[librsvg: 2/3] (#799): Don't leave active points in the current Cairo path after drawing text

[Marge Bot <marge-bot src gnome org>]

commit 31c5024678e58d2807749cb6fe71257c3f72b9b9
Author: Federico Mena Quintero <federico gnome org>
Date:   Mon Oct 4 21:15:45 2021 -0500

    (#799): Don't leave active points in the current Cairo path after drawing text
    
    Pangocairo's show_layout family of functions use the cr's current
    point as the starting point for the text.  Librsvg does a lone
    cr.move_to() to establish this point.
    
    However, Pangocairo does not consume that point; it tries to leave the
    current path alone.  Also, the current path (and current point) are
    not part of cairo's gstate - if on does cairo_save(), then sets the
    path, then cairo_restore(), the latter function call will not remove
    the current path.  So, having a <text> element as the last renderable
    element in an SVG would cause librsvg to leave a lone point as part of
    the cr that the caller passed in.
    
    This commit resets the current subpath after text operations to avoid
    that.
    
    Fixes https://gitlab.gnome.org/GNOME/librsvg/-/issues/799
    
    Part-of: <https://gitlab.gnome.org/GNOME/librsvg/-/merge_requests/598>

 src/drawing_ctx.rs |  4 ++++
 tests/src/api.rs   | 31 +++++++++++++++++++++++++++++++
 2 files changed, 35 insertions(+)
---
diff --git a/src/drawing_ctx.rs b/src/drawing_ctx.rs
index a68484fe..92ba431b 100644
--- a/src/drawing_ctx.rs
+++ b/src/drawing_ctx.rs
@@ -1418,6 +1418,8 @@ impl DrawingCtx {
                                 pangocairo::functions::show_layout(&self.cr, &span.layout);
 
                                 self.cr.set_matrix(matrix);
+
+                                self.cr.new_path();
                             }
                         }
 
@@ -1447,6 +1449,8 @@ impl DrawingCtx {
                                 self.cr.stroke()?;
 
                                 self.cr.set_matrix(matrix);
+
+                                self.cr.new_path();
                             }
                         }
 
diff --git a/tests/src/api.rs b/tests/src/api.rs
index d67814e1..4d099ba4 100644
--- a/tests/src/api.rs
+++ b/tests/src/api.rs
@@ -219,3 +219,34 @@ fn set_stylesheet() {
         .compare(&output_surf)
         .evaluate(&output_surf, "set_stylesheet");
 }
+
+// https://gitlab.gnome.org/GNOME/librsvg/-/issues/799
+#[test]
+fn text_doesnt_leave_points_in_current_path() {
+    let svg = load_svg(
+        br##"<?xml version="1.0" encoding="UTF-8"?>
+<svg xmlns="http://www.w3.org/2000/svg"; width="100" height="100">
+  <text>Hello world!</text>
+</svg>
+"##,
+    )
+    .unwrap();
+
+    let renderer = CairoRenderer::new(&svg);
+
+    let output = cairo::ImageSurface::create(cairo::Format::ARgb32, 100, 100).unwrap();
+    let cr = cairo::Context::new(&output).unwrap();
+
+    assert!(!cr.has_current_point().unwrap());
+
+    let viewport = cairo::Rectangle {
+        x: 0.0,
+        y: 0.0,
+        width: 100.0,
+        height: 100.0,
+    };
+
+    renderer.render_document(&cr, &viewport).unwrap();
+
+    assert!(!cr.has_current_point().unwrap());
+}