Make the app icon work on macOS, Windows, and Linux.

Co-authored-by: Cursor <cursoragent@cursor.com>

CMakeLists.txt

@@ -46,7 +46,8 @@ endif()
 # so MSVC needs mainCRTStartup as the entry point.
 file(GLOB MATURITA_SOURCES CONFIGURE_DEPENDS "${CMAKE_CURRENT_SOURCE_DIR}/*.c")
 if(WIN32)
-    add_executable(maturita WIN32 ${MATURITA_SOURCES})
+    add_executable(maturita WIN32 ${MATURITA_SOURCES}
+                   "${CMAKE_CURRENT_SOURCE_DIR}/maturita.rc")
 else()
     add_executable(maturita ${MATURITA_SOURCES})
 endif()
@@ -66,8 +67,8 @@ else()
     endif()
 endif()
 
-# The GTK stylesheet and window icon are loaded at runtime from the working
-# directory (or next to the binary), so keep copies beside the built binary.
+# The GTK stylesheet, window icon and Freedesktop share/ tree are loaded at
+# runtime from the working directory (or next to the binary).
 add_custom_command(TARGET maturita POST_BUILD
     COMMAND ${CMAKE_COMMAND} -E copy_if_different
             ${CMAKE_CURRENT_SOURCE_DIR}/style.css
@@ -81,4 +82,7 @@ add_custom_command(TARGET maturita POST_BUILD
             ${CMAKE_CURRENT_SOURCE_DIR}/assets/icons/hicolor/512x512/apps
     COMMAND ${CMAKE_COMMAND} -E copy_if_different
             ${CMAKE_CURRENT_SOURCE_DIR}/assets/app-icon.png
-            ${CMAKE_CURRENT_SOURCE_DIR}/assets/icons/hicolor/512x512/apps/maturita.png)
+            ${CMAKE_CURRENT_SOURCE_DIR}/assets/icons/hicolor/512x512/apps/maturita.png
+    COMMAND ${CMAKE_COMMAND} -E copy_directory
+            ${CMAKE_CURRENT_SOURCE_DIR}/share
+            $<TARGET_FILE_DIR:maturita>/share)

Makefile

@@ -17,12 +17,15 @@ GTK_LIBS   := $(shell $(PKG_CONFIG) --libs gtk4)
 CFLAGS = -Wall -Wextra -Wno-deprecated-declarations $(GTK_CFLAGS)
 LIBS = $(GTK_LIBS) -lm
 
-# Windows (MSYS2 / MinGW): .exe suffix and no console window for the GUI.
+# Windows (MSYS2 / MinGW): .exe suffix, no console window, embed .ico.
 ifeq ($(OS),Windows_NT)
 TARGET = maturita.exe
 LIBS += -mwindows
+WINDRES ?= windres
+RC_OBJ = maturita_rc.o
 else
 TARGET = maturita
+RC_OBJ =
 # macOS Dock icon is set via AppKit (see macos_dock.c).
 ifeq ($(shell uname -s 2>/dev/null),Darwin)
 LIBS += -framework AppKit -framework Foundation
@@ -34,6 +37,7 @@ OBJ = $(SRC:.c=.o)
 
 ICON_SRC = assets/app-icon.png
 ICON_DST = assets/icons/hicolor/512x512/apps/maturita.png
+ICON_ICO = assets/app-icon.ico
 
 all: $(TARGET)
 
@@ -41,11 +45,19 @@ $(ICON_DST): $(ICON_SRC)
 	mkdir -p $(dir $@)
 	cp "$(ICON_SRC)" "$@"
 
+ifeq ($(OS),Windows_NT)
+$(RC_OBJ): maturita.rc $(ICON_ICO)
+	$(WINDRES) maturita.rc -o $(RC_OBJ)
+
+$(TARGET): $(SRC) $(ICON_DST) $(RC_OBJ)
+	$(CC) $(CFLAGS) -o $(TARGET) $(SRC) $(RC_OBJ) $(LIBS)
+else
 $(TARGET): $(SRC) $(ICON_DST)
 	$(CC) $(CFLAGS) -o $(TARGET) $(SRC) $(LIBS)
+endif
 
 clean:
-	rm -f $(TARGET) maturita.exe $(OBJ)
+	rm -f $(TARGET) maturita.exe $(OBJ) $(RC_OBJ) maturita_rc.o
 
