[librsvg] Replace FilterContext::with_primitive_units() by a get_view_params()

[Federico Mena Quintero <federico src gnome org>]

commit bbb1e285208a04ddf2df14c2dbc23f70a186f3e8
Author: Federico Mena Quintero <federico gnome org>
Date:   Mon Jan 21 17:09:28 2019 -0600

    Replace FilterContext::with_primitive_units() by a get_view_params()
    
    Similar to the function from DrawingCtx; hopefully this is more legible.

 rsvg_internals/src/filters/bounds.rs  | 37 ++++++++++++++++++-----------------
 rsvg_internals/src/filters/context.rs | 28 +++++++++-----------------
 2 files changed, 28 insertions(+), 37 deletions(-)
---
diff --git a/rsvg_internals/src/filters/bounds.rs b/rsvg_internals/src/filters/bounds.rs
index 94a3c305..685fbeba 100644
--- a/rsvg_internals/src/filters/bounds.rs
+++ b/rsvg_internals/src/filters/bounds.rs
@@ -115,24 +115,25 @@ impl<'a> BoundsBuilder<'a> {
 
         // If any of the properties were specified, we need to respect them.
         if self.x.is_some() || self.y.is_some() || self.width.is_some() || self.height.is_some() {
-            self.ctx.with_primitive_units(draw_ctx, |normalize| {
-                // These replacements are correct only because self.bbox is used with the paffine
-                // matrix.
-                let rect = self.bbox.rect.as_mut().unwrap();
-
-                if let Some(x) = self.x {
-                    rect.x = normalize(&x);
-                }
-                if let Some(y) = self.y {
-                    rect.y = normalize(&y);
-                }
-                if let Some(width) = self.width {
-                    rect.width = normalize(&width);
-                }
-                if let Some(height) = self.height {
-                    rect.height = normalize(&height);
-                }
-            });
+            let params = self.ctx.get_view_params(draw_ctx);
+            let values = self.ctx.get_computed_values_from_node_being_filtered();
+
+            // These replacements are correct only because self.bbox is used with the paffine
+            // matrix.
+            let rect = self.bbox.rect.as_mut().unwrap();
+
+            if let Some(x) = self.x {
+                rect.x = x.normalize(values, &params);
+            }
+            if let Some(y) = self.y {
+                rect.y = y.normalize(values, &params);
+            }
+            if let Some(width) = self.width {
+                rect.width = width.normalize(values, &params);
+            }
+            if let Some(height) = self.height {
+                rect.height = height.normalize(values, &params);
+            }
         }
 
         // Convert into the surface coordinate system.
diff --git a/rsvg_internals/src/filters/context.rs b/rsvg_internals/src/filters/context.rs
index 92e8479b..ab063d5e 100644
--- a/rsvg_internals/src/filters/context.rs
+++ b/rsvg_internals/src/filters/context.rs
@@ -6,8 +6,7 @@ use cairo::{self, MatrixTrait};
 
 use bbox::BoundingBox;
 use coord_units::CoordUnits;
-use drawing_ctx::DrawingCtx;
-use length::Length;
+use drawing_ctx::{DrawingCtx, ViewParams};
 use node::RsvgNode;
 use paint_server::PaintServer;
 use properties::ComputedValues;
@@ -366,28 +365,19 @@ impl FilterContext {
         self.effects_region
     }
 
-    /// Calls the given function with correct behavior for the value of `primitiveUnits`.
-    pub fn with_primitive_units<F, T>(&self, draw_ctx: &mut DrawingCtx, f: F) -> T
-    // TODO: Get rid of this Box? Can't just impl Trait because Rust cannot do higher-ranked types.
-    where
-        for<'b> F: FnOnce(Box<Fn(&Length) -> f64 + 'b>) -> T,
-    {
+    pub fn get_computed_from_node_being_filtered(&self) -> &ComputedValues {
+        &self.computed_from_node_being_filtered
+    }
+
+    /// Pushes the viewport size based on the value of `primitiveUnits`.
+    pub fn get_view_params(&self, draw_ctx: &mut DrawingCtx) -> ViewParams {
         let filter = self.node.get_impl::<NodeFilter>().unwrap();
 
         // See comments in compute_effects_region() for how this works.
         if filter.primitiveunits.get() == CoordUnits::ObjectBoundingBox {
-            let _params = draw_ctx.push_view_box(1.0, 1.0);
-            let rv = f(Box::new(Length::get_unitless));
-
-            rv
+            draw_ctx.push_view_box(1.0, 1.0)
         } else {
-            f(Box::new(|length: &Length| {
-                // Filters use the properties of the target node.
-                length.normalize(
-                    &self.computed_from_node_being_filtered,
-                    &draw_ctx.get_view_params(),
-                )
-            }))
+            draw_ctx.get_view_params()
         }
     }