如何禁用java.awt.Graphics.fillRect（int x，int y，int width，int height）的效果？

这是原始图像：

我使用java.awt.Graphics.fillRect（int x，int y，int width，int height）在图像上添加彩色矩形。

Graphics imageGraphics = image.createGraphics(); Color color = new Color(0,0,0,100); imageGraphics.setColor(color); imageGraphics.fillRect(0, 0, 800, 600); 

所以图像已被反转，看起来像这样： 之后，我想部分清除黑色透明矩形并显示原始图像。 imageGraphics.clearRect（100,100,100,100）; 但效果是这样的：

我的要求是：

我想知道为什么它不起作用，有没有其他方法来实现它？

Answer 1

请记住，绘画具有破坏性。 有可能使用AlphaComposite来实现这个结果，但更简单的解决方案可能是简单的建设性复合形状和涂料。

下面的示例创建了两个Rectangles ，一个是我们要填充的区域，一个是我们想要显示的区域，然后从第一个区域中减去第二个（创建窗口），然后将结果绘制在图像顶​​部

 import java.awt.AlphaComposite; import java.awt.Color; import java.awt.Dimension; import java.awt.EventQueue; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.Rectangle; import java.awt.geom.Area; import java.awt.image.BufferedImage; import java.io.File; import java.io.IOException; import javax.imageio.ImageIO; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.UIManager; import javax.swing.UnsupportedLookAndFeelException; public class ShowArea { public static void main(String[] args) { new ShowArea(); } public ShowArea() { EventQueue.invokeLater(new Runnable() { @Override public void run() { try { UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName()); } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) { ex.printStackTrace(); } JFrame frame = new JFrame("Testing"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.add(new TestPane()); frame.pack(); frame.setLocationRelativeTo(null); frame.setVisible(true); } }); } public class TestPane extends JPanel { private BufferedImage img; public TestPane() { try { img = ImageIO.read(new File("sample.png")); Rectangle bounds = new Rectangle(0, 0, img.getWidth(), img.getHeight()); Rectangle clip = new Rectangle(150, 10, 100, 100); Area area = new Area(bounds); area.subtract(new Area(clip)); Graphics2D g2d = img.createGraphics(); g2d.setColor(Color.BLACK); g2d.setComposite(AlphaComposite.SrcOver.derive(0.5f)); g2d.fill(area); g2d.dispose(); } catch (IOException ex) { ex.printStackTrace(); } } @Override public Dimension getPreferredSize() { return img == null ? new Dimension(200, 200) : new Dimension(img.getWidth(), img.getHeight()); } @Override protected void paintComponent(Graphics g) { super.paintComponent(g); Graphics2D g2d = (Graphics2D) g.create(); int x = (getWidth() - img.getWidth()) / 2; int y = (getHeight() - img.getHeight()) / 2; g2d.drawImage(img, x, y, this); g2d.dispose(); } } } 

如果我正在做某种绘制程序，我会在paintComponent方法中完成所有操作，或者以某种方式使它不影响原始图像，否则你基本会破坏图像直到你重新加载它

另一种解决方案可能是复制一份您想要保留的原始区域，然后将其重新打印回来，例如……

 img = ImageIO.read(new File("sample.png")); // This is the portion of the image we want to save... BufferedImage cutout = img.getSubimage(150, 10, 100, 100); // This is the area we want to paint over... Rectangle bounds = new Rectangle(0, 0, img.getWidth(), img.getHeight()); Graphics2D g2d = img.createGraphics(); g2d.setColor(Color.BLACK); // Save the current Composite so we can reset it... Composite comp = g2d.getComposite(); // Apply the composite and fill the area... g2d.setComposite(AlphaComposite.SrcOver.derive(0.5f)); g2d.fill(area); // Reset the composite g2d.setComposite(comp); // Draw the part of the image we saved previously... g2d.drawImage(cutout, 150, 10, this); g2d.dispose(); 

Answer 2

你不能按照你想要的方式去做。

可以通过创建一个填充了Color(0,0,0,200)的BufferedImage来完成，然后在该图像中绘制颜色为Color(0,0,0,200)矩形，然后将其应用于图像。 请记住，绘制filledRectange不是“撤消操作” – 它写在像素上，无法撤消。

编辑

  Icon imageIcon = new javax.swing.ImageIcon("image.jpg"); BufferedImage mask = new BufferedImage(imageIcon.getIconWidth(), imageIcon.getIconHeight(), BufferedImage.TYPE_4BYTE_ABGR); BufferedImage image = new BufferedImage(imageIcon.getIconWidth(), imageIcon.getIconHeight(), BufferedImage.TYPE_4BYTE_ABGR); imageIcon.paintIcon(null, image.getGraphics(), 0, 0); Graphics maskGraphics = mask.getGraphics(); //drawing grey background maskGraphics.setColor(new Color(0, 0, 0, 120)); maskGraphics.fillRect(0, 0, mask.getWidth(), mask.getHeight()); //drawing black frame maskGraphics.setColor(new Color(0, 0, 0, 255)); maskGraphics.drawRect(99, 99, 301, 301); //drawing original image window maskGraphics.drawImage(image, 100, 100, 400, 400, 100, 100, 400, 400, null); //apply mask on image new ImageIcon(mask).paintIcon(null, image.getGraphics(), 0, 0); //result presentation label.setIcon(new ImageIcon(image)); 

Answer 3

是的，这很容易实现。 问题是任何绘制操作都是破坏性的，你看到的就是你得到的，绘制的信息就会丢失。

像这样存储子图像的东西，做你的绘画操作然后将子图像重新绘制在顶部。

 public class Q23709070 { public static void main(String[] args) { JFrame frame = new JFrame(); Panel p = new Panel(); frame.getContentPane().add(p); frame.pack(); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setLocationRelativeTo(null); frame.setVisible(true); } static class Panel extends JPanel { int w = 400; int h = 400; int x = 100; int y = 100; BufferedImage img; BufferedImage subImg; BufferedImage save; public Panel() { try { img = ImageIO.read(getClass().getResourceAsStream("0qzCf.jpg")); } catch (IOException e) { } subImg = img.getSubimage(x, y, w, h); } @Override protected void paintComponent(Graphics g) { super.paintComponent(g); Graphics2D g2d = (Graphics2D) g.create(); Color g2dColor = g2d.getColor(); Color fillColor = new Color(0, 0, 0, 100); g2d.drawImage(img, 0, 0, null); g2d.setColor(fillColor); g2d.fillRect(0, 0, img.getWidth(), img.getHeight()); g2d.drawImage(subImg, x, y, null); g2d.setColor(g2dColor); if (save == null) { save = new BufferedImage(img.getWidth(), img.getHeight(), img.getType()); this.paint(save.getGraphics()); try { ImageIO.write(save, "jpg", new File("save.jpg")); } catch (IOException e) { } } } @Override @Transient public Dimension getPreferredSize() { return new Dimension(img.getWidth(), img.getHeight()); } } } 

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