renderer/metal: invert text under cursor again

src/renderer/Metal.zig

@@ -565,6 +565,8 @@ pub fn init(alloc: Allocator, options: renderer.Options) !Metal {
             .projection_matrix = undefined,
             .cell_size = undefined,
             .min_contrast = options.config.min_contrast,
+            .cursor_pos = .{ std.math.maxInt(u16), std.math.maxInt(u16) },
+            .cursor_color = undefined,
         },
 
         // Fonts
@@ -683,6 +685,8 @@ pub fn setFontGrid(self: *Metal, grid: *font.SharedGrid) void {
             @floatFromInt(metrics.cell_height),
         },
         .min_contrast = self.uniforms.min_contrast,
+        .cursor_pos = self.uniforms.cursor_pos,
+        .cursor_color = self.uniforms.cursor_color,
     };
 }
 
@@ -1586,6 +1590,8 @@ pub fn setScreenSize(
             @floatFromInt(self.grid_metrics.cell_height),
         },
         .min_contrast = old.min_contrast,
+        .cursor_pos = old.cursor_pos,
+        .cursor_color = old.cursor_color,
     };
 
     // Reset our cell contents.
@@ -1987,11 +1993,30 @@ fn rebuildCells2(
         // If we have no cursor style then we don't render the cursor.
         const style = cursor_style_ orelse {
             self.cells.setCursor(null);
+            self.uniforms.cursor_pos = .{
+                std.math.maxInt(u16),
+                std.math.maxInt(u16),
+            };
             break :cursor;
         };
 
         // Prepare the cursor cell contents.
         self.addCursor2(screen, style);
+
+        // Setup our uniforms for the cursor so that any data
+        // under the cursor can render differently.
+        self.uniforms.cursor_pos = .{ screen.cursor.x, screen.cursor.y };
+        self.uniforms.cursor_color = if (self.config.cursor_text) |txt| .{
+            txt.r,
+            txt.g,
+            txt.b,
+            255,
+        } else .{
+            self.background_color.r,
+            self.background_color.g,
+            self.background_color.b,
+            255,
+        };
     }
 
     // If we have a preedit, we try to render the preedit text on top
@@ -2512,7 +2537,7 @@ fn addCursor2(
     };
 
     self.cells.setCursor(.{
-        .mode = .fg,
+        .mode = .cursor,
         .grid_pos = .{ x, screen.cursor.y },
         .cell_width = if (wide) 2 else 1,
         .color = .{ color.r, color.g, color.b, alpha },

src/renderer/metal/shaders.zig

@@ -116,6 +116,10 @@ pub const Uniforms = extern struct {
     /// The minimum contrast ratio for text. The contrast ratio is calculated
     /// according to the WCAG 2.0 spec.
     min_contrast: f32,
+
+    /// The cursor position and color.
+    cursor_pos: [2]u16,
+    cursor_color: [4]u8,
 };
 
 /// The uniforms used for custom postprocess shaders.
@@ -296,10 +300,10 @@ pub const CellText = extern struct {
     cell_width: u8,
 
     pub const Mode = enum(u8) {
-        bg = 1,
+        fg = 1,
-        fg = 2,
+        fg_constrained = 2,
-        fg_constrained = 3,
+        fg_color = 3,
-        fg_color = 7,
+        cursor = 4,
     };
 };
 

src/renderer/shaders/cell.metal

@@ -4,6 +4,8 @@ struct Uniforms {
   float4x4 projection_matrix;
   float2 cell_size;
   float min_contrast;
+  ushort2 cursor_pos;
+  uchar4 cursor_color;
 };
 
 //-------------------------------------------------------------------
@@ -134,9 +136,10 @@ fragment float4 cell_bg_fragment(CellBgVertexOut in [[stage_in]]) {
 
 // The possible modes that a cell fg entry can take.
 enum CellTextMode : uint8_t {
-  MODE_TEXT = 2u,
+  MODE_TEXT = 1u,
-  MODE_TEXT_CONSTRAINED = 3u,
+  MODE_TEXT_CONSTRAINED = 2u,
-  MODE_TEXT_COLOR = 7u,
+  MODE_TEXT_COLOR = 3u,
+  MODE_TEXT_CURSOR = 4u,
 };
 
 struct CellTextVertexIn {
@@ -243,6 +246,13 @@ vertex CellTextVertexOut cell_text_vertex(unsigned int vid [[vertex_id]],
     out.color = contrasted_color(uniforms.min_contrast, out.color, bg_color);
   }
 
+  // If this cell is the cursor cell, then we need to change the color.
+  if (input.mode != MODE_TEXT_CURSOR &&
+      input.grid_pos.x == uniforms.cursor_pos.x &&
+      input.grid_pos.y == uniforms.cursor_pos.y) {
+    out.color = float4(uniforms.cursor_color) / 255.0f;
+  }
+
   return out;
 }
 
@@ -254,6 +264,7 @@ fragment float4 cell_text_fragment(CellTextVertexOut in [[stage_in]],
   constexpr sampler textureSampler(address::clamp_to_edge, filter::linear);
 
   switch (in.mode) {
+    case MODE_TEXT_CURSOR:
     case MODE_TEXT_CONSTRAINED:
     case MODE_TEXT: {
       // Normalize the texture coordinates to [0,1]