From abeba64d77336b3fbf9aafe9ecc66b779c1e5d02 Mon Sep 17 00:00:00 2001
From: Sean Hall <r.sean.hall@gmail.com>
Date: Mon, 6 Jul 2020 16:22:38 +1000
Subject: Add ability for ThemeCreateParentWindow to center on the monitor.

---
 src/dutil/dpiutil.cpp | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)

(limited to 'src/dutil/dpiutil.cpp')

diff --git a/src/dutil/dpiutil.cpp b/src/dutil/dpiutil.cpp
index edab8f01..a27ee8c5 100644
--- a/src/dutil/dpiutil.cpp
+++ b/src/dutil/dpiutil.cpp
@@ -62,6 +62,59 @@ DAPI_(void) DpiuUninitialize()
     vfDpiuInitialized = FALSE;
 }
 
+DAPI_(HRESULT) DpiuGetMonitorContextFromPoint(
+    __in const POINT* pt,
+    __out DPIU_MONITOR_CONTEXT** ppMonitorContext
+    )
+{
+    HRESULT hr = S_OK;
+    DPIU_MONITOR_CONTEXT* pMonitorContext = NULL;
+    HMONITOR hMonitor = NULL;
+    UINT dpiX = 0;
+    UINT dpiY = 0;
+    HDC hdc = NULL;
+
+    pMonitorContext = reinterpret_cast<DPIU_MONITOR_CONTEXT*>(MemAlloc(sizeof(DPIU_MONITOR_CONTEXT), TRUE));
+    DpiuExitOnNull(pMonitorContext, hr, E_OUTOFMEMORY, "Failed to allocate memory for DpiuMonitorContext.");
+
+    hMonitor = ::MonitorFromPoint(*pt, MONITOR_DEFAULTTONEAREST);
+    DpiuExitOnNull(hMonitor, hr, E_FAIL, "Failed to get monitor from point.");
+
+    pMonitorContext->mi.cbSize = sizeof(pMonitorContext->mi);
+    if (!::GetMonitorInfoW(hMonitor, &pMonitorContext->mi))
+    {
+        DpiuExitOnFailure(hr = E_OUTOFMEMORY, "Failed to get monitor info for point.");
+    }
+
+    if (vpfnGetDpiForMonitor)
+    {
+        hr = vpfnGetDpiForMonitor(hMonitor, MDT_EFFECTIVE_DPI, &dpiX, &dpiY);
+        DpiuExitOnFailure(hr, "Failed to get DPI for monitor.");
+
+        pMonitorContext->nDpi = dpiX;
+    }
+    else
+    {
+        hdc = ::CreateDCW(L"DISPLAY", pMonitorContext->mi.szDevice, NULL, NULL);
+        DpiuExitOnNull(hdc, hr, E_OUTOFMEMORY, "Failed to get device context for monitor.");
+
+        pMonitorContext->nDpi = ::GetDeviceCaps(hdc, LOGPIXELSX);
+    }
+
+    *ppMonitorContext = pMonitorContext;
+    pMonitorContext = NULL;
+
+LExit:
+    if (hdc)
+    {
+        ::ReleaseDC(NULL, hdc);
+    }
+
+    MemFree(pMonitorContext);
+
+    return hr;
+}
+
 DAPI_(void) DpiuGetWindowContext(
     __in HWND hWnd,
     __in DPIU_WINDOW_CONTEXT* pWindowContext
-- 
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