Question

Helo亲爱的stackoverflow人：）

我的项目：我必须编写一个电路编辑器。我的问题：我创建了一个镜像文本，我将其拖到一个Image上，然后将其放入我的程序（Jpanel）中的EditorPanel中。我希望能够使用鼠标移动这个镜像文本，并能够向其添加监听器。

我尝试创建另一个JPanel，将图像放入其中，然后将这个新的JPanel放到EditorPanel中，但我得到nullpointerException，我不知道为什么。请帮忙谢谢

代码：

@Override 
      public void drawMirroredText(Graphics g3,ScrollPanel scrollpanel){ 


      Image OSC=null;

      try{
       OSC= ImageIO.read(new File("C:/Users/transparent.png"));//put transparent background to my image
      }catch(Exception e ){
          System.out.println("Cant load bufferedimages transparent background");
      }


      Graphics OSG = OSC.getGraphics();



      OSG.setColor(getForeground()); //color for text
      OSG.setFont(getFont());

      FontMetrics fm = OSG.getFontMetrics(getFont());
      int xImage = (100 - fm.stringWidth(this.text)) /2;
      int yImage = (100 + fm.getAscent() - fm.getDescent()) / 2;


        System.out.println("X is "+xImage);
         System.out.println("Y is "+yImage);
      OSG.drawString(text, xImage, yImage);
    OSG.dispose();




     // g3.drawImage(OSC, 100, 0, 0, 100, 0, 0, 100, 100, null);//EditorPanel graphics


    JPanel panel=new JPanel();

    Graphics panelG=panel.getGraphics();

    panel.setPreferredSize(new Dimension(100, 100));


    Graphics2D g2dpanel=(Graphics2D) panelG;

     g2dpanel.drawImage(OSC, 100, 0, 0, 100, 0, 0, 100, 100, panel);//draw image with mirrored text



    scrollpanel.add(panel);//Add new Jpanel to EditorPanel



  }

例外：

线程“AWT-EventQueue-0”中的异常 java.lang.NullPointerException at Panels.ScrollPanel $ Text.drawMirroredText（ScrollPanel.java:2336）at at Panels.ScrollPanel.drawallnodes（ScrollPanel.java:648）at Panels.ScrollPanel.paintComponent（ScrollPanel.java:359）at javax.swing.JComponent.paint（JComponent.java:1054）at javax.swing.JComponent.paintToOffscreen（JComponent.java:5219）at javax.swing.RepaintManager中的$ PaintManager.paintDoubleBuffered（RepaintManager.java:1529）在 javax.swing.RepaintManager中的$ PaintManager.paint（RepaintManager.java:1452）在javax.swing.RepaintManager.paint（RepaintManager.java:1249）at javax.swing.JComponent._paintImmediately（JComponent.java:5167）at at javax.swing.JComponent.paintImmediately（JComponent.java:4978）at javax.swing.RepaintManager $ 3.run（RepaintManager.java:808）at javax.swing.RepaintManager $ 3.run（RepaintManager.java:796）at java.security.AccessController.doPrivileged（Native Method）at java.security.ProtectionDomain $ 1.doIntersectionPrivilege（ProtectionDomain.java:76）在 javax.swing.RepaintManager.paintDirtyRegions（RepaintManager.java:796）在 javax.swing.RepaintManager.paintDirtyRegions（RepaintManager.java:769）在 javax.swing.RepaintManager.prePaintDirtyRegions（RepaintManager.java:718）在javax.swing.RepaintManager.access $ 1100（RepaintManager.java:62）at javax.swing.RepaintManager中的$ ProcessingRunnable.run（RepaintManager.java:1677） at java.awt.event.InvocationEvent.dispatch（InvocationEvent.java:251）在java.awt.EventQueue.dispatchEventImpl（EventQueue.java:733）at java.awt.EventQueue.access $ 200（EventQueue.java:103）at java.awt.EventQueue $ 3.run（EventQueue.java:694）at java.awt.EventQueue $ 3.run（EventQueue.java:692）at java.security.AccessController.doPrivileged（Native Method）at java.security.ProtectionDomain $ 1.doIntersectionPrivilege（ProtectionDomain.java:76）在java.awt.EventQueue.dispatchEvent（EventQueue.java:703）at java.awt.EventDispatchThread.pumpOneEventForFilters（EventDispatchThread.java:242）在 java.awt.EventDispatchThread.pumpEventsForFilter（EventDispatchThread.java:161）在 java.awt.EventDispatchThread.pumpEventsForHierarchy（EventDispatchThread.java:150）在 java.awt.EventDispatchThread.pumpEvents（EventDispatchThread.java:146）在 java.awt.EventDispatchThread.pumpEvents（EventDispatchThread.java:138） at java.awt.EventDispatchThread.run（EventDispatchThread.java:91）

将侦听器添加到图像

0 个答案: