Tip | 数据类型占位 & 降采样 & 像素读取 & Bitmap & Color源码

private void displaySelectedImage() {
        if(fileUri == null) return;
        ImageView imageView = (ImageView)this.findViewById(R.id.sample_img);

        BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;

        BitmapFactory.decodeFile(fileUri.getPath(), options);
        int w = options.outWidth;
        int h = options.outHeight;
        int inSample = 1;
        if(w > 1000 || h > 1000) {
            while(Math.max(w/inSample, h/inSample) > 1000) {
                inSample *=2;
            }
        }

        options.inJustDecodeBounds = false;
        options.inSampleSize = inSample;
        options.inPreferredConfig = Bitmap.Config.ARGB_8888;

        Bitmap bm = BitmapFactory.decodeFile(fileUri.getPath(), options);
        imageView.setImageBitmap(bm);
    }

    @ColorInt
    public static int rgb(float red, float green, float blue) {
        return 0xff000000 |
               ((int) (red   * 255.0f + 0.5f) << 16) |
               ((int) (green * 255.0f + 0.5f) <<  8) |
                (int) (blue  * 255.0f + 0.5f);
    }

----------
    @ColorInt
    public static int rgb(
            @IntRange(from = 0, to = 255) int red,
            @IntRange(from = 0, to = 255) int green,
            @IntRange(from = 0, to = 255) int blue) {
        return 0xff000000 | (red << 16) | (green << 8) | blue;
    }

----------
    @IntRange(from = 0, to = 255)
    public static int alpha(int color) {
        return color >>> 24;
    }

----------
    @IntRange(from = 0, to = 255)
    public static int red(int color) {
        return (color >> 16) & 0xFF;
    }

----------
    @IntRange(from = 0, to = 255)
    public static int green(int color) {
        return (color >> 8) & 0xFF;
    }

----------
    @IntRange(from = 0, to = 255)
    public static int blue(int color) {
        return color & 0xFF;
    }

public void getBitmapInfo() {
        Bitmap bm = BitmapFactory.decodeResource(this.getResources(), R.drawable.lena);
        int width = bm.getWidth();
        int height = bm.getHeight();
        Bitmap.Config config = bm.getConfig();

        int a=0, r=0, g=0, b=0;
        for(int row=0; row<height; row++) {
            for(int col=0; col<width; col++) {
                // 读取像素
                int pixel = bm.getPixel(col, row);
                a = Color.alpha(pixel);
                r = Color.red(pixel);
                g = Color.green(pixel);
                b = Color.blue(pixel);
                // 修改像素
                r = 255 - r;
                g = 255 - g;
                b = 255 - b;
                // 保存到Bitmap中
                bm.setPixel(col, row, Color.argb(a, r, g, b));
            }
        }

private void scanPixelsDemo() {
        Bitmap bm = BitmapFactory.decodeResource(this.getResources(), R.drawable.lena).copy(Bitmap.Config.ARGB_8888, true);
        int width = bm.getWidth();
        int height = bm.getHeight();
        Bitmap.Config config = bm.getConfig();

        int[] pixels = new int[width*height];
        bm.getPixels(pixels, 0, width, 0, 0, width, height);
        int a=0, r=0, g=0, b=0;
        int index = 0;
        for(int row=0; row<height; row++) {
            for(int col=0; col<width; col++) {
                // 读取像素
                index = width*row + col;
                a=(pixels[index]>>24)&0xff;
                r=(pixels[index]>>16)&0xff;
                g=(pixels[index]>>8)&0xff;
                b=pixels[index]&0xff;
                // 修改像素
                r = 255 - r;
                g = 255 - g;
                b = 255 - b;
                // 保存到Bitmap中
                pixels[index] = (a << 24) | (r << 16) | (g << 8) | b;
            }
        }

        bm.setPixels(pixels, 0, width, 0, 0, width, height);

        ImageView iv = (ImageView)this.findViewById(R.id.matInfo_imageView);
        iv.setImageBitmap(bm);
        bm.recycle();//释放内存！！！！！！！！

    }

Mat src = Imgcodecs.imread(fileUri.getPath());
if(src.empty()){
　　return;
}
int channels = src.channels();
int width = src.cols();
int height = src.rows();
---

byte[] data = new byte[channels];
int b=0, g=0, r=0;
for(int row=0; row<height; row++) {
　　for(int col=0; col<width; col++) {
　　　　　　// 读取
　　　　　　src.get(row, col, data);//!!!!!!!!!!!!!!!!!!!!!!!读取一个px
　　　　　　b = data[0]&0xff;
　　　　　　g = data[1]&0xff;
　　　　　　r = data[2]&0xff;
　　　　　　// 修改
　　　　　　b = 255 - b;
　　　　　　g = 255 - g;
　　　　　　r = 255 - r;
　　　　　　// 写入
　　　　　　data[0] = (byte)b;
　　　　　　data[1] = (byte)g;
　　　　　　data[2] = (byte)r;
　　　　　　src.put(row, col, data);
　　}
}