Helper.java 文件源码

public static void cropAndRescaleBitmap(final Bitmap src, final Bitmap dst, int sensorOrientation) {
    Assert.assertEquals(dst.getWidth(), dst.getHeight());
    final float minDim = Math.min(src.getWidth(), src.getHeight());

    final Matrix matrix = new Matrix();

    // We only want the center square out of the original rectangle.
    final float translateX = -Math.max(0, (src.getWidth() - minDim) / 2);
    final float translateY = -Math.max(0, (src.getHeight() - minDim) / 2);
    matrix.preTranslate(translateX, translateY);

    final float scaleFactor = dst.getHeight() / minDim;
    matrix.postScale(scaleFactor, scaleFactor);

    // Rotate around the center if necessary.
    if (sensorOrientation != 0) {
        matrix.postTranslate(-dst.getWidth() / 2.0f, -dst.getHeight() / 2.0f);
        matrix.postRotate(sensorOrientation);
        matrix.postTranslate(dst.getWidth() / 2.0f, dst.getHeight() / 2.0f);
    }

    final Canvas canvas = new Canvas(dst);
    canvas.drawBitmap(src, matrix, null);
}