 run: $(TARGET)
 	./$(TARGET)
@@ -61,6 +73,7 @@ bundle: $(TARGET)
 	@cp style.css dist/
 	@mkdir -p dist/icons/hicolor/512x512/apps
 	@cp "$(ICON_DST)" dist/icons/hicolor/512x512/apps/
+	@cp -R share dist/
 	@ldd $(TARGET) | grep -Ei '/(ucrt64|mingw64)/bin/' | awk '{print $$3}' \
 		| xargs -r -I{} cp -f {} dist/
 	@echo "Bundled into dist/ - run dist/$(TARGET)"

build-windows.bat

@@ -1,5 +1,5 @@
 @echo off
-setlocal
+setlocal EnableExtensions
 
 REM ---------------------------------------------------------------------------
 REM Native Windows build with MSVC. No MSYS2 or MinGW shell required.
@@ -67,10 +67,22 @@ if not defined GTK_CFLAGS (
     exit /b 1
 )
 
-REM --- 4. Compile -----------------------------------------------------------
+if not exist "assets\app-icon.ico" (
+    echo [error] assets\app-icon.ico is missing.
+    echo         Generate it with: python scripts\gen-icons.py
+    exit /b 1
+)
+
+REM --- 4. Compile resources + sources ---------------------------------------
 echo Building maturita.exe with MSVC...
+rc /nologo /fo maturita.res maturita.rc
+if errorlevel 1 (
+    echo [error] Resource compile failed.
+    exit /b 1
+)
+
 cl /nologo /O2 /MD /W3 /std:c11 /D_CRT_SECURE_NO_WARNINGS ^
-   %GTK_CFLAGS% maturita.c ^
+   %GTK_CFLAGS% *.c maturita.res ^
    /Fe:maturita.exe ^
    /link /SUBSYSTEM:WINDOWS /ENTRY:mainCRTStartup %GTK_LIBS%
 
@@ -79,7 +91,10 @@ if errorlevel 1 (
     exit /b 1
 )
 
+if not exist icons\hicolor\512x512\apps mkdir icons\hicolor\512x512\apps
+copy /Y assets\app-icon.png icons\hicolor\512x512\apps\maturita.png >nul
+
 echo.
-echo Built maturita.exe
+echo Built maturita.exe ^(icon embedded from assets\app-icon.ico^)
 echo Run it from this terminal with:  maturita.exe
 echo Or use run-windows.bat / double-click maturita.exe.

main.c

@@ -189,6 +189,7 @@ static const char *find_app_icon_file(void) {
     static const char *paths[] = {
         ICON_FILE,
         ICON_THEME_DIR "/hicolor/512x512/apps/" ICON_NAME ".png",
+        SHARE_DIR "/icons/hicolor/512x512/apps/" ICON_NAME ".png",
         ICON_FILE_ALT,
         NULL,
     };
@@ -201,12 +202,84 @@ static const char *find_app_icon_file(void) {
     return NULL;
 }
 
