Method createMask

CodenameOne/src/com/codename1/ui/Image.java:1081–1102

()

    ///
    /// mask object that can be used with applyMask
    public Object createMask() {
        int[] rgb = getRGBCached();
        int rlen = rgb.length;
        byte[] mask;
        if (isSimdOptimizationsEnabled() && rlen >= 16) {
            Simd simd = Simd.get();
            mask = simd.allocByte(rlen);
            // `rgb` came from getRGBCached() / allocateRgbArray() and is therefore
            // a Simd-registered buffer for sizes >= 16, so we can pack straight
            // from it without an intermediate scratch. The previous scratch was
            // allocated via `allocaInt(rlen)`, which on ParparVM lowers to a
            // stack alloca - for image-scale rlen this overflows the per-thread
            // stack on iOS (e.g. a 410x410 image needs ~656 KB).
            simd.packIntToByteTruncate(rgb, 0, mask, 0, rlen);
        } else {
            mask = new byte[rlen];
            for (int iter = 0; iter < rlen; iter++) {
                mask[iter] = (byte) (rgb[iter] & 0xff);
            }
        }
        return new IndexedImage(getWidth(), getHeight(), null, mask);
    }

    /// Applies the given alpha mask onto this image and returns the resulting image
    /// see the createMask method for indication on how to convert an image into an alpha