gfx/cairo/win32-ExtCreatePen-zero-size.patch

   1 From: Robert O'Callahan <robert@ocallahan.org>
   2 Bug 768348. Avoid ExtCreatePen failures by avoiding rounding widths and dash lengths down to zero. r=jrmuizel
   3
   4 diff --git a/gfx/cairo/cairo/src/cairo-win32-printing-surface.c b/gfx/cairo/cairo/src/cairo-win32-printing-surface.c
   5 --- a/gfx/cairo/cairo/src/cairo-win32-printing-surface.c
   6 +++ b/gfx/cairo/cairo/src/cairo-win32-printing-surface.c
   7 @@ -1251,22 +1251,24 @@ static cairo_int_status_t
   8  {
   9      cairo_win32_surface_t *surface = abstract_surface;
  10      cairo_int_status_t status;
  11      HPEN pen;
  12      LOGBRUSH brush;
  13      COLORREF color;
  14      XFORM xform;
  15      DWORD pen_style;
  16 +    DWORD pen_width;
  17      DWORD *dash_array;
  18      HGDIOBJ obj;
  19      unsigned int i;
  20      cairo_solid_pattern_t clear;
  21      cairo_matrix_t mat;
  22      double scale;
  23 +    double scaled_width;
  24
  25      status = _cairo_surface_clipper_set_clip (&surface->clipper, clip);
  26      if (status)
  27         return status;
  28
  29      if (op == CAIRO_OPERATOR_CLEAR) {
  30         _cairo_win32_printing_surface_init_clear_color (surface, &clear);
  31         source = (cairo_pattern_t*) &clear;
  32 @@ -1288,17 +1290,21 @@ static cairo_int_status_t
  33      _cairo_matrix_factor_out_scale (&mat, &scale);
  34
  35      pen_style = PS_GEOMETRIC;
  36      dash_array = NULL;
  37      if (style->num_dashes) {
  38         pen_style |= PS_USERSTYLE;
  39         dash_array = calloc (sizeof (DWORD), style->num_dashes);
  40         for (i = 0; i < style->num_dashes; i++) {
  41 -           dash_array[i] = (DWORD) (scale * style->dash[i]);
  42 +           DWORD dashes = (DWORD) (scale * style->dash[i]);
  43 +           /* zero dash-lengths cause ExtCreatePen to fail. Make the dashes
  44 +            * longer if necessary.
  45 +            */
  46 +           dash_array[i] = MAX(1, dashes);
  47         }
  48      } else {
  49         pen_style |= PS_SOLID;
  50      }
  51
  52      SetMiterLimit (surface->dc, (FLOAT) (style->miter_limit), NULL);
  53      if (source->type == CAIRO_PATTERN_TYPE_SOLID) {
  54         cairo_solid_pattern_t *solid = (cairo_solid_pattern_t *) source;
  55 @@ -1310,18 +1316,29 @@ static cairo_int_status_t
  56         /* Color not used as the pen will only be used by WidenPath() */
  57         color = RGB (0,0,0);
  58      }
  59      brush.lbStyle = BS_SOLID;
  60      brush.lbColor = color;
  61      brush.lbHatch = 0;
  62      pen_style |= _cairo_win32_line_cap (style->line_cap);
  63      pen_style |= _cairo_win32_line_join (style->line_join);
  64 +    scaled_width = scale * style->line_width;
  65 +    if (scaled_width == 0.0)
  66 +        return status;
  67 +    pen_width = (DWORD)scaled_width;
  68 +    if (pen_width == 0) {
  69 +        /* ExtCreatePen will fail if passed zero width. We have to choose
  70 +         * between drawing something too wide, or drawing nothing at all.
  71 +         * Let's draw something.
  72 +         */
  73 +        pen_width = 1;
  74 +    }
  75      pen = ExtCreatePen(pen_style,
  76 -                      scale * style->line_width,
  77 +                      pen_width,
  78                        &brush,
  79                        style->num_dashes,
  80                        dash_array);
  81      if (pen == NULL)
  82         return _cairo_win32_print_gdi_error ("_win32_surface_stroke:ExtCreatePen");
  83      obj = SelectObject (surface->dc, pen);
  84      if (obj == NULL)
  85         return _cairo_win32_print_gdi_error ("_win32_surface_stroke:SelectObject");