我一直在为另一个问题制定答案，但遇到了一个奇怪的问题...
基本上，程序使用AffineTransform来提供Graphics元素的平移、缩放和旋转，这是很简单的事情，在以前做过一千次。
问题是，当屏幕首次出现时，输出不在应该在的位置，但一旦我触摸其中一个控件（调整一个滑块），它就会跳到正确的位置。
根据截图，Graphics内容似乎错位了其他控件的数量。
如果从GUI中删除控件，则它将显示在正确的位置（在中心）。 如果我调整窗口大小，它不会解决问题，只有当其中一个滑块触发DrawPane上的repaint时才会解决...
我已经向输出添加了诊断信息，所有值都相同-即，当程序首次启动和我将所有滑块值调整为其初始值时，它们打印相同的值。
如果我从AffineTransform中删除setRotation和setScale调用，则无法解决它。 如果我删除setTranslation，则该正方形直到面板更新才会被绘制（在屏幕外绘制）
如果我使用Graphics2D g2d = (Graphics)g;而不是g.create()，结果相同（是的，我在paintComponent方法退出前重置了变换；）
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.geom.AffineTransform;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JSlider;
import javax.swing.SwingConstants;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
public class Parker {
public static void main(String[] args) {
new Parker();
}
public Parker() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (Exception ex) {
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new ControlPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class ControlPane extends JPanel {
private JSlider slider; //declare slider
private DrawPane myPanel;
public ControlPane() {
setLayout(new BorderLayout());
myPanel = new DrawPane();
myPanel.setBackground(Color.cyan); //change background color
slider = new JSlider(SwingConstants.VERTICAL, 0, 400, 100);// restrains the slider from scaling square to 0-300 pixels
slider.setMajorTickSpacing(20); //will set tick marks every 10 pixels
slider.setPaintTicks(true); //this actually paints the ticks on the screen
slider.addChangeListener(
new ChangeListener() {
@Override
public void stateChanged(ChangeEvent e) {
myPanel.setScale(slider.getValue()); //Wherever you set the slider, it will pass that value and that will paint on the screen
}
}
);
JSlider rotate = new JSlider(SwingConstants.VERTICAL, 0, 720, 0);
rotate.setMajorTickSpacing(20); //will set tick marks every 10 pixels
rotate.setPaintTicks(true); //this actually paints the ticks on the screen
rotate.addChangeListener(
new ChangeListener() {
@Override
public void stateChanged(ChangeEvent e) {
JSlider slider = (JSlider) e.getSource();
myPanel.setAngle(slider.getValue());
}
}
);
add(slider, BorderLayout.WEST);
add(rotate, BorderLayout.EAST);
add(myPanel);
slider.setValue(0);
slider.setValue(100);
rotate.setValue(0);
}
}
public class DrawPane extends JPanel {
private double scale = 1;
private double angle = 0;
private final int rectWidth = 20;
private final int rectHeight = 20;
@Override
protected void paintComponent(Graphics g)//paints obj on the screen
{
super.paintComponent(g); //prepares graphic object for drawing
int originX = getWidth() / 2;
int originY = getHeight() / 2;
int xOffset = -(rectWidth / 2);
int yOffset = -(rectHeight / 2);
g.setColor(Color.BLACK);
Graphics2D g2d = (Graphics2D) g.create();
AffineTransform at = new AffineTransform();
at.translate(originX, originY);
g2d.setTransform(at);
g2d.scale(scale, scale);
g2d.rotate(Math.toRadians(angle), 0, 0);
g2d.fillRect(xOffset, yOffset, rectWidth, rectHeight);
g2d.dispose();
g.setColor(Color.RED);
g.drawRect(originX + xOffset, originY + yOffset, rectWidth, rectWidth);
}
public void setAngle(double angle) {
this.angle = angle;
repaint();
}
public void setScale(int scale) {
// Scaling is normalized so that 1 = 100%
this.scale = (scale / 100d);
repaint();
}
@Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
}
}
基本上，似乎Graphics上下文在首次绘制时没有被正确地转换，我不知道为什么...
