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; /** * Created by zhangjg on 14-10-10. */ public class DragTouchListener implements View.OnTouchListener { /** * drag directions */ 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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