如何使用滑块更改Java Graphics2D中的图形大小？

我正在尝试用java绘制程序，使用Graphics 2D绘制3到8边之间的多边形，并且我可以使用滑块重新resize，但我不知道如何使用滑块均匀地更改它的大小。

这是我绘制的五边形的一个例子

if (sides == 5){ g.drawLine(110+x,135-y, 10+x,205-y); g.drawLine(10+x,205-y, 48+x, 320-y); g.drawLine(48+x,320-y, 170+x,320-y); g.drawLine(170+x,320-y, 205+x,205-y); g.drawLine(205+x,205-y, 110+x,135-y); } 

现在我想要均匀地改变它的大小。 （我可以在X和Y轴上移动我的多边形）。

提前致谢。

Answer 1

你可以…

使用AffineTransformation缩放Graphics上下文

 import java.awt.BorderLayout; import java.awt.Dimension; import java.awt.EventQueue; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.geom.AffineTransform; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.JSlider; import javax.swing.UIManager; import javax.swing.UnsupportedLookAndFeelException; import javax.swing.event.ChangeEvent; import javax.swing.event.ChangeListener; public class Test { public static void main(String[] args) { new Test(); } public Test() { EventQueue.invokeLater(new Runnable() { @Override public void run() { try { UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName()); } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) { ex.printStackTrace(); } TestPane tp = new TestPane(); JSlider slider = new JSlider(10, 200); slider.addChangeListener(new ChangeListener() { @Override public void stateChanged(ChangeEvent e) { tp.setScale(slider.getValue()); } }); slider.setValue(100); JFrame frame = new JFrame("Testing"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.add(tp); frame.add(slider, BorderLayout.SOUTH); frame.pack(); frame.setLocationRelativeTo(null); frame.setVisible(true); } }); } public class TestPane extends JPanel { private int scale = 100; public TestPane() { } @Override public Dimension getPreferredSize() { return new Dimension(250, 350); } public void setScale(int value) { if (value != scale) { int old = scale; this.scale = value; firePropertyChange("scale", old, scale); repaint(); } } public int getScale() { return scale; } @Override protected void paintComponent(Graphics g) { super.paintComponent(g); Graphics2D g2d = (Graphics2D) g.create(); double scaleValue = getScale() / 100d; System.out.println(scaleValue); AffineTransform at = AffineTransform.getScaleInstance(scaleValue, scaleValue); g2d.setTransform(at); int x = 10; int y = 10; g2d.drawLine(110 + x, 135 - y, 10 + x, 205 - y); g2d.drawLine(10 + x, 205 - y, 48 + x, 320 - y); g2d.drawLine(48 + x, 320 - y, 170 + x, 320 - y); g2d.drawLine(170 + x, 320 - y, 205 + x, 205 - y); g2d.drawLine(205 + x, 205 - y, 110 + x, 135 - y); g2d.dispose(); } } } 

这虽然可以扩大尺寸和位置，但这可能并不理想……

你可以…

请改用2D Graphics shape API。 这将允许您独立定义形状，并根据需要简单地绘制它。 这样做的好处是可以更好地控制转换，转换比例而不改变位置

 import java.awt.BorderLayout; import java.awt.Dimension; import java.awt.EventQueue; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.Shape; import java.awt.geom.AffineTransform; import java.awt.geom.Path2D; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.JSlider; import javax.swing.UIManager; import javax.swing.UnsupportedLookAndFeelException; import javax.swing.event.ChangeEvent; import javax.swing.event.ChangeListener; public class Test { public static void main(String[] args) { new Test(); } public Test() { EventQueue.invokeLater(new Runnable() { @Override public void run() { try { UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName()); } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) { ex.printStackTrace(); } TestPane tp = new TestPane(); JSlider slider = new JSlider(10, 200); slider.addChangeListener(new ChangeListener() { @Override public void stateChanged(ChangeEvent e) { tp.setScale(slider.getValue()); } }); slider.setValue(100); JFrame frame = new JFrame("Testing"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.add(tp); frame.add(slider, BorderLayout.SOUTH); frame.pack(); frame.setLocationRelativeTo(null); frame.setVisible(true); } }); } public class TestPane extends JPanel { private int scale = 100; private PentegonShape pentegonShape; public TestPane() { pentegonShape = new PentegonShape(100, 100); } @Override public Dimension getPreferredSize() { return new Dimension(250, 350); } public void setScale(int value) { if (value != scale) { int old = scale; this.scale = value; firePropertyChange("scale", old, scale); repaint(); } } public int getScale() { return scale; } @Override protected void paintComponent(Graphics g) { super.paintComponent(g); Graphics2D g2d = (Graphics2D) g.create(); int x = 10; int y = 10; double scaleValue = getScale() / 100d; Shape shape = AffineTransform.getScaleInstance(scaleValue, scaleValue).createTransformedShape(pentegonShape); g2d.setTransform(AffineTransform.getTranslateInstance(x, y)); g2d.draw(shape); g2d.dispose(); } } public class PentegonShape extends Path2D.Double { public PentegonShape(double width, double height) { moveTo(width / 2, 0); lineTo(width, height / 3d); lineTo((width / 5d) * 4, height); lineTo((width / 5d), height); lineTo(0, height / 3d); closePath(); } } } 

详细了解2D图形和使用几何