implement faint colors (SGR 2)

src/Grid.zig

@@ -520,6 +520,9 @@ pub fn updateCell(
     };
     if (self.cells.items.len + needed > self.cells.capacity) return false;
 
+    // Alpha multiplier
+    const alpha: u8 = if (cell.attrs.faint) 175 else 255;
+
     // If the cell has a background, we always draw it.
     if (colors.bg) |rgb| {
         var mode: GPUCellMode = .bg;
@@ -542,7 +545,7 @@ pub fn updateCell(
             .bg_r = rgb.r,
             .bg_g = rgb.g,
             .bg_b = rgb.b,
-            .bg_a = 0xFF,
+            .bg_a = alpha,
         });
     }
 
@@ -577,7 +580,7 @@ pub fn updateCell(
             .fg_r = colors.fg.r,
             .fg_g = colors.fg.g,
             .fg_b = colors.fg.b,
-            .fg_a = 255,
+            .fg_a = alpha,
             .bg_r = 0,
             .bg_g = 0,
             .bg_b = 0,
@@ -602,7 +605,7 @@ pub fn updateCell(
             .fg_r = colors.fg.r,
             .fg_g = colors.fg.g,
             .fg_b = colors.fg.b,
-            .fg_a = 255,
+            .fg_a = alpha,
             .bg_r = 0,
             .bg_g = 0,
             .bg_b = 0,

src/terminal/Terminal.zig

@@ -301,6 +301,10 @@ pub fn setAttribute(self: *Terminal, attr: sgr.Attribute) !void {
             self.screen.cursor.pen.attrs.bold = true;
         },
 
+        .faint => {
+            self.screen.cursor.pen.attrs.faint = true;
+        },
+
         .underline => {
             self.screen.cursor.pen.attrs.underline = true;
         },

src/terminal/sgr.zig

@@ -21,6 +21,9 @@ pub const Attribute = union(enum) {
     /// Bold the text.
     bold: void,
 
+    /// Faint/dim text.
+    faint: void,
+
     /// Underline the text
     underline: void,
 
@@ -88,6 +91,8 @@ pub const Parser = struct {
 
             1 => return Attribute{ .bold = {} },
 
+            2 => return Attribute{ .faint = {} },
+
             4 => return Attribute{ .underline = {} },
 
             5 => return Attribute{ .blink = {} },