CODEWITHSUNDEEP
androidmatriximageview
Lisa Anne
Lisa Anne

Reputation: 4595

Android ImageView scale image and center

I need to scale an Image inside an ImageView, I need to use the matrix for doing so,

So I do;

private void scaleImage(float scaleFactor, float focusX,float focusY) {
    Matrix displayMatrix= new Matrix();
    matrix.postScale(scaleFactor, scaleFactor);
    displayMatrix.set(matrix);
    imageView.setImageMatrix(displayMatrix);
}

The problem is no matter what i am not able to center the image inside the ImageView,

I need to put the image at the center (leaving white margins if the image is smaller than the view)

I have been bangin my head for hours, please help.

I have looked extensively at this https://stackoverflow.com/a/6172226/1815311, but without success.

Upvotes: 0

Views: 3456

Answers (2)

Levon
Levon

Reputation: 1691

All you have to do is to find new x and y coordinates where to place the image and then translate the matrix, so the image moves to the center of the ImageView. Your entire scaleImage method can look something like this:

private void scaleImage(float scaleFactor, float focusX, float focusY) {
    Matrix displayMatrix = new Matrix();
    Matrix matrix = imageView.getImageMatrix();

    float x = (imageView.getWidth() - imageView.getDrawable().getIntrinsicWidth() * scaleFactor) / 2;
    float y = (imageView.getHeight() - imageView.getDrawable().getIntrinsicHeight() * scaleFactor) / 2;

    matrix.postScale(scaleFactor, scaleFactor);
    matrix.postTranslate(x, y);

    displayMatrix.set(matrix);
    imageView.setImageMatrix(displayMatrix);
}

Upvotes: 2

Rohit Sharma
Rohit Sharma

Reputation: 2007

Try my code hope will help you:

 private void scaleImage(ImageView view, int boundBoxInDp)
{ 
 // Get the ImageView and its bitmap
 Drawable drawing = view.getDrawable();
 Bitmap bitmap = ((BitmapDrawable)drawing).getBitmap();

 // Get current dimensions
 int width = bitmap.getWidth();
 int height = bitmap.getHeight();

 // Determine how much to scale: the dimension requiring less scaling is
 // closer to the its side. This way the image always stays inside your
 // bounding box AND either x/y axis touches it.
 float xScale = ((float) boundBoxInDp) / width;
 float yScale = ((float) boundBoxInDp) / height;
 float scale = (xScale <= yScale) ? xScale : yScale;

// Create a matrix for the scaling and add the scaling data
 Matrix matrix = new Matrix();
 matrix.postScale(scale, scale);

  // Create a new bitmap and convert it to a format understood by the ImageView
  Bitmap scaledBitmap = Bitmap.createBitmap(bitmap, 0, 0, width, height, matrix, true);
  BitmapDrawable result = new BitmapDrawable(scaledBitmap);
  width = scaledBitmap.getWidth();
  height = scaledBitmap.getHeight();

 // Apply the scaled bitmap
 view.setImageDrawable(result);

 // Now change ImageView's dimensions to match the scaled image
 LinearLayout.LayoutParams params (LinearLayout.LayoutParams)view.getLayoutParams();
 params.width = width;
 params.height = height;
 view.setLayoutParams(params);
}

Upvotes: 0

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