gtk: add support for using GTK Builder UI files and Blueprints (#5714)

Adds buildtime and comptime checks to make sure that Blueprints/UI files
are availble and correctly formed. Will also compile Blueprints to UI
files so that they are available to GTK code.

nix/devShell.nix

@@ -32,6 +32,7 @@
   gtk4,
   gobject-introspection,
   libadwaita,
+  blueprint-compiler,
   adwaita-icon-theme,
   hicolor-icon-theme,
   harfbuzz,
@@ -159,6 +160,7 @@ in
         libXrandr
 
         # Only needed for GTK builds
+        blueprint-compiler
         libadwaita
         gtk4
         glib

nix/package.nix

@@ -15,6 +15,7 @@
   gtk4,
   gobject-introspection,
   libadwaita,
+  blueprint-compiler,
   wrapGAppsHook4,
   gsettings-desktop-schemas,
   git,
@@ -82,6 +83,7 @@ in
         zig_hook
         gobject-introspection
         wrapGAppsHook4
+        blueprint-compiler
       ]
       ++ lib.optionals enableWayland [
         wayland-scanner

src/apprt/gtk/Builder.zig

@@ -0,0 +1,61 @@
+/// Wrapper around GTK's builder APIs that perform some comptime checks.
+const Builder = @This();
+
+const std = @import("std");
+
+const gtk = @import("gtk");
+const gobject = @import("gobject");
+
+resource_name: [:0]const u8,
+
+pub fn init(comptime name: []const u8, comptime kind: enum { blp, ui }) Builder {
+    comptime {
+        switch (kind) {
+            .blp => {
+                // Use @embedFile to make sure that the file exists at compile
+                // time. Zig _should_ discard the data so that it doesn't end
+                // up in the final executable. At runtime we will load the data
+                // from a GResource.
+                _ = @embedFile("ui/" ++ name ++ ".blp");
+
+                // Check to make sure that our file is listed as a
+                // `blueprint_file` in `gresource.zig`. If it isn't Ghostty
+                // could crash at runtime when we try and load a nonexistent
+                // GResource.
+                const gresource = @import("gresource.zig");
+                for (gresource.blueprint_files) |blueprint_file| {
+                    if (std.mem.eql(u8, blueprint_file, name)) break;
+                } else @compileError("missing blueprint file '" ++ name ++ "' in gresource.zig");
+            },
+            .ui => {
+                // Use @embedFile to make sure that the file exists at compile
+                // time. Zig _should_ discard the data so that it doesn't end
+                // up in the final executable. At runtime we will load the data
+                // from a GResource.
+                _ = @embedFile("ui/" ++ name ++ ".ui");
+
+                // Check to make sure that our file is listed as a `ui_file` in
+                // `gresource.zig`. If it isn't Ghostty could crash at runtime
+                // when we try and load a nonexistent GResource.
+                const gresource = @import("gresource.zig");
+                for (gresource.ui_files) |ui_file| {
+                    if (std.mem.eql(u8, ui_file, name)) break;
+                } else @compileError("missing ui file '" ++ name ++ "' in gresource.zig");
+            },
+        }
+    }
+
+    return .{
+        .resource_name = "/com/mitchellh/ghostty/ui/" ++ name ++ ".ui",
+    };
+}
+
+pub fn setWidgetClassTemplate(self: *const Builder, class: *gtk.WidgetClass) void {
+    class.setTemplateFromResource(self.resource_name);
+}
+
+pub fn getObject(self: *const Builder, name: [:0]const u8) ?gobject.Object {
+    const builder = gtk.Builder.newFromResource(self.resource_name);
+    defer builder.unref();
+    return builder.getObject(name);
+}

