SDL2 Pthread Proxy APIs (#9336)

This PR implements various C APIs for SDL2 to work with PROXY_TO_PTHREAD=1 as discussed here: emscripten-ports/SDL2#77

* create C API for setting window title

* create C API for getting window title

* tests: test_html5: test emscripten_{get,set}window_title

* create C API for getting screen size

* tests: test_html5: test emscripten_get_screen_size

site/source/docs/api_reference/emscripten.h.rst

@@ -492,6 +492,20 @@ Functions
   :rtype: double
   :return: The pixel ratio or 1.0 if not supported.
 
+.. c:function:: char *emscripten_get_window_title()
+
+  Returns the window title.
+
+  The returned string will be valid until the next call of the function
+
+.. c:function:: void emscripten_set_window_title(char *title)
+
+  Sets the window title.
+
+.. c:function:: void emscripten_get_screen_size(int *width, int *height)
+
+  Returns the width and height of the screen.
+
 .. c:function:: void emscripten_hide_mouse(void)
 
   Hide the OS mouse cursor over the canvas.

src/library_browser.js

@@ -1381,6 +1381,36 @@ var LibraryBrowser = {
     exit(status);
   },
 
+  emscripten_get_window_title__proxy: 'sync',
+  emscripten_get_window_title__sig: 'iv',
+  emscripten_get_window_title: function() {
+    var buflen = 256;
+
+    if (!_emscripten_get_window_title.buffer) {
+      _emscripten_get_window_title.buffer = _malloc(buflen);
+    }
+
+    writeAsciiToMemory(
+      document.title.slice(0, buflen - 1),
+      _emscripten_get_window_title.buffer
+    );
+
+    return _emscripten_get_window_title.buffer;
+  },
+
+  emscripten_set_window_title__proxy: 'sync',
+  emscripten_set_window_title__sig: 'vi',
+  emscripten_set_window_title: function(title) {
+    setWindowTitle(AsciiToString(title));
+  },
+
+  emscripten_get_screen_size__proxy: 'sync',
+  emscripten_get_screen_size__sig: 'vii',
+  emscripten_get_screen_size: function(width, height) {
+    {{{ makeSetValue('width', '0', 'screen.width', 'i32') }}};
+    {{{ makeSetValue('height', '0', 'screen.height', 'i32') }}};
+  },
+
   emscripten_hide_mouse__proxy: 'sync',
   emscripten_hide_mouse__sig: 'v',
   emscripten_hide_mouse: function() {

system/include/emscripten/emscripten.h

@@ -134,6 +134,9 @@ extern void emscripten_force_exit(int status);
 
 double emscripten_get_device_pixel_ratio(void);
 
+char *emscripten_get_window_title();
+void emscripten_set_window_title(const char *);
+void emscripten_get_screen_size(int *width, int *height);
 void emscripten_hide_mouse(void);
 void emscripten_set_canvas_size(int width, int height) __attribute__((deprecated("This variant does not allow specifying the target canvas", "Use emscripten_set_canvas_element_size() instead")));
 void emscripten_get_canvas_size(int *width, int *height, int *isFullscreen) __attribute__((deprecated("This variant does not allow specifying the target canvas", "Use emscripten_get_canvas_element_size() and emscripten_get_fullscreen_status() instead")));

tests/test_html5.c

@@ -413,7 +413,19 @@ int main()
   ret = emscripten_set_webglcontextrestored_callback("#canvas", 0, 1, webglcontext_callback);
   TEST_RESULT(emscripten_set_webglcontextrestored_callback);
 
-  /* For the events to function, one must either call emscripten_set_main_loop or enable Module.noExitRuntime by some other means. 
+  char *source_window_title = "test window title";
+  emscripten_set_window_title(source_window_title);
+  char *current_window_title = emscripten_get_window_title();
+  ret = (strcmp(source_window_title, current_window_title) == 0 \
+		  ? EMSCRIPTEN_RESULT_SUCCESS : EMSCRIPTEN_RESULT_FAILED);
+  TEST_RESULT(emscripten_get_window_title);
+
+  int width, height;
+  emscripten_get_screen_size(&width, &height);
+  ret = (width && height) ? EMSCRIPTEN_RESULT_SUCCESS : EMSCRIPTEN_RESULT_FAILED;
+  TEST_RESULT(emscripten_get_screen_size);
+
+  /* For the events to function, one must either call emscripten_set_main_loop or enable Module.noExitRuntime by some other means.
      Otherwise the application will exit after leaving main(), and the atexit handlers will clean up all event hooks (by design). */
   EM_ASM(noExitRuntime = true);