Merge pull request #99 from selvanair/dpi-aware

Make the program DPI aware

main.c

@@ -302,6 +302,47 @@ ResumeConnections()
     }
 }
 
+/*
+ * Set scale factor of windows in pixels. Scale = 100% for dpi = 96
+ */
+static void
+dpi_setscale(UINT dpix)
+{
+    /* scale factor in percentage compared to the reference dpi of 96 */
+    if (dpix != 0)
+        o.dpi_scale = MulDiv(dpix, 100, 96);
+    else
+        o.dpi_scale = 100;
+    PrintDebug(L"DPI scale set to %u", o.dpi_scale);
+}
+
+/*
+ * Get dpi of the system and set the scale factor.
+ * The system dpi may be different from the per monitor dpi on
+ * Win 8.1 later. We set dpi awareness to system-dpi level in the
+ * manifest, and let Windows automatically re-scale windows
+ * if/when dpi changes dynamically.
+ */
+static void
+dpi_initialize(void)
+{
+    UINT dpix = 0;
+    HDC hdc = GetDC(NULL);
+
+    if (hdc)
+    {
+        dpix = GetDeviceCaps(hdc, LOGPIXELSX);
+        ReleaseDC(NULL, hdc);
+        PrintDebug(L"System DPI: dpix = %u", dpix);
+    }
+    else
+    {
+        PrintDebug(L"GetDC failed, using default dpi = 96 (error = %lu)", GetLastError());
+        dpix = 96;
+    }
+
+    dpi_setscale(dpix);
+}
 
 /*  This function is called by the Windows function DispatchMessage()  */
 LRESULT CALLBACK WindowProcedure (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
@@ -313,6 +354,7 @@ LRESULT CALLBACK WindowProcedure (HWND hwnd, UINT message, WPARAM wParam, LPARAM
 
       /* Save Window Handle */
       o.hWnd = hwnd;
+      dpi_initialize();
 
       s_uTaskbarRestart = RegisterWindowMessage(TEXT("TaskbarCreated"));
 

main.h

@@ -114,4 +114,6 @@ void PrintDebugMsg(TCHAR *msg);
 
 DWORD GetDllVersion(LPCTSTR lpszDllName);
 
+#define DPI_SCALE(x) MulDiv(x, o.dpi_scale, 100)
+
 #endif

openvpn.c

@@ -821,6 +821,19 @@ Cleanup (connection_t *c)
         CloseHandle (c->exit_event);
     c->exit_event = NULL;
 }
+/*
+ * Helper to position and scale widgets in status window using current dpi
+ * Takes status window width and height in screen pixels as input
+ */
+void
+RenderStatusWindow(HWND hwndDlg, UINT w, UINT h)
+{
+        MoveWindow(GetDlgItem(hwndDlg, ID_EDT_LOG), DPI_SCALE(20), DPI_SCALE(25), w - DPI_SCALE(40), h - DPI_SCALE(70), TRUE);
+        MoveWindow(GetDlgItem(hwndDlg, ID_TXT_STATUS), DPI_SCALE(20), DPI_SCALE(5), w - DPI_SCALE(25), DPI_SCALE(15), TRUE);
+        MoveWindow(GetDlgItem(hwndDlg, ID_DISCONNECT), DPI_SCALE(20), h - DPI_SCALE(30), DPI_SCALE(110), DPI_SCALE(23), TRUE);
+        MoveWindow(GetDlgItem(hwndDlg, ID_RESTART), DPI_SCALE(145), h - DPI_SCALE(30), DPI_SCALE(110), DPI_SCALE(23), TRUE);
+        MoveWindow(GetDlgItem(hwndDlg, ID_HIDE), w - DPI_SCALE(130), h - DPI_SCALE(30), DPI_SCALE(110), DPI_SCALE(23), TRUE);
+}
 
 /*
  * DialogProc for OpenVPN status dialog windows
@@ -871,22 +884,13 @@ StatusDialogFunc(HWND hwndDlg, UINT msg, WPARAM wParam, LPARAM lParam)
         /* Set size and position of controls */
         RECT rect;
         GetClientRect(hwndDlg, &rect);
-        MoveWindow(hLogWnd, 20, 25, rect.right - 40, rect.bottom - 70, TRUE);
-        MoveWindow(GetDlgItem(hwndDlg, ID_TXT_STATUS), 20, 5, rect.right - 25, 15, TRUE);
-        MoveWindow(GetDlgItem(hwndDlg, ID_DISCONNECT), 20, rect.bottom - 30, 110, 23, TRUE);
-        MoveWindow(GetDlgItem(hwndDlg, ID_RESTART), 145, rect.bottom - 30, 110, 23, TRUE);
-        MoveWindow(GetDlgItem(hwndDlg, ID_HIDE), rect.right - 130, rect.bottom - 30, 110, 23, TRUE);
-
+        RenderStatusWindow(hwndDlg, rect.right, rect.bottom);
         /* Set focus on the LogWindow so it scrolls automatically */
         SetFocus(hLogWnd);
         return FALSE;
 
     case WM_SIZE:
-        MoveWindow(GetDlgItem(hwndDlg, ID_EDT_LOG), 20, 25, LOWORD(lParam) - 40, HIWORD(lParam) - 70, TRUE);
-        MoveWindow(GetDlgItem(hwndDlg, ID_DISCONNECT), 20, HIWORD(lParam) - 30, 110, 23, TRUE);
-        MoveWindow(GetDlgItem(hwndDlg, ID_RESTART), 145, HIWORD(lParam) - 30, 110, 23, TRUE);
-        MoveWindow(GetDlgItem(hwndDlg, ID_HIDE), LOWORD(lParam) - 130, HIWORD(lParam) - 30, 110, 23, TRUE);
-        MoveWindow(GetDlgItem(hwndDlg, ID_TXT_STATUS), 20, 5, LOWORD(lParam) - 25, 15, TRUE);
+        RenderStatusWindow(hwndDlg, LOWORD(lParam), HIWORD(lParam));
         InvalidateRect(hwndDlg, NULL, TRUE);
         return TRUE;
 

options.h

@@ -173,6 +173,7 @@ typedef struct {
     HANDLE netcmd_semaphore;
     version_t version;
     char ovpn_version[16]; /* OpenVPN version string: 2.3.12, 2.4_alpha2 etc.. */
+    unsigned int dpi_scale;
 } options_t;
 
 void InitOptions(options_t *);

res/openvpn-gui.manifest

@@ -26,4 +26,10 @@
         </requestedPrivileges>
     </security>
 </trustInfo>
+<asmv3:application xmlns:asmv3="urn:schemas-microsoft-com:asm.v3">
+    <asmv3:windowsSettings
+         xmlns="http://schemas.microsoft.com/SMI/2005/WindowsSettings">
+        <dpiAware>true</dpiAware>
+    </asmv3:windowsSettings>
+</asmv3:application>
 </assembly>