System Touch

Author: mearvk

source/terminal/TerminalImageRenderer.java

@@ -0,0 +1,124 @@
+package terminal;
+
+import javax.imageio.ImageIO;
+import java.awt.*;
+import java.awt.image.BufferedImage;
+import java.io.File;
+
+/**
+ * TerminalImageRenderer
+ *
+ * Renders a JPEG/PNG/BMP image to a GNOME terminal using
+ * Unicode half-block characters and 24-bit ANSI TrueColor.
+ *
+ * Usage:
+ *   javac TerminalImageRenderer.java
+ *   java TerminalImageRenderer path/to/image.png [width]
+ *
+ * If width is omitted, defaults to 80 characters.
+ */
+public class TerminalImageRenderer
+{
+
+    // ANSI escape sequences
+    private static final String ESC = "\u001b[";
+    private static final String RESET = ESC + "0m";
+
+    public static void main(String[] args) throws Exception
+    {
+        if (args.length < 1) {
+            System.err.println("Usage: java TerminalImageRenderer <image> [width]");
+            System.exit(1);
+        }
+
+        String path = args[0];
+        int targetWidth = (args.length >= 2) ? Integer.parseInt(args[1]) : 80;
+
+        BufferedImage img = ImageIO.read(new File(path));
+
+        if (img == null) {
+            System.err.println("Could not read image: " + path);
+            System.exit(1);
+        }
+
+        BufferedImage scaled = scaleToWidth(img, targetWidth);
+        renderHalfBlocksTrueColor(scaled);
+        System.out.print(RESET);
+    }
+
+    /**
+     * Scale image to target terminal width, preserving aspect ratio.
+     * Height is scaled accordingly; we later compress two vertical pixels
+     * into one terminal row using half-block characters.
+     */
+    private static BufferedImage scaleToWidth(BufferedImage src, int targetWidth)
+    {
+        int srcWidth = src.getWidth();
+        int srcHeight = src.getHeight();
+
+        if (srcWidth <= targetWidth) {
+            return src; // no scaling needed
+        }
+
+        double scale = (double) targetWidth / srcWidth;
+        int newWidth = targetWidth;
+        int newHeight = (int) Math.round(srcHeight * scale);
+
+        BufferedImage dst = new BufferedImage(newWidth, newHeight, BufferedImage.TYPE_INT_RGB);
+        Graphics2D g = dst.createGraphics();
+        g.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
+        g.drawImage(src, 0, 0, newWidth, newHeight, null);
+        g.dispose();
+        return dst;
+    }
+
+    /**
+     * Render using Unicode upper half-block (▀) with foreground color
+     * for the top pixel and background color for the bottom pixel.
+     *
+     * Each terminal cell represents two vertical pixels:
+     *   - top pixel -> ANSI 38;2;r;g;b (foreground)
+     *   - bottom pixel -> ANSI 48;2;r;g;b (background)
+     */
+    private static void renderHalfBlocksTrueColor(BufferedImage img)
+    {
+        int width = img.getWidth();
+        int height = img.getHeight();
+
+        // Ensure even height for pairing top/bottom pixels
+        if (height % 2 != 0) {
+            height -= 1;
+        }
+
+        StringBuilder sb = new StringBuilder();
+
+        for (int y = 0; y < height; y += 2) {
+            for (int x = 0; x < width; x++) {
+                int topRGB = img.getRGB(x, y);
+                int bottomRGB = img.getRGB(x, y + 1);
+
+                Color top = new Color(topRGB);
+                Color bottom = new Color(bottomRGB);
+
+                // ANSI TrueColor: foreground (top), background (bottom)
+                sb.append(ESC)
+                        .append("38;2;")
+                        .append(top.getRed()).append(";")
+                        .append(top.getGreen()).append(";")
+                        .append(top.getBlue()).append("m");
+
+                sb.append(ESC)
+                        .append("48;2;")
+                        .append(bottom.getRed()).append(";")
+                        .append(bottom.getGreen()).append(";")
+                        .append(bottom.getBlue()).append("m");
+
+                // Upper half block character
+                sb.append('▀');
+            }
+            sb.append(RESET).append('\n');
+        }
+
+        System.out.print(sb.toString());
+    }
+}