src/apprt/gtk/builder_check.zig

@@ -0,0 +1,39 @@
+const std = @import("std");
+const build_options = @import("build_options");
+
+const gtk = @import("gtk");
+const adw = if (build_options.adwaita) @import("adw") else void;
+
+pub fn main() !void {
+    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+    const alloc = gpa.allocator();
+
+    const filename = filename: {
+        var it = try std.process.argsWithAllocator(alloc);
+        defer it.deinit();
+
+        _ = it.next() orelse return error.NoFilename;
+        break :filename try alloc.dupeZ(u8, it.next() orelse return error.NoFilename);
+    };
+    defer alloc.free(filename);
+
+    const data = try std.fs.cwd().readFileAlloc(alloc, filename, std.math.maxInt(u16));
+    defer alloc.free(data);
+
+    if ((comptime !build_options.adwaita) and std.mem.indexOf(u8, data, "lib=\"Adw\"") != null) {
+        std.debug.print("{s}: skipping builder check because Adwaita is not enabled!\n", .{filename});
+        return;
+    }
+
+    if (gtk.initCheck() == 0) {
+        std.debug.print("{s}: skipping builder check because we can't connect to display!\n", .{filename});
+        return;
+    }
+
+    if (comptime build_options.adwaita) {
+        adw.init();
+    }
+
+    const builder = gtk.Builder.newFromString(data.ptr, @intCast(data.len));
+    defer builder.unref();
+}

src/apprt/gtk/gresource.zig

@@ -53,29 +53,33 @@ const icons = [_]struct {
     },
 };
 
-pub const gresource_xml = comptimeGenerateGResourceXML();
+pub const ui_files = [_][]const u8{};
+pub const blueprint_files = [_][]const u8{};
 
-fn comptimeGenerateGResourceXML() []const u8 {
-    comptime {
-        @setEvalBranchQuota(13000);
-        var counter = std.io.countingWriter(std.io.null_writer);
-        try writeGResourceXML(&counter.writer());
+pub fn main() !void {
+    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+    const alloc = gpa.allocator();
 
-        var buf: [counter.bytes_written]u8 = undefined;
-        var stream = std.io.fixedBufferStream(&buf);
-        try writeGResourceXML(stream.writer());
-        const final = buf;
-        return final[0..stream.getWritten().len];
+    var extra_ui_files = std.ArrayList([]const u8).init(alloc);
+    defer {
+        for (extra_ui_files.items) |item| alloc.free(item);
+        extra_ui_files.deinit();
+    }
+
+    var it = try std.process.argsWithAllocator(alloc);
+    defer it.deinit();
+
+    while (it.next()) |filename| {
+        if (std.mem.eql(u8, std.fs.path.extension(filename), ".ui")) {
+            try extra_ui_files.append(try alloc.dupe(u8, filename));
         }
     }
 
-fn writeGResourceXML(writer: anytype) !void {
+    const writer = std.io.getStdOut().writer();
+
     try writer.writeAll(
         \\<?xml version="1.0" encoding="UTF-8"?>
         \\<gresources>
-        \\
-    );
-    try writer.writeAll(
         \\  <gresource prefix="/com/mitchellh/ghostty">
         \\
     );
@@ -87,9 +91,6 @@ fn writeGResourceXML(writer: anytype) !void {
     }
     try writer.writeAll(
         \\  </gresource>
-        \\
-    );
-    try writer.writeAll(
         \\  <gresource prefix="/com/mitchellh/ghostty/icons">
         \\
     );
@@ -99,6 +100,23 @@ fn writeGResourceXML(writer: anytype) !void {
             .{ icon.alias, icon.source },
         );
     }
+    try writer.writeAll(
+        \\  </gresource>
+        \\  <gresource prefix="/com/mitchellh/ghostty/ui">
+        \\
+    );
+    for (ui_files) |ui_file| {
+        try writer.print(
+            "    <file compressed=\"true\" preprocess=\"xml-stripblanks\" alias=\"{0s}.ui\">src/apprt/gtk/ui/{0s}.ui</file>\n",
+            .{ui_file},
+        );
+    }
+    for (extra_ui_files.items) |ui_file| {
+        try writer.print(
+            "    <file compressed=\"true\" preprocess=\"xml-stripblanks\" alias=\"{s}\">{s}</file>\n",
+            .{ std.fs.path.basename(ui_file), ui_file },
+        );
+    }
     try writer.writeAll(
         \\  </gresource>
         \\</gresources>
@@ -107,12 +125,24 @@ fn writeGResourceXML(writer: anytype) !void {
 }
 
