path: root/recipes/pango/0002-win32-Use-GPrivate-managed-display-device-context.patch

From 01ee140274f85c4fb3e153b39c0b320bb2f89ada Mon Sep 17 00:00:00 2001
From: Aaron Boxer <Aaron Boxer>
Date: Thu, 24 Sep 2020 11:11:18 -0400
Subject: [PATCH 2/2] win32: Use GPrivate-managed display device context

The document of [CreateDCA][1] says:

> If lpszDriver or lpszDevice is DISPLAY, the thread that calls
> CreateDC owns the HDC that is created. When this thread is
> destroyed, the HDC is no longer valid. Thus, if you create the HDC
> and pass it to another thread, then exit the first thread,
> the second thread will not be able to use the HDC.

So this change introduces GPrivate to fix potential problem.

This also fixes the problem caused by accessing the global
variable DC directly, which makes some early call to Pango functions
fail.

(e.g., failure of calling pango_win32_font_description_from_logfontw
from _get_system_font_name in GTK.)

[1]: https://docs.microsoft.com/windows/win32/api/wingdi/nf-wingdi-createdca
---
 pango/pangocairo-win32fontmap.c |  2 +-
 pango/pangowin32-fontmap.c      | 59 ++++++++++++++--------
 pango/pangowin32-private.h      |  4 +-
 pango/pangowin32-shape.c        |  2 +-
 pango/pangowin32.c              | 89 ++++++++++++++++++---------------
 5 files changed, 93 insertions(+), 63 deletions(-)

diff --git a/pango/pangocairo-win32fontmap.c b/pango/pangocairo-win32fontmap.c
index b58d16f6..94500fd6 100644
--- a/pango/pangocairo-win32fontmap.c
+++ b/pango/pangocairo-win32fontmap.c
@@ -121,5 +121,5 @@ static void
 pango_cairo_win32_font_map_init (PangoCairoWin32FontMap *cwfontmap)
 {
   cwfontmap->serial = 1;
-  cwfontmap->dpi = GetDeviceCaps (pango_win32_get_dc (), LOGPIXELSY);
+  cwfontmap->dpi = GetDeviceCaps (_pango_win32_get_display_dc (), LOGPIXELSY);
 }
diff --git a/pango/pangowin32-fontmap.c b/pango/pangowin32-fontmap.c
index afb8272f..eab44765 100644
--- a/pango/pangowin32-fontmap.c
+++ b/pango/pangowin32-fontmap.c
@@ -200,6 +200,12 @@ pango_win32_inner_enum_proc (LOGFONTW    *lfp,
   return 1;
 }
 
+struct EnumProcData
+{
+  HDC hdc;
+  PangoWin32FontMap *font_map;
+};
+
 static int CALLBACK
 pango_win32_enum_proc (LOGFONTW       *lfp,
 		       NEWTEXTMETRICW *metrics,
@@ -207,6 +213,7 @@ pango_win32_enum_proc (LOGFONTW       *lfp,
 		       LPARAM          lParam)
 {
   LOGFONTW lf;
+  struct EnumProcData *data = (struct EnumProcData *) lParam;
 
   PING (("%S: %lu %lx", lfp->lfFaceName, fontType, metrics->ntmFlags));
 
@@ -216,9 +223,9 @@ pango_win32_enum_proc (LOGFONTW       *lfp,
     {
       lf = *lfp;
 
-      EnumFontFamiliesExW (_pango_win32_hdc, &lf,
+      EnumFontFamiliesExW (data->hdc, &lf,
 			   (FONTENUMPROCW) pango_win32_inner_enum_proc,
-			   lParam, 0);
+                           (LPARAM) data->font_map, 0);
     }
 
   return 1;
@@ -725,6 +732,12 @@ static void
 _pango_win32_font_map_init (PangoWin32FontMap *win32fontmap)
 {
   LOGFONTW logfont;
+  HDC hdc = _pango_win32_get_display_dc ();
+
+  struct EnumProcData enum_proc_data = {
+    .hdc = hdc,
+    .font_map = win32fontmap,
+  };
 
   win32fontmap->families =
     g_hash_table_new_full ((GHashFunc) case_insensitive_str_hash,
@@ -738,9 +751,9 @@ _pango_win32_font_map_init (PangoWin32FontMap *win32fontmap)
 
   memset (&logfont, 0, sizeof (logfont));
   logfont.lfCharSet = DEFAULT_CHARSET;
-  EnumFontFamiliesExW (_pango_win32_hdc, &logfont,
+  EnumFontFamiliesExW (hdc, &logfont,
 		       (FONTENUMPROCW) pango_win32_enum_proc,
-		       (LPARAM) win32fontmap, 0);
+                       (LPARAM) &enum_proc_data, 0);
 
   g_hash_table_foreach (win32fontmap->families, synthesize_foreach, win32fontmap);
 
