主要問題(我可以看到)是Graphics上下文的轉換,它偏移了旋轉發生的位置.

我認為“默認情況下”旋轉發生在圖形上下文的頂部/左角(其中它是0x0位置,你已經翻譯成其他東西),這可能導致圖像旋轉出幀(或可見區域)

您應該提供旋轉發生的“錨點”,通常,中心是我個人的偏好.

以下示例只有一個主映像(由于大小限制,我必須縮放它,但您可能不需要它).然后我用這個來生成一個“旋轉”的實例,其大小允許圖像適合in.這對于trig很有趣 – 我從某個地方偷了代碼,所以歸功于那個開發人員.

該示例允許您單擊任何位置,它將更改旋轉軸,以便您可以看到正在發生的事情.默認位置是窗格的中心…

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();

}

}

}

}

總結

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