BufferedImage在SwingWorkers制作后不显示

Question

我在GUI中创建了一个着名的Mandelbrot分形，并加快创建我的图像我决定使用Swing Workers。在doInBackground（）方法中，我正在计算每个像素的颜色，并将所有颜色放入数组中。在done（）方法中，我访问数组并使用适当的颜色为每个像素着色。这种方式在EDT中着色时在不同的线程中进行繁重的计算。我只有一个问题 - 即使我知道它们存储在BufferedImage中（我可以将文件保存到硬盘，直接访问BufferedImage，或者 - 在缩放时 - 我正在创建一个深层副本的BufferedImage - 在这种情况下，我可以看到正确的图像）。我对Java很新，但我希望我的应用程序尽可能好。我的代码如下，在这里：http://pastebin.com/M2iw9rEY

public abstract class UniversalJPanel extends JPanel{ 

    protected BufferedImage image; 
    protected Graphics2D g2d; 

    protected int iterations = 100; // max number of iterations 
    protected double realMin = -2.0; // default min real 
    protected double realMax = 2.0;// default max real 
    protected double imaginaryMin = -1.6; // default min imaginary 
    protected double imaginaryMax = 1.6;// default max imaginary 
    protected int panelHeight; 
    protected int panelWidth; 
    protected Point pressed, released; // points pressed and released - used to calculate drawn rectangle 
    protected boolean dragged; // if is dragged - draw rectangle 
    protected int recWidth, recHeight,xStart, yStart; // variables to calculate rectangle 
    protected FractalWorker[] arrayOfWorkers; // array of Swing workers 



    public abstract int calculateIterations(Complex c); 
    public abstract double getDistance(Complex a, Complex b); 

    public void paintComponent(Graphics g){ 
     super.paintComponent(g); 
     panelHeight = getHeight(); 
     panelWidth = getWidth(); 
     image =new BufferedImage(getWidth(), getHeight(), BufferedImage.TYPE_INT_ARGB); // creating new Bufered image 
     g2d= (Graphics2D) image.getGraphics(); 



     arrayOfWorkers= new FractalWorker[getHeight()]; // create new worker for each row and execute them 
     for(int q = 0; q < getHeight(); q++){ 
       arrayOfWorkers[q] = new FractalWorker(q); 
       arrayOfWorkers[q].execute(); 
     } 

     g.drawImage(image, 0, 0, null); // draw an image 

    } 

// *** getters, setters, different code// 

private class FractalWorker extends SwingWorker<Object, Object>{ 
    private int y; // row on which worker should work now 
    private Color[] arrayOfColors; // array of colors produced by workers 
    public FractalWorker(int z){ 
     y = z;  
    } 
    protected Object doInBackground() throws Exception { 

     arrayOfColors = new Color[getWidth()]; 

     for(int q=0; q<getWidth(); q++){ // calculate and insert into array proper color for given pixel 
      int iter = calculateIterations(setComplexNumber(new Point(q,y))); 
      if(iter == iterations){ 
       arrayOfColors[q] = Color.black; 
      }else{ 
       arrayOfColors[q] = Color.getHSBColor((float)((iter/ 20.0)), 1.0f, 1.0f); 
      } 
     }   
     return null; 
    } 
    protected void done(){ // take color from the array and draw pixel 
     for(int i = 0; i<arrayOfColors.length; i++){    
      g2d.setColor(arrayOfColors[i]); 
      g2d.drawLine(i, y, i, y); 
     } 
    } 

} 

Answer 1

当你调用g.drawImage（...）图像的当前内容都被吸收到组件。那时SwingWorkers还没有完成他们的工作，因为你在drawImage调用之前马上启动它们。你不应该在paintComponent方法中启动SwingWorkers，如果已经收到绘画请求，那么启动一个长的绘图过程已经太晚了。

更好的解决方案可能是在程序启动时创建BufferedImage，然后在组件大小发生更改时重新创建BufferedImage。您应该在需要重绘时启动SwingWorkers，并在完成绘图时调用组件的repaint（）。