[librsvg/librsvg-2.50] Add helper DrawingCtx.push_coord_units()

[Federico Mena Quintero <federico src gnome org>]

commit f3da52791bd4ea076cc41fd8bd27035cabb1c6fe
Author: Federico Mena Quintero <federico gnome org>
Date:   Tue Sep 22 14:39:29 2020 -0500

    Add helper DrawingCtx.push_coord_units()
    
    This takes care of the pattern of pushing a unit-sized viewBox for
    objectBoundingBox.
    
    https://www.w3.org/TR/SVG2/coords.html#ObjectBoundingBoxUnits

 rsvg_internals/src/drawing_ctx.rs     | 47 ++++++++++++++---------------------
 rsvg_internals/src/filter.rs          | 15 +----------
 rsvg_internals/src/filters/context.rs |  6 +----
 3 files changed, 20 insertions(+), 48 deletions(-)
---
diff --git a/rsvg_internals/src/drawing_ctx.rs b/rsvg_internals/src/drawing_ctx.rs
index 2144f46b..aed39b92 100644
--- a/rsvg_internals/src/drawing_ctx.rs
+++ b/rsvg_internals/src/drawing_ctx.rs
@@ -307,6 +307,14 @@ impl DrawingCtx {
             .expect("view_box_stack must never be empty!")
     }
 
+    pub fn push_coord_units(&self, units: CoordUnits) -> ViewParams {
+        if units == CoordUnits::ObjectBoundingBox {
+            self.push_view_box(1.0, 1.0)
+        } else {
+            self.get_view_params()
+        }
+    }
+
     /// Gets the viewport that was last pushed with `push_view_box()`.
     pub fn get_view_params(&self) -> ViewParams {
         let vbox = self.get_top_viewbox();
@@ -448,12 +456,7 @@ impl DrawingCtx {
         let mask_units = mask.get_units();
 
         let mask_rect = {
-            let params = if mask_units == CoordUnits::ObjectBoundingBox {
-                self.push_view_box(1.0, 1.0)
-            } else {
-                self.get_view_params()
-            };
-
+            let params = self.push_coord_units(mask_units);
             mask.get_rect(&values, &params)
         };
 
@@ -495,11 +498,7 @@ impl DrawingCtx {
                 mask_cr.transform(bbtransform.into());
             }
 
-            let _params = if mask.get_content_units() == CoordUnits::ObjectBoundingBox {
-                self.push_view_box(1.0, 1.0)
-            } else {
-                self.get_view_params()
-            };
+            let _params = self.push_coord_units(mask.get_content_units());
 
             self.push_cairo_context(mask_cr);
 
@@ -899,18 +898,14 @@ impl DrawingCtx {
         values: &ComputedValues,
         bbox: &BoundingBox,
     ) -> Result<bool, RenderingError> {
-        let units = gradient.get_units();
-        let transform = if let Ok(t) = bbox.rect_to_transform(units.0) {
+        let GradientUnits(units) = gradient.get_units();
+        let transform = if let Ok(t) = bbox.rect_to_transform(units) {
             t
         } else {
             return Ok(false);
         };
 
-        let params = if units == GradientUnits(CoordUnits::ObjectBoundingBox) {
-            self.push_view_box(1.0, 1.0)
-        } else {
-            self.get_view_params()
-        };
+        let params = self.push_coord_units(units);
 
         let g = match gradient.get_variant() {
             GradientVariant::Linear { x1, y1, x2, y2 } => {
@@ -990,11 +985,7 @@ impl DrawingCtx {
         let content_units = pattern.get_content_units();
         let pattern_transform = pattern.get_transform();
 
-        let params = if units == PatternUnits(CoordUnits::ObjectBoundingBox) {
-            self.push_view_box(1.0, 1.0)
-        } else {
-            self.get_view_params()
-        };
+        let params = self.push_coord_units(units.0);
 
         let pattern_rect = pattern.get_rect(values, &params);
 
@@ -1062,7 +1053,9 @@ impl DrawingCtx {
 
             self.push_view_box(vbox.width(), vbox.height())
         } else {
-            caffine = if content_units == PatternContentUnits(CoordUnits::ObjectBoundingBox) {
+            let PatternContentUnits(content_units) = content_units;
+
+            caffine = if content_units == CoordUnits::ObjectBoundingBox {
                 // If coords are in terms of the bounding box, use them
                 let (bbw, bbh) = bbox.rect.unwrap().size();
                 Transform::new_scale(bbw, bbh)
@@ -1070,11 +1063,7 @@ impl DrawingCtx {
                 Transform::identity()
             };
 
-            if content_units == PatternContentUnits(CoordUnits::ObjectBoundingBox) {
-                self.push_view_box(1.0, 1.0)
-            } else {
-                self.get_view_params()
-            }
+            self.push_coord_units(content_units)
         };
 
         if !scwscale.approx_eq_cairo(1.0) || !schscale.approx_eq_cairo(1.0) {
diff --git a/rsvg_internals/src/filter.rs b/rsvg_internals/src/filter.rs
index f06a3ac5..7d73eab9 100644
--- a/rsvg_internals/src/filter.rs
+++ b/rsvg_internals/src/filter.rs
@@ -67,20 +67,7 @@ impl Filter {
 
         let mut bbox = BoundingBox::new();
 
-        // transform is set up in FilterContext::new() in such a way that for
-        // filterunits == ObjectBoundingBox it includes scaling to correct width, height and
-        // this is why width and height are set to 1, 1 (and for filterunits ==
-        // UserSpaceOnUse, transform doesn't include scaling because in this case the correct
-        // width, height already happens to be the viewbox width, height).
-        //
-        // It's done this way because with ObjectBoundingBox, non-percentage values are supposed to
-        // represent the fractions of the referenced node, and with width and height = 1, 1 this
-        // works out exactly like that.
-        let params = if self.filterunits == CoordUnits::ObjectBoundingBox {
-            draw_ctx.push_view_box(1.0, 1.0)
-        } else {
-            draw_ctx.get_view_params()
-        };
+        let params = draw_ctx.push_coord_units(self.filterunits);
 
         // With filterunits == ObjectBoundingBox, lengths represent fractions or percentages of the
         // referencing node. No units are allowed (it's checked during attribute parsing).
diff --git a/rsvg_internals/src/filters/context.rs b/rsvg_internals/src/filters/context.rs
index d1a4c5d2..4fc47512 100644
--- a/rsvg_internals/src/filters/context.rs
+++ b/rsvg_internals/src/filters/context.rs
@@ -252,11 +252,7 @@ impl FilterContext {
     pub fn get_view_params(&self, draw_ctx: &mut DrawingCtx) -> ViewParams {
         // See comments in compute_effects_region() for how this works.
         let units = borrow_element_as!(self.node, Filter).get_primitive_units();
-        if units == CoordUnits::ObjectBoundingBox {
-            draw_ctx.push_view_box(1.0, 1.0)
-        } else {
-            draw_ctx.get_view_params()
-        }
+        draw_ctx.push_coord_units(units)
     }
 
     /// Retrieves the filter input surface according to the SVG rules.