CODEWITHSUNDEEP
androidgraphicsimage-processing
Rajath
Rajath

Reputation: 11926

rotating and scaling an image in android using matrix

I'm trying to rotate and then scale an image using android.graphics.Matrix. The code is as follows:

    int width = bmp1.getWidth();
    int height = bmp1.getHeight();
    int smallerVal = (height > width) ? width : height;
    int n = 0;
    while (smallerVal > 1)
    {
        smallerVal = smallerVal >> 1;
        n++;
    }

    int pow2 = (int) Math.pow(2, n);
    float scaleWidth = ((float) AppBase.width) / (float)pow2;
    float scaleHeight = ((float) AppBase.height) / (float)pow2;

    Matrix matrix = new Matrix();
    matrix.postRotate(90);
    matrix.postScale(scaleWidth, scaleHeight);
    Bitmap bmp2 = Bitmap.createBitmap(bmp1, 0, 0, pow2, pow2, matrix, true);

pow2 is to get a square power-of-2 image for the sake of applying a texture. bmp2 turns out to have -1 as height and width, ie an invalid image. Am I missing something?

Thanks,
Rajath

Upvotes: 1

Views: 4068

Answers (1)

Rajath
Rajath

Reputation: 11926

The solution I'm using for my problem is below, in case anyone needs it in future.

            int pow2 = getSquareVal(bmp1);
            int width = bmp1.getWidth();
            int height = bmp1.getHeight();
            float scaleWidth = ((float) pow2) / (float)width;
            float scaleHeight = ((float) pow2) / (float)height;

            Matrix matrix = new Matrix();
            matrix.reset();

            matrix.postScale(scaleWidth, scaleHeight);
            if (width > height)
                matrix.postRotate(90);

            bmp2 = Bitmap.createBitmap(bmp1, 0, 0, width, height, matrix, true);

Upvotes: 1

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