我使用Java中的Graphics2D缩放和旋转绘制的图片。现在,我想知道当单击图片中的某个点时的原始坐标是什么。因此,鉴于旋转坐标和缩放坐标,我想计算原始坐标。有没有简单的方法可以做到这一点?
如果保留AffineTransform在绘制图像时使用的副本,则可以使用 AffineTransform.inverseTransform(Point2D ptSrc,Point2D ptDst) 将设备空间坐标转换回用户空间
AffineTransform
编辑 :如果捕获当前Graphics2D绘画的变换,请当心将Graphics2D其重新用于同一窗口/面板的多个轻量级子项,因为这样变换将相对于父组件,而鼠标坐标将相对于父组件这个孩子。您需要捕获对 转换 所做的 更改 ,而不是其最终值。例:
Graphics2D
import java.awt.BasicStroke; import java.awt.Color; import java.awt.Component; import java.awt.Dimension; 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.event.MouseMotionAdapter; import java.awt.geom.AffineTransform; import java.awt.geom.NoninvertibleTransformException; import java.awt.image.BufferedImage; import java.io.IOException; import java.net.MalformedURLException; import java.net.URL; import javax.imageio.ImageIO; import javax.swing.Box; import javax.swing.BoxLayout; import javax.swing.JComponent; import javax.swing.JFrame; public class Main { public static void main(String[] args) throws MalformedURLException, IOException { JFrame frame = new JFrame(); Box box = new Box(BoxLayout.Y_AXIS); BufferedImage image = ImageIO.read(new URL("http://sstatic.net/so/img/logo.png")); AffineTransform xfrm1 = AffineTransform.getScaleInstance(0.95, 1.25); xfrm1.rotate(-0.3); box.add(new ImageView(image, xfrm1)); AffineTransform xfrm2 = AffineTransform.getShearInstance(0.1, 0.2); xfrm2.scale(1.3, 0.9); box.add(new ImageView(image, xfrm2)); frame.add(box); frame.pack(); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setVisible(true); } } @SuppressWarnings("serial") class ImageView extends JComponent { @Override public void paintComponent(Graphics g) { Graphics2D g2d = (Graphics2D) g; try { paintXfrm = g2d.getTransform(); paintXfrm.invert(); g2d.translate(getWidth() / 2, getHeight() / 2); g2d.transform(xfrm); g2d.translate(image.getWidth() * -0.5, image.getHeight() * -0.5); paintXfrm.concatenate(g2d.getTransform()); g2d.drawImage(image, 0, 0, this); } catch (NoninvertibleTransformException ex) { ex.printStackTrace(); } } @Override public Dimension getPreferredSize() { return new Dimension(image.getWidth() * 2, image.getHeight() * 2); } ImageView(final BufferedImage image, final AffineTransform xfrm) { this.canvas = image.createGraphics(); canvas.setColor(Color.BLACK); canvas.setStroke(new BasicStroke(3.0f)); this.image = image; this.xfrm = xfrm; addMouseListener(new MouseAdapter() { @Override public void mousePressed(MouseEvent e) { try { mouseDownCoord = e.getPoint(); paintXfrm.inverseTransform(mouseDownCoord, mouseDownCoord); } catch (NoninvertibleTransformException ex) { } } @Override public void mouseExited(MouseEvent e) { mouseDownCoord = null; } }); addMouseMotionListener(new MouseMotionAdapter() { @Override public void mouseDragged(MouseEvent e) { Point p = e.getPoint(); try { paintXfrm.inverseTransform(p, p); if (mouseDownCoord != null) { canvas.drawLine(mouseDownCoord.x, mouseDownCoord.y, p.x, p.y); for (Component sibling: getParent().getComponents()) { sibling.repaint(); } } mouseDownCoord = p; } catch (NoninvertibleTransformException ex) { ex.printStackTrace(); } } }); } private Graphics2D canvas; private BufferedImage image; private AffineTransform xfrm; private AffineTransform paintXfrm; private Point mouseDownCoord; }