[librsvg: 3/7] filter: mv computation of the effect region in the ctx

[Federico Mena Quintero <federico src gnome org>]

commit 805704f660a9c547c4fd12fe8b769cb903069b6f
Author: Paolo Borelli <pborelli gnome org>
Date:   Sun Nov 29 14:28:04 2020 +0000

    filter: mv computation of the effect region in the ctx

 src/filter.rs          | 35 +++--------------------------------
 src/filters/context.rs | 36 +++++++++++++++++++++++++-----------
 2 files changed, 28 insertions(+), 43 deletions(-)
---
diff --git a/src/filter.rs b/src/filter.rs
index e5fc303c..4cbbe819 100644
--- a/src/filter.rs
+++ b/src/filter.rs
@@ -5,10 +5,9 @@ use markup5ever::{expanded_name, local_name, namespace_url, ns};
 use std::slice::Iter;
 
 use crate::attributes::Attributes;
-use crate::bbox::BoundingBox;
 use crate::coord_units::CoordUnits;
 use crate::document::AcquiredNodes;
-use crate::drawing_ctx::DrawingCtx;
+use crate::drawing_ctx::ViewParams;
 use crate::element::{Draw, Element, ElementResult, SetAttributes};
 use crate::error::ValueErrorKind;
 use crate::iri::IRI;
@@ -17,7 +16,6 @@ use crate::node::{Node, NodeBorrow};
 use crate::parsers::{Parse, ParseValue};
 use crate::properties::ComputedValues;
 use crate::rect::Rect;
-use crate::transform::Transform;
 use crate::url_resolver::Fragment;
 
 /// The <filter> node.
@@ -53,22 +51,7 @@ impl Filter {
         self.primitiveunits
     }
 
-    /// Computes and returns the filter effects region.
-    pub fn compute_effects_region(
-        &self,
-        computed_from_target_node: &ComputedValues,
-        draw_ctx: &mut DrawingCtx,
-        transform: Transform,
-        width: f64,
-        height: f64,
-    ) -> BoundingBox {
-        // Filters use the properties of the target node.
-        let values = computed_from_target_node;
-
-        let mut bbox = BoundingBox::new();
-
-        let params = draw_ctx.push_coord_units(self.filterunits);
-
+    pub fn get_rect(&self, values: &ComputedValues, params: &ViewParams) -> Rect {
         // With filterunits == ObjectBoundingBox, lengths represent fractions or percentages of the
         // referencing node. No units are allowed (it's checked during attribute parsing).
         let (x, y, w, h) = if self.filterunits == CoordUnits::ObjectBoundingBox {
@@ -87,19 +70,7 @@ impl Filter {
             )
         };
 
-        let rect = Rect::new(x, y, x + w, y + h);
-        let other_bbox = BoundingBox::new().with_transform(transform).with_rect(rect);
-
-        // At this point all of the previous viewbox and matrix business gets converted to pixel
-        // coordinates in the final surface, because bbox is created with an identity transform.
-        bbox.insert(&other_bbox);
-
-        // Finally, clip to the width and height of our surface.
-        let rect = Rect::from_size(width, height);
-        let other_bbox = BoundingBox::new().with_rect(rect);
-        bbox.clip(&other_bbox);
-
-        bbox
+        Rect::new(x, y, x + w, y + h)
     }
 }
 
diff --git a/src/filters/context.rs b/src/filters/context.rs
index 6a50a998..ab3996a9 100644
--- a/src/filters/context.rs
+++ b/src/filters/context.rs
@@ -9,7 +9,7 @@ use crate::drawing_ctx::{DrawingCtx, ViewParams};
 use crate::node::{Node, NodeBorrow};
 use crate::parsers::CustomIdent;
 use crate::properties::ComputedValues;
-use crate::rect::IRect;
+use crate::rect::{IRect, Rect};
 use crate::surface_utils::shared_surface::{SharedImageSurface, SurfaceType};
 use crate::transform::Transform;
 
@@ -108,7 +108,8 @@ impl FilterContext {
 
         let filter = borrow_element_as!(filter_node, Filter);
 
-        let affine = match filter.get_filter_units() {
+        let filter_units = filter.get_filter_units();
+        let affine = match filter_units {
             CoordUnits::UserSpaceOnUse => draw_transform,
             CoordUnits::ObjectBoundingBox => Transform::new_unchecked(
                 bbox_rect.width(),
@@ -135,7 +136,27 @@ impl FilterContext {
             .post_transform(&draw_transform),
         };
 
-        let (width, height) = (source_surface.width(), source_surface.height());
+        let effects_region = {
+            let params = draw_ctx.push_coord_units(filter_units);
+            let filter_rect = filter.get_rect(&computed_from_node_being_filtered, &params);
+
+            let mut bbox = BoundingBox::new();
+            let other_bbox = BoundingBox::new()
+                .with_transform(affine)
+                .with_rect(filter_rect);
+
+            // At this point all of the previous viewbox and matrix business gets converted to pixel
+            // coordinates in the final surface, because bbox is created with an identity transform.
+            bbox.insert(&other_bbox);
+
+            // Finally, clip to the width and height of our surface.
+            let (width, height) = (source_surface.width(), source_surface.height());
+            let rect = Rect::from_size(f64::from(width), f64::from(height));
+            let other_bbox = BoundingBox::new().with_rect(rect);
+            bbox.clip(&other_bbox);
+
+            bbox
+        };
 
         Self {
             node_bbox,
@@ -145,13 +166,7 @@ impl FilterContext {
             previous_results: HashMap::new(),
             background_surface: RefCell::new(None),
             primitive_units,
-            effects_region: filter.compute_effects_region(
-                computed_from_node_being_filtered,
-                draw_ctx,
-                affine,
-                f64::from(width),
-                f64::from(height),
-            ),
+            effects_region,
             processing_linear_rgb: false,
             _affine: affine,
             paffine,
@@ -251,7 +266,6 @@ impl FilterContext {
 
     /// Pushes the viewport size based on the value of `primitiveUnits`.
     pub fn get_view_params(&self, draw_ctx: &mut DrawingCtx) -> ViewParams {
-        // See comments in compute_effects_region() for how this works.
         draw_ctx.push_coord_units(self.primitive_units)
     }