-/* GTK4 has no gtk_window_set_icon_from_file(); register a local hicolor
- * theme dir and set the window icon by name instead. On macOS the Dock
- * tile ignores that, so also push the PNG through AppKit. */
+/* Kept alive for gdk_toplevel_set_icon_list() which does not take ownership. */
+static GList *app_icon_textures;
+
+static void clear_app_icon_textures(void) {
+    g_list_free_full(app_icon_textures, g_object_unref);
+    app_icon_textures = NULL;
+}
+
+/* X11 / some compositors use the toplevel icon list for the taskbar tile. */
+static void apply_toplevel_icon(GtkWindow *window) {
+    GdkSurface *surface;
+    const char *path;
+    GError *err = NULL;
+    GdkTexture *tex;
+
+    surface = gtk_native_get_surface(GTK_NATIVE(window));
+    if (!surface || !GDK_IS_TOPLEVEL(surface))
+        return;
+
+    path = find_app_icon_file();
+    if (!path)
+        return;
+
+    tex = gdk_texture_new_from_filename(path, &err);
+    if (!tex) {
+        g_clear_error(&err);
+        return;
+    }
+
+    clear_app_icon_textures();
+    app_icon_textures = g_list_append(NULL, tex);
+    gdk_toplevel_set_icon_list(GDK_TOPLEVEL(surface), app_icon_textures);
+}
+
+static void on_window_realize_icon(GtkWidget *widget, gpointer data) {
+    (void)data;
+    apply_toplevel_icon(GTK_WINDOW(widget));
+}
+
+/* Prepend ./share to XDG_DATA_DIRS so Wayland can find our .desktop file and
+ * hicolor icons without a system install (matches APP_ID). */
+static void setup_portable_share_dir(void) {
+    char *abs;
+    const char *old;
+    char *neu;
+
+    if (!g_file_test(SHARE_DIR "/applications", G_FILE_TEST_IS_DIR) &&
+        !g_file_test(SHARE_DIR "/icons", G_FILE_TEST_IS_DIR))
+        return;
+
+    abs = g_canonicalize_filename(SHARE_DIR, NULL);
+    if (!abs)
+        return;
+
+    old = g_getenv("XDG_DATA_DIRS");
+    if (old && old[0])
+        neu = g_strconcat(abs, G_SEARCHPATH_SEPARATOR_S, old, NULL);
+    else
+        neu = g_strconcat(abs,
+                          G_SEARCHPATH_SEPARATOR_S "/usr/local/share"
+                          G_SEARCHPATH_SEPARATOR_S "/usr/share",
+                          NULL);
+    g_setenv("XDG_DATA_DIRS", neu, TRUE);
+    g_free(neu);
+    g_free(abs);
+}
+
+/* Register icon theme paths + window icon-name (Linux), AppKit Dock (macOS),
+ * and toplevel textures (X11 / fallbacks). Windows uses the .ico embedded
+ * via maturita.rc at link time. */
 static void setup_window_icon(GtkWindow *window) {
     GtkIconTheme *theme;
-    static const char *dirs[] = { ICON_THEME_DIR, ICON_THEME_DIR_ALT, NULL };
+    static const char *dirs[] = {
+        ICON_THEME_DIR,
+        ICON_THEME_DIR_ALT,
+        SHARE_DIR "/icons",
+        NULL,
+    };
     const char *icon_file;
     int i;
 
@@ -220,16 +293,21 @@ static void setup_window_icon(GtkWindow *window) {
         gtk_window_set_default_icon_name(ICON_NAME);
         gtk_window_set_icon_name(window, ICON_NAME);
     } else {
-        g_warning("App icon '%s' not found (tried %s/ and %s/)",
-                  ICON_NAME, ICON_THEME_DIR, ICON_THEME_DIR_ALT);
+        g_warning("App icon '%s' not found (tried %s/, %s/, %s/icons/)",
+                  ICON_NAME, ICON_THEME_DIR, ICON_THEME_DIR_ALT, SHARE_DIR);
     }
 
     icon_file = find_app_icon_file();
     if (icon_file)
         macos_set_dock_icon(icon_file);
+#ifdef __APPLE__
     else
         g_warning("Dock icon PNG not found (tried %s and %s)",
                   ICON_FILE, ICON_FILE_ALT);
+#endif
+
+    g_signal_connect(window, "realize",
+                     G_CALLBACK(on_window_realize_icon), NULL);
 }
 
 void activate(GtkApplication *app, gpointer user_data) {
@@ -398,9 +476,14 @@ int main(int argc, char **argv) {
     GtkApplication *app;
     int status;
 
-    app = gtk_application_new("org.example.maturita", G_APPLICATION_DEFAULT_FLAGS);
+    /* Must run before GtkApplication so Wayland can resolve our .desktop
+     * file / icons via the application id. */
+    setup_portable_share_dir();
+
+    app = gtk_application_new(APP_ID, G_APPLICATION_DEFAULT_FLAGS);
     g_signal_connect(app, "activate", G_CALLBACK(activate), NULL);
     status = g_application_run(G_APPLICATION(app), argc, argv);
+    clear_app_icon_textures();
     g_object_unref(app);
 
     return status;

maturita.h

@@ -15,11 +15,13 @@
 #define HW_SUBJ        2    /* index of "Technické vybavení"          */
 #define CZ_SUBJ        3    /* index of "Český jazyk a literatura"    */
 #define CSS_FILE      "style.css"
+#define APP_ID        "org.maturita.Maturita"
 #define ICON_NAME     "maturita"
 #define ICON_FILE     "assets/app-icon.png"
 #define ICON_THEME_DIR "assets/icons"   /* cwd when run from source tree */
 #define ICON_THEME_DIR_ALT "icons"      /* next to the binary after install */
 #define ICON_FILE_ALT "icons/hicolor/512x512/apps/maturita.png"
+#define SHARE_DIR     "share"           /* portable Freedesktop data root */
 #define PROGRESS_DIR  "progress"
 #define PROGRESS_U1   "progress/unit1.conf"
 #define PROGRESS_U2   "progress/unit2.conf"

