[PATCH 0/3] MR5317: win32u: Fix a possible condition that makes EnumDisplayMonitors() not reporting any monitors.

[Zhiyi Zhang (＠zhiyi)]

When there are two monitors and they are mirrored, both of them are considered primary. When the
first primary monitor happens to be a clone, EnumDisplayMonitors() ends up not reporting any
monitors because should_enumerate_monitor() returns FALSE and we break out the loop to enumerate
primary monitors after that.

This is a regression from b59619d and my review comments. My indent was to break out of the loop
after finding the *master* primary monitor, not cloned primary monitors, to avoid unnecessary
iterations. However, the primary monitor count is small and it's cleaner this way so let's break
when should_enumerate_monitor() returns TRUE.

[PATCH 1/3] win32u: Fix a possible condition that makes EnumDisplayMonitors() not reporting any monitors.

[Zhiyi Zhang]

From: Zhiyi Zhang

When there are two monitors and they are mirrored, both of them are considered primary. When the
first primary monitor happens to be a clone, EnumDisplayMonitors() ends up not reporting any
monitors because should_enumerate_monitor() returns FALSE and we break out the loop to enumerate
primary monitors after that.

This is a regression from b59619d and my review comments. My indent was to break out of the loop
after finding the *master* primary monitor, not cloned primary monitors, to avoid unnecessary
iterations. However, the primary monitor count is small and it's cleaner this way so let's break
when should_enumerate_monitor() returns TRUE.
---
 dlls/win32u/sysparams.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/dlls/win32u/sysparams.c b/dlls/win32u/sysparams.c
index 7cefb3822a3..d2f7396971b 100644
--- a/dlls/win32u/sysparams.c
+++ b/dlls/win32u/sysparams.c
@@ -3459,8 +3459,10 @@ BOOL WINAPI NtUserEnumDisplayMonitors( HDC hdc, RECT *rect, MONITORENUMPROC proc
     {
         if (!is_monitor_primary( monitor )) continue;
         if (should_enumerate_monitor( monitor, &origin, &limit, &enum_info[count].rect ))
+        {
             enum_info[count++].handle = monitor->handle;
-        break;
+            break;
+        }
     }

/* then non-primary monitors */

[PATCH 2/3] win32u: Don't enumerate mirrored monitor clones for GetSystemMetrics(SM_CMONITORS).

[Zhiyi Zhang]

From: Zhiyi Zhang

Only one monitor in a mirrored monitor set contributes to the result of GetSystemMetrics(SM_CMONITORS).
Tested manually on Win7 and Win10.
---
 dlls/win32u/sysparams.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/dlls/win32u/sysparams.c b/dlls/win32u/sysparams.c
index d2f7396971b..6e638922629 100644
--- a/dlls/win32u/sysparams.c
+++ b/dlls/win32u/sysparams.c
@@ -3348,15 +3348,15 @@ struct monitor_enum_info
     RECT rect;
 };

-static unsigned int active_monitor_count(void)
+static unsigned int active_unique_monitor_count(void)
 {
     struct monitor *monitor;
     unsigned int count = 0;

LIST_FOR_EACH_ENTRY(monitor, &monitors, struct monitor, entry)
     {
-        if (!is_monitor_active( monitor )) continue;
-        count++;
+        if (is_monitor_active( monitor ) && !monitor->is_clone)
+            count++;
     }
     return count;
 }
@@ -5941,7 +5941,7 @@ int get_system_metrics( int index )
         return rect.bottom - rect.top;
     case SM_CMONITORS:
         if (!lock_display_devices()) return FALSE;
-        ret = active_monitor_count();
+        ret = active_unique_monitor_count();
         unlock_display_devices();
         return ret;
     case SM_SAMEDISPLAYFORMAT:

[PATCH 3/3] win32u: Don't enumerate mirrored monitor clones when unnecessary.

[Zhiyi Zhang]

From: Zhiyi Zhang

These functions don't need to enumerate mirrored monitor clones.
---
 dlls/win32u/sysparams.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/dlls/win32u/sysparams.c b/dlls/win32u/sysparams.c
index 6e638922629..07b9d46d9eb 100644
--- a/dlls/win32u/sysparams.c
+++ b/dlls/win32u/sysparams.c
@@ -2248,7 +2248,7 @@ RECT get_virtual_screen_rect( UINT dpi )

LIST_FOR_EACH_ENTRY( monitor, &monitors, struct monitor, entry )
     {
-        if (!is_monitor_active( monitor )) continue;
+        if (!is_monitor_active( monitor ) || monitor->is_clone) continue;
         union_rect( &rect, &rect, &monitor->rc_monitor );
     }

@@ -2269,7 +2269,7 @@ static BOOL is_window_rect_full_screen( const RECT *rect )
     {
         RECT monrect;

-        if (!is_monitor_active( monitor )) continue;
+        if (!is_monitor_active( monitor ) || monitor->is_clone) continue;

monrect = map_dpi_rect( monitor->rc_monitor, get_monitor_dpi( monitor->handle ),
                                 get_thread_dpi() );
@@ -3558,7 +3558,7 @@ HMONITOR monitor_from_rect( const RECT *rect, UINT flags, UINT dpi )
     {
         RECT intersect, monitor_rect;

-        if (!is_monitor_active( monitor )) continue;
+        if (!is_monitor_active( monitor ) || monitor->is_clone) continue;

monitor_rect = map_dpi_rect( monitor->rc_monitor, get_monitor_dpi( monitor->handle ), system_dpi );
         if (intersect_rect( &intersect, &monitor_rect, &r ))

[PATCH 0/3] MR5317: win32u: Fix a possible condition that makes EnumDisplayMonitors() not reporting any monitors. - approved

[Rémi Bernon (＠rbernon)]

This merge request was approved by Rémi Bernon.