[FancyZones] Fix taskbar size issues (#9856)

* Fix taskbar size issues

* Fix issue with DPI unaware apps

src/modules/fancyzones/lib/Zone.cpp

@@ -21,46 +21,6 @@ namespace
                rect.bottom >= ZoneConstants::MAX_NEGATIVE_SPACING &&
                width >= 0 && height >= 0;
     }
-
-    BOOL CALLBACK saveDisplayToVector(HMONITOR monitor, HDC hdc, LPRECT rect, LPARAM data)
-    {
-        reinterpret_cast<std::vector<HMONITOR>*>(data)->emplace_back(monitor);
-        return true;
-    }
-
-    bool allMonitorsHaveSameDpiScaling()
-    {
-        std::vector<HMONITOR> monitors;
-        EnumDisplayMonitors(NULL, NULL, saveDisplayToVector, reinterpret_cast<LPARAM>(&monitors));
-
-        if (monitors.size() < 2)
-        {
-            return true;
-        }
-
-        UINT firstMonitorDpiX;
-        UINT firstMonitorDpiY;
-
-        if (S_OK != GetDpiForMonitor(monitors[0], MDT_EFFECTIVE_DPI, &firstMonitorDpiX, &firstMonitorDpiY))
-        {
-            return false;
-        }
-
-        for (int i = 1; i < monitors.size(); i++)
-        {
-            UINT iteratedMonitorDpiX;
-            UINT iteratedMonitorDpiY;
-
-            if (S_OK != GetDpiForMonitor(monitors[i], MDT_EFFECTIVE_DPI, &iteratedMonitorDpiX, &iteratedMonitorDpiY) ||
-                iteratedMonitorDpiX != firstMonitorDpiX)
-            {
-                return false;
-            }
-        }
-
-        return true;
-    }
-
 }
 
 struct Zone : winrt::implements<Zone, IZone>
@@ -92,9 +52,6 @@ RECT Zone::ComputeActualZoneRect(HWND window, HWND zoneWindow) const noexcept
 
     RECT frameRect{};
 
-    const auto level = DPIAware::GetAwarenessLevel(GetWindowDpiAwarenessContext(window));
-    const bool accountForUnawareness = level < DPIAware::PER_MONITOR_AWARE;
-
     if (SUCCEEDED(DwmGetWindowAttribute(window, DWMWA_EXTENDED_FRAME_BOUNDS, &frameRect, sizeof(frameRect))))
     {
         LONG leftMargin = frameRect.left - windowRect.left;
@@ -108,22 +65,6 @@ RECT Zone::ComputeActualZoneRect(HWND window, HWND zoneWindow) const noexcept
     // Map to screen coords
     MapWindowRect(zoneWindow, nullptr, &newWindowRect);
 
-    MONITORINFO mi{ sizeof(mi) };
-    if (GetMonitorInfoW(MonitorFromWindow(zoneWindow, MONITOR_DEFAULTTONEAREST), &mi))
-    {
-        const auto taskbar_left_size = std::abs(mi.rcMonitor.left - mi.rcWork.left);
-        const auto taskbar_top_size = std::abs(mi.rcMonitor.top - mi.rcWork.top);
-        OffsetRect(&newWindowRect, -taskbar_left_size, -taskbar_top_size);
-
-        if (accountForUnawareness && !allMonitorsHaveSameDpiScaling())
-        {
-            newWindowRect.left = max(mi.rcMonitor.left, newWindowRect.left);
-            newWindowRect.right = min(mi.rcMonitor.right - taskbar_left_size, newWindowRect.right);
-            newWindowRect.top = max(mi.rcMonitor.top, newWindowRect.top);
-            newWindowRect.bottom = min(mi.rcMonitor.bottom - taskbar_top_size, newWindowRect.bottom);
-        }
-    }
-
     if ((::GetWindowLong(window, GWL_STYLE) & WS_SIZEBOX) == 0)
     {
         newWindowRect.right = newWindowRect.left + (windowRect.right - windowRect.left);

src/modules/fancyzones/lib/util.cpp

@@ -305,6 +305,88 @@ namespace FancyZonesUtils
         monitorInfo = std::move(sortedMonitorInfo);
     }
 
