我正在研究一个项目,我正在试图制作一个绘画程序。到目前为止,我已经使用Netbeans来创建GUI并设置程序。
到目前为止,我可以调用所有必要的协调来绘制它,但我对如何真正在其中绘画感到困惑。
在我的代码结束时,我尝试在面板内绘制失败。
任何人都可以在这样的例子中解释/展示如何使用图形?
我找到的所有例子都是做成一个类并将其扩展,JPanel
但我不知道我是否可以这样做,因为它是在netbeans中生成的。
我需要在里面画一个JPanel
,在我的里面JFrame
。我不知道该把图形课放在哪里。
package javapaint;
import java.awt.*;
import javax.swing.*;
public class JavaPaintUI extends javax.swing.JFrame {
public JavaPaintUI() {
initComponents();
}
private void initComponents() {
jPanel2 = new javax.swing.JPanel();
jPanel2.setBackground(new java.awt.Color(255, 255, 255));
jPanel2.setBorder(javax.swing.BorderFactory.createBevelBorder(javax.swing.border.BevelBorder.RAISED));
jPanel2.addMouseListener(new java.awt.event.MouseAdapter() {
public void mousePressed(java.awt.event.MouseEvent evt) {
jPanel2MousePressed(evt);
}
public void mouseReleased(java.awt.event.MouseEvent evt) {
jPanel2MouseReleased(evt);
}
});
jPanel2.addMouseMotionListener(new java.awt.event.MouseMotionAdapter() {
public void mouseDragged(java.awt.event.MouseEvent evt) {
jPanel2MouseDragged(evt);
}
});
pack();
}// </editor-fold>
int currentX, currentY, oldX, oldY;
private void jPanel2MouseDragged(java.awt.event.MouseEvent evt) {
if (tool == 1) {
currentX = evt.getX();
currentY = evt.getY();
oldX = currentX;
oldY = currentY;
System.out.println(currentX + " " + currentY);
System.out.println("PEN!!!!");
}
}
private void jPanel2MousePressed(java.awt.event.MouseEvent evt) {
oldX = evt.getX();
oldY = evt.getY();
System.out.println(oldX + " " + oldY);
}
//mouse released//
private void jPanel2MouseReleased(java.awt.event.MouseEvent evt) {
if (tool == 2) {
currentX = evt.getX();
currentY = evt.getY();
System.out.println("line!!!! from" + oldX + "to" + currentX);
}
}
//set ui visible//
public static void main(String args[]) {
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new JavaPaintUI().setVisible(true);
}
});
}
// Variables declaration - do not modify
private javax.swing.JPanel jPanel2;
// End of variables declaration
class jPanel2 extends JPanel {
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawString("BLAH", 20, 20);
g.drawRect(200, 200, 200, 200);
}
}
}
整个事情是一个JFrame
和中心的白色部分jPanel2
是我想要画的。
发布于 2018-02-28 14:34:53
请注意额外的评论。
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;
class JavaPaintUI extends JFrame {
private int tool = 1;
int currentX, currentY, oldX, oldY;
public JavaPaintUI() {
initComponents();
}
private void initComponents() {
// we want a custom Panel2, not a generic JPanel!
jPanel2 = new Panel2();
jPanel2.setBackground(new java.awt.Color(255, 255, 255));
jPanel2.setBorder(BorderFactory.createBevelBorder(BevelBorder.RAISED));
jPanel2.addMouseListener(new MouseAdapter() {
public void mousePressed(MouseEvent evt) {
jPanel2MousePressed(evt);
}
public void mouseReleased(MouseEvent evt) {
jPanel2MouseReleased(evt);
}
});
jPanel2.addMouseMotionListener(new MouseMotionAdapter() {
public void mouseDragged(MouseEvent evt) {
jPanel2MouseDragged(evt);
}
});
// add the component to the frame to see it!
this.setContentPane(jPanel2);
// be nice to testers..
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
pack();
}// </editor-fold>
private void jPanel2MouseDragged(MouseEvent evt) {
if (tool == 1) {
currentX = evt.getX();
currentY = evt.getY();
oldX = currentX;
oldY = currentY;
System.out.println(currentX + " " + currentY);
System.out.println("PEN!!!!");
}
}
private void jPanel2MousePressed(MouseEvent evt) {
oldX = evt.getX();
oldY = evt.getY();
System.out.println(oldX + " " + oldY);
}
//mouse released//
private void jPanel2MouseReleased(MouseEvent evt) {
if (tool == 2) {
currentX = evt.getX();
currentY = evt.getY();
System.out.println("line!!!! from" + oldX + "to" + currentX);
}
}
//set ui visible//
public static void main(String args[]) {
EventQueue.invokeLater(new Runnable() {
public void run() {
new JavaPaintUI().setVisible(true);
}
});
}
// Variables declaration - do not modify
private JPanel jPanel2;
// End of variables declaration
// This class name is very confusing, since it is also used as the
// name of an attribute!
//class jPanel2 extends JPanel {
class Panel2 extends JPanel {
Panel2() {
// set a preferred size for the custom panel.
setPreferredSize(new Dimension(420,420));
}
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawString("BLAH", 20, 20);
g.drawRect(200, 200, 200, 200);
}
}
}
HFOE提供了一个很好的链接,作为对此主题的第一评论。Camickr还在BufferedImage
“ 自定义绘画方法”文章中描述了活动绘画与绘画。
另请参阅此方法在a中BufferedImage
使用绘画。
发布于 2018-02-28 15:26:36
使用图形用户界面时,需要记住在Java AWT / Swing事件队列中完成在窗格上的绘图。你不能只使用// Graphics
之外的对象。方法。paint()paintComponent()
但是,您可以使用称为“ 帧缓冲 ” 的技术。基本上,你需要有一个BufferedImage的,并直接在其上描绘(看到它的createGraphics()
方法是你可以保持和重用多个操作在同一图形上下文BufferedImage
情况下,无需重新创建它所有的时间,创建一个新的实例只有当) 。然后,在你JPanel
的paintComponent()
身上,你只需要把这个BufferedImage
实例提取出来JPanel
。使用这种技术,您可以通过仿射变换相当轻松地执行缩放,平移和旋转操作。
https://stackoverflow.com/questions/-100007455
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