java 如何实现Graphics2D画的图形进行缩放？

MinQuanRen 2010-07-27 05:50:44

在java的面板(Jpanel)中用Graphics2D画的图形，如矩形，直线等，该如何实现放大或缩小功能呢？

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huntor 2010-07-28

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java.awt.Graphics2D
java.awt.geom.AffineTransform
提供的scale变换。

awusoft 2010-07-28

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放大缩小实际是重新画的吧.

小p变砖头 2010-07-28

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没有尝试过缩放但个人认为可以通过改变坐标和长度等属性实现这就是你编码能力的问题了貌似java没有现成的方法实现缩放

MinQuanRen 2010-07-28

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csdn里高手哪里去了，难倒没人会吗？
小弟急等............

MinQuanRen 2010-07-28

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(3)NewKFPoint.java这是我自定义的一个结构类
public class NewKFPoint {
private float x;
private float y;
private boolean isRemove;

public NewKFPoint() {
x = 0.0f;
y = 0.0f;
isRemove = false;
}

public NewKFPoint(float x_, float y_) {
this.x = x_;
this.y = y_;
isRemove = false;
}

public void setX(float x_) {
this.x = x_;
}

public void setY(float y_) {
this.y = y_;
}

public float getX() {
return this.x;
}

public float getY() {
return this.y;
}

public void setScale(boolean increase, double scale) {
if (increase) {
this.x *= (float)scale;
// this.y *= (float)scale;
} else {
this.x /= (float)scale;
// this.y /= (float)scale;
}
}
}

MinQuanRen 2010-07-28

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由于不能上传附件我大概把代码贴下来把
（1）NewJFrame.java(控件两个按钮、一个JScrollPane、和NewSubKFEditorPanel)大概如下：
public class NewJFrame extends javax.swing.JFrame {
private double scale[] = {1.0, 1.4, 1.7, 2.0, 2.2, 2.5, 2.7, 2.8, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0};
int i = 0;
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
if ((i > -1) && (i < scale.length)) {
System.out.println("i = " + i);
newSubKFEditorPanel1.increaseZoomScale(scale[i++]);

}
}

private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {
if ((i > 0) && (i <= scale.length)) {
System.out.println("i = " + --i);
newSubKFEditorPanel1.decreaseZoomScale(scale[i]);
}
}
private javax.swing.JButton jButton1;
private javax.swing.JButton jButton2;
private javax.swing.JScrollPane jScrollPane1;
private com.sony.threedee.gui.NewSubKFEditorPanel newSubKFEditorPanel1;
// End of variables declaration

}

（2）NewSubKFEditorPanel.java
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/

/*
* NewSubKFEditorPanel.java
*
* Created on 2010年7月27日, 上午10:21:44
*/

package com.sony.threedee.gui;

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.geom.AffineTransform;
import java.awt.geom.GeneralPath;
import java.awt.geom.Line2D;
import java.awt.geom.Rectangle2D;
import java.math.BigDecimal;

/**
*
* @author lichuanfeng
*/
public class NewSubKFEditorPanel extends javax.swing.JPanel {
//for test code
private static final float dash1[] = {10.0f};
private NewKFPoint[] kfPoints = new NewKFPoint[5];
private boolean bzoomScale = true;
// private double sx = 1.0;
// private double sy = 1.0;
private int panel_Width = 0;
// private int panel_Height = 0;
private int offset = 3;

private int fact_panelWidth = 0;
// private int fact_panelHeight = 0;
private AffineTransform at = new AffineTransform(); //AffineTransform

private Color color = new Color(255, 255, 255);
private static final float panelWidth = 499.0f;
private static final float panelHeight = 100.0f;
private static final float halfPanelWidth = 249.5f;
private static final float halfPanelHeight = 50.0f;
// private static float centerX = 250.0f;
// private static float centerY = 50.0f;
private Line2D centerLine = new Line2D.Float(0.0f, halfPanelHeight, panelWidth, halfPanelHeight);
public NewSubKFEditorPanel() {
initComponents();
Dimension dimension = this.getPreferredSize();
fact_panelWidth = dimension.width;
// fact_panelHeight = dimension.height;

int x = 10;
for (int i = 0; i < 5; i++) {
kfPoints[i] = new NewKFPoint(x, 10);
x += 10;
}
}

