Merge pull request #2095 from qwerasd205/flicker

Fix flickering when resizing surface.

src/Surface.zig

@@ -1197,15 +1197,6 @@ fn resize(self: *Surface, size: renderer.ScreenSize) !void {
     // Save our screen size
     self.screen_size = size;
 
-    // Mail the renderer so that it can update the GPU and re-render
-    _ = self.renderer_thread.mailbox.push(.{
-        .resize = .{
-            .screen_size = self.screen_size,
-            .padding = self.padding,
-        },
-    }, .{ .forever = {} });
-    try self.queueRender();
-
     // Recalculate our grid size. Because Ghostty supports fluid resizing,
     // its possible the grid doesn't change at all even if the screen size changes.
     // We have to update the IO thread no matter what because we send

src/renderer/Metal.zig

@@ -908,12 +908,14 @@ pub fn updateFrame(
         }
 
         // If our terminal screen size doesn't match our expected renderer
-        // size then we skip a frame. This can happen if we get resized
-        // before the terminal gets resized. The terminal resize event also
-        // wakes up the renderer so we'll get another chance to update frame
-        // data.
-        if (self.cells.size.rows < state.terminal.rows or
-            self.cells.size.columns < state.terminal.cols)
+        // size then we skip a frame. This can happen if the terminal state
+        // is resized between when the renderer mailbox is drained and when
+        // the state mutex is acquired inside this function.
+        //
+        // For some reason this doesn't seem to cause any significant issues
+        // with flickering while resizing. '\_('-')_/'
+        if (self.cells.size.rows != state.terminal.rows or
+            self.cells.size.columns != state.terminal.cols)
         {
             return;
         }
@@ -2012,11 +2014,13 @@ pub fn setScreenSize(
         .cursor_color = old.cursor_color,
     };
 
-    // Reset our cell contents.
+    // Reset our cell contents if our grid size has changed.
+    if (!self.cells.size.equals(grid_size)) {
         try self.cells.resize(self.alloc, grid_size);
 
         // Reset our viewport to force a rebuild
         self.cells_viewport = null;
+    }
 
     // If we have custom shaders then we update the state
     if (self.custom_shader_state) |*state| {

src/renderer/OpenGL.zig

@@ -739,6 +739,19 @@ pub fn updateFrame(
             self.foreground_color = bg;
         }
 
+        // If our terminal screen size doesn't match our expected renderer
+        // size then we skip a frame. This can happen if the terminal state
+        // is resized between when the renderer mailbox is drained and when
+        // the state mutex is acquired inside this function.
+        //
+        // For some reason this doesn't seem to cause any significant issues
+        // with flickering while resizing. '\_('-')_/'
+        if (self.grid_size.rows != state.terminal.rows or
+            self.grid_size.columns != state.terminal.cols)
+        {
+            return;
+        }
+
         // Get the viewport pin so that we can compare it to the current.
         const viewport_pin = state.terminal.screen.pages.pin(.{ .viewport = .{} }).?;
 

src/renderer/Thread.zig

@@ -480,7 +480,7 @@ fn drawCallback(
     r: xev.Timer.RunError!void,
 ) xev.CallbackAction {
     _ = r catch unreachable;
-    const t = self_ orelse {
+    const t: *Thread = self_ orelse {
         // This shouldn't happen so we log it.
         log.warn("render callback fired without data set", .{});
         return .disarm;
@@ -504,7 +504,7 @@ fn renderCallback(
     r: xev.Timer.RunError!void,
 ) xev.CallbackAction {
     _ = r catch unreachable;
-    const t = self_ orelse {
+    const t: *Thread = self_ orelse {
         // This shouldn't happen so we log it.
         log.warn("render callback fired without data set", .{});
         return .disarm;
@@ -522,6 +522,8 @@ fn renderCallback(
         t.flags.cursor_blink_visible,
     ) catch |err|
         log.warn("error rendering err={}", .{err});
+
+    // Draw
     t.drawFrame(false);
 
     return .disarm;
@@ -543,7 +545,7 @@ fn cursorTimerCallback(
         },
     };
 
-    const t = self_ orelse {
+    const t: *Thread = self_ orelse {
         // This shouldn't happen so we log it.
         log.warn("render callback fired without data set", .{});
         return .disarm;

src/termio/Termio.zig

@@ -378,14 +378,20 @@ pub fn resize(
         // immediately for a resize. This is allowed by the spec.
         self.terminal.modes.set(.synchronized_output, false);
 
-        // Wake up our renderer so any changes will be shown asap
-        self.renderer_wakeup.notify() catch {};
-
         // If we have size reporting enabled we need to send a report.
         if (self.terminal.modes.get(.in_band_size_reports)) {
             try self.sizeReportLocked(td, .mode_2048);
         }
     }
+
+    // Mail the renderer so that it can update the GPU and re-render
+    _ = self.renderer_mailbox.push(.{
+        .resize = .{
+            .screen_size = screen_size,
+            .padding = padding,
+        },
+    }, .{ .forever = {} });
+    self.renderer_wakeup.notify() catch {};
 }
 
 /// Make a size report.