[librsvg/rustify-rsvg-convert: 24/78] rsvg-convert: set background color before rendering

[Sven Neumann <sneumann src gnome org>]

commit 1aa511bcedabc5a2ea150ac7e5dc3d21c8cdac51
Author: Sven Neumann <sven svenfoo org>
Date:   Mon Nov 2 20:41:09 2020 +0100

    rsvg-convert: set background color before rendering

 src/bin/rsvg-convert/main.rs    | 14 +++++++++++++-
 src/bin/rsvg-convert/surface.rs | 14 ++++++++------
 2 files changed, 21 insertions(+), 7 deletions(-)
---
diff --git a/src/bin/rsvg-convert/main.rs b/src/bin/rsvg-convert/main.rs
index 27997250..cf21a830 100644
--- a/src/bin/rsvg-convert/main.rs
+++ b/src/bin/rsvg-convert/main.rs
@@ -6,6 +6,7 @@ mod input;
 mod output;
 mod surface;
 
+use cssparser::Color;
 use librsvg::{CairoRenderer, Loader, RenderingError};
 
 use crate::cli::Args;
@@ -66,8 +67,19 @@ fn main() {
         }
 
         if let Some(ref surface) = target {
+            let cr = cairo::Context::new(surface);
+
+            if let Some(Color::RGBA(rgba)) = args.background_color {
+                cr.set_source_rgba(
+                    rgba.red_f32().into(),
+                    rgba.green_f32().into(),
+                    rgba.blue_f32().into(),
+                    rgba.alpha_f32().into(),
+                );
+            }
+
             surface
-                .render(&renderer, args.export_id())
+                .render(&renderer, &cr, args.export_id())
                 .unwrap_or_else(|e| match e {
                     RenderingError::InvalidId(_) => exit!(
                         "File {} does not have an object with id \"{}\")",
diff --git a/src/bin/rsvg-convert/surface.rs b/src/bin/rsvg-convert/surface.rs
index e834c349..616fc6ad 100644
--- a/src/bin/rsvg-convert/surface.rs
+++ b/src/bin/rsvg-convert/surface.rs
@@ -88,13 +88,15 @@ impl Surface {
         }
     }
 
-    pub fn render(&self, renderer: &CairoRenderer, id: Option<&str>) -> Result<(), RenderingError> {
-        let cr = cairo::Context::new(self);
-        let viewport = self.bounds();
-        let show_page = |_| self.show_page(&cr);
-
+    pub fn render(
+        &self,
+        renderer: &CairoRenderer,
+        cr: &cairo::Context,
+        id: Option<&str>,
+    ) -> Result<(), RenderingError> {
+        let show_page = |_| self.show_page(cr);
         renderer
-            .render_layer(&cr, id, &viewport)
+            .render_layer(cr, id, &self.bounds())
             .and_then(show_page)
     }