Windows: Make puglGetScaleFactor always return a reasonable value

This guesses the likely scale factor when the view hasn't been realized (and so
there's no real window to get information for).  It may still be wrong for
multiple display systems, but will always return some scale factor that
"exists" on the system, and should always be correct when there's only one
display.

1 files changed, 24 insertions, 4 deletions

diff --git a/src/win.c b/src/win.c
index 5defb8d..fa50034 100644
--- a/src/win.c
+++ b/src/win.c
@@ -136,6 +136,27 @@ puglWinGetWindowExFlags(const PuglView* const view)
   return WS_EX_NOINHERITLAYOUT | (view->parent ? 0U : WS_EX_APPWINDOW);
 }
 
+static HWND
+puglWinGetWindow(const PuglView* const view)
+{
+  return view->impl->hwnd        ? view->impl->hwnd
+         : view->parent          ? (HWND)view->parent
+         : view->transientParent ? (HWND)view->transientParent
+                                 : NULL;
+}
+
+static HMONITOR
+puglWinGetMonitor(const PuglView* const view)
+{
+  const HWND hwnd = puglWinGetWindow(view);
+  if (hwnd) {
+    return MonitorFromWindow(hwnd, MONITOR_DEFAULTTOPRIMARY);
+  }
+
+  const POINT point = {(long)view->frame.x, (long)view->frame.y};
+  return MonitorFromPoint(point, MONITOR_DEFAULTTOPRIMARY);
+}
+
 static double
 puglWinGetViewScaleFactor(const PuglView* const view)
 {
@@ -156,9 +177,7 @@ puglWinGetViewScaleFactor(const PuglView* const view)
   DWORD scaleFactor = 100;
   if (GetProcessDpiAwareness && GetScaleFactorForMonitor &&
       !GetProcessDpiAwareness(NULL, &dpiAware) && dpiAware) {
-    GetScaleFactorForMonitor(
-      MonitorFromWindow(view->impl->hwnd, MONITOR_DEFAULTTOPRIMARY),
-      &scaleFactor);
+    GetScaleFactorForMonitor(puglWinGetMonitor(view), &scaleFactor);
   }
 
   FreeLibrary(shcore);
@@ -1174,7 +1193,8 @@ adjustedWindowRect(PuglView* const view,
 double
 puglGetScaleFactor(const PuglView* const view)
 {
-  return view->impl->scaleFactor;
+  return view->impl->scaleFactor ? view->impl->scaleFactor
+                                 : puglWinGetViewScaleFactor(view);
 }
 
 PuglStatus