 pub const dependencies = deps: {
-    var deps: [css_files.len + icons.len][]const u8 = undefined;
-    for (css_files, 0..) |css_file, i| {
-        deps[i] = std.fmt.comptimePrint("src/apprt/gtk/{s}", .{css_file});
+    const total = css_files.len + icons.len + ui_files.len + blueprint_files.len;
+    var deps: [total][]const u8 = undefined;
+    var index: usize = 0;
+    for (css_files) |css_file| {
+        deps[index] = std.fmt.comptimePrint("src/apprt/gtk/{s}", .{css_file});
+        index += 1;
     }
-    for (icons, css_files.len..) |icon, i| {
-        deps[i] = std.fmt.comptimePrint("images/icons/icon_{s}.png", .{icon.source});
+    for (icons) |icon| {
+        deps[index] = std.fmt.comptimePrint("images/icons/icon_{s}.png", .{icon.source});
+        index += 1;
+    }
+    for (ui_files) |ui_file| {
+        deps[index] = std.fmt.comptimePrint("src/apprt/gtk/ui/{s}.ui", .{ui_file});
+        index += 1;
+    }
+    for (blueprint_files) |blueprint_file| {
+        deps[index] = std.fmt.comptimePrint("src/apprt/gtk/ui/{s}.blp", .{blueprint_file});
+        index += 1;
     }
     break :deps deps;
 };

src/build/SharedDeps.zig

@@ -490,8 +490,48 @@ pub fn add(
                 {
                     const gresource = @import("../apprt/gtk/gresource.zig");
 
-                    const wf = b.addWriteFiles();
-                    const gresource_xml = wf.add("gresource.xml", gresource.gresource_xml);
+                    const gresource_xml = gresource_xml: {
+                        const generate_gresource_xml = b.addExecutable(.{
+                            .name = "generate_gresource_xml",
+                            .root_source_file = b.path("src/apprt/gtk/gresource.zig"),
+                            .target = b.host,
+                        });
+
+                        const generate = b.addRunArtifact(generate_gresource_xml);
+
+                        for (gresource.blueprint_files) |blueprint_file| {
+                            const blueprint_compiler = b.addSystemCommand(&.{
+                                "blueprint-compiler",
+                                "compile",
+                                "--output",
+                            });
+                            const ui_file = blueprint_compiler.addOutputFileArg(b.fmt("{s}.ui", .{blueprint_file}));
+                            blueprint_compiler.addFileArg(b.path(b.fmt("src/apprt/gtk/ui/{s}.blp", .{blueprint_file})));
+                            generate.addFileArg(ui_file);
+                        }
+
+                        break :gresource_xml generate.captureStdOut();
+                    };
+
+                    {
+                        const gtk_builder_check = b.addExecutable(.{
+                            .name = "gtk_builder_check",
+                            .root_source_file = b.path("src/apprt/gtk/builder_check.zig"),
+                            .target = b.host,
+                        });
+                        gtk_builder_check.root_module.addOptions("build_options", self.options);
+                        gtk_builder_check.linkSystemLibrary2("gtk4", dynamic_link_opts);
+                        if (self.config.adwaita) gtk_builder_check.linkSystemLibrary2("libadwaita-1", dynamic_link_opts);
+                        gtk_builder_check.linkLibC();
+
+                        for (gresource.dependencies) |pathname| {
+                            const extension = std.fs.path.extension(pathname);
+                            if (!std.mem.eql(u8, extension, ".ui")) continue;
+                            const check = b.addRunArtifact(gtk_builder_check);
+                            check.addFileArg(b.path(pathname));
+                            step.step.dependOn(&check.step);
+                        }
+                    }
 
                     const generate_resources_c = b.addSystemCommand(&.{
                         "glib-compile-resources",