了解困难的Java摇摆 [英] understanding difficulties java swing
问题描述
im试图通过单击JMenu在JPanel上绘制随机(尚未)的圆圈. 我正在使用JTextField(并且必须保留此输出)用于某些输出. 这是我的课程:
im trying to paint random (not yet) circles on a JPanel through click on a JMenu. Im using a JTextField (and have to keep this) for some output. Here is my Class:
class RandomDrawer extends JPanel implements ActionListener {
@Override
public void actionPerformed(ActionEvent e) {
//double x = Math.random();
//double y = Math.random();
Random generator = new Random();
int x = generator.nextInt(100)+1;
int y = generator.nextInt(100)+1;
//System.out.printf("x = %d y = %d\n", x, y);
status.setText(String.format("rnd draw x: %d y: %d", x, y));
Graphics2D gg = (Graphics2D) canvas.getGraphics();
gg.setColor(Color.BLACK);
gg.drawOval(50, 50, 50, 50);
}
}
只要我让线
status.setText(String.format("rnd draw x:％d y:％d"，x，y));
status.setText(String.format("rnd draw x: %d y: %d", x, y));
呆在那里，我什么都没画.没有它，我就不知所措了，我不确定是什么问题.我不知道为什么什么也没画.
stay in there i get nothing drawn. Without it i get my circle, im not sure what the problem is. I cant figure out why nothing is drawn.
非常感谢
您好，我试图了解给定的信息.
可悲的是我必须使用Graphics2D类进行绘制，所以我想我不能使用形状进行绘制.所以我尝试了一下，可惜它还没有画出来，你能给我一些提示吗?
我试图创建一个新的类DrawShape，我的想法是我可以跟踪那些对象.
据我了解，现在应该有一个绘制的椭圆形
gg.drawOval(100,100,100,100);
Hello, i tried to understand the given informations.
Sadly I have to draw using the Graphics2D class, so i guess i can not draw using shapes. So i tried this, sadly it wont draw yet, can u give me some tips?
I tried to create a new class DrawShape, my thought was that i could keep track with those objects.
In my understanding there should be a drawn oval right now
gg.drawOval(100,100,100,100);
谢谢.
class DrawShape {
public DrawShape(String string) {
// TODO Auto-generated constructor stub
}
}
class RandomDrawer extends JPanel implements ActionListener {
/* (non-Javadoc)
* @see java.awt.event.ActionListener#actionPerformed(java.awt.event.ActionEvent)
*/
private List<DrawShape> shapes = new ArrayList<DrawShape>();
public void addShape(DrawShape s) {
shapes.add(s);
repaint();
}
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
final Graphics2D gg = (Graphics2D) g;
gg.setColor(Color.BLACK);
gg.drawOval(100, 100, 100, 100);
}
@Override
public void actionPerformed(ActionEvent e) {
Random generator = new Random();
int x = generator.nextInt(100)+100;
int y = generator.nextInt(100)+100;
if (e.getActionCommand()==("Draw RandomCircle")) {
System.out.printf("x = %d y = %d\n", x, y);
status.setText(String.format("rnd draw x:%d y:%d ", x, y));
DrawShape circle = new DrawShape("Circle");
addShape(circle);
int count = shapes.size();
System.out.printf("objects in array: %d\n", count);
}
else if (e.getActionCommand()==("Draw RandomRectangle")) {
System.out.printf("x = %d y = %d\n", x, y);
//status.setText(String.format("rnd draw x: y: "));
//Graphics2D gg = (Graphics2D) canvas.getGraphics();
//gg.setColor(Color.BLACK);
//gg.drawRect(x, y, generator.nextInt(x), generator.nextInt(y));
}
}
}
推荐答案
绘画和此类事件是事件驱动的.如果需要重绘一个组件，则调用其paintComponent方法.
Painting and such happens event-driven. If a a piece of a component needs to be redrawn its paintComponent method is called.
这意味着您需要一个组件，例如，现在该如何绘制:
This means you need a component that nows how to draw by for instance:
public class DrawShape {
public final String text;
public final Color color;
public final Shape shape;
public DrawShape(String text, Color color, Shape shape) {
this.text = text;
this.color = color;
this.shape = shape;
}
}
public class CanvasWithShapes extends JPanel {
private List<DrawShape> shapes = new ArrayList<>();
public void addShape(DrawShape shape) {
shapes.add(shape);
}
@Override
public void paintComponent(Graphics g) {
final Graphics2D gg = (Graphics2D) g;
// Java 8: shapes.stream().forEach((shape) -> gg.draw(shape));
for (DrawShape drawShape : shapes) {
gg.setColor(drawShape.color);
gg.draw(drawShape.shape);
Rectangle bounds = shape.getBounds();
gg.drawString(shape.text, bounds.x+ 10, bounds.y + 20);
}
}
}
然后添加形状以便稍后重绘.
And then just add shapes to be redrawn a bit later.
Shape oval = ...;
c.add(oval);
c.repaint(50L); // A bit later
更详细
More detailed
形状具有许多实现像矩形和椭圆形的兴趣. Graphics2D可以绘制和填充Shape.因此，在您的情况下，添加这样的Shape是理想的.也许还有颜色和文字.因此，我带上了DrawShape类来保存这些属性.
A Shape has many implementations of interest like rectangle and oval. Graphics2D can draw and fill a Shape. So in your case it would be ideal to add such a Shape. Maybe together with color and text. So I took your DrawShape class to hold these properties.
Random generator = new Random();
int x = generator.nextInt(100)+100;
int y = generator.nextInt(100)+100;
if (e.getActionCommand().equals("Draw RandomCircle")) {
System.out.printf("x = %d y = %d\n", x, y);
status.setText(String.format("rnd draw x:%d y:%d ", x, y));
int w = generator.nextInt(100) + 10;
int h = w;
Shape circle = new Ellipse2D.Double(x, y, w, h);
addShape(new DrawShape(text, Color.BLACK, circle));
int count = shapes.size();
System.out.printf("objects in array: %d\n", count);
} else if (e.getActionCommand().equals("Draw RandomRectangle")) {
System.out.printf("x = %d y = %d\n", x, y);
generator.nextInt(y)); 整数w = generator.nextInt(100)+ 10; int h = generator.nextInt(100)+ 10; 形状rect = Rectangle2D.Double(x，y，w，h) addShape(new DrawShape(text，Color.BLACK，rect)); }
generator.nextInt(y)); int w = generator.nextInt(100) + 10; int h = generator.nextInt(100) + 10; Shape rect = Rectangle2D.Double(x, y, w, h) addShape(new DrawShape(text, Color.BLACK, rect)); }
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