Java 鼠标拖动和绘制
我无法显示所有三角形。我用鼠标拖动画了一个三角形。每次我画一个新的三角形,以前的三角形就消失了。如何使三角形保持不变,使绘图面板上有许多三角形Java 鼠标拖动和绘制,java,shapes,Java,Shapes,我无法显示所有三角形。我用鼠标拖动画了一个三角形。每次我画一个新的三角形,以前的三角形就消失了。如何使三角形保持不变,使绘图面板上有许多三角形 ..... private class PaintSurface extends JComponent { Point startDrag, endDrag, midPoint; Polygon triangle; public PaintSurface() { this.addMouseListener(new Mouse
.....
private class PaintSurface extends JComponent {
Point startDrag, endDrag, midPoint;
Polygon triangle;
public PaintSurface() {
this.addMouseListener(new MouseAdapter() {
public void mousePressed(MouseEvent e) {
startDrag = new Point(e.getX(), e.getY());
endDrag = startDrag;
repaint();
}
public void mouseReleased(MouseEvent e) {
Shape r = makeRectangle(startDrag.x, startDrag.y, e.getX(), e.getY());
shapes.add(r);
if (startDrag.x > endDrag.x)
midPoint = new Point((endDrag.x +(Math.abs(startDrag.x - endDrag.x)/2)),e.getY());
else
midPoint = new Point((endDrag.x -(Math.abs(startDrag.x - endDrag.x)/2)),e.getY());
int[] xs = { startDrag.x, endDrag.x, midPoint.x };
int[] ys = { startDrag.y, startDrag.y, midPoint.y };
triangle = new Polygon(xs, ys, 3);
startDrag = null;
endDrag = null;
repaint();
}
});
this.addMouseMotionListener(new MouseMotionAdapter() {
public void mouseDragged(MouseEvent e) {
endDrag = new Point(e.getX(), e.getY());
repaint();
}
});
}
public void paint(Graphics g) {
Graphics2D g2 = (Graphics2D) g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
paintBackground(g2);
Color[] colors = { Color.YELLOW, Color.MAGENTA, Color.CYAN , Color.RED, Color.BLUE, Color.PINK};
int colorIndex = 0;
g2.setStroke(new BasicStroke(1));
g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.50f));
g2.fillPolygon(triangle);
}
}
您在屏幕上看到的是您在绘制函数中绘制的内容。目前,您只在三角形变量中存储一个三角形,并不断替换和绘制它 您需要的是存储一个三角形列表,并在MouseRelease中每次向列表中添加一个新的三角形。以下是需要更改的内容:
private class PaintSurface extends JComponent {
...
//Polygon triangle;
List<Polygon> triangles = new LinkedList<Polygon>();
...
public PaintSurface() {
public void mouseReleased(MouseEvent e) {
...
//triangle = new Polygon(xs, ys, 3);
triangles.add( new Polygon(xs, ys, 3); );
...
}
});
...
}
public void paint(Graphics g) {
...
//g2.fillPolygon(triangle);
for (Polygon triangle : triangles) g2.fillPolygon(triangle);
...
}
}
私有类PaintSurface扩展JComponent{
...
//多边形三角形;
列表三角形=新建LinkedList();
...
公共漆面(){
公共无效MouseEvent(MouseEvent e){
...
//三角形=新多边形(xs,ys,3);
添加(新多边形(xs,ys,3););
...
}
});
...
}
公共空间涂料(图g){
...
//g2.填充多边形(三角形);
对于(多边形三角形:三角形)g2.fillPolygon(三角形);
...
}
}
您在屏幕上看到的是您在绘制功能中绘制的内容。目前,您只在三角形变量中存储一个三角形,并不断替换和绘制它
您需要的是存储一个三角形列表,并在MouseRelease中每次向列表中添加一个新的三角形。以下是需要更改的内容:
private class PaintSurface extends JComponent {
...
//Polygon triangle;
List<Polygon> triangles = new LinkedList<Polygon>();
...
public PaintSurface() {
public void mouseReleased(MouseEvent e) {
...
//triangle = new Polygon(xs, ys, 3);
triangles.add( new Polygon(xs, ys, 3); );
...
}
});
...
}
public void paint(Graphics g) {
...
//g2.fillPolygon(triangle);
for (Polygon triangle : triangles) g2.fillPolygon(triangle);
...
}
}
私有类PaintSurface扩展JComponent{
...
//多边形三角形;
列表三角形=新建LinkedList();
...
公共漆面(){
公共无效MouseEvent(MouseEvent e){
...
//三角形=新多边形(xs,ys,3);
添加(新多边形(xs,ys,3););
...
}
});
...
}
公共空间涂料(图g){
...
//g2.填充多边形(三角形);
对于(多边形三角形:三角形)g2.fillPolygon(三角形);
...
