Java 使用AffineTransform旋转图像
我上课了Airplane。在这个类中，我有img一个BufferedImage类型的变量。更重要的是，我有WorldMap重写功能的类paintComponent(Graphics g)：
@Overridepublic void paintComponent(Graphics g) {
Graphics2D g2d = (Graphics2D) g;
g2d.drawImage(mapa, 0, 0, getWidth(), getHeight(), null);
drawAirplanes(g2d);
}
函数drawAirplanes()看起来像这样：
private void drawAirplane(Graphics2D g){ for(Samolot i: s){
i.rotateAirplane();
g.drawImage(i.getImg(),i.getX(),i.getY(),(int)i.getDim().getWidth(),(int)i.getDim().getHeight(), null);
}
}
它只需要1）旋转飞机（飞机对象内部的BufferedImage）2）画他。
我的Airplane.rotateAirplane（）函数如下所示：
public void rotateSamolot() { AffineTransform tx = new AffineTransform();
tx.translate(10,10); //10, 10 is height and width of img divide by 2
tx.rotate(Math.PI / 2);
tx.translate(-10,-10);
AffineTransformOp op = new AffineTransformOp(tx, AffineTransformOp.TYPE_BILINEAR);
BufferedImage newImage =new BufferedImage(20, 20, img.getType()); //20, 20 is a height and width of img ofc
op.filter(img, newImage);
this.img = newImage;
}
我运行我的程序时，ofc仅mapa绘制对象。当我删除此车道时
this.img = newImage;我也有我的飞机，但是没有旋转。
回答：
主要的问题（我可以看到）是Graphics上下文的转换，它与旋转将发生的位置相抵消。
默认情况下，我“认为”旋转发生在Graphics上下文的左上角（0x0位置，你已将其转换为其他位置），这可能导致图像旋转出帧（或可见区域） ）
你应该提供旋转发生的“锚点”，通常，中心是我的个人喜好。
以下示例仅具有一个主图像（由于尺寸限制，我不得不对其进行缩放，但你可能不需要此图像）。然后，我用它生成一个“旋转的”实例，该实例的大小允许图像适合放入其中。trig带来了很多乐趣-我从某个地方偷了代码，因此归功于该开发人员。
该示例允许你单击任意位置，它将更改旋转轴，因此你可以看到发生了什么。默认位置是窗格的中心…
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.Point;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
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 SampleRotation {
public static void main(String[] args) {
new SampleRotation();
}
public SampleRotation() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
final RotationPane rotationPane = new RotationPane();
final JSlider slider = new JSlider(0, 100);
slider.addChangeListener(new ChangeListener() {
@Override
public void stateChanged(ChangeEvent e) {
double angle = 720d * (slider.getValue() / 100d);
rotationPane.setAngle(angle);
}
});
slider.setValue(0);
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(rotationPane);
frame.add(slider, BorderLayout.SOUTH);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class RotationPane extends JPanel {
private BufferedImage img;
private BufferedImage rotated;
private double angle;
private Point clickPoint;
public RotationPane() {
try {
img = ImageIO.read(new File("/Users/swhitehead/Dropbox/MegaTokyo/issue459.jpg"));
BufferedImage scaled = new BufferedImage(img.getWidth() / 2, img.getHeight() / 2, BufferedImage.TYPE_INT_ARGB);
Graphics2D g2d = scaled.createGraphics();
g2d.setTransform(AffineTransform.getScaleInstance(0.5d, 0.5d));
g2d.drawImage(img, 0, 0, this);
g2d.dispose();
img = scaled;
setAngle(0d);
} catch (IOException ex) {
ex.printStackTrace();
}
addMouseListener(new MouseAdapter() {
@Override
public void mouseClicked(MouseEvent e) {
clickPoint = e.getPoint();
repaint();
}
});
}
public void setAngle(double angle) {
this.angle = angle;
double rads = Math.toRadians(getAngle());
double sin = Math.abs(Math.sin(rads)), cos = Math.abs(Math.cos(rads));
int w = img.getWidth();
int h = img.getHeight();
int newWidth = (int) Math.floor(w * cos + h * sin);
int newHeight = (int) Math.floor(h * cos + w * sin);
rotated = new BufferedImage(newWidth, newHeight, BufferedImage.TYPE_INT_ARGB);
Graphics2D g2d = rotated.createGraphics();
AffineTransform at = new AffineTransform();
at.translate((newWidth - w) / 2, (newHeight - h) / 2);
int x = clickPoint == null ? w / 2 : clickPoint.x;
int y = clickPoint == null ? h / 2 : clickPoint.y;
at.rotate(rads, x, y);
g2d.setTransform(at);
g2d.drawImage(img, 0, 0, this);
g2d.setColor(Color.RED);
g2d.drawRect(0, 0, newWidth - 1, newHeight - 1);
g2d.dispose();
repaint();
}
public double getAngle() {
return angle;
}
@Override
public Dimension getPreferredSize() {
return img == null ? new Dimension(200, 200) : new Dimension(img.getWidth(this), img.getHeight(this));
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (rotated != null) {
Graphics2D g2d = (Graphics2D) g.create();
int x = (getWidth() - rotated.getWidth()) / 2;
int y = (getHeight() - rotated.getHeight()) / 2;
g2d.drawImage(rotated, x, y, this);
g2d.setColor(Color.RED);
x = clickPoint == null ? getWidth() / 2 : clickPoint.x;
y = clickPoint == null ? getHeight()/ 2 : clickPoint.y;
x -= 5;
y -= 5;
g2d.drawOval(x, y, 10, 10);
g2d.dispose();
}
}
}
}
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