从内向外循环一个 for int 循环

Question

所以我一直在制作一个程序，它会截取屏幕截图然后对其进行分析。问题是它在检查时从左上角到右下角，我不知道如何从图片中间向外实施检查。这是我已经走了多远：

breakthis : {
    for (int xpos = 250; xpos < 500; xpos++) {
        for (int ypos = 250; ypos < 500; ypos++) { //Starts at the middle (250), and supposed to go outwards for example : 251, 249, 252 etc..
            int color = image.getRGB(xpos, ypos);
            int red = (color & 0x00ff0000) >> 16;
            int green = (color & 0x0000ff00) >> 8;
            int blue = color & 0x000000ff;
            if (red == 255) {
                System.out.println("Red has been found inside the picture");
                break breakthis;
            }
        }
    }
}

编辑：我还考虑过将直到 500 的每个数字都放入一个数组列表中，然后根据它们到 250 的距离以某种方式对它们进行排序并改用它，但我也无法这样做

Answer 1

这可能不是最快或设计最好的方法，但它会接受消费者，您可以在其中对 Point 对象进行操作，从图像中间螺旋循环直到到达最后一个角落。图片不必是方形的。

import java.awt.*;
import java.util.HashSet;
import java.util.Set;
import java.util.function.Consumer;

public class Main {

    public static void main(String[] args) {

        SpiralLoop.loop((Point p) -> System.out.println(p.x + "," + p.y), 500, 200);
    }
}

class SpiralLoop{
    public static void loop(Consumer<Point> consumer, int maxX, int maxY ) {
        int middleX = maxX/2;
        int middleY = maxY/2;
        Set<Point> edgesLeft = new HashSet<>();
        edgesLeft.add(new Point(0,0));
        edgesLeft.add(new Point(0,maxY));
        edgesLeft.add(new Point(maxX,0));
        edgesLeft.add(new Point(maxX,maxY));

        MovingPoint currentPoint = new MovingPoint(middleX, middleY,maxX,maxY);

        Set<Point> pointsDone = new HashSet<>();
        pointsDone.add(new Point(currentPoint.x,currentPoint.y));

        int directionIndex = 0;
        int length = 1;
        boolean lengthFlag = true;
        while(!edgesLeft.isEmpty()){
            for(int i=0; i<length;i++){
                switch(directionIndex){
                    case 0 : currentPoint.moveLeft(); break;
                    case 1 : currentPoint.moveUp(); break;
                    case 2 : currentPoint.moveRight(); break;
                    case 3 : currentPoint.moveDown(); break;
                }
                if(pointsDone.contains(currentPoint)){
                    continue;
                }
                pointsDone.add(new Point(currentPoint.x,currentPoint.y));
                consumer.accept(currentPoint);
                if(edgesLeft.contains(currentPoint)){
                    edgesLeft.remove(currentPoint);
                    if(edgesLeft.isEmpty()){
                        break;
                    }
                }
            }
            if(++directionIndex > 3){
                directionIndex = 0;
            }
            if((lengthFlag = !lengthFlag)){
                length++;
            }
        }
    }
    static class MovingPoint extends Point{
        private int maxX;
        private int maxY;

        MovingPoint(int x, int y, int maxX, int maxY){
            super(x,y);
            this.maxX = maxX;
            this.maxY = maxY;
        }

        void moveUp(){
            if(this.y != 0){
                this.y--;
            }
        }

        void moveDown(){
            if(this.y != maxY){
                this.y++;
            }
        }

        void moveRight(){
            if(this.x != maxX){
                this.x++;
            }
        }

        void moveLeft(){
            if(this.x != 0){
                this.x--;
            }
        }
    }
}

从您的代码中处理图像看起来有点类似于：

here :{
            SpiralLoop.loop((Point p) -> {
            int color = image.getRGB(p.x, p.y);
            int red = (color & 0x00ff0000) >> 16;
            int green = (color & 0x0000ff00) >> 8;
            int blue = color & 0x000000ff;
            if (red == 255) {
                System.out.println("Red has been found inside the picture");
                break here;
            }
        }), image.width, image.height);
        }