@@ -749,7 +762,7 @@ _pango_win32_font_map_init (PangoWin32FontMap *win32fontmap)
   create_standard_family (win32fontmap, "Serif");
   create_standard_family (win32fontmap, "Monospace");
 
-  win32fontmap->resolution = (PANGO_SCALE / (double) GetDeviceCaps (_pango_win32_hdc, LOGPIXELSY)) * 72.0;
+  win32fontmap->resolution = (PANGO_SCALE / (double) GetDeviceCaps (hdc, LOGPIXELSY)) * 72.0;
 }
 
 static void
@@ -802,7 +815,7 @@ _pango_win32_font_map_class_init (PangoWin32FontMapClass *class)
   fontmap_class->list_families = pango_win32_font_map_list_families;
   fontmap_class->shape_engine_type = PANGO_RENDER_TYPE_WIN32;
 
-  pango_win32_get_dc ();
+  _pango_win32_get_display_dc ();
 }
 
 /**
@@ -1125,6 +1138,7 @@ get_family_nameA (const LOGFONTA *lfp)
 {
   HFONT hfont;
   HFONT oldhfont;
+  HDC hdc;
 
   struct name_header header;
   struct name_record record;
@@ -1155,17 +1169,19 @@ get_family_nameA (const LOGFONTA *lfp)
   if ((hfont = CreateFontIndirect (lfp)) == NULL)
     goto fail0;
 
-  if ((oldhfont = SelectObject (_pango_win32_hdc, hfont)) == NULL)
+  hdc = _pango_win32_get_display_dc ();
+
+  if ((oldhfont = SelectObject (hdc, hfont)) == NULL)
     goto fail1;
 
-  if (!_pango_win32_get_name_header (_pango_win32_hdc, &header))
+  if (!_pango_win32_get_name_header (hdc, &header))
     goto fail2;
 
   PING (("%d name records", header.num_records));
 
   for (i = 0; i < header.num_records; i++)
     {
-      if (!_pango_win32_get_name_record (_pango_win32_hdc, i, &record))
+      if (!_pango_win32_get_name_record (hdc, i, &record))
 	goto fail2;
 
       if ((record.name_id != 1 && record.name_id != 16) || record.string_length <= 0)
@@ -1199,11 +1215,11 @@ get_family_nameA (const LOGFONTA *lfp)
   else
     goto fail2;
 
-  if (!_pango_win32_get_name_record (_pango_win32_hdc, name_ix, &record))
+  if (!_pango_win32_get_name_record (hdc, name_ix, &record))
     goto fail2;
 
   string = g_malloc (record.string_length + 1);
-  if (GetFontData (_pango_win32_hdc, NAME,
+  if (GetFontData (hdc, NAME,
 		   header.string_storage_offset + record.string_offset,
 		   string, record.string_length) != record.string_length)
     goto fail2;
@@ -1229,14 +1245,14 @@ get_family_nameA (const LOGFONTA *lfp)
 
   PING (("%s", name));
 
-  SelectObject (_pango_win32_hdc, oldhfont);
+  SelectObject (hdc, oldhfont);
   DeleteObject (hfont);
 
   return name;
 
  fail2:
   g_free (string);
-  SelectObject (_pango_win32_hdc, oldhfont);
+  SelectObject (hdc, oldhfont);
 
  fail1:
   DeleteObject (hfont);
@@ -1308,6 +1324,7 @@ get_family_nameW (const LOGFONTW *lfp)
 {
   HFONT hfont;
   HFONT oldhfont;
+  HDC hdc;
 
   struct name_header header;
   struct name_record record;
@@ -1338,17 +1355,19 @@ get_family_nameW (const LOGFONTW *lfp)
   if ((hfont = CreateFontIndirectW (lfp)) == NULL)
     goto fail0;
 
