Android ImageView的图片不透明区域响应点击事件，图片透明区域不响应点击事件，底层控件响应

首先看一下页面布局：

对应的布局文件：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
                android:layout_width="match_parent"
                android:layout_height="match_parent">
                
    <com.zpw.views.exercise7.CameraImageView
        android:id="@+id/img_camera"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@color/colorAccent"/>

    <com.zpw.views.exercise7.NoticeImageView
        android:id="@+id/img_notice"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:src="@mipmap/test_alpha_click"/>
</RelativeLayout>

test_alpha_click图片：

除了边框黄色区域和中心橙色区域之外均为透明。需要点击透明处由背景CameraImageView组件响应点击事件。否则由NoticeImageView组件自己响应点击事件。

首先需要做的是判断点击的NoticeImageView位置是否为透明。可以在NoticeImageView中设置监听事件：

setOnTouchListener(new OnTouchListener() {
    @Override
    public boolean onTouch(View view, MotionEvent motionEvent) {
        if (motionEvent.getAction() == MotionEvent.ACTION_UP) {
            Bitmap bitmap = ((BitmapDrawable) getDrawable()).getBitmap();
            int pixel = bitmap.getPixel((int) motionEvent.getX(), (int) motionEvent.getY());
            if (pixel == 0) {
                Toast.makeText(mContext, TAG + "->透明区域", Toast.LENGTH_SHORT).show();
                return true;//消费掉事件，不会传递到onClick
            }
        }
        return false;
    }
});

然后需要将事件传递到CameraImageView。因为CameraImageView与NoticeImageView同属于一个父View，我们可以获取到父View，然后获取CameraImageView的实例。调用对应的方法。

ViewGroup parent = (ViewGroup) getParent();
int childCount = parent.getChildCount();
for (int i = 0; i < childCount; i++) {
    View child = parent.getChildAt(i);
    if (child.getId() == R.id.img_camera && child instanceof CameraImageView) {
        ((CameraImageView)child).click(child);
        break;
    }
}

整体代码如下：

NoticeImageView

public class NoticeImageView extends AppCompatImageView {
    private final String TAG = "NoticeImageView";
    private Context mContext;

    public NoticeImageView(Context context) {
        this(context, null);
    }

    public NoticeImageView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
        mContext = context;
        setOnTouchListener(new OnTouchListener() {
            @Override
            public boolean onTouch(View view, MotionEvent motionEvent) {
                if (motionEvent.getAction() == MotionEvent.ACTION_UP) {
                    Bitmap bitmap = ((BitmapDrawable) getDrawable()).getBitmap();
                    int pixel = bitmap.getPixel((int) motionEvent.getX(), (int) motionEvent.getY());
                    if (pixel == 0) {
                        Toast.makeText(mContext, TAG + "->透明区域", Toast.LENGTH_SHORT).show();
                        ViewGroup parent = (ViewGroup) getParent();
                        int childCount = parent.getChildCount();
                        for (int i = 0; i < childCount; i++) {
                            View child = parent.getChildAt(i);
                            if (child.getId() == R.id.img_camera && child instanceof CameraImageView) {
                                ((CameraImageView)child).click(child);
                                break;
                            }
                        }
                        return true;
                    }
                }
                return false;
            }
        });

        setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View view) {
                Toast.makeText(mContext, TAG + "->点击事件", Toast.LENGTH_SHORT).show();
            }
        });
    }
}

CameraImageView

public class CameraImageView extends AppCompatImageView {
    private final String TAG = "CameraImageView";
    private Context mContext;

    public CameraImageView(Context context) {
        this(context, null);
    }

    public CameraImageView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
        mContext = context;
    }

    public void click(View view) {
        Toast.makeText(mContext, TAG + "->点击事件", Toast.LENGTH_SHORT).show();
    }
}