[librsvg] Move the viewport-is-zero-sized check to viewport_to_viewbox_transform()

[Federico Mena Quintero <federico src gnome org>]

commit 6ff5220cc37c1ebc07e75d45b380af6df4483ca1
Author: Federico Mena Quintero <federico gnome org>
Date:   Mon Mar 4 09:41:59 2019 -0600

    Move the viewport-is-zero-sized check to viewport_to_viewbox_transform()
    
    Maybe we can remove draw_in_viewport() soon?

 rsvg_internals/src/aspect_ratio.rs | 10 ++++++++++
 rsvg_internals/src/viewport.rs     | 11 -----------
 2 files changed, 10 insertions(+), 11 deletions(-)
---
diff --git a/rsvg_internals/src/aspect_ratio.rs b/rsvg_internals/src/aspect_ratio.rs
index 77d8c185..1d0b9769 100644
--- a/rsvg_internals/src/aspect_ratio.rs
+++ b/rsvg_internals/src/aspect_ratio.rs
@@ -155,6 +155,16 @@ impl AspectRatio {
         vbox: Option<ViewBox>,
         viewport: &cairo::Rectangle,
     ) -> Option<cairo::Matrix> {
+        // width or height set to 0 disables rendering of the element
+        // https://www.w3.org/TR/SVG/struct.html#SVGElementWidthAttribute
+        // https://www.w3.org/TR/SVG/struct.html#UseElementWidthAttribute
+        // https://www.w3.org/TR/SVG/struct.html#ImageElementWidthAttribute
+        // https://www.w3.org/TR/SVG/painting.html#MarkerWidthAttribute
+
+        if viewport.width.approx_eq_cairo(&0.0) || viewport.height.approx_eq_cairo(&0.0) {
+            return None;
+        }
+
         // the preserveAspectRatio attribute is only used if viewBox is specified
         // https://www.w3.org/TR/SVG/coords.html#PreserveAspectRatioAttribute
         if let Some(vbox) = vbox {
diff --git a/rsvg_internals/src/viewport.rs b/rsvg_internals/src/viewport.rs
index 679d5e14..8f1c202e 100644
--- a/rsvg_internals/src/viewport.rs
+++ b/rsvg_internals/src/viewport.rs
@@ -3,7 +3,6 @@ use cairo::Rectangle;
 use aspect_ratio::AspectRatio;
 use drawing_ctx::DrawingCtx;
 use error::RenderingError;
-use float_eq_cairo::ApproxEqCairo;
 use node::RsvgNode;
 use properties::ComputedValues;
 use viewbox::*;
@@ -25,16 +24,6 @@ pub fn draw_in_viewport(
     clipping: bool,
     draw_fn: &mut FnMut(&mut DrawingCtx) -> Result<(), RenderingError>,
 ) -> Result<(), RenderingError> {
-    // width or height set to 0 disables rendering of the element
-    // https://www.w3.org/TR/SVG/struct.html#SVGElementWidthAttribute
-    // https://www.w3.org/TR/SVG/struct.html#UseElementWidthAttribute
-    // https://www.w3.org/TR/SVG/struct.html#ImageElementWidthAttribute
-    // https://www.w3.org/TR/SVG/painting.html#MarkerWidthAttribute
-
-    if viewport.width.approx_eq_cairo(&0.0) || viewport.height.approx_eq_cairo(&0.0) {
-        return Ok(());
-    }
-
     draw_ctx.with_discrete_layer(node, values, clipping, &mut |dc| {
         let _params = dc.push_new_viewport(vbox, viewport, preserve_aspect_ratio, clip_mode);