附注- 在Windows 7下测试Java 6和Java 7
附注2- 我也尝试在屏幕可见之前将初始比例和旋转设置为其他值，结果相同。
系统属性
awt.toolkit=sun.awt.windows.WToolkit
file.encoding=UTF-8
file.encoding.pkg=sun.io
file.separator=\
java.awt.graphicsenv=sun.awt.Win32GraphicsEnvironment
java.awt.printerjob=sun.awt.windows.WPrinterJob
java.class.path=C:\DevWork\personal\java\projects\wip\SystemProperties\build\classes
java.class.version=51.0
java.endorsed.dirs=C:\Program Files\Java\jdk1.7.0_51\jre\lib\endorsed
java.ext.dirs=C:\Program Files\Java\jdk1.7.0_51\jre\lib\ext;C:\Windows\Sun\Java\lib\ext
java.home=C:\Program Files\Java\jdk1.7.0_51\jre
java.io.tmpdir=C:\Users\shane\AppData\Local\Temp\
java.runtime.name=Java(TM) SE Runtime Environment
java.runtime.version=1.7.0_51-b13
java.specification.name=Java Platform API Specification
java.specification.vendor=Oracle Corporation
java.specification.version=1.7
java.vendor=Oracle Corporation
java.vendor.url=http://java.oracle.com/
java.vendor.url.bug=http://bugreport.sun.com/bugreport/
java.version=1.7.0_51
java.vm.info=mixed mode
java.vm.name=Java HotSpot(TM) 64-Bit Server VM
java.vm.specification.name=Java Virtual Machine Specification
java.vm.specification.vendor=Oracle Corporation
java.vm.specification.version=1.7
java.vm.vendor=Oracle Corporation
java.vm.version=24.51-b03
os.arch=amd64
os.name=Windows 7
os.version=6.1
path.separator=;
sun.arch.data.model=64
sun.cpu.endian=little
sun.cpu.isalist=amd64
sun.desktop=windows
sun.io.unicode.encoding=UnicodeLittle
sun.java.command=systemproperties.SystemProperties
sun.java.launcher=SUN_STANDARD
sun.jnu.encoding=Cp1252
sun.management.compiler=HotSpot 64-Bit Tiered Compilers
sun.os.patch.level=Service Pack 1
user.country=AU
user.dir=C:\DevWork\personal\java\projects\wip\SystemProperties
user.home=C:\Users\shane
user.language=en
user.name=shane
user.script=
user.timezone=
user.variant=
更新
如果我使用...
g2d.translate(originX, originY);
g2d.scale(scale, scale);
g2d.rotate(Math.toRadians(angle), 0, 0);
AffineTransform不起作用，无论我如何使用AffineTransform(仅平移、旋转或缩放)，似乎都得到相同的结果。更新后附有示例图片
示例显示缩放框...
注意：矩形的最后一个位置移动是下面提到的
MouseListener的结果。然而，如果我向
DrawPane添加MosueListener（直接在类内部或通过myPanel实例外部添加），并在mouseClicked上调用repaint，它会正确对齐:P更新后
如果我使用以下方法平移
Shape，AffineTransform at = new AffineTransform();
at.translate(originX, originY);
at.scale(scale, scale);
at.rotate(Math.toRadians(angle), 0, 0);
g2d.setTransform(at);
Rectangle2D rect = new Rectangle2D.Double(xOffset, yOffset, rectWidth, rectHeight);
Shape shape = at.createTransformedShape(rect);
System.out.println(rect.getBounds());
System.out.println(shape.getBounds());
输出结果符合预期，但(图形)输出仍然错误...
AffineTransform而使用Graphics#translate/scale/rotate，它可以工作:P - MadProgrammer