Revert "GskRenderNode: Fix fallback border drawing"

This reverts commit c18d2872f2.

While this commit fixes some aspects of border drawing
that show up in our reference tests, it breaks highly
visible button corners.

gsk/gskrendernodeimpl.c

@@ -542,52 +542,56 @@ gsk_border_node_draw (GskRenderNode *node,
   else
     {
       const graphene_rect_t *bounds = &self->outline.bounds;
+      /* distance to center "line":
+       * +-------------------------+
+       * |                         |
+       * |                         |
+       * |     ---this-line---     |
+       * |                         |
+       * |                         |
+       * +-------------------------+
+       * That line is equidistant from all sides. It's either horiontal
+       * or vertical, depending on if the rect is wider or taller.
+       * We use the 4 sides spanned up by connecting the line to the corner
+       * points to color the regions of the rectangle differently.
+       * Note that the call to cairo_fill() will add the potential final
+       * segment by closing the path, so we don't have to care.
+       */
+      float dst = MIN (bounds->size.width, bounds->size.height) / 2.0;
 
       cairo_clip (cr);
 
-      /* Top */
-      if (self->border_width[0] > 0)
-        {
-          cairo_move_to (cr, bounds->origin.x, bounds->origin.y);
-          cairo_rel_line_to (cr, self->border_width[3], self->border_width[0]);
-          cairo_rel_line_to (cr, bounds->size.width - self->border_width[3] - self->border_width[1], 0);
-          cairo_rel_line_to (cr, self->border_width[1], - self->border_width[0]);
-          gdk_cairo_set_source_rgba (cr, &self->border_color[0]);
-          cairo_fill (cr);
-        }
+      /* top */
+      cairo_move_to (cr, bounds->origin.x + dst, bounds->origin.y + dst);
+      cairo_rel_line_to (cr, - dst, - dst);
+      cairo_rel_line_to (cr, bounds->size.width, 0);
+      cairo_rel_line_to (cr, - dst, dst);
+      gdk_cairo_set_source_rgba (cr, &self->border_color[0]);
+      cairo_fill (cr);
 
-      /* Right */
-      if (self->border_width[1] > 0)
-        {
-          cairo_move_to (cr, bounds->origin.x + bounds->size.width, bounds->origin.y);
-          cairo_rel_line_to (cr, - self->border_width[1], self->border_width[0]);
-          cairo_rel_line_to (cr, 0, bounds->size.height - self->border_width[0] - self->border_width[2]);
-          cairo_rel_line_to (cr, self->border_width[1], self->border_width[2]);
-          gdk_cairo_set_source_rgba (cr, &self->border_color[1]);
-          cairo_fill (cr);
-        }
+      /* right */
+      cairo_move_to (cr, bounds->origin.x + bounds->size.width - dst, bounds->origin.y + dst);
+      cairo_rel_line_to (cr, dst, - dst);
+      cairo_rel_line_to (cr, 0, bounds->size.height);
+      cairo_rel_line_to (cr, - dst, - dst);
+      gdk_cairo_set_source_rgba (cr, &self->border_color[1]);
+      cairo_fill (cr);
 
-      /* Bottom */
-      if (self->border_width[2] > 0)
-        {
-          cairo_move_to (cr, bounds->origin.x, bounds->origin.y + bounds->size.height);
-          cairo_rel_line_to (cr, self->border_width[3], - self->border_width[2]);
-          cairo_rel_line_to (cr, bounds->size.width - self->border_width[3] - self->border_width[1], 0);
-          cairo_rel_line_to (cr, self->border_width[1], self->border_width[2]);
-          gdk_cairo_set_source_rgba (cr, &self->border_color[2]);
-          cairo_fill (cr);
-        }
+      /* bottom */
+      cairo_move_to (cr, bounds->origin.x + bounds->size.width - dst, bounds->origin.y + bounds->size.height - dst);
+      cairo_rel_line_to (cr, dst, dst);
+      cairo_rel_line_to (cr, - bounds->size.width, 0);
+      cairo_rel_line_to (cr, dst, - dst);
+      gdk_cairo_set_source_rgba (cr, &self->border_color[2]);
+      cairo_fill (cr);
 
-      /* Left */
-      if (self->border_width[3] > 0)
-        {
-          cairo_move_to (cr, bounds->origin.x, bounds->origin.y);
-          cairo_rel_line_to (cr, self->border_width[3], self->border_width[0]);
-          cairo_rel_line_to (cr, 0, bounds->size.height - self->border_width[0] - self->border_width[2]);
-          cairo_rel_line_to (cr, - self->border_width[3], self->border_width[2]);
-          gdk_cairo_set_source_rgba (cr, &self->border_color[3]);
-          cairo_fill (cr);
-        }
+      /* left */
+      cairo_move_to (cr, bounds->origin.x + dst, bounds->origin.y + bounds->size.height - dst);
+      cairo_rel_line_to (cr, - dst, dst);
+      cairo_rel_line_to (cr, 0, - bounds->size.height);
+      cairo_rel_line_to (cr, dst, dst);
+      gdk_cairo_set_source_rgba (cr, &self->border_color[3]);
+      cairo_fill (cr);
     }
 
   cairo_restore (cr);