paintComponent不起作用(Java) [英] paintComponent is not working (Java)

问题描述

我一直在尝试重写并使用paint组件方法而不是paint方法，因为我在这里遇到了多个问题.

I have been trying to override and use the paint component method instead of the paint method because I've seen it been suggested in multiple questions around here.

我已经浏览了许多问题，但似乎还是无法解决这个问题.我正在发布用于渲染屏幕的原始代码.我认为扩展JFrame不是正确的方法，相反，我需要扩展JPanel，并从那里使用paint组件.我有另一个对象，我实际上在其中扩展了JPanel，并添加了JFrame(用于渲染).

I've looked through many questions but I still can't seem to get this to work. I'm posting my original piece of code used to render a screen. I am thinking that extending JFrame is not the right way to go and instead I need to extend JPanel, and use paint component from there. I have another object where I actually extend the JPanel, and add in the JFrame (for rendering).

这是我用来渲染的对象，顺便说一句，它可以完美地覆盖paint方法.

Here is the object I use to render, this, by the way works perfectly overriding the paint method.

package render;


import java.util.Arrays;

import javax.swing.*;

import java.awt.*; //Graphics, Graphics2D, Image

import sprites.Picture;


public class Window extends JFrame{
    private static final long serialVersionUID = 1L;

    public static Picture[] image_list =  new Picture[0]; // All the images I want to render
    private static String win_title = "Window"; // The name of the window
    private static CustomComponents cc = new CustomComponents();


    public Window(){
        setTitle(win_title); // set my title
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); // close when you hit x button
        setUndecorated(true); // window has nothing on it

    }


    // paints all the images in image list according to their priority

    public void display(){
        add(cc);
        CustomComponents.updateImageList(image_list);
        pack();

        setMinimumSize(getSize());
        setLocationRelativeTo(null); // puts the screen in the middle
        setResizable(false); // can't resize the window
        setVisible(true); // to see the window


    }



    public double[] getWinSize(){
        double[] size = {this.getSize().getWidth(),this.getSize().getWidth()};

        return size;
    }

    public static void endAll(){
        for (Picture i:image_list){
            i = null;
        }
        image_list = new Picture[0];
        CustomComponents.updateImageList(image_list);
    }

    // close the window (seen in the game object)
    public static void close(){
        System.exit(0);
    }

    // called when adding a new sprite to the image_list array
    public static void addPicture(Picture element){
        Picture[] result = Arrays.copyOf(image_list, image_list.length +1); // does the same thing as the addObject method in objects
        result[image_list.length] = element;
        image_list = result;
        Arrays.sort(image_list);
        CustomComponents.updateImageList(image_list);

    }

    // updates the screen... Just repaints everything
    public void update() {
        cc.repaint();

    }

}


class CustomComponents extends JComponent {

    private static final long serialVersionUID = 1L;

    private static Picture[] image_list;

    public static void updateImageList(Picture[] image_list){
        CustomComponents.image_list = image_list;
    }

    @Override
    public Dimension getMinimumSize() {
        return new Dimension(640,360);
    }

    @Override
    public Dimension getPreferredSize() {
        return new Dimension(640,360);
    }

    @Override
    public Dimension getMaximumSize() {
        return new Dimension(640,360);
    }

    @Override
    public void paintComponent(Graphics graphics) {
        super.paintComponent(graphics);
        Graphics2D g2d = (Graphics2D) graphics;
        for (Picture i:image_list){
            if (i.getVisibility()){
            g2d.drawImage(i.getPic(), i.getXY()[0], i.getXY()[1], this);
            }
        }
        Toolkit.getDefaultToolkit().sync(); // this is for linux machines
        graphics.dispose(); // just good programming practice to collect the garbage
    }
}

我会发布实际上添加到窗口中的对象，但是现在它太复杂了，只发生了几件事.在构造函数中，我在上面添加了JFrame窗口，然后使用计时器调用JFrame对象上的update方法.

I would post the object that actually adds in the window but it's way too convoluted now, and only a few thing happens. In the constructor I add the JFrame window above, and then I use a timer to call the update method on the JFrame object.

如果你们真的需要代码，我可以发布它，但希望这足够了.

If you guys really need to the code I can post it but hopefully this will be enough.

推荐答案

• 不绘画

  • don't paint

    1. 直接使用paintComponent()到JFrame
    2. 直接绘画到JFrame并不是一个好主意，JFrame不是完成此任务的合适容器
    3. 必须使用paint()代替paintComponent()来使用JFrame
    1. by using paintComponent() directly to the JFrame,
    2. not good idea to paint directly to JFrame, JFrame isn't proper container for this job
    3. have to use paint() instead of paintComponent() for JFrame,

  • 在您认为 应该覆盖父方法的任何方法(此处为paintComponent(...)方法)之前添加@Override.这样，如果您实际上没有超越您原本的想法，编译器就会警告您.

  • Add @Override before any methods that you think should override a parent method, here the paintComponent(...) method. This way, the compiler will warn you if you are in fact not overriding what you thought you were.

    将JComponent / JPanel放入JFrame

    覆盖JComponent / JPanel(您的硬编码// window size handle)的getPreferredSize，否则，JComponent / JPanel返回零尺寸，简单的什么都看不到.

    override getPreferredSize for JComponent / JPanel (your hardcoded // window size handle) , otherwise JComponent / JPanel returns zero dimension, simple nothing will be visible on the creen

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