如何在透明窗口上繪製圖像？

Question

我試圖用JFrame上的Graphics2D繪製圖像。
但此代碼僅顯示空白背景。
如何做到這一點？

Java版本：SE-1.6
IDE：Eclipse的

我的代碼如下所示：

import java.awt.BasicStroke; 
import java.awt.Color; 
import java.awt.Graphics2D; 
import java.awt.image.BufferStrategy; 
import java.awt.geom.Line2D; 
import java.util.TimerTask; 

import javax.swing.JFrame; 

public class GraphicTest extends JFrame{ 

    public static void main(String[] args) { 
     GraphicTest gt = new GraphicTest(); 
     gt.start(); 
    } 

    JFrame frame; 
    BufferStrategy strategy; 

    GraphicTest(){ 
     int width = 320; 
     int height = 240; 

     this.frame = new JFrame("test"); 

     this.frame.setSize(width, height); 
     this.frame.setLocationRelativeTo(null); 
     this.frame.setLocation(576, 336); 
     this.frame.setDefaultCloseOperation(javax.swing.JFrame.EXIT_ON_CLOSE); 

     this.frame.setUndecorated(true); 
     this.frame.setBackground(new Color(0, 0, 0, 50)); 

     this.frame.setVisible(true); 

     this.frame.setIgnoreRepaint(true); 
     this.frame.createBufferStrategy(2); 
     this.strategy = this.frame.getBufferStrategy(); 
    } 

    public void onExit(){ 
     System.exit(0); 
    } 

    void start(){ 
     java.util.Timer timer = new java.util.Timer(); 
     timer.schedule(new RenderTask(), 0, 16); 
    } 

    class RenderTask extends TimerTask{ 
     int count = 0; 

     @Override 
     public void run() { 
      GraphicTest.this.render(); 
     } 
    } 

    void render() { 
     // Some moving images 
     Graphics2D g2 = (Graphics2D)this.strategy.getDrawGraphics(); 
     g2.setStroke(new BasicStroke(5.0f)); 
     Line2D line = new Line2D.Double(20, 40, 120, 140); 
     g2.draw(line); 
     this.strategy.show(); 
    } 
} 

感謝您的幫助，您可以提供。

Answer 1

• BufferStrategy通常與重量較大的組件相關聯，它們沒有任何透明度的概念。
• 透明和半透明（每阿爾法pixeling）不是「正式」支持的Java 6
• 製作一個窗口半透明效果別的畫給它下......這非常討厭，無論你使用的是Java 6或7

祕訣是讓窗口開始透明，然後覆蓋具有特殊「半透明」塗料效果的透明組件。

在Java 6（更新10我認爲）下，可用的私有API稱爲AWTUtilities，它提供了使窗口透明或半透明的能力，以下示例基於該API。

import java.awt.BorderLayout; 
import java.awt.Color; 
import java.awt.Dimension; 
import java.awt.EventQueue; 
import java.awt.Graphics; 
import java.awt.Graphics2D; 
import java.awt.Window; 
import java.awt.event.ActionEvent; 
import java.awt.event.ActionListener; 
import java.awt.image.BufferedImage; 
import java.io.File; 
import java.io.IOException; 
import java.lang.reflect.Method; 
import javax.imageio.ImageIO; 
import javax.swing.JFrame; 
import javax.swing.JPanel; 
import javax.swing.Timer; 
import javax.swing.UIManager; 
import javax.swing.UnsupportedLookAndFeelException; 

public class TransparentWindowAnimation { 

    public static void main(String[] args) { 
     new TransparentWindowAnimation(); 
    } 

    public TransparentWindowAnimation() { 
     EventQueue.invokeLater(new Runnable() { 
      @Override 
      public void run() { 
       try { 
        UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName()); 
       } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) { 
       } 

       if (supportsPerAlphaPixel()) { 
        try { 
         JFrame frame = new JFrame("Testing"); 
         frame.setUndecorated(true); 
         setOpaque(frame, false); 
         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
         frame.setLayout(new BorderLayout()); 
         frame.add(new PaintPane()); 
         frame.pack(); 
         frame.setLocationRelativeTo(null); 
         frame.setVisible(true); 
        } catch (Exception exp) { 
         exp.printStackTrace(); 
        } 
       } else { 
        System.err.println("Per pixel alphering is not supported"); 
       } 
      } 
     }); 
    } 

    public static boolean supportsPerAlphaPixel() { 
     boolean support = false; 
     try { 
      Class<?> awtUtilsClass = Class.forName("com.sun.awt.AWTUtilities"); 
      support = true; 
     } catch (Exception exp) { 
     } 
     return support; 
    } 

    public static void setOpaque(Window window, boolean opaque) throws Exception { 
     try { 
      Class<?> awtUtilsClass = Class.forName("com.sun.awt.AWTUtilities"); 
      if (awtUtilsClass != null) { 
       Method method = awtUtilsClass.getMethod("setWindowOpaque", Window.class, boolean.class); 
       method.invoke(null, window, opaque); 
      } 
     } catch (Exception exp) { 
      throw new Exception("Window opacity not supported"); 
     } 
    } 

    public class PaintPane extends JPanel { 

     private BufferedImage img; 

     private int xPos, yPos = 100; 
     private int xDelta = 0; 
     private int yDelta = 0; 

     public PaintPane() { 
      while (xDelta == 0) { 
       xDelta = (int)((Math.random() * 8)) - 4; 
      } 
      while (yDelta == 0) { 
       yDelta = (int)((Math.random() * 8)) - 4; 
      } 
      setOpaque(false); 
      try { 
       img = ImageIO.read(new File("AngryBird.png")); 
      } catch (IOException ex) { 
       ex.printStackTrace(); 
      } 

      Timer timer = new Timer(40, new ActionListener() { 
       @Override 
       public void actionPerformed(ActionEvent e) { 
        xPos += xDelta; 
        yPos += yDelta; 
        if (xPos - (img.getWidth()/2) <= 0) { 
         xPos = img.getWidth()/2; 
         xDelta *= -1; 
        } 
        if (xPos + (img.getWidth()/2) >= getWidth()) { 
         xPos = getWidth() - (img.getWidth()/2); 
         xDelta *= -1; 
        } 
        if (yPos - (img.getHeight()/2) <= 0) { 
         yPos = img.getHeight()/2; 
         yDelta *= -1; 
        } 
        if (yPos + (img.getHeight()/2) >= getHeight()) { 
         yPos = getHeight() - (img.getHeight()/2); 
         yDelta *= -1; 
        } 
        repaint(); 
       } 
      }); 
      timer.start(); 
     } 

     @Override 
     public Dimension getPreferredSize() { 
      return new Dimension(200, 200); 
     } 

     @Override 
     protected void paintComponent(Graphics g) { 
      super.paintComponent(g); 
      Graphics2D g2d = (Graphics2D) g.create(); 
      g2d.setColor(new Color(128, 128, 128, 128)); 
      g2d.fillRect(0, 0, getWidth(), getHeight()); 
      int x = xPos - (img.getWidth()/2); 
      int y = yPos - (img.getHeight()/ 2); 
      g2d.drawImage(img, x, y, this); 
      g2d.dispose(); 
     } 
    } 

} 

Answer 2

通過這個環節去你能得到的透明窗口公用事業

http://docs.oracle.com/javase/tutorial/uiswing/misc/trans_shaped_windows.html

支持的JDK 7

Answer 3

另一種方式的想法可以看出here。它可以通過

frame.setBackground(new Color(0, 0, 0, 0)); 
.... 
setOpaque(false); //for the JPanel being painted on. 

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