[英]How to use AffineTransform.quadrantRotate to rotate a bitmap?
I want to rotate a bitmap about its center point , and then draw it into a larger graphics context . 我想围绕其中心点旋转位图 ,然后将其绘制到更大的图形上下文中 。
The bitmap is 40x40 pixels
. 位图是40x40 pixels
。 The graphics context is 500x500 pixels
. 图形上下文为500x500 pixels
。 This is what I'm doing: 这就是我在做什么:
BufferedImage bi = new BufferedImage(500, 500, BufferedImage.TYPE_INT_ARGB);
Graphics2D g = bi.createGraphics();
AffineTransform at = new AffineTransform();
at.quadrantRotate(1, -20, -20); // rotate 90 degrees around center point.
at.translate(100, 40); // I want to put its top-left corner at 100,40.
g.drawImage(smallerBitmap, at, null);
...
I'm probably using quadrantRotate()
incorrectly - if I remove that line, my image gets drawn at position 100,40
correctly at least. 我可能不正确地使用了quadrantRotate()
-如果我删除那条线,我的图像至少会正确地绘制在位置100,40
处。
What am I doing wrong? 我究竟做错了什么?
Thanks 谢谢
The order of your transformation matters. 转换的顺序很重要。 Basically your example code is saying "rotate the image by 90 degrees AND then translate it...." 基本上,您的示例代码说:“将图像旋转90度,然后将其翻译...。”
So, using your code (rotate, then translate) produces... 因此,使用您的代码(旋转然后翻译)会产生...
Switching the order (translate then rotate) produces 切换顺序(平移然后旋转)会产生
... ...
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 java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
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 TestRotation100 {
public static void main(String[] args) {
new TestRotation100();
}
public TestRotation100() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
final TestPane testPane = new TestPane();
final JSlider slider = new JSlider(0, 3);
slider.addChangeListener(new ChangeListener() {
@Override
public void stateChanged(ChangeEvent e) {
testPane.setQuad(slider.getValue());
}
});
slider.setValue(0);
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(testPane);
frame.add(slider, BorderLayout.SOUTH);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private BufferedImage img;
private int quad = 0;
public TestPane() {
try {
img = ImageIO.read(new File("/Users/swhitehead/Dropbox/MegaTokyo/Rampage_Small.png"));
} catch (IOException ex) {
ex.printStackTrace();
}
}
public void setQuad(int quad) {
this.quad = quad;
repaint();
}
@Override
public Dimension getPreferredSize() {
return new Dimension(400, 400);
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
AffineTransform at = new AffineTransform();
at.translate(100, 40);
at.quadrantRotate(quad, img.getWidth() / 2, img.getHeight() / 2);
g2d.drawImage(img, at, this);
g2d.dispose();
}
}
}
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