使用以下代码,我能够绘制一条虚线:
public void foo(Graphics2D g2d, Shape shape)
{
Stroke stroke = BasicStroke(1, BasicStroke.CAP_BUTT, BasicStroke.JOIN_BEVEL, 10, new float[]{10}, 0);
g2d.setStroke(stroke);
g2d.draw(shape);
}
一旦创建了一个形状,我希望能够放大该形状(最多20 000次)。我的问题是,当我在形状上放大太多时,应用程序开始滞后,如果我继续缩放,最终会崩溃。
简单来说,我没有问题。
因此,我的问题如下:有没有办法用虚线绘制非常大的形状(例如:一个200 000像素×300 000像素的矩形)?
谢谢。
编辑:
这是一个简短的例子,我可以重现我的问题:
import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.Shape;
import java.awt.Stroke;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.JFrame;
import javax.swing.JPanel;
class Scale
{
private static int _scale = 1;
public static int getScale()
{
return _scale;
}
public static void setScale(int scale)
{
_scale = scale;
}
}
class Surface extends JPanel implements ActionListener
{
private static Surface _surface;
boolean isBlue = false;
private Surface()
{
}
public static Surface getInstance()
{
if (_surface == null)
{
_surface = new Surface();
}
return _surface;
}
private void doDrawing(Graphics g)
{
Shape rectangle = new Rectangle(0, 0, 600 * Scale.getScale(), 400 * Scale.getScale());
Graphics2D g2d = (Graphics2D) g.create();
g2d.setColor(Color.blue);
Stroke stroke = new BasicStroke(10, BasicStroke.CAP_BUTT, BasicStroke.JOIN_BEVEL, 10.0f, new float[]{10.0f}, 0);
g2d.setStroke(stroke);
// Adding a clip don't seem to do the trick :(
g2d.clip(new Rectangle(0, 0, 100, 100));
long startTime = System.nanoTime();
g2d.draw(rectangle);
long elapseTime = System.nanoTime() - startTime;
// Printing the time it took each time I render my shape. As the size increase, the time increase. If the shape decrease, the time decrease as well.
System.out.println(elapseTime);
g2d.dispose();
}
@Override
public void paintComponent(Graphics g)
{
super.paintComponent(g);
doDrawing(g);
}
@Override
public void actionPerformed(ActionEvent e)
{
repaint();
}
}
public class MainFrame extends JFrame implements KeyListener
{
public MainFrame()
{
initUI();
setFocusable(true);
addKeyListener(this);
}
public static void main(String[] args)
{
EventQueue.invokeLater(new Runnable()
{
@Override
public void run()
{
MainFrame ex = new MainFrame();
ex.setVisible(true);
}
});
}
private void initUI()
{
final Surface surface = Surface.getInstance();
add(surface);
setTitle("My boggus apps");
setSize(600, 400);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
@Override
public void keyTyped(final KeyEvent e)
{
}
@Override
public void keyPressed(final KeyEvent e)
{
int key = e.getKeyCode();
if (key == KeyEvent.VK_UP)
{
Scale.setScale(Scale.getScale() * 2);
if (Scale.getScale() > 200000)
{
Scale.setScale(200000);
}
Surface.getInstance().repaint();
}
else if (key == KeyEvent.VK_DOWN)
{
Scale.setScale(Scale.getScale() / 2);
if (Scale.getScale() < 1)
{
Scale.setScale(1);
}
Surface.getInstance().repaint();
}
else
{
System.out.println(key);
}
}
@Override
public void keyReleased(final KeyEvent e)
{
}
}
对于带有虚线笔划的长行,渲染性能不佳是AWT Graphics2D和JavaFX 2中一个已知且仍未解决的问题:
它仍然没有在Java 8u152和9.0.1中得到解决。但是,9.0.1中的性能稍好一些(在我的一个测试9.0.1与8u152中,大约1.5s与4.0s相比)。
背景:长虚线分解为它们包含的每个短划线,即使这些短划线都没有触及剪切区域。
已知但主要是不满意的解决方法:
这是使用区域交叉的解决方案。为了确保您不会最终绘制剪辑区域的一部分,我根据当前笔划的大小填充剪辑区域,假设它是一个BasicStroke。
private void drawLimited(Shape primitive, Graphics2D canvas) {
Rectangle r = canvas.getClipBounds();
Rectangle2D r2 = primitive.getBounds2D();
if (r.contains(r2)) {
canvas.draw(primitive);
} else {
int pad = canvas.getStroke() instanceof BasicStroke
? (int) Math.ceil(((BasicStroke) canvas.getStroke()).getLineWidth())
: 5;
Rectangle paddedClip = new Rectangle(r.x - pad, r.y - pad,
r.width + 2 * pad, r.height + 2 * pad);
Area a = new Area(paddedClip);
a.intersect(new Area(primitive));
canvas.draw(a);
}
}