-  if ((oldhfont = SelectObject (_pango_win32_hdc, hfont)) == NULL)
+  hdc = _pango_win32_get_display_dc ();
+
+  if ((oldhfont = SelectObject (hdc, hfont)) == NULL)
     goto fail1;
 
-  if (!_pango_win32_get_name_header (_pango_win32_hdc, &header))
+  if (!_pango_win32_get_name_header (hdc, &header))
     goto fail2;
 
   PING (("%d name records", header.num_records));
 
   for (i = 0; i < header.num_records; i++)
     {
-      if (!_pango_win32_get_name_record (_pango_win32_hdc, i, &record))
+      if (!_pango_win32_get_name_record (hdc, i, &record))
 	goto fail2;
 
       if ((record.name_id != 1 && record.name_id != 16) || record.string_length <= 0)
@@ -1382,11 +1401,11 @@ get_family_nameW (const LOGFONTW *lfp)
   else
     goto fail2;
 
-  if (!_pango_win32_get_name_record (_pango_win32_hdc, name_ix, &record))
+  if (!_pango_win32_get_name_record (hdc, name_ix, &record))
     goto fail2;
 
   string = g_malloc (record.string_length + 1);
-  if (GetFontData (_pango_win32_hdc, NAME,
+  if (GetFontData (hdc, NAME,
 		   header.string_storage_offset + record.string_offset,
 		   string, record.string_length) != record.string_length)
     goto fail2;
@@ -1412,14 +1431,14 @@ get_family_nameW (const LOGFONTW *lfp)
 
   PING (("%s", name));
 
-  SelectObject (_pango_win32_hdc, oldhfont);
+  SelectObject (hdc, oldhfont);
   DeleteObject (hfont);
 
   return name;
 
  fail2:
   g_free (string);
-  SelectObject (_pango_win32_hdc, oldhfont);
+  SelectObject (hdc, oldhfont);
 
  fail1:
   DeleteObject (hfont);
diff --git a/pango/pangowin32-private.h b/pango/pangowin32-private.h
index 88e5655d..72cae50e 100644
--- a/pango/pangowin32-private.h
+++ b/pango/pangowin32-private.h
@@ -291,7 +291,9 @@ _pango_win32_shape (PangoFont        	*font,
 		    const char          *paragraph_text G_GNUC_UNUSED,
 		    unsigned int         paragraph_length G_GNUC_UNUSED);
 
-extern HDC _pango_win32_hdc;
+_PANGO_EXTERN
+HDC             _pango_win32_get_display_dc                 (void);
+
 extern OSVERSIONINFO _pango_win32_os_version_info;
 extern gboolean _pango_win32_debug;
 
diff --git a/pango/pangowin32-shape.c b/pango/pangowin32-shape.c
index aad0243e..36d43413 100644
--- a/pango/pangowin32-shape.c
+++ b/pango/pangowin32-shape.c
@@ -607,7 +607,7 @@ uniscribe_shape (PangoFont           *font,
 {
   wchar_t *wtext;
   long wlen;
-  HDC hdc = _pango_win32_hdc;
+  HDC hdc = _pango_win32_get_display_dc ();
   gboolean retval = TRUE;
 
   if (!pango_win32_font_select_font (font, hdc))
diff --git a/pango/pangowin32.c b/pango/pangowin32.c
index 630898e0..71204606 100644
--- a/pango/pangowin32.c
+++ b/pango/pangowin32.c
@@ -47,7 +47,6 @@
 			  ((ch) >= 0x20000 && (ch) <= 0x2A6DF) ||	\
 			  ((ch) >= 0x2F800 && (ch) <= 0x2FA1F))
 
-HDC _pango_win32_hdc;
 OSVERSIONINFO _pango_win32_os_version_info;
 gboolean _pango_win32_debug = FALSE;
 
@@ -143,24 +142,17 @@ _pango_win32_font_init (PangoWin32Font *win32font)
   win32font->glyph_info = g_hash_table_new_full (NULL, NULL, NULL, g_free);
 }
 