+    BOOL CALLBACK saveDisplayToVector(HMONITOR monitor, HDC hdc, LPRECT rect, LPARAM data)
+    {
+        reinterpret_cast<std::vector<HMONITOR>*>(data)->emplace_back(monitor);
+        return true;
+    }
+
+    bool allMonitorsHaveSameDpiScaling()
+    {
+        std::vector<HMONITOR> monitors;
+        EnumDisplayMonitors(NULL, NULL, saveDisplayToVector, reinterpret_cast<LPARAM>(&monitors));
+
+        if (monitors.size() < 2)
+        {
+            return true;
+        }
+
+        UINT firstMonitorDpiX;
+        UINT firstMonitorDpiY;
+
+        if (S_OK != GetDpiForMonitor(monitors[0], MDT_EFFECTIVE_DPI, &firstMonitorDpiX, &firstMonitorDpiY))
+        {
+            return false;
+        }
+
+        for (int i = 1; i < monitors.size(); i++)
+        {
+            UINT iteratedMonitorDpiX;
+            UINT iteratedMonitorDpiY;
+
+            if (S_OK != GetDpiForMonitor(monitors[i], MDT_EFFECTIVE_DPI, &iteratedMonitorDpiX, &iteratedMonitorDpiY) ||
+                iteratedMonitorDpiX != firstMonitorDpiX)
+            {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    void ScreenToWorkAreaCoords(HWND window, RECT& rect)
+    {
+        // First, find the correct monitor. The monitor cannot be found using the given rect itself, we must first
+        // translate it to relative workspace coordinates.
+        HMONITOR monitor = MonitorFromRect(&rect, MONITOR_DEFAULTTOPRIMARY);
+        MONITORINFOEXW monitorInfo{ sizeof(MONITORINFOEXW) };
+        GetMonitorInfoW(monitor, &monitorInfo);
+
+        auto xOffset = monitorInfo.rcWork.left - monitorInfo.rcMonitor.left;
+        auto yOffset = monitorInfo.rcWork.top - monitorInfo.rcMonitor.top;
+
+        auto referenceRect = rect;
+
+        referenceRect.left -= xOffset;
+        referenceRect.right -= xOffset;
+        referenceRect.top -= yOffset;
+        referenceRect.bottom -= yOffset;
+
+        // Now, this rect should be used to determine the monitor and thus taskbar size. This fixes
+        // scenarios where the zone lies approximately between two monitors, and the taskbar is on the left.
+        monitor = MonitorFromRect(&referenceRect, MONITOR_DEFAULTTOPRIMARY);
+        GetMonitorInfoW(monitor, &monitorInfo);
+
+        xOffset = monitorInfo.rcWork.left - monitorInfo.rcMonitor.left;
+        yOffset = monitorInfo.rcWork.top - monitorInfo.rcMonitor.top;
+
+        rect.left -= xOffset;
+        rect.right -= xOffset;
+        rect.top -= yOffset;
+        rect.bottom -= yOffset;
+
+        const auto level = DPIAware::GetAwarenessLevel(GetWindowDpiAwarenessContext(window));
+        const bool accountForUnawareness = level < DPIAware::PER_MONITOR_AWARE;
+
+        if (accountForUnawareness && !allMonitorsHaveSameDpiScaling())
+        {
+            rect.left = max(monitorInfo.rcMonitor.left, rect.left);
+            rect.right = min(monitorInfo.rcMonitor.right - xOffset, rect.right);
+            rect.top = max(monitorInfo.rcMonitor.top, rect.top);
+            rect.bottom = min(monitorInfo.rcMonitor.bottom - yOffset, rect.bottom);
+        }
+    }
+
     void SizeWindowToRect(HWND window, RECT rect) noexcept
     {
         WINDOWPLACEMENT placement{};
@@ -331,6 +413,8 @@ namespace FancyZonesUtils
             placement.flags &= ~WPF_RESTORETOMAXIMIZED;
         }
 
+        ScreenToWorkAreaCoords(window, rect);
+
         placement.rcNormalPosition = rect;
         placement.flags |= WPF_ASYNCWINDOWPLACEMENT;
 

src/modules/fancyzones/lib/util.h

@@ -188,6 +188,8 @@ namespace FancyZonesUtils
 
     UINT GetDpiForMonitor(HMONITOR monitor) noexcept;
     void OrderMonitors(std::vector<std::pair<HMONITOR, RECT>>& monitorInfo);
+
+    // Parameter rect must be in screen coordinates (e.g. obtained from GetWindowRect)
     void SizeWindowToRect(HWND window, RECT rect) noexcept;
 
     bool HasNoVisibleOwner(HWND window) noexcept;