用不同嵌套函数重构重复循环代码

Question

我有两个for循环，通过一个2D像素数组进行图像操作。

但是，for循环的代码在这些方法中的每个方法中都是重复的。

我有办法把它拔出来吗？

/**
 * Get pixel array from current image.
 */
public void updatePixels() {
    pixels = new int[IMAGE_HEIGHT][IMAGE_WIDTH];
    for (int row = 0; row < IMAGE_HEIGHT; row++) {
        for (int col = 0; col < IMAGE_WIDTH; col ++) {
            pixels[row][col] = image.getRGB(col, row);
        }
    }
}

/**
 * Set pixel array to current image.
 */
public void commitPixels() {
    for (int row = 0; row < IMAGE_HEIGHT; row++) {
        for (int col = 0; col < IMAGE_WIDTH; col ++) {
            image.setRGB(col, row, pixels[row][col]);
        }
    }
}

public void greyscale() {
    updatePixels();
    
    for (int row = 0; row < IMAGE_HEIGHT; row++) {
        for (int col = 0; col < IMAGE_WIDTH; col++) {
            Color currentColour = new Color(pixels[row][col]);
            int r = currentColour.getRed();
            int g = currentColour.getGreen();
            int b = currentColour.getBlue();
            
            int avg = Math.round((float)((r + g + b) / 3));
            pixels[row][col] = new Color(avg, avg, avg).getRGB();
        }
    }
    commitPixels();
}

public void mirror() {
    updatePixels();
    
    int [][] pixelCopy = pixels.clone();
    
    for (int row = 0; row < IMAGE_HEIGHT; row++) {
        for (int col = 0; col < IMAGE_WIDTH; col++) {
            pixels[row][col] = pixelCopy[row][IMAGE_WIDTH - col - 1];
        }
    }
    commitPixels();
}

Answer 1

从代码来看，updatePixels和commitpixels似乎可以移到greyscale的for循环中

// updatePixel and commitPixel could be made inline as well.
public void updatePixel(int row, int col) {
    pixels[row][col] = image.getRGB(col, row);
}
    

public void commitPixel(int row, int col) {
    image.setRGB(col, row, pixels[row][col]);    
}

public void computeColor(int row, int col) {
    Color currentColour = new Color(pixels[row][col]);
    int r = currentColour.getRed();
    int g = currentColour.getGreen();
    int b = currentColour.getBlue();
                
    int avg = Math.round((float)((r + g + b) / 3));
    pixels[row][col] = new Color(avg, avg, avg).getRGB();
}
    
public void greyscale() {
    pixels = new int[IMAGE_HEIGHT][IMAGE_WIDTH];
    
    for (int row = 0; row < IMAGE_HEIGHT; row++) {
        for (int col = 0; col < IMAGE_WIDTH; col++) {
            updatePixel(row, col);
            computeColor(row, col);
            commitPixel(row, col);
        }
    }       
}

使用这种方法，可以将执行for循环的次数从3次减少到1次。