BitmapUtils.java

package it.sephiroth.android.library.imagezoom.test.utils;

import android.graphics.Bitmap;
import android.graphics.Matrix;

/**
 * Various bitmap utilities
 *
 * @author alessandro
 */
public class BitmapUtils {

    /**
     * Resize a bitmap
     *
     * @param input
     * @param destWidth
     * @param destHeight
     * @return
     * @throws OutOfMemoryError
     */
    public static Bitmap resizeBitmap(final Bitmap input, int destWidth, int destHeight) throws OutOfMemoryError {
        return resizeBitmap(input, destWidth, destHeight, 0);
    }

    /**
     * Resize a bitmap object to fit the passed width and height
     *
     * @param input      The bitmap to be resized
     * @param destWidth  Desired maximum width of the result bitmap
     * @param destHeight Desired maximum height of the result bitmap
     * @return A new resized bitmap
     * @throws OutOfMemoryError if the operation exceeds the available vm memory
     */
    public static Bitmap resizeBitmap(final Bitmap input, int destWidth, int destHeight, int rotation) throws OutOfMemoryError {

        int dstWidth = destWidth;
        int dstHeight = destHeight;
        final int srcWidth = input.getWidth();
        final int srcHeight = input.getHeight();

        if (rotation == 90 || rotation == 270) {
            dstWidth = destHeight;
            dstHeight = destWidth;
        }

        boolean needsResize = false;
        float p;
        if ((srcWidth > dstWidth) || (srcHeight > dstHeight)) {
            needsResize = true;
            if ((srcWidth > srcHeight) && (srcWidth > dstWidth)) {
                p = (float) dstWidth / (float) srcWidth;
                dstHeight = (int) (srcHeight * p);
            } else {
                p = (float) dstHeight / (float) srcHeight;
                dstWidth = (int) (srcWidth * p);
            }
        } else {
            dstWidth = srcWidth;
            dstHeight = srcHeight;
        }

        if (needsResize || rotation != 0) {
            Bitmap output;

            if (rotation == 0) {
                output = Bitmap.createScaledBitmap(input, dstWidth, dstHeight, true);
            } else {
                Matrix matrix = new Matrix();
                matrix.postScale((float) dstWidth / srcWidth, (float) dstHeight / srcHeight);
                matrix.postRotate(rotation);
                output = Bitmap.createBitmap(input, 0, 0, srcWidth, srcHeight, matrix, true);
            }
            return output;
        } else
            return input;
    }

}