我正在尝试使用颜色创建一个小塔防御游戏，但是颜色不起作用，这是我绘制rects的方式。
public static void fill(GridLocation loc, Color c){
Main.frame.getGraphics().setColor(c);
Main.frame.getGraphics().fillRect(loc.toFrameLocation().x, loc.toFrameLocation().y, 20, 20);
Main.frame.getGraphics().dispose();
}
，这就是我打电话/创建jframe
的方式public static void main(String[] args) {
frame = new JFrame("Tower defense");
frame.setSize(1000, 700);
frame.setVisible(true);
frame.setLayout(null);
frame.setLocationRelativeTo(null);
frame.setResizable(false);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
while (frame.isVisible()){
Grid.fill(new GridLocation(1,1), new Color(1F,0F,0F));
Grid.fill(new GridLocation(2,1), Color.gray);
Grid.drawGrid();
Grid.fill(new GridLocation(3,1), Color.green);
}
}
我的问题：矩形总是黑色的？
请注意，如果您在组件上使用getGraphics()来获取图形上下文，那么获得的图形将不会持久。例如，在下面的代码中，您会看到，如果按下按钮，则会出现蓝色矩形，但是如果GUI最小化并进行调整，则它会消失。
另外，根据我的评论：
- 绘制jpanel的paintComponent方法。
- 使用不久（true）循环的摆动计时器。
- 在该计时器中，更改图形JPanel的状态（更改其字段），然后调用RepAlt（）。
- 然后让PaintComponent方法使用字段来告诉其如何绘制。
- 不要忘记在替补中调用超级绘画方法。
例如：
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import javax.swing.*;
@SuppressWarnings("serial")
public class UnstableStableGraphics extends JPanel {
private static final int PREF_W = 800;
private static final int PREF_H = 400;
private static final int GAP = 20;
public UnstableStableGraphics() {
add(new JButton(new DrawBlueRectAction()));
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(Color.RED);
int w = PREF_W / 2 - 2 * GAP;
int h = PREF_H - 2 * GAP;
g.fillRect(GAP, GAP, w, h);
}
@Override
public Dimension getPreferredSize() {
return new Dimension(PREF_W, PREF_H);
}
private class DrawBlueRectAction extends AbstractAction {
public DrawBlueRectAction() {
super("Draw Unstable Blue Rectangle");
}
@Override
public void actionPerformed(ActionEvent arg0) {
Graphics g = getGraphics();
g.setColor(Color.BLUE);
int x = PREF_W / 2 + GAP;
int w = PREF_W / 2 - 2 * GAP;
int h = PREF_H - 2 * GAP;
g.fillRect(x, GAP, w, h);
g.dispose();
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> createAndShowGui());
}
private static void createAndShowGui() {
UnstableStableGraphics mainPanel = new UnstableStableGraphics();
JFrame frame = new JFrame("UnstableStableGraphics");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
}
说过，使用通过 getGraphics()获得的图形对象是完全可以的PaintComponent方法，通常是作为背景图像。但是，通常，我在BufferedImage上调用createGraphics()，因为它返回更强大的Graphics2d对象，而不是图形对象。
例如，包括使用背景图像，精灵图像和摆动计时器：
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.RenderingHints;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import javax.swing.*;
@SuppressWarnings("serial")
public class BackgroundExample extends JPanel {
private static final int PREF_W = 600;
private static final int PREF_H = PREF_W;
private static final int SPRITE_W = 20;
private static final Color SPRITE_COLOR = Color.RED;
private static final int TIMER_DELAY = 20;
private Image background = null;
private Image sprite = null;
private int spriteX = 0;
private int spriteY = 0;
public BackgroundExample() {
background = createBackground();
sprite = createSprite();
new Timer(TIMER_DELAY, new TimerListener()).start();
}
private Image createSprite() {
BufferedImage img = new BufferedImage(SPRITE_W, SPRITE_W, BufferedImage.TYPE_INT_ARGB);
Graphics2D g2 = img.createGraphics();
g2.setColor(SPRITE_COLOR);
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
int x = 1;
int y = 1;
int width = SPRITE_W -2;
int height = SPRITE_W - 2;
g2.fillOval(x, y, width, height);
g2.dispose();
return img;
}
private Image createBackground() {
BufferedImage img = new BufferedImage(PREF_W, PREF_H, BufferedImage.TYPE_INT_ARGB);
Graphics2D g2 = img.createGraphics();
g2.setColor(Color.GREEN);
g2.fillRect(0, 0, PREF_W, PREF_H);
g2.setColor(Color.GRAY);
int x = 0;
int y = 0;
g2.fillRect(x, y, 2 * SPRITE_W, 2 * SPRITE_W);
x = PREF_W - 2 * SPRITE_W;
g2.fillRect(x, y, 2 * SPRITE_W, 2 * SPRITE_W);
y = PREF_H - 2 * SPRITE_W;
g2.fillRect(x, y, 2 * SPRITE_W, 2 * SPRITE_W);
x = 0;
g2.fillRect(x, y, 2 * SPRITE_W, 2 * SPRITE_W);
g2.dispose();
return img;
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (background != null) {
g.drawImage(background, 0, 0, this);
}
if (sprite != null) {
g.drawImage(sprite, spriteX, spriteY, this);
}
}
@Override
public Dimension getPreferredSize() {
if (isPreferredSizeSet()) {
return super.getPreferredSize();
} else {
return new Dimension(PREF_W, PREF_H);
}
}
private class TimerListener implements ActionListener {
@Override
public void actionPerformed(ActionEvent e) {
spriteX++;
spriteY++;
repaint();
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> createAndShowGui());
}
private static void createAndShowGui() {
BackgroundExample mainPanel = new BackgroundExample();
JFrame frame = new JFrame("BackgroundExample");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(mainPanel);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
}