Fix T88384: Improved Win32 Window Sizing and Positioning

When creating Win32 windows, the sizes and placements can be out by a
small amount, mostly noticeable near monitor edges. This is because
Windows 10 includes a thin invisible border (typically 7 pixels) when
determining position. Therefore the correct values can sometimes be
just outside the monitor bounds, but we clamp them at those bounds.

This patch fixes this by first clamping the requested values to monitor
bounds, adjusting for window chrome with AdjustWindowRectEx(), and then
using those adjusted values in CreateWindowExW().

see D11314 for more details.

Differential Revision: https://developer.blender.org/D11314

Reviewed by Ray Molenkamp

1 files changed, 20 insertions, 14 deletions

diff --git a/intern/ghost/intern/GHOST_WindowWin32.cpp b/intern/ghost/intern/GHOST_WindowWin32.cpp
index ef155d96f99..bf142239606 100644
--- a/intern/ghost/intern/GHOST_WindowWin32.cpp
+++ b/intern/ghost/intern/GHOST_WindowWin32.cpp
@@ -121,22 +121,28 @@ GHOST_WindowWin32::GHOST_WindowWin32(GHOST_SystemWin32 *system,
   monitor.dwFlags = 0;
   GetMonitorInfo(MonitorFromRect(&win_rect, MONITOR_DEFAULTTONEAREST), &monitor);
 
-  /* Adjust our requested size to allow for caption and borders and constrain to monitor. */
-  AdjustWindowRectEx(&win_rect, WS_CAPTION, FALSE, 0);
+  /* Constrain size to fit within this monitor. */
   width = min(monitor.rcWork.right - monitor.rcWork.left, win_rect.right - win_rect.left);
-  left = min(max(monitor.rcWork.left, win_rect.left), monitor.rcWork.right - width);
   height = min(monitor.rcWork.bottom - monitor.rcWork.top, win_rect.bottom - win_rect.top);
-  top = min(max(monitor.rcWork.top, win_rect.top), monitor.rcWork.bottom - height);
-
-  m_hWnd = ::CreateWindowExW(extended_style,        // window extended style
-                             s_windowClassName,     // pointer to registered class name
-                             title_16,              // pointer to window name
-                             style,                 // window style
-                             left,                  // horizontal position of window
-                             top,                   // vertical position of window
-                             width,                 // window width
-                             height,                // window height
-                             m_parentWindowHwnd,    // handle to parent or owner window
+
+  win_rect.left = min(max(monitor.rcWork.left, win_rect.left), monitor.rcWork.right - width);
+  win_rect.right = win_rect.left + width;
+  win_rect.top = min(max(monitor.rcWork.top, win_rect.top), monitor.rcWork.bottom - height);
+  win_rect.bottom = win_rect.top + height;
+
+  /* Adjust our requested values to allow for caption, borders, shadows, etc.
+     Windows API Note: You cannot specify WS_OVERLAPPED when calling. */
+  AdjustWindowRectEx(&win_rect, style & ~WS_OVERLAPPED, FALSE, extended_style);
+
+  m_hWnd = ::CreateWindowExW(extended_style,                  // window extended style
+                             s_windowClassName,               // pointer to registered class name
+                             title_16,                        // pointer to window name
+                             style,                           // window style
+                             win_rect.left,                   // horizontal position of window
+                             win_rect.top,                    // vertical position of window
+                             win_rect.right - win_rect.left,  // window width
+                             win_rect.bottom - win_rect.top,  // window height
+                             m_parentWindowHwnd,              // handle to parent or owner window
                              0,                     // handle to menu or child-window identifier
                              ::GetModuleHandle(0),  // handle to application instance
                              0);                    // pointer to window-creation data