使用Java绘图:将边界/轮廓应用于形状 [英] Drawing with Java: Applying Borders/Outlines to Shapes

问题描述

我不知道如何获取"g.setStroke(new BasicStroke(5));"设置为我创建的所有形状(在本例中为椭圆形).

I can't figure out how to get "g.setStroke(new BasicStroke(5));" to be set to all my created shapes (in this case ovals).

我的代码:

import java.awt.*;
import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.BasicStroke;

public class Rings 
{
    public static void main(String[] args) 
    {
        DrawingPanel panel = new DrawingPanel(300, 300);

        Graphics2D g = panel.getGraphics();
        g.setStroke(new BasicStroke(5)); // Sets Outer Line Width of Shapes
        g.setColor(new Color(255, 0, 0));
        g.fillOval(50, 50, 200, 200); // Large Oval
        g.setColor(new Color(200, 0, 0));
        g.fillOval(100, 100, 100, 100); // Medium Oval
        g.setColor(new Color(150, 0, 0));
        g.fillOval(125, 125, 50, 50); // Small Oval
        g.setColor(new Color(100, 0, 0));
        g.fillOval(137, 137, 25, 25); // Tiny Oval
    }
}

我的输出:

正确的输出:

推荐答案

当您调用fillOval时，笔触无关紧要，而当您调用 drawOval 时，笔触并不重要.所以我建议:

The stroke doesn't matter so much when you call fillOval but moreso when you call drawOval. So I recommend:

• 在执行操作时调用 fillOval
• 在每个 fillOval 之后，将Color更改为Color.BLACK(或所需的任何轮廓颜色)，然后调用 drawOval .
• 查看图形，如果您最小化GUI，然后将其还原，将会发生什么情况.
• 因此，为了避免NullPointerException错误，我们建议您不要使用通过Swing组件上的 getGraphics()调用获得的Graphics对象.这样的Graphics对象是短暂的.取而代之的是，教程和大多数其他类似的问题都会告诉您:在扩展JPanel或JComponent的类中的适当的 paintComponent 中重写.

• Call fillOval as you're doing
• After each fillOval, then change Color to Color.BLACK (or whatever outline color you desire), and call drawOval.
• See what happens to your drawing if you minimize the GUI and then restore it.
• It is for this reason, and to avoid NullPointerException errors, that we don't recommend that you use a Graphics object obtained via a getGraphics() call on a Swing component. Such a Graphics object is short-lived. Instead do as the tutorials and most other similar questions will tell you: within a proper paintComponent override inside a class that extends JPanel or JComponent.

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