mac版Java 7不重绘
mac版Java 7不重绘
提问于 2013-10-02 00:54:06
我正在尝试创建一个简单的绘图程序，但是每次我调用myDrawingPanel2.reaint()时，该程序只是擦除所绘制的旧点，并将其替换为新位置的一个点。我使用最新版本的Java JDK(u15)和最新版本的Netbeans在MacOSX10.8上运行此程序。我希望程序在不删除前一个点的情况下继续绘制点。
以下是我的申请表的代码：
private void myDrawingPanel2MouseClicked(java.awt.event.MouseEvent evt) {
myDrawingPanel2.setxC(evt.getX());
myDrawingPanel2.setyC(evt.getY());
myDrawingPanel2.repaint();
}
private void myDrawingPanel2MouseDragged(java.awt.event.MouseEvent evt) {
myDrawingPanel2.setxC(evt.getX());
myDrawingPanel2.setyC(evt.getY());
myDrawingPanel2.repaint();
}
private void upActionPerformed(java.awt.event.ActionEvent evt) {
myDrawingPanel2.setyC(myDrawingPanel2.getyC()-5);
myDrawingPanel2.repaint();
}
private void downActionPerformed(java.awt.event.ActionEvent evt) {
myDrawingPanel2.setyC(myDrawingPanel2.getyC()+5);
myDrawingPanel2.repaint();
}
private void leftActionPerformed(java.awt.event.ActionEvent evt) {
myDrawingPanel2.setxC(myDrawingPanel2.getxC()-5);
myDrawingPanel2.repaint();
}
private void rightActionPerformed(java.awt.event.ActionEvent evt) {
myDrawingPanel2.setxC(myDrawingPanel2.getxC()+5);
myDrawingPanel2.repaint();
}
private void upKeyPressed(java.awt.event.KeyEvent evt) {
if(evt.getKeyCode() == 38) {
myDrawingPanel2.setyC(myDrawingPanel2.getyC()-5);
}
if(evt.getKeyCode() == 40) {
myDrawingPanel2.setyC(myDrawingPanel2.getyC()+5);
}
if(evt.getKeyCode() == 39) {
myDrawingPanel2.setxC(myDrawingPanel2.getxC()+5);
}
if(evt.getKeyCode() == 37) {
myDrawingPanel2.setxC(myDrawingPanel2.getxC()-5);
}
myDrawingPanel2.repaint();
}
private void leftKeyPressed(java.awt.event.KeyEvent evt) {
if(evt.getKeyCode() == 38) {
myDrawingPanel2.setyC(myDrawingPanel2.getyC()-5);
}
if(evt.getKeyCode() == 40) {
myDrawingPanel2.setyC(myDrawingPanel2.getyC()+5);
}
if(evt.getKeyCode() == 39) {
myDrawingPanel2.setxC(myDrawingPanel2.getxC()+5);
}
if(evt.getKeyCode() == 37) {
myDrawingPanel2.setxC(myDrawingPanel2.getxC()-5);
}
myDrawingPanel2.repaint();
}
private void downKeyPressed(java.awt.event.KeyEvent evt) {
if(evt.getKeyCode() == 38) {
myDrawingPanel2.setyC(myDrawingPanel2.getyC()-5);
}
if(evt.getKeyCode() == 40) {
myDrawingPanel2.setyC(myDrawingPanel2.getyC()+5);
}
if(evt.getKeyCode() == 39) {
myDrawingPanel2.setxC(myDrawingPanel2.getxC()+5);
}
if(evt.getKeyCode() == 37) {
myDrawingPanel2.setxC(myDrawingPanel2.getxC()-5);
}
myDrawingPanel2.repaint();
}
private void rightKeyPressed(java.awt.event.KeyEvent evt) {
if(evt.getKeyCode() == 38) {
myDrawingPanel2.setyC(myDrawingPanel2.getyC()-5);
}
if(evt.getKeyCode() == 40) {
myDrawingPanel2.setyC(myDrawingPanel2.getyC()+5);
}
if(evt.getKeyCode() == 39) {
myDrawingPanel2.setxC(myDrawingPanel2.getxC()+5);
}
if(evt.getKeyCode() == 37) {
myDrawingPanel2.setxC(myDrawingPanel2.getxC()-5);
}
myDrawingPanel2.repaint();
} 下面是我的JPanel的代码：
package drawingdemo;
import java.awt.Color;
import java.awt.Graphics;
import javax.swing.JPanel;
public class MyDrawingPanel extends JPanel{
int xC = 150;
int yC = 100;
int diameter = 25;
public int getxC() {
return xC;
}
public void setxC(int xC) {
this.xC = xC;
}
public int getyC() {
return yC;
}
public void setyC(int yC) {
this.yC = yC;
}
public int getDiameter() {
return diameter;
}
public void setDiameter(int diameter) {
this.diameter = diameter;
}
@Override
public void paintComponent(Graphics g){
//super.paintComponent(g);
g.setColor(Color.RED);
g.fillOval(xC - (diameter/2), yC - (diameter/2), diameter, diameter);
}
}回答 1
Stack Overflow用户
发布于 2013-10-02 05:20:53
程序会按照你的指示去做。paintComponent用于绘制整个组件，而您的实现只绘制一个点。如果希望组件显示多个点，则需要提供一个绘制多个点paintComponent实现。这意味着你必须记住所有点的位置。
有一些技巧可以强迫Swing不清除背景，但这些将是杂乱无章的，因为你没有实现正确的语义。屏幕上的可见状态可能会在任何时候丢失，例如，当另一个窗口与您的窗口重叠时，或者用户最小化并恢复该窗口时，或者显示设置发生更改时。因此，您必须提供一个能够还原整个预期显示内容的paintComponent实现。
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/19121810
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