Java 自定义绘画代码没有正确更新,我试图尊重剪辑区域。跑过去看看
这是可运行的java代码。如果您想测试它,请复制下面的两段代码摘录。编译并运行Triangleframe.java 我在一个JPanel上画了两个三角形(稍后我可能会添加更多)。我点击 然后拖动其中一个三角形。在我决定尊重Oracle在本课中推荐的剪辑区域之前,这项功能曾经发挥过(某种程度上)作用: 我从Java 自定义绘画代码没有正确更新,我试图尊重剪辑区域。跑过去看看,java,swing,repaint,custom-painting,Java,Swing,Repaint,Custom Painting,这是可运行的java代码。如果您想测试它,请复制下面的两段代码摘录。编译并运行Triangleframe.java 我在一个JPanel上画了两个三角形(稍后我可能会添加更多)。我点击 然后拖动其中一个三角形。在我决定尊重Oracle在本课中推荐的剪辑区域之前,这项功能曾经发挥过(某种程度上)作用: 我从repaint()切换到repaint(x,y,with,height)的原因是,当我尝试拖动其中一个三角形时,它重新绘制的速度非常慢,而且它也不太擅长跟随鼠标指针(滞后?)。我的理由是,保持
repaint()
切换到repaint(x,y,with,height)
的原因是,当我尝试拖动其中一个三角形时,它重新绘制的速度非常慢,而且它也不太擅长跟随鼠标指针(滞后?)。我的理由是,保持在一定范围内,只重新绘制我正在使用的屏幕部分可以解决问题。它确实修复了延迟,但现在只要按下鼠标按钮,我正在重新绘制的边界框似乎就不会移动。三角形仅在边界框内移动。直到我释放鼠标按钮(在该点创建一个新三角形)。我更愿意只重绘三角形而不是边界框,但为了方便起见,我尝试先解决这个问题。希望三角形能够重叠
请参阅代码中的注释以获得更深入的解释
导入java.awt.Color;
导入java.awt.Graphics;
导入java.awt.Point;
导入java.awt.Polygon;
导入java.awt.Rectangle;
导入java.awt.event.MouseEvent;
导入java.awt.event.MouseListener;
导入java.awt.event.MouseMotionListener;
导入javax.swing.JPanel;
//********************************************************************
//***这是代码的精简版本,显示***
//***这个问题。只需通过运行***创建类的实例
//***TriangleFrame.java。然后尝试用鼠标拖动任一三角形***
//***老鼠***
//********************************************************************
公共类TrianglePanel扩展JPanel实现MouseListener,
MouseMotionListener{
三角形三角形1=零;
三角形三角形2=零;
矩形边框=空;
int lastXPos=0;
int lastYPos=0;
布尔值draggable=false;
公共三角板(){
三角形1=新三角形(新点(100,10),新点(50,100),
新点(150100);;
三角形2=新三角形(新点(250,10),新点(150,100),
新点(350100);;
lastXPos=this.getX();
lastYPos=this.getY();
addMouseListener(这个);
addMouseMotionListener(此);
}
@凌驾
公共无效MouseEvent(MouseEvent e){
三角形1.createNewTriangle();
三角形2.createNewTriangle();
}
@凌驾
公共无效鼠标按下(MouseEvent e){
可拖动=错误;
如果(triangle1.getPos()包含(e.getPoint())
||triangle2.getPos()包含(例如getPoint()){
draggable=true;
lastXPos=e.getX();
lastYPos=e.getY();
}
}
@凌驾
公共无效鼠标标记(鼠标事件e){
如果(可拖动){
isInside(三角形1,e);
isInside(三角形2,e);
}
}
专用空隙(三角形t,鼠标事件e){
如果(t.getPos()包含(e.getPoint())
更新点(t,e);
}
//*****************************************************************
//***接下来,我尝试做正确的事情,只是重新粉刷***
//***我使用的面板部分***
//***好吧,差不多了。现在让它尽可能简单***
//***我使用一个包围盒矩形并在其中重新绘制***
//***边界。问题似乎是面板的其他部分***
//***不希望重新绘制边界以外的任何内容***
//***框,直到我释放鼠标按钮(单击+拖动后)***
//***释放鼠标按钮时,将创建一个新的三角形**
//***在同一地点。Se鼠标释放方法。否则***
//***我只能拖动三角形一次***
//*****************************************************************
私有void更新(三角形t、MouseEvent事件){
boundingBox=t.getPos().getBounds();
//存储为最终变量,以避免重复调用方法。
//这有问题吗?有人想解释一下吗?
