android-使用setPolytoply()不仅可以对齐,还可以切断图像

Bitmap 保存原始版本-这正是我所需要的,所以这里有一个解决方案:

int w = 72;
int h = 48;
float srcPoints[] = {108, 201,
                         532, 26,
                         554, 301,
                         55,  372};
float dstPoints[] = {0, 0,
                     w, 0,
                     w, h,
                     0, h};
Matrix m = new Matrix();
m.setPolyToPoly(srcPoints, 0, dstPoints, 0, dstPoints.length >> 1);
Bitmap srcBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.macedonia);
Bitmap dstBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.RGB_565);
Canvas canvas = new Canvas(dstBitmap);
canvas.clipRect(0, 0, w, h);
canvas.drawBitmap(srcBitmap, m, null);

但如果您不想使用额外内存,请使用其他方法:

class BD extends BitmapDrawable {
    Matrix matrix = new Matrix();
    int w = 72;
    int h = 48;
    RectF clip = new RectF(0, 0, w, h);

    public BD(Resources res, int resId) {
        super(res, BitmapFactory.decodeResource(res, resId));
        float src[] = {108,201,532,26,554,301,55,372};
        float dst[] = {0,0,w,0,w,h,0,h};
        matrix.setPolyToPoly(src, 0, dst, 0, src.length / 2);
    }

    @Override public int getIntrinsicWidth() {return w;}
    @Override public int getIntrinsicHeight() {return h;}

    @Override
    public void draw(Canvas canvas) {
        canvas.clipRect(clip);
        canvas.drawBitmap(getBitmap(), matrix, null);
    }
}