我想实现一个裁剪功能，在这里我想有一个小矩形了一个ImageView的。矩形应该是静态的，我想移动的图像，并获得图像要在矩形区域内冒出。然后取矩形作为裁剪后的图像内的图像。 我曾尝试创建使用位图作为参数画布，但它并没有奏效。我已经尝试了很多寻找如何做到这一点。但找不到它的任何地方。请帮助..

I want to implement a crop feature, where I want to have a small rectangle over an imageView. The rectangle should be static and I want to move the image and get the image to be cropped within the rectangular area. Then fetch the image within the rectangle as an cropped image. I have tried creating a canvas using Bitmap as a parameter but it doesn't worked. I have tried a lot to search how to do this. but couldn't find it anywhere. Please help..

Bitmap bitmap=BitmapFactory.decodeResource(this.getResources(), R.drawable.indoor);

    Bitmap mutBitmap = Bitmap.createBitmap(200, 400,bitmap.getConfig());

    Canvas canvas = new Canvas(mutBitmap);

            Paint paint = new Paint();
            paint.setColor(Color.BLACK);
            paint.setStyle(Paint.Style.FILL_AND_STROKE);
            paint.setStrokeWidth(10);
            float leftx = 20;
            float topy = 20;
            float rightx = 50;
            float bottomy = 100;
            canvas.drawRect(leftx, topy, rightx, bottomy, paint);

我使用上述code，但没有绘制矩形的ImageView的。

I'm using the above code, but no rectangle is drawn on the imageView..

推荐答案

您需要把图纸code在视图中的的OnDraw（）方法它被证明。您应该创建一个继承自ImageView的自定义类，然后重写的OnDraw（）的方法如下：

You need to put the drawing code in the onDraw() method of the view for it to be shown. You should create a custom class that inherits from imageView, then override the onDraw() method as below:

class DrawView extends ImageView {

    public DrawView(Context context) {
        super(context);
    }

    DrawView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    DrawView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    @Override
    public void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        Paint paint = new Paint();
        paint.setColor(Color.BLACK);
        paint.setStyle(Paint.Style.FILL_AND_STROKE);
        paint.setStrokeWidth(10);
        float leftx = 20;
        float topy = 20;
        float rightx = 50;
        float bottomy = 100;
        canvas.drawRect(leftx, topy, rightx, bottomy, paint);
    }
}

现在在你的布局，包括 drawView函数，而不是你现在的的ImageView

Now in your layout, include DrawView instead of your current ImageView