bug#36315: 27.0.50; SVG transparency handling is inaccurate

[YAMAMOTO Mitsuharu]

On Thu, 27 Jun 2019 00:57:48 +0900,
Eli Zaretskii wrote:
> 
> > > Maybe it's just me, but I'm uneasy to bypass librsvg and call Cairo
> > > directly for manipulating SVG images.  Why doesn't librsvg provide a
> > > way to do this via its own APIs?
> > >
> > > Does anyone else think it's unusual to make such direct calls to what
> > > is essentially a lower-level library?
> > 
> > What kind of operations do you think librsvg should provide us with,
> > instead of letting us use cairo?
> 
> Those for which you called the Cairo functions directly.

Which one, concretely?  Or you mean something in other parts?

+  cairo_surface_t *surface;
+#ifdef USE_CAIRO
+  surface = cairo_image_surface_create_for_data ((unsigned char *) ximg->data,
+                                                CAIRO_FORMAT_RGB24,
+                                                width, height,
+                                                ximg->bytes_per_line);
+#else
+  surface = cairo_image_surface_create (CAIRO_FORMAT_RGB24, width, height);
+#endif
+  if (cairo_surface_status (surface) != CAIRO_STATUS_SUCCESS)
+    goto rsvg_error;
+  cairo_t *cr = cairo_create (surface);
+  cairo_set_source_rgb (cr, background.red / 65535.0,
+                       background.green / 65535.0,
+                       background.blue / 65535.0);
+  cairo_paint (cr);
+  cairo_set_source_rgb (cr, 0.0, 0.0, 0.0);
+  rsvg_handle_render_cairo (rsvg_handle, cr);
+  cairo_destroy (cr);
+  g_object_unref (rsvg_handle);

> I tried with the second patch.  I tried now again with the above one:
> still no rectangle.

Seems like a problem in DLL loading.  Please try the attached one.

                                     YAMAMOTO Mitsuharu
                                mituharu@math.s.chiba-u.ac.jp

svg-cairo.diff
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