Java AWT繪制圓形邊框

Question

使用java awt，如何使代碼繪制圓的邊界。 此后的代碼存在性能問題，如果僅繪制輪廓，則可能會運行得更快。

       g.fillOval(gameLogic.getParticleXCoor(i) - 3,
                  gameLogic.getParticleYCoor(i) - 3,
                  gameLogic.getParticleSize(i) + 6,
                  gameLogic.getParticleSize(i) + 6);
       g.setColor(gameLogic.getParticleColor(i));
       g.fillOval(gameLogic.getParticleXCoor(i),
                  gameLogic.getParticleYCoor(i),
                  gameLogic.getParticleSize(i),
                  gameLogic.getParticleSize(i));

Answer 1

您可以嘗試用drawOval代替fillOval 。

Answer 2

如果要繪制圓，請使用Ellipse2D類：

Ellipse2D.Double circleBorder = new Ellipse2D.Double(x, y, 15, 15); 

只需從Graphics2D調用draw()方法

g2.draw(circleBorder);

例如，繪制圓圈圖標的完整代碼如下：

@Override
public void paintIcon(@Nonnull Component c, @Nonnull Graphics g, int x, int y) {
    Graphics2D g2 = (Graphics2D) g;
    RenderingHints hints = new RenderingHints(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
    BasicStroke dashed =new BasicStroke(3.0f,BasicStroke.CAP_BUTT,BasicStroke.JOIN_MITER,10.0f);
    Ellipse2D.Double circle = new Ellipse2D.Double(x+1, y+1, 14, 14);
    Ellipse2D.Double circleBorder = new Ellipse2D.Double(x, y, 15, 15);
    g2.setColor(getColor());
    g2.setRenderingHints(hints);
    g2.fill(circle);
    Composite oldComposite=g2.getComposite();
    g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0));        
    g2.setColor(new Color(1,1,1,1));
    g2.setStroke(dashed);
    g2.draw(circleBorder);
    g2.setComposite(oldComposite);
}