-/**
- * pango_win32_get_dc:
- *
- * Obtains a handle to the Windows device context that is used by Pango.
- *
- * Return value: A handle to the Windows device context that is used by Pango.
- **/
+static GPrivate display_dc_key = G_PRIVATE_INIT ((GDestroyNotify) DeleteDC);
+
 HDC
-pango_win32_get_dc (void)
+_pango_win32_get_display_dc (void)
 {
-  if (g_once_init_enter (&_pango_win32_hdc))
+  HDC hdc = g_private_get (&display_dc_key);
+
+  if (hdc == NULL)
     {
-      HDC hdc = CreateDC ("DISPLAY", NULL, NULL, NULL);
-      memset (&_pango_win32_os_version_info, 0,
-	      sizeof (_pango_win32_os_version_info));
-      _pango_win32_os_version_info.dwOSVersionInfoSize =
-	sizeof (OSVERSIONINFO);
-      GetVersionEx (&_pango_win32_os_version_info);
+      hdc = CreateDC ("DISPLAY", NULL, NULL, NULL);
+      g_private_set (&display_dc_key, hdc);
 
       /* Also do some generic pangowin32 initialisations... this function
        * is a suitable place for those as it is called from a couple
@@ -170,10 +162,22 @@ pango_win32_get_dc (void)
       if (getenv ("PANGO_WIN32_DEBUG") != NULL)
 	_pango_win32_debug = TRUE;
 #endif
-      g_once_init_leave (&_pango_win32_hdc, hdc);
     }
 
-  return _pango_win32_hdc;
+  return hdc;
+}
+
+/**
+ * pango_win32_get_dc:
+ *
+ * Obtains a handle to the Windows device context that is used by Pango.
+ *
+ * Return value: A handle to the Windows device context that is used by Pango.
+ **/
+HDC
+pango_win32_get_dc (void)
+{
+    return _pango_win32_get_display_dc ();
 }
 
 /**
@@ -212,7 +216,7 @@ _pango_win32_font_class_init (PangoWin32FontClass *class)
   class->done_font = pango_win32_font_real_done_font;
   class->get_metrics_factor = pango_win32_font_real_get_metrics_factor;
 
-  pango_win32_get_dc ();
+  _pango_win32_get_display_dc ();
 }
 
 /**
@@ -462,15 +466,14 @@ pango_win32_font_get_glyph_extents (PangoFont      *font,
 
   if (!info)
     {
+      HDC hdc = _pango_win32_get_display_dc ();
       info = g_new0 (PangoWin32GlyphInfo, 1);
 
       memset (&gm, 0, sizeof (gm));
 
       hfont = _pango_win32_font_get_hfont (font);
-      SelectObject (_pango_win32_hdc, hfont);
-      /* FIXME: (Alex) This constant reuse of _pango_win32_hdc is
-	 not thread-safe */
-      res = GetGlyphOutlineA (_pango_win32_hdc,
+      SelectObject (hdc, hfont);
+      res = GetGlyphOutlineA (hdc,
 			      glyph_index,
 			      GGO_METRICS | GGO_GLYPH_INDEX,
 			      &gm,
@@ -492,7 +495,7 @@ pango_win32_font_get_glyph_extents (PangoFont      *font,
       info->ink_rect.y = - PANGO_SCALE * gm.gmptGlyphOrigin.y;
       info->ink_rect.height = PANGO_SCALE * gm.gmBlackBoxY;
 
-      GetTextMetrics (_pango_win32_hdc, &tm);
+      GetTextMetrics (hdc, &tm);
       info->logical_rect.x = 0;
       info->logical_rect.width = PANGO_SCALE * gm.gmCellIncX;
       info->logical_rect.y = - PANGO_SCALE * tm.tmAscent;
@@ -569,9 +572,10 @@ pango_win32_font_get_metrics (PangoFont     *font,
 	{
 	  PangoCoverage *coverage;
 	  TEXTMETRIC tm;
+	  HDC hdc = _pango_win32_get_display_dc ();
 
