w32_common: implement VOCTRL_GET_DISPLAY_NAMES

This should make display-names usable on Windows. It returns a list of
GDI monitor names like "\\.\DISPLAY1". Since it may be useful to get the
monitor that Windows considers associated with the window (with
MonitorFromWindow,) this will always be returned as the first argument.
This monitor is the one used for display-fps and icc-profile-auto.

1 files changed, 52 insertions, 0 deletions

diff --git a/video/out/w32_common.c b/video/out/w32_common.c
index 736da59dff..f4fbb20ea9 100644
--- a/video/out/w32_common.c
+++ b/video/out/w32_common.c
@@ -722,6 +722,10 @@ static LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam,
         ClientToScreen(w32->window, &p);
         w32->window_x = p.x;
         w32->window_y = p.y;
+
+        // Window may intersect with new monitors (see VOCTRL_GET_DISPLAY_NAMES)
+        signal_events(w32, VO_EVENT_WIN_STATE);
+
         update_display_info(w32);  // if we moved between monitors
         MP_VERBOSE(w32, "move window: %d:%d\n", w32->window_x, w32->window_y);
         break;
@@ -1482,6 +1486,51 @@ fail:
     return 0;
 }
 
+struct disp_names_data {
+    HMONITOR assoc;
+    int count;
+    char **names;
+};
+
+static BOOL CALLBACK disp_names_proc(HMONITOR mon, HDC dc, LPRECT r, LPARAM p)
+{
+    struct disp_names_data *data = (struct disp_names_data*)p;
+
+    // get_disp_names() adds data->assoc to the list, so skip it here
+    if (mon == data->assoc)
+        return TRUE;
+
+    MONITORINFOEXW mi = { .cbSize = sizeof mi };
+    if (GetMonitorInfoW(mon, (MONITORINFO*)&mi)) {
+        MP_TARRAY_APPEND(NULL, data->names, data->count,
+                         mp_to_utf8(NULL, mi.szDevice));
+    }
+    return TRUE;
+}
+
+static char **get_disp_names(struct vo_w32_state *w32)
+{
+    // Get the client area of the window in screen space
+    RECT rect = { 0 };
+    GetClientRect(w32->window, &rect);
+    MapWindowPoints(w32->window, NULL, (POINT*)&rect, 2);
+
+    struct disp_names_data data = { .assoc = w32->monitor };
+
+    // Make sure the monitor that Windows considers to be associated with the
+    // window is first in the list
+    MONITORINFOEXW mi = { .cbSize = sizeof mi };
+    if (GetMonitorInfoW(data.assoc, (MONITORINFO*)&mi)) {
+        MP_TARRAY_APPEND(NULL, data.names, data.count,
+                         mp_to_utf8(NULL, mi.szDevice));
+    }
+
+    // Get the names of the other monitors that intersect the client rect
+    EnumDisplayMonitors(NULL, &rect, disp_names_proc, (LPARAM)&data);
+    MP_TARRAY_APPEND(NULL, data.names, data.count, NULL);
+    return data.names;
+}
+
 static int gui_thread_control(struct vo_w32_state *w32, int request, void *arg)
 {
     switch (request) {
@@ -1563,6 +1612,9 @@ static int gui_thread_control(struct vo_w32_state *w32, int request, void *arg)
         update_display_info(w32);
         *(double*) arg = w32->display_fps;
         return VO_TRUE;
+    case VOCTRL_GET_DISPLAY_NAMES:
+        *(char ***)arg = get_disp_names(w32);
+        return VO_TRUE;
     case VOCTRL_GET_ICC_PROFILE:
         update_display_info(w32);
         if (w32->color_profile) {