最终int CURR_X=boundingBox.X;
final int CURR_Y=boundingBox.Y;
最终int CURR_W=boundingBox.width;
最终int CURR_H=boundingBox.height;
最终整数偏移=1;
if((CURR_X!=event.getX())(CURR_Y!=event.getY()){
//在旧三角形的边界框上绘制
重新喷漆(当前X、当前Y、当前W+偏移、当前H+偏移);
//更新x坐标
int xPos=event.getX();
int[]xPoints=t.getPos().xPoints;//获取旧的x坐标
for(int i=0;i// paint inside bounding box of the new triangle
t.getPos().invalidate();
boundingBox = t.getPos().getBounds();
repaint(boundingBox);
package com.ggl.triangle;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.Polygon;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JPanel;
//********************************************************************
//*** This is a stripped down version of the code which shows ***
//*** the problem. Just create an instance of the class by running ***
//*** TriangleFrame.java. Then try to drag either triangle with ***
//*** the mouse. ***
//********************************************************************
public class TrianglePanel extends JPanel implements MouseListener,
MouseMotionListener {
private static final long serialVersionUID = 5615435125201426466L;
private static final boolean DEBUG = false;
private List<Triangle> triangles;
private Triangle dragTriangle;
private int originalXPos = 0;
private int originalYPos = 0;
private boolean draggable = false;
public TrianglePanel() {
setPreferredSize(new Dimension(600, 400));
triangles = new ArrayList<>();
triangles.add(new Triangle(Color.RED, new Point(100, 10), new Point(50,
100), new Point(150, 100)));
triangles.add(new Triangle(Color.BLUE, new Point(350, 10), new Point(
250, 100), new Point(450, 100)));
addMouseListener(this);
addMouseMotionListener(this);
}
@Override
public void mouseReleased(MouseEvent e) {
if (draggable) {
repaint();
}
this.originalXPos = 0;
this.originalYPos = 0;
this.draggable = false;
}
@Override
public void mousePressed(MouseEvent e) {
this.draggable = false;
Point p = e.getPoint();
if (DEBUG) {
System.out.println("mousePressed: x: " + p.x + ", y: " + p.y);
}
for (Triangle triangle : triangles) {
if (DEBUG) {
System.out.println(triangle);
}
if (triangle.contains(p.x, p.y)) {
if (DEBUG) {
System.out.println("Mouse pressed point is contained "
+ "in the triangle");
}
originalXPos = p.x;
originalYPos = p.y;
dragTriangle = triangle;
draggable = true;
break;
} else {
if (DEBUG) {
System.out.println("Mouse pressed point is not "
+ "contained in the triangle");
}
}
}
}
@Override
public void mouseDragged(MouseEvent e) {
if (draggable) {
dragTriangle.moveTriangle(e.getX() - originalXPos, e.getY()
- originalYPos);
originalXPos = e.getX();
originalYPos = e.getY();
repaint();
}
}
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
for (Triangle triangle : triangles) {
triangle.draw(g);
}
}
// not used
@Override
public void mouseMoved(MouseEvent e) {
}
@Override
public void mouseClicked(MouseEvent e) {
}
@Override
public void mouseEntered(MouseEvent e) {
}
@Override
public void mouseExited(MouseEvent e) {
}
/**
*
* Inner Triangle Class. A polygon object is used for convenience to create
* the Triangle. Otherwise I would have to deal with Points all through the
* program. Which means 3 coordinate pairs = 6 coordinates, which means more
* code.
*
*/
private class Triangle {
private Color color;
private Polygon polygon;
private Triangle(Color color, Point p1, Point p2, Point p3) {
this.color = color;
polygon = new Polygon();
polygon.addPoint(p1.x, p1.y);
polygon.addPoint(p2.x, p2.y);
polygon.addPoint(p3.x, p3.y);
}
public boolean contains(int x, int y) {
return polygon.contains(x, y);
}
public void moveTriangle(int x, int y) {
polygon.translate(x, y);
}
public void draw(Graphics g) {
g.setColor(color);
g.fillPolygon(polygon);
}
@Override
public String toString() {
StringBuilder builder = new StringBuilder();
builder.append("Triangle [polygon=");
polygonToString(builder, polygon);
builder.append("]");
return builder.toString();
}
private void polygonToString(StringBuilder builder, Polygon polygon) {
for (int i = 0; i < polygon.npoints; i++) {
Point p = new Point(polygon.xpoints[i], polygon.ypoints[i]);
builder.append(p);
if (i < (polygon.npoints - 1)) {
builder.append(",");
} else {
builder.append("]");
}
}
}
} // end inner class Triangle
} // end outer class TrianglePanel
package com.ggl.triangle;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;
public class TriangleFrame extends JFrame {
private static final long serialVersionUID = -4599398094173430071L;
public TriangleFrame() {
init();
}
private void init() {
this.setTitle("Draggable triangles. Click one and drag "
+ "it with the mouse.");
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
TrianglePanel panel = new TrianglePanel();
this.add(panel);
pack();
}
public static void main(String[] args) {
Runnable runnable = new Runnable() {
@Override
public void run() {
TriangleFrame frame = new TriangleFrame();
frame.setVisible(true);
}
};
SwingUtilities.invokeLater(runnable);
}
}