test5.java

import java.awt.*;
import java.awt.image.BufferedImage;

public class CrosshatchDrawer {

    /**
     * Draws a crosshatch pattern (two sets of diagonal lines) on the given image.
     *
     * @param image   the BufferedImage to draw on
     * @param spacing distance (in pixels) between diagonal lines
     * @param color   the color for the hatch lines
     */
    public static void drawCrosshatch(BufferedImage image, int spacing, Color color) {
        int width = image.getWidth();
        int height = image.getHeight();

        Graphics2D g2d = image.createGraphics();

        // Enable anti-aliasing if desired (optional)
        g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

        // Set color and basic stroke (line thickness can be changed)
        g2d.setColor(color);
        g2d.setStroke(new BasicStroke(1.0f));

        // Draw diagonal lines with slope +1 (45°)
        // We shift the diagonal offset "d" from negative to positive
        for (int d = -height; d <= width; d += spacing) {
            // For slope +1, any line can be parameterized as y = x - d.
            // We'll figure out the segment that lies within the image:
            //   Start point (x1, y1) on the left or bottom boundary
            //   End point   (x2, y2) on the right or top boundary

            // x1, y1
            int x1 = Math.max(0, d);  // if d is negative, x1=0, else x1=d
            int y1 = x1 - d;          // y1 = x1 - d

            // y could exceed image height, so clamp
            if (y1 > height) {
                // if y1 is beyond bottom, adjust x1 so y1=height
                y1 = height;
                x1 = y1 + d;
            }

            // x2, y2
            int x2 = Math.min(width, height + d); // we want x2 <= width, also x2 = height + d if the line's top intersects y=0
            int y2 = x2 - d;                      // y2 = x2 - d

            // if y2 < 0, clamp it, meaning we hit the top boundary
            if (y2 < 0) {
                y2 = 0;
                x2 = y2 + d;
            }

            // Draw the line if it's within the image bounds
            if (0 <= x1 && x1 <= width && 0 <= y1 && y1 <= height &&
                0 <= x2 && x2 <= width && 0 <= y2 && y2 <= height) {
                g2d.drawLine(x1, y1, x2, y2);
            }
        }

        // Draw diagonal lines with slope -1 (135°)
        // Similar approach, but now y = -x + d
        for (int d = 0; d <= width + height; d += spacing) {
            // y = -x + d
            // We'll find the segment within the image.

            // x1, y1
            int x1 = Math.max(0, d - height);  // if d < height, x1=0; otherwise x1=d-height
            int y1 = -x1 + d;                  // y1 = -x1 + d

            // if y1 < 0, shift x1 until y1=0
            if (y1 < 0) {
                y1 = 0;
                x1 = d - y1; // x1 = d - 0 => x1 = d
            }

            // x2, y2
            int x2 = Math.min(d, width);
            int y2 = -x2 + d;

            // if y2 > height, clamp
            if (y2 > height) {
                y2 = height;
                x2 = d - y2;
            }

            // Draw the line if it's within the image bounds
            if (0 <= x1 && x1 <= width && 0 <= y1 && y1 <= height &&
                0 <= x2 && x2 <= width && 0 <= y2 && y2 <= height) {
                g2d.drawLine(x1, y1, x2, y2);
            }
        }

        g2d.dispose();
    }

    // Example usage
    public static void main(String[] args) {
        // Suppose we have a 400x300 BufferedImage
        BufferedImage image = new BufferedImage(400, 300, BufferedImage.TYPE_INT_ARGB);

        // Fill the background (optional)
        Graphics2D g = image.createGraphics();
        g.setColor(Color.WHITE);
        g.fillRect(0, 0, image.getWidth(), image.getHeight());
        g.dispose();

        // Draw crosshatch with a 20-pixel spacing
        drawCrosshatch(image, 20, Color.BLACK);

        // At this point, 'image' has the crosshatch drawn on it.
        // You can write it to a file if desired:
        /*
        try {
            ImageIO.write(image, "PNG", new File("crosshatch_output.png"));
        } catch (IOException e) {
            e.printStackTrace();
        }
        */
    }
}