mParams.rightMargin = viewOriginMargin;
view.setLayoutParams(mParams);
onDragRebound(view);
}
}else if (mDragDirection == DIRECTION_RIGHT){
if (isTouched && nowX - mStartX > mDragDistance){
onDragComplete(view);
}else if ( nowX - mStartX > 0 && nowX - mStartX < mDragDistance ){
mParams.leftMargin = viewOriginMargin;
view.setLayoutParams(mParams);
onDragRebound(view);
}
}
isTouched = false;
break;
}
return false;
}
}
在使用时继承该类， 并覆盖三个回调方法， 就可以在合适的时机得到回调。
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