用鼠标绘制在画布上线:Java的AWT [英] Drawing lines with mouse on canvas : Java awt
问题描述
企图是使鼠标在AWT画布上的人物绘画(现在的线)。 IAM的尝试Java的图形首次。所以不知道如何去做。这是我第一次尝试:
The attempt is to enable drawing of figures(a line for now) with mouse on the awt canvas . Iam trying out java graphics for the first time . So not sure how to go about it . This is my first attempt :
package def.grafi;
import java.awt.Canvas;
import java.awt.Frame;
import java.awt.Graphics;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
public class Dra {
Frame f = new Frame();
public void disp() {
f.setBounds(100, 100, 200, 200);
MosL ml = new MosL();
Can c = new Can();
f.add(c);
c.addMouseListener(ml);
c.addMouseMotionListener(ml);
f.setVisible(true);
}
public static void main(String[] args) {
Dra d = new Dra();
d.disp();
}
public class MosL extends MouseAdapter {
int sx = 0;
int sy = 0;
boolean onDrag = false;
@Override
public void mouseDragged(MouseEvent e) {
if (onDrag) {
int x = e.getX();
int y = e.getY();
Canvas comp = (Canvas) e.getSource();
Graphics g = comp.getGraphics();
// comp.repaint(); << for cleaning up the intermediate lines : doesnt work :(
g.drawLine(sx, sy, x, y);
return;
}
onDrag = true;
sx = e.getX();
sy = e.getY();
System.out.println("Draggg");
}
@Override
public void mousePressed(MouseEvent e) {
System.out.println("Pressed");
}
@Override
public void mouseReleased(MouseEvent e) {
System.out.println("Released");
if (onDrag)
onDrag = false;
}
}
public class Can extends Canvas {
@Override
public void paint(Graphics g) {
}
}
}
问题:
1)当窗口最小化和恢复,画线消失(因重绘)
2)我想是该行应遵循鼠标(它被拖到时)。最后一行应该从pressing的点到小鼠的释放点延伸。现在仪式,当鼠标移动,新的生产线越来越绘制。我不知道如何清理从画布中间线。
Problems : 1) When the windows is minimized and restored , the drawn line is gone (due to repaint) 2) What i want is the line should follow the mouse (when it is dragged) . the final line should extend from the point of pressing to the point of release of the mouse . Rite now , when the mouse moves , new lines are getting drawn . I am not sure how to clean up the intermediate lines from the canvas .
有人可以帮我在这些问题呢?
Can someone help me out on these problems ?
推荐答案
下面是这样的清明上河图一个简单的例子:
Here is a simple example of such "painting":
public static void main ( String[] args )
{
JFrame paint = new JFrame ();
paint.add ( new JComponent ()
{
private List<Shape> shapes = new ArrayList<Shape> ();
private Shape currentShape = null;
{
MouseAdapter mouseAdapter = new MouseAdapter ()
{
public void mousePressed ( MouseEvent e )
{
currentShape = new Line2D.Double ( e.getPoint (), e.getPoint () );
shapes.add ( currentShape );
repaint ();
}
public void mouseDragged ( MouseEvent e )
{
Line2D shape = ( Line2D ) currentShape;
shape.setLine ( shape.getP1 (), e.getPoint () );
repaint ();
}
public void mouseReleased ( MouseEvent e )
{
currentShape = null;
repaint ();
}
};
addMouseListener ( mouseAdapter );
addMouseMotionListener ( mouseAdapter );
}
protected void paintComponent ( Graphics g )
{
Graphics2D g2d = ( Graphics2D ) g;
g2d.setPaint ( Color.BLACK );
for ( Shape shape : shapes )
{
g2d.draw ( shape );
}
}
} );
paint.setSize ( 500, 500 );
paint.setLocationRelativeTo ( null );
paint.setVisible ( true );
}
它会记住所有的绘制的形状,并用一个小的努力,你可以扩展它来画你喜欢的任何其他形状。
it will remember all of the drawn shapes and with a small effort you can extend it to draw any other shapes you like.
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