为什么paintComponent()从未被repaint()调用?

时间:2011-05-05 19:19:28

标签: java swing awt jlayeredpane paintcomponent

我一直在研究一个将自定义JComponents绘制到JLayeredPane上的程序,但是对组件上的repaint()的所有调用似乎什么也没做,但是当重新调整窗口时,会自动调用paintComponent方法。

我一直在遵循这里给出的一些建议: Why is paint()/paintComponent() never called?

但是没有解决方案似乎解决了我的问题,在EDT上更新swing组件,在调用repaint()之前手动设置组件大小,在重写的paintComponent()中调用super.paintComponent(g)并调用revalidate()on添加新组件后的框架(虽然在这种情况下显然不是问题)

任何可能阻止通话的想法?在此先感谢:)

以下是View和SVGElementContainer的代码,view.setFile()是在需要显示新文档时调用的入口点。

public class View extends JLayeredPane implements SVGViewport {

    private SVGDocument document;
    //Array list of the SVGElementContainer components
    private ArrayList<SVGElementContainer> elemContainers;
    private SVGFrame frame;
    private int elemCount;
    private Border viewBorder;
    private int borderWidth = 1;

    //panels displayed on the JLayeredPane
    private JPanel backgroundPanel;

    /** Creates a new view */
    public View(SVGFrame frame) {
        super();
        this.frame = frame;
        elemCount = 0;

        elemContainers = new ArrayList<SVGElementContainer>();
        viewBorder = BorderFactory.createLineBorder(Color.BLACK, borderWidth);
    }

    public float getViewportWidth() {
        return getWidth();
    }

    public float getViewportHeight() {
        return getHeight();
    }

    // paints all elements and adds them to the JLayeredPane
    public void paintAllElements(){

        System.out.println("Painting all elements");

        // Paint document
        for (SVGElement elem : document) {
            //only paint stylable (rect, line, circle) elements
            if (elem instanceof SVGStylable){
                //create a new SVGElementContainer
                SVGElementContainer newElemCont = new SVGElementContainer();

                //add component to JLayeredPane
                elemCount++;
                this.add(newElemCont, new Integer(elemCount + 1));

                //set the current element within its container and calls repaint() on the component
                System.out.println("Painting element #" + elemCount);
                newElemCont.setElement(elem);
                newElemCont.repaint();
            }
            else {
                System.out.println("Skip painting group element!");
            }
        }
    }

    /** Gets the document currently being displayed by the view. */
    public SVGDocument getDocument() {
        return document;
    }

    /** Sets the document that the view should display.
     *
     * @param document the document to set
     */
    public void setDocument(SVGDocument document) {
        this.document = document;
        //paintBackground();
        paintAllElements();
        revalidate();
    }

    public void revalidate(){
        //calls validate() on the frame in order to display newly added components
        frame.getContentPane().validate();
    }
}

public class SVGElementContainer extends JPanel{

    private SVGElement elem;

    public SVGElementContainer(){
        super();
    }

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);

        System.out.println("PAINT METHOD CALLED!");
        paint2D((Graphics2D) g);
    }

    //paint the element onto this JComponent
    public void paint2D(Graphics2D g){
        if (!(elem instanceof SVGStylable)){
            System.out.println("Skipping non-stylable element!");
            return;
        }

        setOpaque(false);

        Shape shape = elem.createShape();

        // get fill stroke and width properties
        SVGStylable style = (SVGStylable) elem;
        SVGPaint fillPaint = style.getFill();
        SVGPaint strokePaint = style.getStroke();
        SVGLength strokeWidth = style.getStrokeWidth();

        // Fill the interior of the shape
        if (fillPaint.getPaintType() == SVGPaint.SVG_PAINTTYPE_RGBCOLOR) {
            g.setPaint(fillPaint.getRGBColor());
            g.fill(shape);
        }

        // Stroke the outline of the shape
        if (strokePaint.getPaintType() == SVGPaint.SVG_PAINTTYPE_RGBCOLOR) {
            Stroke stroke = new BasicStroke(strokeWidth.getValue());
            g.setStroke(stroke);
            g.setColor(strokePaint.getRGBColor());
            g.draw(shape);
        }
    }

    public void setElement(SVGElement elem){
        this.elem = elem;
        setComponentSize();
    }

    private void setComponentSize(){

        //this.setPreferredSize(new Dimension(
        //  (int)elem.getDocument().getWidth().getValue(),
        //  (int)elem.getDocument().getHeight().getValue()));

        this.setSize(new Dimension(
                (int)elem.getDocument().getWidth().getValue(),
                (int)elem.getDocument().getHeight().getValue()));
    }

}

3 个答案:

答案 0 :(得分:2)

我看到你正在调用setOpaque(false)。来自setOpaque javadoc,强调我的:

如果为true,则组件绘制其边界内的每个像素。否则,组件可能无法绘制部分或全部像素,从而允许底层像素显示。

“可能”是在repaint()调用期间第一次没有调用paintComponent()的原因。 Swing可以决定组件没有“改变”,因此不需要重新绘制。

答案 1 :(得分:2)

  

在调用repaint()之前手动设置组件大小,在重写的paintComponent()中调用super.paintComponent(g)并在添加新组件后在框架上调用revalidate()

您的代码在这些概念上是错误的。

a)从不调用setSize()方法。这是布局管理器的工作。您应该通过覆盖getPreferredSize()等方法来为布局管理器提供提示,以返回组件的首选大小

b)不要覆盖revalidate()方法。该技巧的要点是使用如下代码:

panel.add( .... );
panel.revalidate();
panel.repaint();

但我真的不知道你的所有代码应该做什么,所以我无法确定你的代码是否有意义。我也觉得你扩展JLayeredPane很奇怪。

答案 2 :(得分:1)

我可以看到扩展JPanel以获得缓冲和UI委托,但不透明度依赖于L&amp; F.相反,您应该从JComponent开始,并为您的(假设的)SVGEvent实施EventListenerList管道。