Add SVG rendering support to ICairoShim interface

- Added renderSVG(void* svgHandle, double width, double height) to ICairoShim
- Added SVGRenderer::handle() method to expose RsvgHandle* for ICairoShim
- Implemented renderSVG in CairoShimCairo using librsvg
- Updated GodleyIcon, Group, Ravel, and Lock to use cairoShim.renderSVG()
- Removed 3 more _internalGetCairoContext calls (down from 14 to 11)
- SVG rendering now fully abstracted through ICairoShim interface

Co-authored-by: highperformancecoder <3075825+highperformancecoder@users.noreply.github.com>

Author: Copilot

engine/cairoShimCairo.cc

@@ -4,6 +4,13 @@
 #include <cairo.h>
 #undef CAIRO_WIN32_STATIC_BUILD
 #include <pango.h>
+#include <librsvg/rsvg.h>
+
+// if not #ifdef protected, you get a deprecated warning, which is
+// made fatal by -Werror
+#ifndef RSVG_CAIRO_H
+#include <librsvg/rsvg-cairo.h>
+#endif
 
 using namespace std;
 
@@ -137,4 +144,27 @@ namespace minsky
       m_pango.reset(new ecolab::Pango(cairo));
     return *m_pango;
   }
+
+  // SVG rendering support
+  void CairoShimCairo::renderSVG(void* svgHandle, double width, double height) const
+  {
+    if (!svgHandle) return;
+    
+    RsvgHandle* svg = static_cast<RsvgHandle*>(svgHandle);
+#ifdef MXE // MXE doesn't currently have a Rust compiler, so librsvg can be no later than 2.40.21
+    RsvgDimensionData dims;
+    rsvg_handle_get_dimensions(svg, &dims);
+    cairo_scale(cairo, width/dims.width, height/dims.height);
+    rsvg_handle_render_cairo(svg, cairo);
+#else
+    GError* err=nullptr;
+    const RsvgRectangle rect{0,0,width,height};
+    rsvg_handle_render_document(svg, cairo, &rect, &err);
+    if (err)
+      {
+        g_error_free(err);
+        // Silently ignore errors for now to avoid breaking rendering
+      }
+#endif
+  }
 }

engine/cairoShimCairo.h

@@ -77,6 +77,9 @@ namespace minsky
     // Pango support
     ecolab::Pango& pango() const override;
 
+    // SVG rendering support
+    void renderSVG(void* svgHandle, double width, double height) const override;
+    
     // TEMPORARY: Internal accessor for migration - to be removed once all implementations are updated
     cairo_t* _internalGetCairoContext() const { return cairo; }
   };

model/ICairoShim.h

@@ -90,6 +90,13 @@ namespace minsky
 
     // Pango support for text rendering
     virtual ecolab::Pango& pango() const = 0;
+
+    // SVG rendering support
+    /// Render a pre-loaded SVG resource into a region of size width x height
+    /// @param svgHandle - RsvgHandle* from SVGRenderer::handle(), passed as void* for abstraction
+    /// @param width - target width for rendering
+    /// @param height - target height for rendering
+    virtual void renderSVG(void* svgHandle, double width, double height) const = 0;
   };
 }
 

model/SVGItem.h

@@ -44,6 +44,8 @@ namespace minsky
     void setResource(const std::string& resource);
     /// render SVG into region of size \a width \a height
     void render(cairo_t*, double width, double height) const;
+    /// get the internal RsvgHandle* for use with ICairoShim
+    void* handle() const {return svg;}
   };
 
 

model/godleyIcon.cc

@@ -566,9 +566,8 @@ namespace minsky
       {
         cairoShim.save();
         cairoShim.translate(left+leftMargin(),top);
-        // SVGRenderer requires cairo_t* (librsvg dependency)
-        auto& shimImpl = dynamic_cast<const CairoShimCairo&>(cairoShim);
-        svgRenderer.render(shimImpl._internalGetCairoContext(), w-leftMargin(), h-bottomMargin());
+        // Render SVG using ICairoShim abstraction
+        cairoShim.renderSVG(svgRenderer.handle(), w-leftMargin(), h-bottomMargin());
         titley=top+0.1*(h-bottomMargin());
         cairoShim.restore();
       }

model/group.cc

@@ -1114,8 +1114,8 @@ namespace minsky
             {
               cairoShim.rectangle(0, 0,width, height);
               cairoShim.clip();
-              // SVGRenderer requires cairo_t* (librsvg dependency)
-              svgRenderer.render(cairo,width, height);
+              // Render SVG using ICairoShim abstraction
+              cairoShim.renderSVG(svgRenderer.handle(), width, height);
             }
         }
       cairoShim.restore();

model/lock.cc

@@ -113,9 +113,8 @@ namespace minsky
       cairoShim.save();
       cairoShim.translate(-0.5*w,-0.5*h);
       SVGRenderer* icon=locked()? &lockedIcon: &unlockedIcon;
-      // TODO: Add SVGRenderer support to ICairoShim
-      auto& shimImpl = dynamic_cast<const CairoShimCairo&>(cairoShim);
-      icon->render(shimImpl._internalGetCairoContext(),w,h);
+      // Render SVG using ICairoShim abstraction
+      cairoShim.renderSVG(icon->handle(), w, h);
       cairoShim.restore();
     }
 

model/ravelWrap.cc

@@ -198,9 +198,8 @@ namespace minsky
       else
         {
           cairoShim.translate(-r,-r);
-          // TODO: SVGRenderer needs ICairoShim support
-          auto& shimImpl = dynamic_cast<const CairoShimCairo&>(cairoShim);
-          svgRenderer.render(shimImpl._internalGetCairoContext(),2*r,2*r);
+          // Render SVG using ICairoShim abstraction
+          cairoShim.renderSVG(svgRenderer.handle(), 2*r, 2*r);
         }
       cairoShim.restore();
     }