ImageView ScaleType.CENTER_CROP 实现逻辑

CalculateCenterCropPercent.java

class Scratch {

    private static int[] calculateCropPercent(int srcWidth, int srcHeight, int dstWidth, int dstHeight) {
        float targetAspect = (float) dstHeight / (float) dstWidth;
        int outWidth, outHeight;

        if (srcHeight > srcWidth * targetAspect) {
            // limited by narrow width; reduce height
            outWidth = srcWidth;
            outHeight = (int) (srcWidth * targetAspect);
        } else {
            // limited by short height; restrict width
            outHeight = srcHeight;
            outWidth = (int) (srcHeight / targetAspect);
        }

        int[] outOffset = new int[]{(srcWidth - outWidth) / 2, (srcHeight - outHeight) / 2};
        float[] outOffsetPercent = new float[]{outOffset[0] / (float) srcWidth, outOffset[1] / (float) srcHeight};


        System.out.println("src: " + srcWidth + "x" + srcHeight);
        System.out.println("dst: " + dstWidth + "x" + dstHeight);
        System.out.println("out: " + outWidth + "x" + outHeight);
        System.out.println("outOffset: " + outOffset[0] + "x" + outOffset[1]);
        System.out.println("outOffsetPercent: " + outOffsetPercent[0] + "x" + outOffsetPercent[1]);


        return outOffset;
    }

    public static void main(String[] args) {
        calculateCropPercent(720, 1280, 228, 180);
    }
}