我正在尝试使用AffineTransform从其中心缩放矩形。我确信解决方案很明显,但我不能让它发挥作用!这是我到目前为止测试过的......
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.geom.AffineTransform;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
public class Test extends JPanel {
Test()
{
super(null);
setOpaque(true);
setBackground(Color.WHITE);
setPreferredSize(new Dimension(200,200));
}
@Override
protected void paintComponent(Graphics g1) {
super.paintComponent(g1);
Rectangle r= new Rectangle(5,5,getWidth()-10,getHeight()-10);
double cx= r.getCenterX();
double cy= r.getCenterY();
Graphics2D g=(Graphics2D)g1;
g.setColor(Color.BLACK);
AffineTransform old= g.getTransform();
for(double zoom=0.9; zoom>=0.5; zoom-=0.1)
{
AffineTransform tr2= new AffineTransform(old);
tr2.translate(-cx, -cy);
tr2.scale(zoom, zoom);
tr2.translate(cx/zoom,cy/zoom);
g.setTransform(tr2);
g.draw(r);
g.setTransform(old);
}
}
public static void main(String[] args) {
JOptionPane.showMessageDialog(null, new Test());
}
}
但它不起作用......有什么建议吗?
答案 0 :(得分:5)
假设缩放修正了矩形左上角的位置(我认为这是正确的,但是自从我用Java完成图形以来已经很长时间了),你需要将矩形转换为与缩放。
tr2.translate(
r.getWidth()*(1-zoom)/2,
r.getHeight()*(1-zoom)/2
);
tr2.scale(zoom,zoom);
g.setTransform(tr2);
所以你将矩形向左和向上移动一半的宽度和高度变化。
答案 1 :(得分:5)
当你处理矩形时,我明白了你的意思。原因是因为翻译的初始计算没有考虑容器对象的大小。
请改用:
tr2.translate(
(this.getWidth()/2) - (r.getWidth()*(zoom))/2,
(this.getHeight()/2) - (r.getHeight()*(zoom))/2
);
tr2.scale(zoom,zoom);
g.setTransform(tr2);
这样做是在缩放之前将矩形平移到面板的中心。在我的测试中,它运作得很好。
答案 2 :(得分:1)
我正在研究桌面应用程序来裁剪Brittney Spear的脸(D.A.Y.)裁剪矩形必须围绕其中心点进行缩放:
import javafx.scene.Cursor;
import javafx.scene.Group;
import javafx.scene.input.MouseEvent;
import javafx.scene.input.ScrollEvent;
import javafx.scene.paint.Color;
import javafx.scene.paint.Paint;
import javafx.scene.shape.Rectangle;
class ResizableRectangle extends Rectangle {
ResizableRectangle(double x, double y, double width, double height, Group group) {
super(x, y, width, height);
// Set scroll listener for crop selection
group.addEventHandler(ScrollEvent.SCROLL, event -> {
double zoomFactor = 1.10;
double deltaY = event.getDeltaY();
if (deltaY > 0) {
zoomFactor = 2.0 - zoomFactor;
}
super.setX(getX() + (super.getWidth() * (1 - zoomFactor) / 2)); // Set new X position
super.setWidth(getWidth() * zoomFactor); // Set new Width
super.setY(getY() + (super.getHeight() * (1 - zoomFactor) / 2)); // Set new Y position
super.setHeight(getHeight() * zoomFactor); // Set new Height
event.consume();
});
});
}
通常,算法的工作方式如下:
x + (width * (1 - zoomFactor) / 2)
y + (height * (1 - zoomFactor) / 2)
width * zoomFactor
height * zoomFactor
答案 3 :(得分:0)
这涉及一个称为共轭变换的过程。
如果S是您想要的缩放,并且T是将点(0,0)转换为缩放中心的点的变换,那么执行该作业的变换是
T(S(倒数(T)))
答案 4 :(得分:0)
(稍后)这是一个解决方案,在没有事先了解面板尺寸的情况下工作。
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Shape;
import java.awt.geom.AffineTransform;
import java.awt.geom.Ellipse2D;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
public class Test extends JPanel
{
private static final long serialVersionUID = 1L;
private Test()
{
super(null);
setOpaque(true);
setBackground(Color.WHITE);
setPreferredSize(new Dimension(600,600));
}
@Override
protected void paintComponent(Graphics g1) {
super.paintComponent(g1);
Shape r= new Ellipse2D.Double(5,380,400,200);
double cx= r.getBounds2D().getCenterX();
double cy= r.getBounds2D().getCenterY();
Graphics2D g=(Graphics2D)g1;
g.setColor(Color.BLACK);
AffineTransform old= g.getTransform();
g.drawLine((int)cx-10, (int)cy, (int)cx+10, (int)cy);
g.drawLine((int)cx, (int)cy-10, (int)cx, (int)cy+10);
for(double zoom=1; zoom>=0.1; zoom-=0.1)
{
AffineTransform tr2 =AffineTransform.getTranslateInstance(-cx, -cy);
AffineTransform tr= AffineTransform.getScaleInstance(zoom,zoom);
tr.concatenate(tr2); tr2=tr;
tr =AffineTransform.getTranslateInstance(cx, cy);
tr.concatenate(tr2); tr2=tr;
tr= new AffineTransform(old);
tr.concatenate(tr2); tr2=tr;
g.setTransform(tr2);
g.draw(r);
g.setTransform(old);
}
}
public static void main(String[] args) {
JOptionPane.showMessageDialog(null, new Test());
}
}