Question

我一直在尝试在画布上画画，但我无法使它工作，我可以看到JFrame但是它似乎并没有在Mover()调用paint方法正在添加{1}}对象。这是第一次使用画布，所以我不知道我错过了什么。这是代码：

import java.awt.image.BufferedImage;
import java.awt.image.DataBufferByte;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.*;
import java.util.*;
import java.awt.*;
import java.io.File;

public class Move extends Canvas
{

    private static int [][]imgRGB;

    public Move()
    {
        try
        {
           BufferedImage hugeImage = ImageIO.read(new File("C:/Users/pc/Pictures/Nave.gif"));
           imgRGB = convertToRGB(hugeImage);

        }
        catch(IOException e)
        {
            System.out.println(e);
        }
    }

    public void Paint(Graphics g)
    {
        super.paint(g);

        for(int i=0 ; i<imgRGB.length ; i++)
        {
            for(int j=0 ; j<imgRGB[i].length; j++)
            {
                g.setColor(new Color(imgRGB[i][j]));
                g.drawLine(i,j,i,j);
            }
        }
    }

    private static int[][] convertToRGB(BufferedImage image) {

      final byte[] pixels = ((DataBufferByte) image.getRaster().getDataBuffer()).getData();
      final int width = image.getWidth();
      final int height = image.getHeight();
      final boolean hasAlphaChannel = image.getAlphaRaster() != null;

      int[][] result = new int[height][width];
      if (hasAlphaChannel) {
         final int pixelLength = 4;
         for (int pixel = 0, row = 0, col = 0; pixel < pixels.length; pixel += pixelLength) {
            int argb = 0;
            argb += (((int) pixels[pixel] & 0xff) << 24); // alpha
            argb += ((int) pixels[pixel + 1] & 0xff); // blue
            argb += (((int) pixels[pixel + 2] & 0xff) << 8); // green
            argb += (((int) pixels[pixel + 3] & 0xff) << 16); // red
            result[row][col] = argb;
            col++;
            if (col == width) {
               col = 0;
               row++;
            }
         }
      } else {
         final int pixelLength = 3;
         for (int pixel = 0, row = 0, col = 0; pixel < pixels.length; pixel += pixelLength) {
            int argb = 0;
            argb += -16777216; // 255 alpha
            argb += ((int) pixels[pixel] & 0xff); // blue
            argb += (((int) pixels[pixel + 1] & 0xff) << 8); // green
            argb += (((int) pixels[pixel + 2] & 0xff) << 16); // red
            result[row][col] = argb;
            col++;
            if (col == width) {
               col = 0;
               row++;
            }
         }
      }

      return result;
    }

    public static void main(String[] args) 
    {
        JFrame container = new JFrame("pixel");
        container.add(new Move());
        container.setSize(400,400);
        container.setVisible(true);
        container.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);        
    }

}

Answer 1

public void Paint(Graphics g)

方法名称区分大小写。您应该覆盖paint(...)。

始终使用@Override注释，当您尝试覆盖不存在的方法时，编译器会通知您：

@Override
public void paint(Graphics g)
{
...
}

但是，您不应该在Swing应用程序中覆盖Canvas。

相反，您应该扩展JPanel，然后您应该覆盖paintComponent(...)方法。

阅读Custom Painting上Swing教程中的部分，了解更多信息和工作示例。

无法在画布上绘画

1 个答案: