Android - Crop an image from multipoints

2019-01-14 05:16发布

问题:

I need to crop a Bitmap, but instead of having a rectangular cropped image (which I managed successfully to do), I need it to be any form defined by coordinates.

I'm following the answer from this thread: Cutting a multipoint ploygon out of Bitmap and placing it on transparency , and trying to implement it, but unfortunatly it does not clip the image.

I did as in the description, but it seems there's a bug somewhere. The image is drawn in rectangular way. Am I missing something?

Bitmap originalBitmap=BitmapFactory.decodeResource(getResources(), R.drawable.test_image);
// Image cropped
Bitmap croppedBitmap=Bitmap.createBitmap(originalBitmap, 10, 10, 200, 200);
Canvas canvas=new Canvas(croppedBitmap);

// Create a path
Path path=new Path();
path.setFillType(FillType.INVERSE_EVEN_ODD);
path.moveTo(0, 0);
path.moveTo(0, 100);
path.moveTo(100, 0);
path.moveTo(0, 0);

// Paint with Xfermode
Paint paint=new Paint();
paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));

// Draw the path
canvas.drawPath(path, paint);

imageView.setImageBitmap(croppedBitmap);

回答1:

I was very close to the solution. Here it is:

compositeImageView = (ImageView) findViewById(R.id.imageView);

Bitmap bitmap1=BitmapFactory.decodeResource(getResources(), R.drawable.batman_ad);
Bitmap bitmap2=BitmapFactory.decodeResource(getResources(), R.drawable.logo);

Bitmap resultingImage=Bitmap.createBitmap(320, 480, bitmap1.getConfig());

Canvas canvas = new Canvas(resultingImage);

Paint paint = new Paint();
paint.setAntiAlias(true);
Path path=new Path();
path.lineTo(150, 0);
path.lineTo(230, 120);
path.lineTo(70, 120);
path.lineTo(150, 0);

canvas.drawPath(path, paint);

paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
canvas.drawBitmap(bitmap2, 0, 0, paint);

compositeImageView.setImageBitmap(resultingImage);