[librsvg: 47/90] Clarify just when we are measuring the toplevel SVG

[Federico Mena Quintero <federico src gnome org>]

commit a061a7d838335a184c62f57d71de9eea5993cb28
Author: Federico Mena Quintero <federico gnome org>
Date:   Fri Mar 15 08:54:43 2019 -0600

    Clarify just when we are measuring the toplevel SVG

 rsvg_internals/src/structure.rs | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)
---
diff --git a/rsvg_internals/src/structure.rs b/rsvg_internals/src/structure.rs
index d285a274..6e51942f 100644
--- a/rsvg_internals/src/structure.rs
+++ b/rsvg_internals/src/structure.rs
@@ -280,20 +280,23 @@ impl NodeTrait for NodeSvg {
 
         let svg_viewport = self.get_viewport(values, &params);
 
-        let (viewport, vbox) = if !has_parent && draw_ctx.is_measuring() {
+        let is_measuring_toplevel_svg = !has_parent && draw_ctx.is_measuring();
+
+        let (viewport, vbox) = if is_measuring_toplevel_svg {
+            // We are obtaining the toplevel SVG's geometry.  This means, don't care about the
+            // DrawingCtx's viewport, just use the SVG's intrinsic dimensions and see how far
+            // it wants to extend.
             (svg_viewport, self.vbox.get())
         } else {
             let viewport = if has_parent {
                 svg_viewport
             } else {
-                /*
-                cairo::Rectangle {
-                    x: 0.0,
-                    y: 0.0,
-                    width: params.view_box_width,
-                    height: params.view_box_height,
-                }
-                 */
+                // cairo::Rectangle {
+                // x: 0.0,
+                // y: 0.0,
+                // width: params.view_box_width,
+                // height: params.view_box_height,
+                // }
                 draw_ctx.toplevel_viewport()
             };