Resizing a bitmap to a fixed value but without changing the aspect ratio

Try this, calculate the ratio and then rescale.

private Bitmap scaleBitmap(Bitmap bm) {    int width = bm.getWidth();    int height = bm.getHeight();    Log.v("Pictures", "Width and height are " + width + "--" + height);    if (width > height) {        // landscape        float ratio = (float) width / maxWidth;        width = maxWidth;        height = (int)(height / ratio);    } else if (height > width) {        // portrait        float ratio = (float) height / maxHeight;        height = maxHeight;        width = (int)(width / ratio);    } else {        // square        height = maxHeight;        width = maxWidth;    }    Log.v("Pictures", "after scaling Width and height are " + width + "--" + height);    bm = Bitmap.createScaledBitmap(bm, width, height, true);    return bm;}

The answer by Coen Damen doesn't always respect Max Height and Max Width.Here's an answer that does:

 private static Bitmap resize(Bitmap image, int maxWidth, int maxHeight) {    if (maxHeight > 0 && maxWidth > 0) {        int width = image.getWidth();        int height = image.getHeight();        float ratioBitmap = (float) width / (float) height;        float ratioMax = (float) maxWidth / (float) maxHeight;        int finalWidth = maxWidth;        int finalHeight = maxHeight;        if (ratioMax > 1) {            finalWidth = (int) ((float)maxHeight * ratioBitmap);        } else {            finalHeight = (int) ((float)maxWidth / ratioBitmap);        }        image = Bitmap.createScaledBitmap(image, finalWidth, finalHeight, true);        return image;    } else {        return image;    }}

I have stumbled upon the same problem a number of times in my projects and each time due to lack of time (and laziness) I would be satisfied with a less than optimum solution. But recently I found some time to crack down this particular issue. Here is my solution and I hope it helps someone down the line.

Bitmap scaleDownLargeImageWithAspectRatio(Bitmap image)            {                int imageVerticalAspectRatio,imageHorizontalAspectRatio;                float bestFitScalingFactor=0;                float percesionValue=(float) 0.2;                    //getAspect Ratio of Image                int imageHeight=(int) (Math.ceil((double) image.getHeight()/100)*100);                int imageWidth=(int) (Math.ceil((double) image.getWidth()/100)*100);                int GCD=BigInteger.valueOf(imageHeight).gcd(BigInteger.valueOf(imageWidth)).intValue();                imageVerticalAspectRatio=imageHeight/GCD;                imageHorizontalAspectRatio=imageWidth/GCD;                Log.i("scaleDownLargeImageWIthAspectRatio","Image Dimensions(W:H): "+imageWidth+":"+imageHeight);                Log.i("scaleDownLargeImageWIthAspectRatio","Image AspectRatio(W:H): "+imageHorizontalAspectRatio+":"+imageVerticalAspectRatio);                    //getContainer Dimensions                int displayWidth = getWindowManager().getDefaultDisplay().getWidth();                int displayHeight = getWindowManager().getDefaultDisplay().getHeight();               //I wanted to show the image to fit the entire device, as a best case. So my ccontainer dimensions were displayWidth & displayHeight. For your case, you will need to fetch container dimensions at run time or you can pass static values to these two parameters                     int leftMargin = 0;                int rightMargin = 0;                int topMargin = 0;                int bottomMargin = 0;                int containerWidth = displayWidth - (leftMargin + rightMargin);                int containerHeight = displayHeight - (topMargin + bottomMargin);                Log.i("scaleDownLargeImageWIthAspectRatio","Container dimensions(W:H): "+containerWidth+":"+containerHeight);                    //iterate to get bestFitScaleFactor per constraints                while((imageHorizontalAspectRatio*bestFitScalingFactor <= containerWidth) &&                         (imageVerticalAspectRatio*bestFitScalingFactor<= containerHeight))                {                    bestFitScalingFactor+=percesionValue;                }                    //return bestFit bitmap                int bestFitHeight=(int) (imageVerticalAspectRatio*bestFitScalingFactor);                int bestFitWidth=(int) (imageHorizontalAspectRatio*bestFitScalingFactor);                Log.i("scaleDownLargeImageWIthAspectRatio","bestFitScalingFactor: "+bestFitScalingFactor);                Log.i("scaleDownLargeImageWIthAspectRatio","bestFitOutPutDimesions(W:H): "+bestFitWidth+":"+bestFitHeight);                image=Bitmap.createScaledBitmap(image, bestFitWidth,bestFitHeight, true);                    //Position the bitmap centre of the container                int leftPadding=(containerWidth-image.getWidth())/2;                int topPadding=(containerHeight-image.getHeight())/2;                Bitmap backDrop=Bitmap.createBitmap(containerWidth, containerHeight, Bitmap.Config.RGB_565);                Canvas can = new Canvas(backDrop);                can.drawBitmap(image, leftPadding, topPadding, null);                    return backDrop;            }