我需要画一个给定厚度的环,看起来像这样:
中心必须是透明的,这样它就不会覆盖之前绘制的形状。 (或其他戒指)我试过这样的事情:
//g is a Graphics2D object
g.setColor(Color.RED);
g.drawOval(x,y,width,height);
g.setColor(Color.WHITE);
g.drawOval(x+thickness,y+thickness,width-2*thickness,height-2*thickness);
其中画出一个满意的圆环,却覆盖了其他形状;内部是白色的,不透明。我如何修改/重写我的代码以使其不这样做?
最佳答案
您可以创建一个 Area
来自 Ellipse2D
描述外圈,subtract
描述内圆的椭圆。这样,您将获得实际的 Shape
可以是 drawn或 filled (这仅指环实际覆盖的区域!)。
优点是您确实拥有戒指的几何形状。例如,这允许您检查环形形状 contains
是否某个点,或者用 Paint
填充它这不仅仅是一种颜色:
这是一个例子,相关部分是createRingShape
方法:
import java.awt.Color;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.RenderingHints;
import java.awt.Shape;
import java.awt.geom.Area;
import java.awt.geom.Ellipse2D;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class RingPaintTest
{
public static void main(String[] args)
{
SwingUtilities.invokeLater(new Runnable()
{
@Override
public void run()
{
createAndShowGUI();
}
});
}
private static void createAndShowGUI()
{
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
RingPaintTestPanel p = new RingPaintTestPanel();
f.getContentPane().add(p);
f.setSize(800,800);
f.setLocationRelativeTo(null);
f.setVisible(true);
}
}
class RingPaintTestPanel extends JPanel
{
@Override
protected void paintComponent(Graphics gr)
{
super.paintComponent(gr);
Graphics2D g = (Graphics2D)gr;
g.setRenderingHint(
RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g.setColor(Color.RED);
g.drawString("Text", 100, 100);
g.drawString("Text", 300, 100);
Shape ring = createRingShape(100, 100, 80, 20);
g.setColor(Color.CYAN);
g.fill(ring);
g.setColor(Color.BLACK);
g.draw(ring);
Shape otherRing = createRingShape(300, 100, 80, 20);
g.setPaint(new GradientPaint(
new Point(250, 40), Color.RED,
new Point(350, 200), Color.GREEN));
g.fill(otherRing);
g.setColor(Color.BLACK);
g.draw(otherRing);
}
private static Shape createRingShape(
double centerX, double centerY, double outerRadius, double thickness)
{
Ellipse2D outer = new Ellipse2D.Double(
centerX - outerRadius,
centerY - outerRadius,
outerRadius + outerRadius,
outerRadius + outerRadius);
Ellipse2D inner = new Ellipse2D.Double(
centerX - outerRadius + thickness,
centerY - outerRadius + thickness,
outerRadius + outerRadius - thickness - thickness,
outerRadius + outerRadius - thickness - thickness);
Area area = new Area(outer);
area.subtract(new Area(inner));
return area;
}
}
关于java - 绘制具有给定厚度、位置和半径的环。 (Java2D),我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/35524394/