更改亮度

Question

我正在尝试用Java绘制RGB色轮，但我无法通过圆形形状获得渐变。我只想在屏幕上绘制它，完全没有用户交互。

这就是我现在所拥有的一切：

public void paint (Graphics g){
        super.paint(g);

        int red = 255;
        int green = 0;
        int blue = 0;
        int x1 = 500;
        int y1 = 305;
        int x2 = 500;
        int y2 = 50;

        while (green != 255){
            g.setColor(new Color(red, green, blue));
            green++;
            g.drawLine(x1, y1, x2, y2);
            x2++;
            if (y2 < y1){
                y2++;
            }
        }
        while (red != 0){
            g.setColor(new Color(red, green, blue));
            red--;
            g.drawLine(x1, y1, x2, y2);
            x2--;
            y2++;
        }
        x2 = 500;
        while (blue != 255){
            g.setColor(new Color(red, green, blue));
            blue++;
            g.drawLine(x1, y1, x2, y2);
            x2--;
            if (y2 > y1){
                y2--;
            }
        }

        while (red != 255){
            green--;
            g.setColor(new Color(red, green, blue));
            red++;
            g.drawLine(x1, y1, x2, y2);
            x2++;
            y2--;
        }
    }                
}

Which draws the gradient like this

这是what I want

Answer 1

以下是我用Java绘制RGB色轮的解决方案：

public class Main {

    public static void main(String[] args) {
        int rad = 1024;
        BufferedImage img = new BufferedImage(rad, rad, BufferedImage.TYPE_INT_RGB);

        // Center Point (MIDDLE, MIDDLE)
        int centerX = img.getWidth() / 2;
        int centerY = img.getHeight() / 2;
        int radius = (img.getWidth() / 2) * (img.getWidth() / 2);

        // Red Source is (RIGHT, MIDDLE)
        int redX = img.getWidth();
        int redY = img.getHeight() / 2;
        int redRad = img.getWidth() * img.getWidth();

        // Green Source is (LEFT, MIDDLE)
        int greenX = 0;
        int greenY = img.getHeight() / 2;
        int greenRad = img.getWidth() * img.getWidth();

        // Blue Source is (MIDDLE, BOTTOM)
        int blueX = img.getWidth() / 2;
        int blueY = img.getHeight();
        int blueRad = img.getWidth() * img.getWidth();

        for (int i = 0; i < img.getWidth(); i++) {
            for (int j = 0; j < img.getHeight(); j++) {
                int a = i - centerX;
                int b = j - centerY;

                int distance = a * a + b * b;
                if (distance < radius) {
                    int rdx = i - redX;
                    int rdy = j - redY;
                    int redDist = (rdx * rdx + rdy * rdy);
                    int redVal = (int) (255 - ((redDist / (float) redRad) * 256));

                    int gdx = i - greenX;
                    int gdy = j - greenY;
                    int greenDist = (gdx * gdx + gdy * gdy);
                    int greenVal = (int) (255 - ((greenDist / (float) greenRad) * 256));

                    int bdx = i - blueX;
                    int bdy = j - blueY;
                    int blueDist = (bdx * bdx + bdy * bdy);
                    int blueVal = (int) (255 - ((blueDist / (float) blueRad) * 256));

                    Color c = new Color(redVal, greenVal, blueVal);

                    float hsbVals[] = Color.RGBtoHSB(c.getRed(), c.getGreen(), c.getBlue(), null);

                    Color highlight = Color.getHSBColor(hsbVals[0], hsbVals[1], 1);

                    img.setRGB(i, j, RGBtoHEX(highlight));
                } else {
                    img.setRGB(i, j, 0xFFFFFF);
                }
            }
        }

        try {
            ImageIO.write(img, "png", new File("wheel.png"));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static int RGBtoHEX(Color color) {
        String hex = Integer.toHexString(color.getRGB() & 0xffffff);
        if (hex.length() < 6) {
            if (hex.length() == 5)
                hex = "0" + hex;
            if (hex.length() == 4)
                hex = "00" + hex;
            if (hex.length() == 3)
                hex = "000" + hex;
        }
        hex = "#" + hex;
        return Integer.decode(hex);
    }
}

Answer 2

更改亮度

From here，似乎最简单的方法是将颜色变为HSB。

float hsbVals[] = Color.RGBtoHSB( originalColor.getRed(),
                                   originalColor.getGreen(),
                                   originalColor.getBlue(), null );

    Color highlight = Color.getHSBColor( hsbVals[0], hsbVals[1], 
      0.5f * ( 1f + hsbVals[2] )); // Play with this part to modify rate of change

将其设为循环

根据你所拥有的，你看起来基本上需要擦除中间的所有圆形区域。

从this answer开始，看起来Area类最简单。

 public void paintComponent(Graphics g) {
        Graphics2D g2 = (Graphics2D)g.create();
        Rectangle2D rectangleNotToDrawIn = new Rectangle2D.Double(100, 100, 20, 30); 
           // You will need to find out what size ellipse you need
        Area outside = calculateOutside(rectangleNotToDrawIn);

        // draw color wheel here

        g2.setPaint(Color.black); // assuming you want black
        g2.setClip(outside);
        g2.drawLine(0, 0, getWidth(), getHeight());

    }

// Change this method to take in an ellipse shape.
    private Area calculateOutside(Rectangle2D r) {
        Area outside = new Area(new Rectangle2D.Double(0, 0, getWidth(), getHeight()));
        outside.subtract(new Area(r));
        return outside;
    }

如何用Java绘制RGB色轮

2 个答案:

更改亮度

将其设为循环