Android 多个ImageView拖拽互换图片

马上又是新的一年了,

在写这篇博客之前,深海预祝大家新的一年里健康快乐,万事如意.

话不多说直接上代码:

首先是XML文件代码:

<LinearLayout                    
 android:layout_width="match_parent"                    
 android:layout_height="match_parent"
 android:orientation="horizontal"      >
                <LinearLayout
                    android:id="@+id/release_img0_layout"
                    android:layout_width="0px"
                    android:layout_height="match_parent"
                    android:layout_marginLeft="20px"
                    android:layout_weight="1">

                    <ImageView
                        android:id="@+id/release_img0"
                        android:layout_width="match_parent"
                        android:layout_height="match_parent"
                        android:scaleType="centerCrop" />

                </LinearLayout>

                <LinearLayout
                    android:id="@+id/release_img1_layout"
                    android:layout_width="0px"
                    android:layout_height="match_parent"
                    android:layout_marginLeft="20px"
                    android:layout_weight="1">

                    <ImageView
                        android:id="@+id/release_img1"
                        android:layout_width="match_parent"
                        android:layout_height="match_parent"
                        android:scaleType="centerCrop" />

                </LinearLayout>
 </LinearLayout>

重点注意,两个ImageView要分别用Layout单独装起来,后面会说原因

接下来是初始化:

 mImg0 = findViewById(R.id.release_img0);
 mImg1 = findViewById(R.id.release_img1);
mImg0_layout = findViewById(R.id.release_img0_layout);
mImg1_layout = findViewById(R.id.release_img1_layout);
//添加ImageView的触摸监听和各自父布局的拖拽监听
 mImg0.setOnTouchListener(ImgUtils.MyTouchEvent);
 mImg0_layout.setOnDragListener(ImgUtils.MyDragListener);
 mImg1.setOnTouchListener(ImgUtils.MyTouchEvent);
 mImg1_layout.setOnDragListener(ImgUtils.MyDragListener);

监听详情:

public class ImgUtils {
    private static long lastTime;
    public static View.OnTouchListener MyTouchEvent = new View.OnTouchListener() {
        @Override
        public boolean onTouch(View v, MotionEvent event) {
            if (event.getAction() == MotionEvent.ACTION_DOWN) {
                LogUtils.loge("ACTION_DOWN");
                long lastTime1 = System.currentTimeMillis();

                lastTime=lastTime1;
                ClipData data = ClipData.newPlainText("", "");
                View.DragShadowBuilder shadowBuilder = new View.DragShadowBuilder(v);
                v.startDrag(data, shadowBuilder, v, 0);
                if ((lastTime1-lastTime)<200){
                    v.setAlpha((float) 1.0);
                    return false;
                }
                v.setAlpha((float) 0.5);
            } else if (event.getAction() == MotionEvent.ACTION_UP){
                LogUtils.loge("ACTION_UP");
                long time = System.currentTimeMillis();
                if ((time - lastTime)<500){ // 间隔小于500毫秒,视为点击事件
                    return false;
                }
            }else if (event.getAction() == MotionEvent.ACTION_MOVE){
                LogUtils.loge("ACTION_MOVE");
            }

            return false;

        }
    };

    public static View.OnDragListener MyDragListener = new View.OnDragListener() {

        @RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN)
        @Override
        public boolean onDrag(View v, DragEvent event) {
            View visitorView = (View) event.getLocalState();
            if (visitorView == null) return true;
            ViewGroup visitorOwner = (ViewGroup) visitorView.getParent();
            ViewGroup visitedOwner = (ViewGroup) v;
            View visitedImage = visitedOwner.getChildAt(0);
            switch (event.getAction()) {
                case DragEvent.ACTION_DRAG_ENTERED:
                    v.setAlpha((float)0.7);
                    break;
                case DragEvent.ACTION_DROP:
                    visitedImage.setAlpha((float)1.0);
                    if (visitorOwner != visitedOwner) {
                        visitedOwner.removeView(visitedImage);
                        visitorOwner.removeView(visitorView);
                        visitorOwner.addView(visitedImage);
                        LinearLayout container = (LinearLayout) v;
                        container.addView(visitorView);
                    }else {
                        visitedImage.performClick(); // 如果归复原位  响应点击事件
                    }
                    break;
                case DragEvent.ACTION_DRAG_ENDED:
                    v.setAlpha((float)1.0);
                    visitedImage.setAlpha((float)1.0);
                    break;
                case DragEvent.ACTION_DRAG_EXITED:
                    v.setAlpha((float)1.0);
                    break;
            }
            return true;
        }
    };


}

在这里,我将监听提出来写成了公共的静态方法,

一方面是为了复用,

另一方面是为了多个ImageView互相拖拽时候的多指拖动冲突.核心思想:判断子控件触摸监听的调用间隔.

另外,我这边处理了点击事件和滑动事件的冲突,核心思想:在父布局的拖拽监听里判断子控件拖出去是否放回了原处,如放回了原处,则调用子控件的模拟点击,