Android GridView拖動效果實現代碼

1. 重新GridView控件

package com.whbs.drag.widget;

 

import com.whbs.drag.DragGridActivity.DragGridAdapter;

 

import android.content.Context;

import android.graphics.Bitmap;

import android.graphics.PixelFormat;

import android.util.AttributeSet;

import android.util.Log;

import android.view.Gravity;

import android.view.MotionEvent;

import android.view.ViewGroup;

import android.view.WindowManager;

import android.widget.AdapterView;

import android.widget.GridView;

import android.widget.ImageView;

 

public class GragGridView extends GridView{

private static final String TAG = "GragGridView";

//定義基本的成員變量

private ImageView dragImageView; //拖動的影像

private int dragSrcPosition;//原始對應位置

private int dragPosition;//拖動到坐標對應的位置

 

//x,y坐標的計算

private int dragPointX; //按下坐標相對於當前項位置-- 相對

private int dragPointY;

private int dragOffsetX;//當前窗體和屏幕的距離 --絕對

private int dragOffsetY;

 

private WindowManager windowManager;//窗口控制類

private WindowManager.LayoutParams windowParams; //用於控制拖動項的顯示參數

 

// private int scaledTouchSlop; //判斷滑動的距離

private int upScrollBounce; //拖動時候,開始向上滾動的邊界

private int downScrollBounce;//拖動時候,開始向下滾動的邊界

 

public GragGridView(Context context) {

super(context);

}

public GragGridView(Context context, AttributeSet attrs, int defStyle) {

super(context, attrs, defStyle);

// TODO Auto-generated constructor stub

}

 

public GragGridView(Context context, AttributeSet attrs) {

super(context, attrs);

// TODO Auto-generated constructor stub

}

 

//觸控攔截事件

@Override

public boolean onInterceptTouchEvent(MotionEvent ev) {

if(ev.getAction() == MotionEvent.ACTION_DOWN){

int x = (int)ev.getX();

int y = (int)ev.getY();

 

//選中數據項位置 ,

dragSrcPosition = dragPosition = pointToPosition(x, y);

if(dragPosition == AdapterView.INVALID_POSITION){//無效位置(超出邊蛸,分割線)

return super.onInterceptTouchEvent(ev);

}

Log.i(TAG, "[onInterceptTouchEvent] dragSrcPosition:"+dragSrcPosition+",getFirstVisiblePosition():"+getFirstVisiblePosition());

//getFirstVisiblePosition()返回第一個dispaly在界面的view在adapter的位置 可能是0,也可能是4

ViewGroup itemView = (ViewGroup)getChildAt(dragPosition - getFirstVisiblePosition());

//計算按下的坐標相對當前項的位置

dragPointX = x - itemView.getLeft();//在當前項的X位置

dragPointY = y - itemView.getTop();

//當前窗體和屏幕的距離

dragOffsetX = (int) (ev.getRawX()-x);

dragOffsetY = (int) (ev.getRawY() -y);

Log.i(TAG, "[onInterceptTouchEvent] [x:"+x+",y:"+y+"],[rawX:"+ev.getRawX()+",rawY:"+ev.getRawY()+"]");

Log.i(TAG, "[onInterceptTouchEvent] [dragPointX:"+dragPointX+",dragPointY:"+dragPointY+"],[dragOffsetX:"+dragOffsetX+",dragOffsetY:"+dragOffsetY+"]");

//

// upScrollBounce = Math.min(y-scaledTouchSlop, getHeight()/4);

// downScrollBounce = Math.max(y+scaledTouchSlop, getHeight()*3/4);

 

upScrollBounce = Math.min(y, getHeight()/4);//向上可以滾動的距離

downScrollBounce = Math.max(y, getHeight()*3/4);//向下可以滾動的距離

 

itemView.setDrawingCacheEnabled(true);

Bitmap bm = Bitmap.createBitmap(itemView.getDrawingCache());

startDrag(bm,x,y);

