terminal/kitty: add virtual placeholders placements

src/terminal/kitty/graphics_exec.zig

@@ -184,21 +184,26 @@ fn display(
     // Make sure our response has the image id in case we looked up by number
     result.id = img.id;
 
-    // Track a new pin for our cursor. The cursor is always tracked but we
-    // don't want this one to move with the cursor.
-    const placement_pin = terminal.screen.pages.trackPin(
-        terminal.screen.cursor.page_pin.*,
-    ) catch |err| {
-        log.warn("failed to create pin for Kitty graphics err={}", .{err});
-        result.message = "EINVAL: failed to prepare terminal state";
-        return result;
+    // Location where the placement will go.
+    const location: ImageStorage.Placement.Location = location: {
+        // Virtual placements are not tracked
+        if (d.virtual_placement) break :location .{ .virtual = {} };
+
+        // Track a new pin for our cursor. The cursor is always tracked but we
+        // don't want this one to move with the cursor.
+        const pin = terminal.screen.pages.trackPin(
+            terminal.screen.cursor.page_pin.*,
+        ) catch |err| {
+            log.warn("failed to create pin for Kitty graphics err={}", .{err});
+            result.message = "EINVAL: failed to prepare terminal state";
+            return result;
+        };
+        break :location .{ .pin = pin };
     };
 
     // Add the placement
     const p: ImageStorage.Placement = .{
-        .location = .{
-            .pin = placement_pin,
-        },
+        .location = location,
         .x_offset = d.x_offset,
         .y_offset = d.y_offset,
         .source_x = d.x,
@@ -222,6 +227,7 @@ fn display(
 
     // Apply cursor movement setting. This only applies to pin placements.
     switch (p.location) {
+        .virtual => {},
         .pin => |pin| switch (d.cursor_movement) {
             .none => {},
             .after => {

src/terminal/kitty/graphics_storage.zig

@@ -218,6 +218,7 @@ pub const ImageStorage = struct {
         cmd: command.Delete,
     ) void {
         switch (cmd) {
+            // TODO: virtual placeholders must not be deleted according to spec
             .all => |delete_images| if (delete_images) {
                 // We just reset our entire state.
                 self.deinit(alloc, &t.screen);
@@ -318,7 +319,7 @@ pub const ImageStorage = struct {
                 var it = self.placements.iterator();
                 while (it.next()) |entry| {
                     const img = self.imageById(entry.key_ptr.image_id) orelse continue;
-                    const rect = entry.value_ptr.rect(img, t);
+                    const rect = entry.value_ptr.rect(img, t) orelse continue;
                     if (rect.top_left.x <= x and rect.bottom_right.x >= x) {
                         entry.value_ptr.deinit(&t.screen);
                         self.placements.removeByPtr(entry.key_ptr);
@@ -345,7 +346,7 @@ pub const ImageStorage = struct {
                 var it = self.placements.iterator();
                 while (it.next()) |entry| {
                     const img = self.imageById(entry.key_ptr.image_id) orelse continue;
-                    const rect = entry.value_ptr.rect(img, t);
+                    const rect = entry.value_ptr.rect(img, t) orelse continue;
 
                     // We need to copy our pin to ensure we are at least at
                     // the top-left x.
@@ -365,6 +366,14 @@ pub const ImageStorage = struct {
             .z => |v| {
                 var it = self.placements.iterator();
                 while (it.next()) |entry| {
+                    switch (entry.value_ptr.location) {
+                        .pin => {},
+
+                        // Virtual placeholders cannot delete by z according
+                        // to the spec.
+                        .virtual => continue,
+                    }
+
                     if (entry.value_ptr.z == v.z) {
                         const image_id = entry.key_ptr.image_id;
                         entry.value_ptr.deinit(&t.screen);
@@ -451,7 +460,7 @@ pub const ImageStorage = struct {
         var it = self.placements.iterator();
         while (it.next()) |entry| {
             const img = self.imageById(entry.key_ptr.image_id) orelse continue;
-            const rect = entry.value_ptr.rect(img, t);
+            const rect = entry.value_ptr.rect(img, t) orelse continue;
             if (target_pin.isBetween(rect.top_left, rect.bottom_right)) {
                 if (filter) |f| if (!f(filter_ctx, entry.value_ptr.*)) continue;
                 entry.value_ptr.deinit(&t.screen);
@@ -577,10 +586,7 @@ pub const ImageStorage = struct {
 
     pub const Placement = struct {
         /// The location where this placement should be drawn.
-        location: union(enum) {
-            /// Exactly placed on a screen pin.
-            pin: *PageList.Pin,
-        },
+        location: Location,
 
         /// Offset of the x/y from the top-left of the cell.
         x_offset: u32 = 0,
@@ -599,12 +605,21 @@ pub const ImageStorage = struct {
         /// The z-index for this placement.
         z: i32 = 0,
 
+        pub const Location = union(enum) {
+            /// Exactly placed on a screen pin.
+            pin: *PageList.Pin,
+
+            /// Virtual placement (U=1) for unicode placeholders.
+            virtual: void,
+        };
+
         pub fn deinit(
             self: *const Placement,
             s: *terminal.Screen,
         ) void {
             switch (self.location) {
                 .pin => |p| s.pages.untrackPin(p),
+                .virtual => {},
             }
         }
 
@@ -647,16 +662,18 @@ pub const ImageStorage = struct {
         }
 
         /// Returns a selection of the entire rectangle this placement
-        /// occupies within the screen.
+        /// occupies within the screen. This can return null if the placement
+        /// doesn't have an associated rect (i.e. a virtual placement).
         pub fn rect(
             self: Placement,
             image: Image,
             t: *const terminal.Terminal,
-        ) Rect {
-            assert(self.location == .pin);
-
+        ) ?Rect {
             const grid_size = self.gridSize(image, t);
-            const pin = self.location.pin;
+            const pin = switch (self.location) {
+                .pin => |p| p,
+                .virtual => return null,
+            };
 
             var br = switch (pin.downOverflow(grid_size.rows - 1)) {
                 .offset => |v| v,