maturita.rc

@@ -0,0 +1,3 @@
+/* Windows application icon embedded into maturita.exe.
+ * The first ICON resource becomes the Explorer / taskbar icon. */
+1 ICON "assets/app-icon.ico"

scripts/gen-icons.py

@@ -0,0 +1,85 @@
+#!/usr/bin/env python3
+"""Regenerate assets/app-icon.ico and share/icons from assets/app-icon.png.
+
+Uses macOS `sips` when available; otherwise requires Pillow.
+Run from the repository root.
+"""
+from __future__ import annotations
+
+import struct
+import subprocess
+import sys
+import tempfile
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parent.parent
+SRC = ROOT / "assets" / "app-icon.png"
+ICO = ROOT / "assets" / "app-icon.ico"
+ICO_SIZES = [16, 32, 48, 64, 128, 256]
+SHARE_SIZES = [16, 32, 48, 64, 128, 256, 512]
+
+
+def resize_png(src: Path, dest: Path, size: int) -> None:
+    dest.parent.mkdir(parents=True, exist_ok=True)
+    if subprocess.call(["which", "sips"], stdout=subprocess.DEVNULL,
+                       stderr=subprocess.DEVNULL) == 0:
+        subprocess.check_call(
+            ["sips", "-z", str(size), str(size), str(src), "--out", str(dest)],
+            stdout=subprocess.DEVNULL,
+        )
+        return
+    try:
+        from PIL import Image
+    except ImportError as exc:
+        raise SystemExit(
+            "Need macOS sips or Pillow to resize icons"
+        ) from exc
+    img = Image.open(src).convert("RGBA")
+    img = img.resize((size, size), Image.Resampling.LANCZOS)
+    img.save(dest, format="PNG")
+
+
+def write_ico(entries: list[tuple[int, bytes]], dest: Path) -> None:
+    count = len(entries)
+    header = struct.pack("<HHH", 0, 1, count)
+    offset = 6 + 16 * count
+    direntries = []
+    blobs = []
+    for size, data in entries:
+        w = 0 if size >= 256 else size
+        h = 0 if size >= 256 else size
+        direntries.append(
+            struct.pack("<BBBBHHII", w, h, 0, 0, 1, 32, len(data), offset)
+        )
+        blobs.append(data)
+        offset += len(data)
+    dest.write_bytes(header + b"".join(direntries) + b"".join(blobs))
+
+
+def main() -> int:
+    if not SRC.is_file():
+        print(f"missing {SRC}", file=sys.stderr)
+        return 1
+
+    with tempfile.TemporaryDirectory(prefix="maturita-ico-") as tmp:
+        entries: list[tuple[int, bytes]] = []
+        for size in ICO_SIZES:
+            png = Path(tmp) / f"icon_{size}.png"
+            resize_png(SRC, png, size)
+            entries.append((size, png.read_bytes()))
+        write_ico(entries, ICO)
+        print(f"wrote {ICO.relative_to(ROOT)}")
+
+    for size in SHARE_SIZES:
+        dest = ROOT / "share" / "icons" / "hicolor" / f"{size}x{size}" / "apps" / "maturita.png"
+        resize_png(SRC, dest, size)
+        print(f"wrote {dest.relative_to(ROOT)}")
+
+    assets_icon = ROOT / "assets" / "icons" / "hicolor" / "512x512" / "apps" / "maturita.png"
+    resize_png(SRC, assets_icon, 512)
+    print(f"wrote {assets_icon.relative_to(ROOT)}")
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())

share/applications/org.maturita.Maturita.desktop

@@ -0,0 +1,14 @@
+[Desktop Entry]
+Type=Application
+Version=1.0
+Name=maturita.c
+GenericName=Maturita study app
+GenericName[cs]=Příprava na maturitu
+Comment=Educational GTK app for maturita exam preparation
+Comment[cs]=Vzdělávací GTK aplikace pro přípravu na maturitu
+Exec=maturita
+Icon=maturita
+Terminal=false
+Categories=Education;GTK;
+StartupNotify=true
+StartupWMClass=org.maturita.Maturita