tdf#106265 ScopedHDC to clean-up hDC when rendering glyphs

Change-Id: I96ecf625126740610200c012c3c7002fac7e1548
Reviewed-on: https://gerrit.libreoffice.org/37347Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Tomaž Vajngerl <quikee@gmail.com>

vcl/inc/win/ScopedHDC.hxx

+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#ifndef INCLUDED_VCL_INC_WIN_SCOPEDHDC_HXX
+#define INCLUDED_VCL_INC_WIN_SCOPEDHDC_HXX
+
+class ScopedHDC
+{
+private:
+    HDC m_hDC;
+
+public:
+    explicit ScopedHDC(HDC hDC)
+        : m_hDC(hDC)
+    {}
+
+    ScopedHDC(const ScopedHDC&) = delete;
+    ScopedHDC& operator=(const ScopedHDC&) = delete;
+
+    ~ScopedHDC()
+    {
+        if (m_hDC)
+            DeleteDC(m_hDC);
+    }
+
+    HDC get() const
+    {
+        return m_hDC;
+    }
+
+    explicit operator bool() const
+    {
+        return m_hDC != nullptr;
+    }
+};
+
+#endif // INCLUDED_VCL_INC_WIN_SCOPEDHDC_HXX
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */

vcl/win/gdi/winlayout.cxx

@@ -34,6 +34,7 @@
 #include "sft.hxx"
 #include "sallayout.hxx"
 #include "CommonSalLayout.hxx"
+#include "win/ScopedHDC.hxx"
 
 #include <cstdio>
 #include <cstdlib>
@@ -57,17 +58,17 @@ bool WinFontInstance::CacheGlyphToAtlas(HDC hDC, HFONT hFont, int nGlyphIndex, S
 {
     OpenGLGlyphDrawElement aElement;
 
-    HDC hNewDC = CreateCompatibleDC(hDC);
-    if (hNewDC == nullptr)
+    ScopedHDC aHDC(CreateCompatibleDC(hDC));
+
+    if (!aHDC)
     {
         SAL_WARN("vcl.gdi", "CreateCompatibleDC failed: " << WindowsErrorString(GetLastError()));
         return false;
     }
-    HFONT hOrigFont = static_cast<HFONT>(SelectObject(hNewDC, hFont));
+    HFONT hOrigFont = static_cast<HFONT>(SelectObject(aHDC.get(), hFont));
     if (hOrigFont == nullptr)
     {
         SAL_WARN("vcl.gdi", "SelectObject failed: " << WindowsErrorString(GetLastError()));
-        DeleteDC(hNewDC);
         return false;
     }
 
@@ -76,10 +77,9 @@ bool WinFontInstance::CacheGlyphToAtlas(HDC hDC, HFONT hFont, int nGlyphIndex, S
     if (!pTxt)
         return false;
 
-    if (!pTxt->BindFont(hNewDC))
+    if (!pTxt->BindFont(aHDC.get()))
     {
         SAL_WARN("vcl.gdi", "Binding of font failed. The font might not be supported by Direct Write.");
-        DeleteDC(hNewDC);
         return false;
     }