Fix gradient transformation (#588)

* Fix with perfect circle

* Actually fix rotated gradient

* Gradient transform & fix on rotated canvas

* Cleanup & remove logging

graphene/src/layers/shape_layer.rs

@@ -32,6 +32,10 @@ pub struct ShapeLayer {
 impl LayerData for ShapeLayer {
 	fn render(&mut self, svg: &mut String, svg_defs: &mut String, transforms: &mut Vec<DAffine2>, view_mode: ViewMode) {
 		let mut path = self.path.clone();
+
+		let kurbo::Rect { x0, y0, x1, y1 } = path.bounding_box();
+		let layer_bounds = [(x0, y0).into(), (x1, y1).into()];
+
 		let transform = self.transform(transforms, view_mode);
 		let inverse = transform.inverse();
 		if !inverse.is_finite() {
@@ -40,12 +44,20 @@ impl LayerData for ShapeLayer {
 		}
 		path.apply_affine(glam_to_kurbo(transform));
 
+		let kurbo::Rect { x0, y0, x1, y1 } = path.bounding_box();
+		let transformed_bounds = [(x0, y0).into(), (x1, y1).into()];
+
 		let _ = writeln!(svg, r#"<g transform="matrix("#);
 		inverse.to_cols_array().iter().enumerate().for_each(|(i, entry)| {
 			let _ = svg.write_str(&(entry.to_string() + if i == 5 { "" } else { "," }));
 		});
 		let _ = svg.write_str(r#")">"#);
-		let _ = write!(svg, r#"<path d="{}" {} />"#, path.to_svg(), self.style.render(view_mode, svg_defs));
+		let _ = write!(
+			svg,
+			r#"<path d="{}" {} />"#,
+			path.to_svg(),
+			self.style.render(view_mode, svg_defs, transform, layer_bounds, transformed_bounds)
+		);
 		let _ = svg.write_str("</g>");
 	}
 

graphene/src/layers/style/mod.rs

@@ -61,7 +61,11 @@ impl Gradient {
 	}
 
 	/// Adds the gradient def with the uuid specified
-	fn render_defs(&self, svg_defs: &mut String) {
+	fn render_defs(&self, svg_defs: &mut String, multiplied_transform: DAffine2, bounds: [DVec2; 2], transformed_bounds: [DVec2; 2]) {
+		let bound_transform = DAffine2::from_scale_angle_translation(bounds[1] - bounds[0], 0., bounds[0]);
+		let transformed_bound_transform = DAffine2::from_scale_angle_translation(transformed_bounds[1] - transformed_bounds[0], 0., transformed_bounds[0]);
+		let updated_transform = multiplied_transform * bound_transform;
+
 		let positions = self
 			.positions
 			.iter()
@@ -69,11 +73,13 @@ impl Gradient {
 			.map(|(position, color)| format!(r##"<stop offset="{}" stop-color="#{}" />"##, position, color.rgba_hex()))
 			.collect::<String>();
 
-		let start = self.transform.inverse().transform_point2(self.start);
-		let end = self.transform.inverse().transform_point2(self.end);
+		let mod_gradient = transformed_bound_transform.inverse();
+		let mod_points = mod_gradient.inverse() * transformed_bound_transform.inverse() * updated_transform;
 
-		let transform = self
-			.transform
+		let start = mod_points.transform_point2(self.start);
+		let end = mod_points.transform_point2(self.end);
+
+		let transform = mod_gradient
 			.to_cols_array()
 			.iter()
 			.enumerate()
@@ -122,12 +128,12 @@ impl Fill {
 	}
 
 	/// Renders the fill, adding necessary defs.
-	pub fn render(&self, svg_defs: &mut String) -> String {
+	pub fn render(&self, svg_defs: &mut String, multiplied_transform: DAffine2, bounds: [DVec2; 2], transformed_bounds: [DVec2; 2]) -> String {
 		match self {
 			Self::None => r#" fill="none""#.to_string(),
 			Self::Solid(color) => format!(r##" fill="#{}"{}"##, color.rgb_hex(), format_opacity("fill", color.a())),
 			Self::LinearGradient(gradient) => {
-				gradient.render_defs(svg_defs);
+				gradient.render_defs(svg_defs, multiplied_transform, bounds, transformed_bounds);
 				format!(r##" fill="url('#{}')""##, gradient.uuid)
 			}
 		}
@@ -430,10 +436,10 @@ impl PathStyle {
 		self.stroke = None;
 	}
 
-	pub fn render(&self, view_mode: ViewMode, svg_defs: &mut String) -> String {
+	pub fn render(&self, view_mode: ViewMode, svg_defs: &mut String, multiplied_transform: DAffine2, bounds: [DVec2; 2], transformed_bounds: [DVec2; 2]) -> String {
 		let fill_attribute = match (view_mode, &self.fill) {
-			(ViewMode::Outline, _) => Fill::None.render(svg_defs),
-			(_, fill) => fill.render(svg_defs),
+			(ViewMode::Outline, _) => Fill::None.render(svg_defs, multiplied_transform, bounds, transformed_bounds),
+			(_, fill) => fill.render(svg_defs, multiplied_transform, bounds, transformed_bounds),
 		};
 		let stroke_attribute = match (view_mode, &self.stroke) {
 			(ViewMode::Outline, _) => Stroke::new(LAYER_OUTLINE_STROKE_COLOR, LAYER_OUTLINE_STROKE_WIDTH).render(),

graphene/src/layers/text_layer/mod.rs

@@ -63,9 +63,20 @@ impl LayerData for TextLayer {
 		} else {
 			let mut path = self.to_bez_path();
 
+			let kurbo::Rect { x0, y0, x1, y1 } = path.bounding_box();
+			let bounds = [(x0, y0).into(), (x1, y1).into()];
+
 			path.apply_affine(glam_to_kurbo(transform));
 
-			let _ = write!(svg, r#"<path d="{}" {} />"#, path.to_svg(), self.style.render(view_mode, svg_defs));
+			let kurbo::Rect { x0, y0, x1, y1 } = path.bounding_box();
+			let transformed_bounds = [(x0, y0).into(), (x1, y1).into()];
+
+			let _ = write!(
+				svg,
+				r#"<path d="{}" {} />"#,
+				path.to_svg(),
+				self.style.render(view_mode, svg_defs, transform, bounds, transformed_bounds)
+			);
 		}
 		let _ = svg.write_str("</g>");
 	}