🐛 Fix blend mode against background

frontend/src/app/main/ui/workspace/viewport_wasm.cljs

@@ -284,7 +284,8 @@
              (p/fmap (fn [ready?]
                        (when ready?
                          (reset! canvas-init? true)
-                         (wasm.api/assign-canvas canvas)))))
+                         (wasm.api/assign-canvas canvas)
+                         (wasm.api/set-canvas-background background)))))
         (fn []
           (wasm.api/clear-canvas))))
 
@@ -304,6 +305,10 @@
       (when @canvas-init?
         (wasm.api/set-view zoom vbox)))
 
+    (mf/with-effect [background]
+      (when @canvas-init?
+        (wasm.api/set-canvas-background background)))
+
     (hooks/setup-dom-events zoom disable-paste in-viewport? read-only? drawing-tool drawing-path?)
     (hooks/setup-viewport-size vport viewport-ref)
     (hooks/setup-cursor cursor alt? mod? space? panning drawing-tool drawing-path? node-editing? z? read-only?)

frontend/src/app/render_wasm/api.cljs

@@ -345,6 +345,11 @@
   (set! (.-width canvas) (* dpr (.-clientWidth ^js canvas)))
   (set! (.-height canvas) (* dpr (.-clientHeight ^js canvas))))
 
+(defn set-canvas-background
+  [background]
+  (let [rgba (rgba-from-hex background 1)]
+    (h/call internal-module "_set_canvas_background" rgba)))
+
 (defonce module
   (delay
     (if (exists? js/dynamicImport)