android-rotate.java

    private Bitmap rotateBitmap(Bitmap source, byte[] data) {
        int exifOffset = Exif.getOrientation(data);
        int rotation = this.rotation;
        int rotate = 0;

        if ((rotation < (270 + 45) && rotation > (270 - 45))) {
            Log.e("BLIMP", "270 degrees ...");
            rotate = -90;
        } else if (rotation < (90 + 45) && rotation > (90 - 45)) {
            Log.e("BLIMP", "90 degrees ...");
            rotate = 90;
        }
        rotate += exifOffset;
        if (rotate != 0) {
            Matrix matrix = new Matrix();
            Size size = resize(source.getWidth(), source.getHeight(), 1200, 1200);
            matrix.setScale(size.getScaleRatio(), size.getScaleRatio());
            matrix.postRotate(rotate, size.getWidth() / 2, size.getHeight() / 2);
            return Bitmap.createBitmap(source, 0, 0, size.getWidth(), size.getHeight(), matrix, false);
        } else {
            return source;
        }
    }

    private Size resize(int width, int height, int maxWidth, int maxHeight) {
        Size size = new Size();
        if (maxHeight > 0 && maxWidth > 0) {
            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);
            }
            Log.e("BLIMP", "Scale " + finalWidth + "," + finalHeight);
            size.setWidth(finalWidth);
            size.setHeight(finalHeight);

            int maxEdgeLength = 1200;
            float scaleRatio = (float) 1.0;

            size.setScaleRatio(scaleRatio);
// If image is smaller than target, don’t scale
            if(width <= maxEdgeLength && height <= maxEdgeLength) {
                return size;
            }

// Otherwise, compute scaling on longer edge
            if(width >= height) {
                scaleRatio = maxEdgeLength/width;
            } else {
                scaleRatio = maxEdgeLength/height;
            }
            size.setScaleRatio(scaleRatio);

            return size;
        }
        return null;
    }