java 在 BufferedImage 中绘制多条线
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Drawing multiple lines in a BufferedImage
提问by Adith
I am trying to draw horizontal and vertical lines on a bufferedimage. It should end up looking like a grid of cells. But when I run the code, I see only two lines: the leftmost line and the topmost line (ie. a line from 0,0 to 0,height of image & 0,0 to width of image,0) Heres the code snippet:
我正在尝试在缓冲图像上绘制水平线和垂直线。它最终应该看起来像一个单元格网格。但是当我运行代码时，我只看到两行：最左边的一行和最上面的一行（即从 0,0 到 0，图像高度和 0,0 到图像宽度，0 的线）这是代码片段：
BufferedImage mazeImage = new BufferedImage(imgDim.width, imgDim.height, BufferedImage.TYPE_INT_RGB);
Graphics2D g2d = mazeImage.createGraphics();
g2d.setBackground(Color.WHITE);
g2d.fillRect(0, 0, imgDim.width, imgDim.height);
g2d.setColor(Color.BLACK);
BasicStroke bs = new BasicStroke(2);
g2d.setStroke(bs);
// draw the black vertical and horizontal lines
for(int i=0;i<21;i++){
g2d.drawLine((imgDim.width+2)*i, 0, (imgDim.width+2)*i, imgDim.height-1);
g2d.drawLine(0, (imgDim.height+2)*i, imgDim.width-1, (imgDim.height+2)*i);
}
And the overriden paint method:
和重写的paint方法：
public void paint(Graphics g) {
g.drawImage(mazeImage, 0, 0, this);
}
This is all in a class called RobotMaze that extends JPanel. Any help is appreciated.
这一切都在一个名为 RobotMaze 的类中，它扩展了 JPanel。任何帮助表示赞赏。
回答by Andrew Thompson
import java.awt.*;
import java.awt.image.*;
import javax.swing.*;
class GridLines {
public static void main(String[] args) {
Dimension imgDim = new Dimension(200,200);
BufferedImage mazeImage = new BufferedImage(imgDim.width, imgDim.height, BufferedImage.TYPE_INT_RGB);
Graphics2D g2d = mazeImage.createGraphics();
g2d.setBackground(Color.WHITE);
g2d.fillRect(0, 0, imgDim.width, imgDim.height);
g2d.setColor(Color.BLACK);
BasicStroke bs = new BasicStroke(2);
g2d.setStroke(bs);
// draw the black vertical and horizontal lines
for(int i=0;i<21;i++){
// unless divided by some factor, these lines were being
// drawn outside the bound of the image..
g2d.drawLine((imgDim.width+2)/20*i, 0, (imgDim.width+2)/20*i,imgDim.height-1);
g2d.drawLine(0, (imgDim.height+2)/20*i, imgDim.width-1, (imgDim.height+2)/20*i);
}
ImageIcon ii = new ImageIcon(mazeImage);
JOptionPane.showMessageDialog(null, ii);
}
}
回答by dogbane
Print out your coordinates and you will see that you are plotting points outside the width and height of the image:
打印出你的坐标，你会看到你在图像的宽度和高度之外绘制点：
System.out.printf("Vertical: (%d,%d)->(%d,%d)\n",(imgDim.width+2)*i, 0, (imgDim.width+2)*i, imgDim.height-1);
System.out.printf("Horizontal: (%d,%d)->(%d,%d)\n",0, (imgDim.height+2)*i, imgDim.width-1, (imgDim.height+2)*i);
回答by jarnbjo
How do you expect the result of (imgDim.width+2)*ito be within the image boundaries if i > 0?
(imgDim.width+2)*i如果 i > 0，您如何期望 的结果在图像边界内？