}
}
您保留了对总共一个三角形对象的引用,因此每次重新绘制画布时,您都将绘制这一个多边形
有两种解决方案:
- 创建
对象的列表,并在调用多边形
时绘制所有对象。您的鼠标侦听器将向列表中添加一个新条目绘制
- 将多边形绘制到图形上,然后使用“绘制”方法。如果计划绘制多个三角形,这可能是更好的选择
- 创建
对象的列表,并在调用多边形
时绘制所有对象。您的鼠标侦听器将向列表中添加一个新条目绘制
- 将多边形绘制到图形上,然后使用“绘制”方法。如果计划绘制多个三角形,这可能是更好的选择
- 不太奇怪。您有一个三角形对象,一旦开始绘制新三角形,就会覆盖该对象
创建一个三角形数组/列表,并让绘图例程绘制该数组/列表
我的java修改:
.....
private class PaintSurface extends JComponent {
Point startDrag, endDrag, midPoint;
List triangles = new ArrayList();
public PaintSurface() {
this.addMouseListener(new MouseAdapter() {
public void mousePressed(MouseEvent e) {
startDrag = new Point(e.getX(), e.getY());
endDrag = startDrag;
repaint();
}
public void mouseReleased(MouseEvent e) {
Shape r = makeRectangle(startDrag.x, startDrag.y, e.getX(), e.getY());
shapes.add(r);
if (startDrag.x > endDrag.x)
midPoint = new Point((endDrag.x +(Math.abs(startDrag.x - endDrag.x)/2)),e.getY());
else
midPoint = new Point((endDrag.x -(Math.abs(startDrag.x - endDrag.x)/2)),e.getY());
int[] xs = { startDrag.x, endDrag.x, midPoint.x };
int[] ys = { startDrag.y, startDrag.y, midPoint.y };
Polygon triangle = new Polygon(xs, ys, 3);
traingles.add(triangle);
startDrag = null;
endDrag = null;
repaint();
}
});
this.addMouseMotionListener(new MouseMotionAdapter() {
public void mouseDragged(MouseEvent e) {
endDrag = new Point(e.getX(), e.getY());
repaint();
}
});
}
public void paint(Graphics g) {
Graphics2D g2 = (Graphics2D) g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
paintBackground(g2);
Color[] colors = { Color.YELLOW, Color.MAGENTA, Color.CYAN , Color.RED, Color.BLUE, Color.PINK};
int colorIndex = 0;
g2.setStroke(new BasicStroke(1));
g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.50f));
Iterator iter = triangles.iterator();
while( iter.hasNext() ) {
g2.fillPolygon((Polygon)iter.next());
}
}
}
不太奇怪。您有一个三角形对象,一旦开始绘制新三角形,就会覆盖该对象 创建一个三角形数组/列表,并让绘图例程绘制该数组/列表 我的java修改:
.....
private class PaintSurface extends JComponent {
Point startDrag, endDrag, midPoint;
List triangles = new ArrayList();
public PaintSurface() {
this.addMouseListener(new MouseAdapter() {
public void mousePressed(MouseEvent e) {
startDrag = new Point(e.getX(), e.getY());
endDrag = startDrag;
repaint();
}
public void mouseReleased(MouseEvent e) {
Shape r = makeRectangle(startDrag.x, startDrag.y, e.getX(), e.getY());
shapes.add(r);
if (startDrag.x > endDrag.x)
midPoint = new Point((endDrag.x +(Math.abs(startDrag.x - endDrag.x)/2)),e.getY());
else
midPoint = new Point((endDrag.x -(Math.abs(startDrag.x - endDrag.x)/2)),e.getY());
int[] xs = { startDrag.x, endDrag.x, midPoint.x };
int[] ys = { startDrag.y, startDrag.y, midPoint.y };
Polygon triangle = new Polygon(xs, ys, 3);
traingles.add(triangle);
startDrag = null;
endDrag = null;
repaint();
}
});
this.addMouseMotionListener(new MouseMotionAdapter() {
public void mouseDragged(MouseEvent e) {
endDrag = new Point(e.getX(), e.getY());
repaint();
}
});
}
public void paint(Graphics g) {
Graphics2D g2 = (Graphics2D) g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
paintBackground(g2);
Color[] colors = { Color.YELLOW, Color.MAGENTA, Color.CYAN , Color.RED, Color.BLUE, Color.PINK};
int colorIndex = 0;
g2.setStroke(new BasicStroke(1));
g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.50f));
Iterator iter = triangles.iterator();
while( iter.hasNext() ) {
g2.fillPolygon((Polygon)iter.next());
}
}
}
自定义绘制应在paintComponent()方法中完成,而不是在paint()方法中完成。自定义绘制应在paintComponent()方法中完成,而不是在paint()方法中完成。