[cairo] Re: Problem with bitmap fonts

[Behdad Esfahbod]

Oops.  Second patch attached.

Filed as:

  https://bugs.freedesktop.org/show_bug.cgi?id=5734

behdad

On Wed, 25 Jan 2006, Behdad Esfahbod wrote:

> Hi,
>
> Trying to fix some of the "pango+cairo crashes" bugs led me to
> this problem:
>
> If a bitmap font has a 0x0 glyphs, the current
> cairo-ft-font.c:_get_bitmap_surface returns a NULL surface:
>
> -    if (width * height == 0) {
> -       if (own_buffer && bitmap->buffer)
> -           free (bitmap->buffer);
> -
> -       *surface = NULL;
> -    } else {
>
> which indeed crashes in the calling function immediately.  So I
> first fixed that by fixing the calling function.  This is the
> first patch attached.
>
> But seems like (at least) the xlib backend expects non-NULL glyph
> surfaces:
>
> (gdb) f 0
> #0  0x00477e66 in _cairo_xlib_surface_add_glyph (dpy=0x9ef1878, scaled_font=0xa1d0238,
>     scaled_glyph=0xa1d4518) at cairo-xlib-surface.c:2121
> 2121        glyph_info.x = -(int) glyph_surface->base.device_x_offset;
>
>
> So I backed up and removed the special case for 0x0 glyphs.
> Everything seems to be fine now.  That's the second patch
> attached.  I think it can be committed (with some format change
> maybe), as 0x0 glyphs are not common enough to try to save a 0x0
> surface for them...
>
> Both patches fix another problem, _render_glyph_bitmap should
> check the status returned by _get_bitmap_surface.
>
>
> Cheers,
>
> --behdad
> http://behdad.org/
>
> "Commandment Three says Do Not Kill, Amendment Two says Blood Will Spill"
> 	-- Dan Bern, "New American Language"

--behdad
http://behdad.org/

"Commandment Three says Do Not Kill, Amendment Two says Blood Will Spill"
	-- Dan Bern, "New American Language"
-------------- next part --------------
Index: src/cairo-ft-font.c
===================================================================
RCS file: /cvs/cairo/cairo/src/cairo-ft-font.c,v
retrieving revision 1.115
diff -u -p -r1.115 cairo-ft-font.c
--- src/cairo-ft-font.c	21 Dec 2005 16:19:47 -0000	1.115
+++ src/cairo-ft-font.c	26 Jan 2006 01:04:11 -0000
@@ -715,12 +715,7 @@ _get_bitmap_surface (FT_Bitmap		     *bi
     width = bitmap->width;
     height = bitmap->rows;
     
-    if (width * height == 0) {
-	if (own_buffer && bitmap->buffer)
-	    free (bitmap->buffer);
-	
-	*surface = NULL;
-    } else {
+    {
 	switch (bitmap->pixel_mode) {
 	case FT_PIXEL_MODE_MONO:
 	    stride = (((width + 31) & ~31) >> 3);
@@ -1074,7 +1069,9 @@ _render_glyph_bitmap (FT_Face		      fac
     if (error)
 	return CAIRO_STATUS_NO_MEMORY;
 
-    _get_bitmap_surface (&glyphslot->bitmap, FALSE, font_options, surface);
+    status = _get_bitmap_surface (&glyphslot->bitmap, FALSE, font_options, surface);
+    if (status)
+	return status;
     
     /*
      * Note: the font's coordinate system is upside down from ours, so the