如何使java图形根据百分比填充图像图形？

Question

我正在研究 java Paint 组件和一个空的玻璃图像，如下所示。我的想法是根据用户给出的百分比用油漆颜色绘制此图像。例如，如果用户将 50% 的输入输入到我的 jframe 程序中，它将在下面输出半彩色的玻璃图像。我是图形 java 的新手，我们该怎么做。

我正在考虑使用 fillRect(x,y,w,h) 作为绘制图形，但我如何进行用户给出的计算，在绘制 fillRect() 上使用它并相应地显示带有图形的玻璃填充？

我可以对 fillRect() 进行什么计算？

转到这个

• 我用 ms paint 在上面画图

Answer 1

绘制矩形的 x 和宽度将是恒定的。所以有这些常数。 （我只是反复试验这些值

private static final int GLASS_WIDTH = 75;
private static final int GLASS_X = 75;

所以你只需要计算矩形的 y 和 height 值。为此，我使用了一些辅助常量

private static final int HORIZON = 210;
private static final int GLASS_Y_TOP = 10;
private static final int GLASS_HEIGHT = HORIZON - GLASS_Y_TOP;

HORIZON 是矩形的最底部，GLASS_Y_TOP 是矩形的最高点，GLASS_HEIGHT 是矩形的 100%。

知道了这些，我可以计算出 100% 的矩形

private double glassY = GLASS_Y_TOP;
private double rectHeight = GLASS_HEIGHT;
...
rect = new Rectangle2D.Double(GLASS_X, glassY, GLASS_WIDTH, rectHeight);

glassY 和rectHeight 这两个新变量是您在用户输入值更改时需要更改的值。您可以在方法调用中看到它的实现，以根据从 JSpinner 传递的值更改值

private void calculateGlassValues(int value) {
    rectHeight = GLASS_HEIGHT * (value / 100.0);
    glassY = HORIZON - rectHeight;
    rect.setRect(GLASS_X, glassY, GLASS_WIDTH, rectHeight);
    System.out.print(rect.getBounds());
}

---

最终产品

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.geom.Rectangle2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.net.URL;

import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JSpinner;
import javax.swing.SpinnerNumberModel;
import javax.swing.SwingUtilities;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;

public class PaintPercentImage extends JPanel {

    private static final int GLASS_WIDTH = 75;
    private static final int GLASS_X = 75;
    private static final int HORIZON = 210;
    private static final int GLASS_Y_TOP = 10;
    private static final int GLASS_HEIGHT = HORIZON - GLASS_Y_TOP;

    private double glassY = GLASS_Y_TOP;
    private double rectHeight = GLASS_HEIGHT;
    private BufferedImage image;
    private Rectangle2D rect;
    private int imageWidth;
    private int imageHeight;

    private static JSpinner spinner;

    public PaintPercentImage() {
        try {
            image = ImageIO.read(new URL("http://i.stack.imgur.com/G4IEu.jpg"));
            imageWidth = image.getWidth();
            imageHeight = image.getHeight();
            System.out.println(imageHeight);
        } catch (IOException e) {
            e.printStackTrace();
        }

        rect = new Rectangle2D.Double(GLASS_X, glassY, GLASS_WIDTH, rectHeight);
        spinner = createSpinner();
    }

    private JSpinner createSpinner() {
        final JSpinner spinner = new JSpinner();
        SpinnerNumberModel model = new SpinnerNumberModel(100, 0, 100, 1);
        spinner.setModel(model);
        spinner.addChangeListener(new ChangeListener() {

            @Override
            public void stateChanged(ChangeEvent e) {
                int value = (Integer) spinner.getModel().getValue();
                calculateGlassValues(value);
                System.out.println(value);
                repaint();
            }

        });
        return spinner;
    }

    private void calculateGlassValues(int value) {
        rectHeight = GLASS_HEIGHT * (value / 100.0);
        glassY = HORIZON - rectHeight;
        rect.setRect(GLASS_X, glassY, GLASS_WIDTH, rectHeight);
        System.out.print(rect.getBounds());
    }

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D) g;
        g2.drawImage(image, 0, 0, imageWidth, imageHeight, this);
        g2.setPaint(Color.YELLOW);
        g2.fill(rect);
    }

    @Override
    public Dimension getPreferredSize() {
        return new Dimension(imageWidth, imageHeight);
    }

    public static void showGui() {
        JFrame frame = new JFrame();
        frame.add(new PaintPercentImage());
        frame.add(spinner, BorderLayout.NORTH);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                showGui();
            }
        });
    }
}