config: add window-padding-color

src/config.zig

@@ -20,6 +20,7 @@ pub const RepeatableCodepointMap = Config.RepeatableCodepointMap;
 pub const RepeatableFontVariation = Config.RepeatableFontVariation;
 pub const RepeatableString = Config.RepeatableString;
 pub const ShellIntegrationFeatures = Config.ShellIntegrationFeatures;
+pub const WindowPaddingColor = Config.WindowPaddingColor;
 
 // Alternate APIs
 pub const CAPI = @import("config/CAPI.zig");

src/config/Config.zig

@@ -669,6 +669,16 @@ keybind: Keybinds = .{},
 /// given a certain viewport size and grid cell size.
 @"window-padding-balance": bool = false,
 
+/// The color of the padding area of the window. Valid values are:
+///
+/// * `background` - The background color specified in `background`.
+/// * `extend` - Extend the background color of the nearest grid cell.
+///
+/// The default value is "extend". This allows for smooth resizing of a
+/// terminal grid without having visible empty areas around the edge. The edge
+/// cells may appear slightly larger due to the extension.
+@"window-padding-color": WindowPaddingColor = .extend,
+
 /// Synchronize rendering with the screen refresh rate. If true, this will
 /// minimize tearing and align redraws with the screen but may cause input
 /// latency. If false, this will maximize redraw frequency but may cause tearing,
@@ -2678,6 +2688,11 @@ pub const OptionAsAlt = enum {
     right,
 };
 
+pub const WindowPaddingColor = enum {
+    background,
+    extend,
+};
+
 /// Color represents a color using RGB.
 ///
 /// This is a packed struct so that the C API to read color values just

src/renderer/Metal.zig

@@ -345,6 +345,7 @@ pub const DerivedConfig = struct {
     invert_selection_fg_bg: bool,
     bold_is_bright: bool,
     min_contrast: f32,
+    padding_color: configpkg.WindowPaddingColor,
     custom_shaders: std.ArrayListUnmanaged([:0]const u8),
     links: link.Set,
     vsync: bool,
@@ -402,6 +403,7 @@ pub const DerivedConfig = struct {
             .invert_selection_fg_bg = config.@"selection-invert-fg-bg",
             .bold_is_bright = config.@"bold-is-bright",
             .min_contrast = @floatCast(config.@"minimum-contrast"),
+            .padding_color = config.@"window-padding-color",
 
             .selection_background = if (config.@"selection-background") |bg|
                 bg.toTerminalRGB()
@@ -1960,10 +1962,16 @@ pub fn setScreenSize(
     const padded_dim = dim.subPadding(padding);
 
     // Blank space around the grid.
-    const blank = dim.blankPadding(padding, grid_size, .{
+    const blank: renderer.Padding = switch (self.config.padding_color) {
+        // We can use zero padding because the backgroudn color is our
+        // clear color.
+        .background => .{},
+
+        .extend => dim.blankPadding(padding, grid_size, .{
             .width = self.grid_metrics.cell_width,
             .height = self.grid_metrics.cell_height,
-    }).add(padding);
+        }).add(padding),
+    };
 
     // Set the size of the drawable surface to the bounds
     self.layer.setProperty("drawableSize", macos.graphics.Size{