w32: always get screenrc from an HMONITOR

This simplifies update_screen_rect a bit. Unless --fs-screen=all is
used, it will always get an HMONITOR and call GetMonitorInfo to
determine its dimensions. This will make it easier for the next few
commits to determine the colour profile and the refresh rate from the
HMONITOR.

There is a slight change in behaviour. When selecting a screen that is
out of range, such as --screen=9 on a machine with only two monitors,
the old code would silently select the last existing monitor. The new
code prints an error message and falls back to the default screen (same
as the Cocoa code.)

Signed-off-by: wm4 <wm4@nowhere>

1 files changed, 41 insertions, 21 deletions

diff --git a/video/out/w32_common.c b/video/out/w32_common.c
index 372dc33f43..f76384b451 100644
--- a/video/out/w32_common.c
+++ b/video/out/w32_common.c
@@ -89,8 +89,6 @@ struct vo_w32_state {
     bool disable_screensaver;
     bool cursor_visible;
     int event_flags;
-    int mon_cnt;
-    int mon_id;
 
     BOOL tracking;
     TRACKMOUSEEVENT trackEvent;
@@ -862,24 +860,37 @@ static void run_message_loop(struct vo_w32_state *w32)
         mp_dispatch_queue_process(w32->dispatch, 1000);
 }
 
-static BOOL CALLBACK mon_enum(HMONITOR hmon, HDC hdc, LPRECT r, LPARAM p)
+struct get_monitor_data {
+    int i;
+    int target;
+    HMONITOR mon;
+};
+
+static BOOL CALLBACK get_monitor_proc(HMONITOR mon, HDC dc, LPRECT r, LPARAM p)
 {
-    struct vo_w32_state *w32 = (void *)p;
-    // this defaults to the last screen if specified number does not exist
-    w32->screenrc = (struct mp_rect){r->left, r->top, r->right, r->bottom};
+    struct get_monitor_data *data = (struct get_monitor_data*)p;
 
-    if (w32->mon_cnt == w32->mon_id)
+    if (data->i == data->target) {
+        data->mon = mon;
         return FALSE;
-
-    w32->mon_cnt++;
+    }
+    data->i++;
     return TRUE;
 }
 
+static HMONITOR get_monitor(int id)
+{
+    struct get_monitor_data data = { .target = id };
+    EnumDisplayMonitors(NULL, NULL, get_monitor_proc, (LPARAM)&data);
+    return data.mon;
+}
+
 static void update_screen_rect(struct vo_w32_state *w32)
 {
     struct mp_vo_opts *opts = w32->opts;
     int screen = w32->current_fs ? opts->fsscreen_id : opts->screen_id;
 
+    // Handle --fs-screen=all
     if (w32->current_fs && screen == -2) {
         struct mp_rect rc = {
             GetSystemMetrics(SM_XVIRTUALSCREEN),
@@ -890,20 +901,29 @@ static void update_screen_rect(struct vo_w32_state *w32)
         rc.x1 += rc.x0;
         rc.y1 += rc.y0;
         w32->screenrc = rc;
-    } else if (screen == -1) {
-        MONITORINFO mi;
-        HMONITOR m = MonitorFromWindow(w32->window, MONITOR_DEFAULTTOPRIMARY);
-        mi.cbSize = sizeof(mi);
-        GetMonitorInfoW(m, &mi);
-        w32->screenrc = (struct mp_rect){
-            mi.rcMonitor.left, mi.rcMonitor.top,
-            mi.rcMonitor.right, mi.rcMonitor.bottom,
-        };
+        return;
+    }
+
+    // When not using --fs-screen=all, mpv belongs to a specific HMONITOR
+    HMONITOR mon;
+    if (screen == -1) {
+        // Handle --fs-screen=current and --screen=default
+        mon = MonitorFromWindow(w32->window, MONITOR_DEFAULTTOPRIMARY);
     } else {
-        w32->mon_cnt = 0;
-        w32->mon_id = screen;
-        EnumDisplayMonitors(NULL, NULL, mon_enum, (LONG_PTR)w32);
+        mon = get_monitor(screen);
+        if (!mon) {
+            MP_INFO(w32, "Screen %d does not exist, falling back to primary\n",
+                    screen);
+            mon = MonitorFromPoint((POINT){0, 0}, MONITOR_DEFAULTTOPRIMARY);
+        }
     }
+
+    MONITORINFO mi = { .cbSize = sizeof(mi) };
+    GetMonitorInfoW(mon, &mi);
+    w32->screenrc = (struct mp_rect){
+        mi.rcMonitor.left, mi.rcMonitor.top,
+        mi.rcMonitor.right, mi.rcMonitor.bottom,
+    };
 }
 
 static DWORD update_style(struct vo_w32_state *w32, DWORD style)