canvas: cache layers

keeping a reference to the layer provider around and using it after a
call to update() isn't a good idea since the object handed to update()
may be already gone when rendering

so cache the layers for later use

meson.build

@@ -313,6 +313,7 @@ src_common_ui = files(
 
 src_canvas = files(
     'src/canvas/canvas.cpp',
+    'src/canvas/canvas_layer_provider.cpp',
     'src/canvas/appearance.cpp',
     'src/canvas/render.cpp',
     'src/canvas/draw.cpp',

src/canvas/canvas.cpp

@@ -201,7 +201,7 @@ void Canvas::add_triangle(int layer, const Coordf &p0, const Coordf &p1, const C
 void Canvas::update(const Symbol &sym, const Placement &tr, SymbolMode mode)
 {
     clear();
-    layer_provider = &sym;
+    layer_provider.update(sym);
     transform = tr;
     render(sym, mode);
     request_push();
@@ -210,7 +210,7 @@ void Canvas::update(const Symbol &sym, const Placement &tr, SymbolMode mode)
 void Canvas::update(const Sheet &sheet)
 {
     clear();
-    layer_provider = &sheet;
+    layer_provider.update(sheet);
     update_markers();
     render(sheet);
     request_push();
@@ -219,46 +219,46 @@ void Canvas::update(const Sheet &sheet)
 void Canvas::update(const Padstack &padstack, bool edit)
 {
     clear();
-    layer_provider = &padstack;
+    layer_provider.update(padstack);
     render(padstack, edit);
     request_push();
 }
 
 void Canvas::update(const Package &pkg, bool edit)
 {
     clear();
-    layer_provider = &pkg;
+    layer_provider.update(pkg);
     render(pkg, edit);
     request_push();
 }
 
 void Canvas::update(const Board &brd, PanelMode mode)
 {
     clear();
-    layer_provider = &brd;
+    layer_provider.update(brd);
     render(brd, true, mode);
     request_push();
 }
 void Canvas::update(const class Frame &fr, bool edit)
 {
     clear();
-    layer_provider = &fr;
+    layer_provider.update(fr);
     render(fr, !edit);
     request_push();
 }
 
 void Canvas::update(const class Decal &dec, bool edit)
 {
     clear();
-    layer_provider = &dec;
+    layer_provider.update(dec);
     render(dec, edit);
     request_push();
 }
 
 void Canvas::update(const class BlockSymbol &sym, bool edit)
 {
     clear();
-    layer_provider = &sym;
+    layer_provider.update(sym);
     render(sym, !edit);
     request_push();
 }

src/canvas/canvas.hpp

@@ -20,6 +20,7 @@
 #include "util/vector_pair.hpp"
 #include "text_renderer.hpp"
 #include "show_via_span.hpp"
+#include "canvas_layer_provider.hpp"
 
 namespace horizon {
 class Canvas {
@@ -244,7 +245,7 @@ class Canvas {
     std::vector<Target> targets;
     Target target_current;
 
-    const class LayerProvider *layer_provider = nullptr;
+    CanvasLayerProvider layer_provider;
     std::map<int, Color> layer_colors;
     Color get_layer_color(int layer) const;
     int work_layer = 0;

src/canvas/canvas_layer_provider.cpp

@@ -0,0 +1,16 @@
+#include "canvas_layer_provider.hpp"
+
+namespace horizon {
+
+void CanvasLayerProvider::update(const LayerProvider &other)
+{
+    layers = other.get_layers();
+}
+
+const std::map<int, Layer> &CanvasLayerProvider::get_layers() const
+{
+    return layers;
+}
+
+
+} // namespace horizon

src/canvas/canvas_layer_provider.hpp

@@ -0,0 +1,13 @@
+#pragma once
+#include "common/layer_provider.hpp"
+
+namespace horizon {
+class CanvasLayerProvider : public LayerProvider {
+public:
+    void update(const LayerProvider &other);
+    const std::map<int, Layer> &get_layers() const override;
+
+private:
+    std::map<int, Layer> layers;
+};
+} // namespace horizon

src/canvas/render.cpp

@@ -778,7 +778,7 @@ void Canvas::render(const SchematicSymbol &sym)
 
 void Canvas::render(const Text &text, bool interactive, ColorP co)
 {
-    const bool rev = layer_provider->get_layers().at(text.layer).reverse;
+    const bool rev = layer_provider.get_layers().at(text.layer).reverse;
     img_patch_type(PatchType::TEXT);
     triangle_type_current = TriangleInfo::Type::TEXT;
     img_text(&text);

src/canvas/triangle_renderer.cpp

@@ -300,7 +300,7 @@ void TriangleRenderer::render_layer_batch(int layer, HighlightMode highlight_mod
                 if (ca.appearance.colors.count(k))
                     buf.colors[i] = apply_highlight(ca.appearance.colors.at(k), highlight_mode, layer);
             }
-            auto lc = ca.get_layer_color(ca.layer_provider ? ca.layer_provider->get_color_layer(layer) : layer);
+            auto lc = ca.get_layer_color(ca.layer_provider.get_color_layer(layer));
             buf.colors[static_cast<int>(ColorP::AIRWIRE_ROUTER)] =
                     gl_array_from_color(ca.appearance.colors.at(ColorP::AIRWIRE_ROUTER));
             buf.colors[static_cast<int>(ColorP::FROM_LAYER)] = apply_highlight(lc, highlight_mode, layer);
@@ -371,14 +371,10 @@ void TriangleRenderer::render()
             layers.push_back(it.first);
     }
 
-    if (ca.layer_provider) {
-        std::sort(layers.begin(), layers.end(), [this](auto la, auto lb) {
-            return ca.layer_provider->get_layer_position(la) < ca.layer_provider->get_layer_position(lb);
-        });
-    }
-    else {
-        std::sort(layers.begin(), layers.end());
-    }
+    std::sort(layers.begin(), layers.end(), [this](auto la, auto lb) {
+        return ca.layer_provider.get_layer_position(la) < ca.layer_provider.get_layer_position(lb);
+    });
+
     if (ca.work_layer < 0) {
         std::reverse(layers.begin(), layers.end());
     }