-	  SelectObject (_pango_win32_hdc, hfont);
-	  GetTextMetrics (_pango_win32_hdc, &tm);
+	  SelectObject (hdc, hfont);
+	  GetTextMetrics (hdc, &tm);
 
 	  metrics->ascent = tm.tmAscent * PANGO_SCALE;
 	  metrics->descent = tm.tmDescent * PANGO_SCALE;
@@ -1489,19 +1493,20 @@ font_get_cmap (PangoFont *font)
 {
   PangoWin32Font *win32font = (PangoWin32Font *)font;
   gpointer cmap;
+  HDC hdc = _pango_win32_get_display_dc ();
 
   if (win32font->win32face->cmap)
     return win32font->win32face->cmap;
 
-  pango_win32_font_select_font (font, _pango_win32_hdc);
+  pango_win32_font_select_font (font, hdc);
 
   /* Prefer the format 12 cmap */
-  if ((cmap = get_format_12_cmap (_pango_win32_hdc)) != NULL)
+  if ((cmap = get_format_12_cmap (hdc)) != NULL)
     {
       win32font->win32face->cmap_format = 12;
       win32font->win32face->cmap = cmap;
     }
-  else if ((cmap = get_format_4_cmap (_pango_win32_hdc)) != NULL)
+  else if ((cmap = get_format_4_cmap (hdc)) != NULL)
     {
       win32font->win32face->cmap_format = 4;
       win32font->win32face->cmap = cmap;
@@ -1519,11 +1524,12 @@ pango_win32_font_get_type1_glyph_index (PangoFont *font,
   wchar_t unicode[2];
   WORD glyph_index;
   gint32 res;
+  HDC hdc = _pango_win32_get_display_dc ();
 
   unicode[0] = wc;
   unicode[1] = 0;
-  pango_win32_font_select_font (font, _pango_win32_hdc);
-  res = GetGlyphIndicesW (_pango_win32_hdc, unicode, 1, &glyph_index, 0);
+  pango_win32_font_select_font (font, hdc);
+  res = GetGlyphIndicesW (hdc, unicode, 1, &glyph_index, 0);
   pango_win32_font_done_font (font);
 
   if (res == 1)
@@ -1656,24 +1662,25 @@ font_has_name_in (PangoFont                       *font,
   struct name_record record;
   gint i;
   gboolean retval = FALSE;
+  HDC hdc = _pango_win32_get_display_dc ();
 
   if (cjkv == PANGO_WIN32_COVERAGE_UNSPEC)
     return TRUE;
 
   hfont = _pango_win32_font_get_hfont (font);
-  oldhfont = SelectObject (_pango_win32_hdc, hfont);
+  oldhfont = SelectObject (hdc, hfont);
 
-  if (!_pango_win32_get_name_header (_pango_win32_hdc, &header))
+  if (!_pango_win32_get_name_header (hdc, &header))
     {
-      SelectObject (_pango_win32_hdc, oldhfont);
+      SelectObject (hdc, oldhfont);
       return FALSE;
     }
 
   for (i = 0; i < header.num_records; i++)
     {
-      if (!_pango_win32_get_name_record (_pango_win32_hdc, i, &record))
+      if (!_pango_win32_get_name_record (hdc, i, &record))
 	{
-	  SelectObject (_pango_win32_hdc, oldhfont);
+	  SelectObject (hdc, oldhfont);
 	  return FALSE;
 	}
 
@@ -1705,7 +1712,7 @@ font_has_name_in (PangoFont                       *font,
 	  }
     }
 
-  SelectObject (_pango_win32_hdc, oldhfont);
+  SelectObject (hdc, oldhfont);
   return retval;
 }
 
@@ -1718,14 +1725,16 @@ pango_win32_font_calc_type1_coverage (PangoFont     *font,
   gint32 res;
   guint32 ch;
   guint32 i;
+  HDC hdc = _pango_win32_get_display_dc ();
+
   
-  pango_win32_font_select_font (font, _pango_win32_hdc);
-  res = GetFontUnicodeRanges(_pango_win32_hdc, NULL);
+  pango_win32_font_select_font (font, hdc);
+  res = GetFontUnicodeRanges(hdc, NULL);
   if (res == 0)
     goto fail1;
 
   glyph_set = g_malloc (res);
-  res = GetFontUnicodeRanges(_pango_win32_hdc, glyph_set);
+  res = GetFontUnicodeRanges(hdc, glyph_set);
   if (res == 0)
     goto fail2;
   
-- 
2.17.1