char image support

mirai-core/src/main/java/net/mamoe/mirai/utils/CharImageConverter.java

+package net.mamoe.mirai.utils;
+
+import java.awt.*;
+import java.awt.image.BufferedImage;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.Callable;
+
+/**
+ * Convert IMAGE into Chars that could shows in terminal
+ * @author NaturalHG
+ */
+public class CharImageConverter implements Callable<String> {
+
+    /**
+     * width should depends on the width of the terminal
+     */
+    private BufferedImage image;
+    private int width;
+    private double ignoreRate;
+
+    public CharImageConverter(BufferedImage image, int width){
+        this(image,width,0.95);
+    }
+
+    public CharImageConverter(BufferedImage image, int width, double ignoreRate){
+        this.image = image;
+        this.width = width;
+        this.ignoreRate = ignoreRate;
+    }
+
+    @Override
+    public String call(){
+       /*
+       * resize Image
+       * */
+        int newHeight = (int)(this.image.getHeight() * (((double)width) /this.image.getWidth()));
+        Image tmp = image.getScaledInstance(width, newHeight, Image.SCALE_SMOOTH);
+        BufferedImage dimg = new BufferedImage(width, newHeight, BufferedImage.TYPE_INT_ARGB);
+        Graphics2D g2d = dimg.createGraphics();
+        g2d.drawImage(tmp, 0, 0, null);
+        this.image = dimg;
+
+       int background = this.gray(image.getRGB(0,0));
+
+       StringBuilder builder = new StringBuilder();
+
+       List<StringBuilder> lines = new ArrayList<>(this.image.getHeight());
+
+       int minXPos = this.width;
+       int maxXPos = 0;
+
+       for (int y = 0; y < image.getHeight(); y++) {
+           StringBuilder builderLine = new StringBuilder();
+           for (int x = 0; x < image.getWidth(); x++) {
+               int gray = this.gray(image.getRGB(x, y));
+               if (grayCompare(gray, background)) {
+                   builderLine.append(" ");
+               } else {
+                   builderLine.append("#");
+                   if (x < minXPos) {
+                       minXPos = x;
+                   }
+                   if (x > maxXPos) {
+                       maxXPos = x;
+                   }
+               }
+           }
+           if (builderLine.toString().isBlank()) {
+               continue;
+           }
+           lines.add(builderLine);
+       }
+        for (int i=0;i<lines.size();++i) {
+            builder.append(lines.get(i).substring(minXPos, maxXPos)).append("\n");
+        }
+       return builder.toString();
+    }
+
+    private int gray(int rgb) {
+        int R = (rgb & 0xff0000) >> 16;
+        int G = (rgb & 0x00ff00) >> 8;
+        int B = rgb & 0x0000ff;
+        int gray = (R * 30 + G * 59 + B * 11 + 50) / 100;
+        return (R * 30 + G * 59 + B * 11 + 50) / 100;
+    }
+
+    public boolean grayCompare(int g1, int g2){
+        return ((double)Math.min(g1,g2)/Math.max(g1,g2)) >= ignoreRate;
+    }
+
+}

mirai-core/src/main/java/net/mamoe/mirai/utils/CharImageUtil.java

 package net.mamoe.mirai.utils;
-
-import java.awt.*;
 import java.awt.image.BufferedImage;
 
-/**
- * 图片转字符图片, 来自 CSDN 开源
- *
- * @author zhoujie https://blog.csdn.net/qq_37902949/article/details/81228566
- */
 public final class CharImageUtil {
 
     public static String createCharImg(BufferedImage image) {
@@ -15,41 +8,7 @@ public final class CharImageUtil {
     }
 
     public static String createCharImg(BufferedImage image, int sizeWeight, int sizeHeight) {
-        //生成字符图片
-        image = resize(image, sizeWeight, sizeHeight);
-        int width = image.getWidth();
-        int height = image.getHeight();
-
-        StringBuilder output = new StringBuilder();
-        for (int i = 0; i < height; i++) {
-            StringBuilder line = new StringBuilder();
-            for (int j = 0; j < width; j++) {
-                int rgb = image.getRGB(j, i);
-                int R = (rgb & 0xff0000) >> 16;
-                int G = (rgb & 0x00ff00) >> 8;
-                int B = rgb & 0x0000ff;
-                int gray = (R * 30 + G * 59 + B * 11 + 50) / 100;
-                int index = 31 * gray / 255;
-                line.append(asc[index]); //添加每个字符
-            }
-            output.append(line).append("\n");
-        }
-        return output.toString();
+        return new CharImageConverter(image,sizeWeight).call();
     }
 
-    public static BufferedImage resize(BufferedImage img, int newW, int newH) {
-        Image tmp = img.getScaledInstance(newW, newH, Image.SCALE_SMOOTH);
-        BufferedImage dimg = new BufferedImage(newW, newH, BufferedImage.TYPE_INT_ARGB);
-
-        Graphics2D g2d = dimg.createGraphics();
-        g2d.drawImage(tmp, 0, 0, null);
-        g2d.dispose();
-
-        return dimg;
-    }
-
-    private final static char[] asc = {' ', '`', '.', '^', ',', ':', '~', '"',
-            '<', '!', 'c', 't', '+', '{', 'i', '7', '?', 'u', '3', '0', 'p', 'w',
-            '4', 'A', '8', 'D', 'X', '%', '#', 'H', 'W', 'M'};
-
 }
\ No newline at end of file

mirai-core/src/test/java/ImageOutputTest.java

+import net.mamoe.mirai.utils.CharImageConverter;
+
+import javax.imageio.ImageIO;
+import java.awt.image.BufferedImage;
+import java.io.File;
+import java.io.IOException;
+
+public class ImageOutputTest {
+    public static void main(String[] args) throws IOException {
+        BufferedImage image = ImageIO.read(new File((System.getProperty("user.dir") + "/VerificationCode.png").replace("//","/")));
+        CharImageConverter charImageConvertor = new CharImageConverter(image,100);
+        System.out.println(charImageConvertor.call());
+    }
+}