Scaled Bitmap maintaining aspect ratio

Here I have a tested solution where I create a scaled Bitmap out of a bitmap file:

    int scaleSize =1024;

    public Bitmap resizeImageForImageView(Bitmap bitmap) {
        Bitmap resizedBitmap = null;
        int originalWidth = bitmap.getWidth();
        int originalHeight = bitmap.getHeight();
        int newWidth = -1;
        int newHeight = -1;
        float multFactor = -1.0F;
        if(originalHeight > originalWidth) {
            newHeight = scaleSize ;
            multFactor = (float) originalWidth/(float) originalHeight;
            newWidth = (int) (newHeight*multFactor);
        } else if(originalWidth > originalHeight) {
            newWidth = scaleSize ;
            multFactor = (float) originalHeight/ (float)originalWidth;
            newHeight = (int) (newWidth*multFactor);
        } else if(originalHeight == originalWidth) {
            newHeight = scaleSize ;
            newWidth = scaleSize ;
        }
        resizedBitmap = Bitmap.createScaledBitmap(bitmap, newWidth, newHeight, false);
        return resizedBitmap;
    }

Notice that I need scaled Bitmaps which have a maximum size of 4096x4096 Pixels but the aspect ratio needs to be kept while resizing. If you need other values for width or height just replace the values "4096".

This is just an addition to the answer of Coen but the problem in his code is the line where he calculates the ratio. Dividing two Integers gives an Integer and if the result is < 1 it will be rounded to 0. So this throws the "divide by zero" exception.

here is a method from my Utils class, that does the job:

public static Bitmap scaleBitmapAndKeepRation(Bitmap targetBmp,int reqHeightInPixels,int reqWidthInPixels)
    {
        Matrix matrix = new Matrix();
        matrix .setRectToRect(new RectF(0, 0, targetBmp.getWidth(), targetBmp.getHeight()), new RectF(0, 0, reqWidthInPixels, reqHeightInPixels), Matrix.ScaleToFit.CENTER);
        Bitmap scaledBitmap = Bitmap.createBitmap(targetBmp, 0, 0, targetBmp.getWidth(), targetBmp.getHeight(), matrix, true);
        return scaledBitmap;
    }

What about this:

Bitmap background = Bitmap.createBitmap((int)width, (int)height, Config.ARGB_8888);

float originalWidth = originalImage.getWidth(); 
float originalHeight = originalImage.getHeight();

Canvas canvas = new Canvas(background);

float scale = width / originalWidth;

float xTranslation = 0.0f;
float yTranslation = (height - originalHeight * scale) / 2.0f;

Matrix transformation = new Matrix();
transformation.postTranslate(xTranslation, yTranslation);
transformation.preScale(scale, scale);

Paint paint = new Paint();
paint.setFilterBitmap(true);

canvas.drawBitmap(originalImage, transformation, paint);

return background;

I added a paint to filter the scaled bitmap.

This will respect maxWidth and maxHeight, which means the resulting bitmap will never have dimensions larger then those:

 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 > ratioBitmap) {
            finalWidth = (int) ((float)maxHeight * ratioBitmap);
        } else {
            finalHeight = (int) ((float)maxWidth / ratioBitmap);
        }
        image = Bitmap.createScaledBitmap(image, finalWidth, finalHeight, true);
        return image;
    } else {
        return image;
    }
}