@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {

setAutoscrolls(true);

javax.swing.GroupLayout layout = new javax.swing.GroupLayout(this);
this.setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 508, Short.MAX_VALUE)
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 143, Short.MAX_VALUE)
);
}// </editor-fold>

// Variables declaration - do not modify
// End of variables declaration

public void setBackGroundColor(Color col) {
color = col;
}

public void setZoomScale() {
bzoomScale = false;
repaint();
}

public void setScale(boolean b, double scale) {
for (int i = 0; i < 5; i++) {
kfPoints[i].setScale(b, scale);
}
}

public void increaseZoomScale(double scale) {
if (at != null) {
// sx = scale;
// sy = scale;
setScale(true, scale);
}

panel_Width = (int)(fact_panelWidth*scale);
setPreferredSize(new Dimension(panel_Width, this.getHeight()));

updateUI();
}

public void decreaseZoomScale(double scale) {

if (at != null) {
// sx = scale;
// sy = scale;
setScale(false, scale);
}

panel_Width = (int)(panel_Width/scale);
setPreferredSize(new Dimension(panel_Width, this.getHeight()));
updateUI();
}

public void paintComponent(Graphics g) {
Graphics2D g2 = (Graphics2D) g;
// panel_Width = this.getWidth();
// panel_Height = this.getHeight();
// at = g2.getTransform();
// at.scale(sx, sy);
// g2.setTransform(at);

g2.setBackground(color);
g2.clearRect(0, 0, getWidth(), getHeight());
g2.setPaint(Color.black);
g2.draw(centerLine);

//for test code
// g2.draw(new Rectangle2D.Double(2, 2, panel_Width-20, panel_Height-20));

GeneralPath polyline = new GeneralPath();

for (int j = 0; j < 5; j++) {
polyline.moveTo (kfPoints[j].getX(), kfPoints[j].getY()-offset);
polyline.lineTo(kfPoints[j].getX()-offset, kfPoints[j].getY());
polyline.lineTo(kfPoints[j].getX(), kfPoints[j].getY()+offset);
polyline.lineTo(kfPoints[j].getX()+offset, kfPoints[j].getY());
polyline.lineTo(kfPoints[j].getX(), kfPoints[j].getY()-offset);

}
polyline.closePath();
g2.setPaint(Color.red);
g2.fill(polyline);
g2.draw(polyline);
g2.dispose();
}
}

MinQuanRen 2010-07-28

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缩放原理我大概能明白了。
现在我们的需求有变化，要求是这样的：
假如我的Panel上画了5个小菱形，现在有两个按钮对进行放大和缩小，要求如下：
（1）按固定比例值进行缩放。
（2）缩放必须横向缩放，纵向不动，缩放过程中菱形的大小不改变，改变的只是坐标位置（其实也就是横向坐标）。
（3）缩放必须以panle的中心进行两边缩放。

我是如下实现的，在一个NewSubKFEditorPanel上进行画图操作，在NewJFrame上拖动了JScrollPane，然后把NewSubKFEditorPanel放到JScrollPane上，通过比例值来改变NewSubKFEditorPanel上面的菱形坐标，同时
根据这个比例值变更NewSubKFEditorPanel的大小，以使JScrollPane滚动条出来。
但是存在两个问题：
（1）根据比例值放大并改变NewSubKFEditorPanel大小时，会导致最后找不到菱形。
（2）没有以中心点进行缩放。

一会把代码提交，请高手帮忙，再次多谢了。

heying876 2010-07-28