}

 

return super.onInterceptTouchEvent(ev);

 

}

 

//開始拖動

public void startDrag(Bitmap bm,int x,int y){

stopDrag();

windowParams = new WindowManager.LayoutParams();

windowParams.gravity = Gravity.TOP|Gravity.LEFT;

windowParams.x = x - dragPointX + dragOffsetX;//計算當前項Left離窗體的距離

windowParams.y = y - dragPointY + dragOffsetY;//計算當前項Top離窗體的距離

 

windowParams.width = WindowManager.LayoutParams.WRAP_CONTENT;

 

windowParams.height = WindowManager.LayoutParams.WRAP_CONTENT;

 

windowParams.flags = WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE | WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE

| WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON

| WindowManager.LayoutParams.FLAG_LAYOUT_IN_SCREEN;

 

windowParams.format = PixelFormat.TRANSLUCENT;

 

windowParams.windowAnimations = 0;

 

ImageView imageView = new ImageView(getContext());

imageView.setImageBitmap(bm);

windowManager = (WindowManager)getContext().getSystemService(getContext().WINDOW_SERVICE);

windowManager.addView(imageView, windowParams);

dragImageView = imageView;

}

//停止拖到

public void stopDrag(){

if(dragImageView != null){

windowManager.removeView(dragImageView);

dragImageView = null;

}

}

 

//拖動

public void onDrag(int x,int y){

if(dragImageView != null){

windowParams.alpha = 0.9f;

windowParams.x = x - dragPointX + dragOffsetX;

windowParams.y = y - dragPointY + dragOffsetY;

windowManager.updateViewLayout(dragImageView, windowParams);

 

}

int tempPosition = pointToPosition(x, y);

if(tempPosition != INVALID_POSITION){

dragPosition = tempPosition;

}

 

if(y < upScrollBounce || y > downScrollBounce){

setSelection(dragPosition);

}

}

 

@Override

public boolean onTouchEvent(MotionEvent ev) {

if(dragImageView != null && dragPosition != INVALID_POSITION){

int action = ev.getAction();

switch(action){

case MotionEvent.ACTION_UP:

int upx = (int)ev.getX();

int upY = (int)ev.getY();

stopDrag();

onDrop(upx,upY);

break;

case MotionEvent.ACTION_MOVE:

int moveX = (int)ev.getX();

int moveY = (int)ev.getY();

onDrag(moveX, moveY);

break;

}

return true;

}

 

 

return super.onTouchEvent(ev);

}

 

//拖到落下

public void onDrop(int x,int y){

int tempPosition = pointToPosition(x,y);

if(tempPosition != INVALID_POSITION){

dragPosition = tempPosition;

}

//超出邊界

if(y < getChildAt(0).getTop()){

dragPosition = 0;

}else if(y > getChildAt(getChildCount()-1).getBottom() ||

(y > getChildAt(getChildCount()-1).getTop() &&

x > getChildAt(getChildCount()-1).getRight())){

//超出下邊界

dragPosition = getAdapter().getCount() -1;

}

//數據交換當前拖動的於拖到到位置上的圖片交換

if(dragPosition != dragSrcPosition && dragPosition > -1 && dragPosition < getAdapter().getCount()){

DragGridAdapter adapter = (DragGridAdapter)getAdapter();

String dragSrcItem = adapter.getItem(dragSrcPosition);

String dragTargetItem = adapter.getItem(dragPosition);

 

adapter.remove(dragSrcItem);

adapter.insert(dragSrcItem, dragPosition);

 

adapter.remove(dragTargetItem);

adapter.insert(dragTargetItem, dragSrcPosition);

 

System.out.println("srcPosition="+dragSrcPosition+" dragPosition="+dragPosition);

//Toast.makeText(getContext(), adapter.getList().toString(), Toast.LENGTH_SHORT).show();

}

 

}

}