From 6d419a45ae2b141c25e12f4f73eb1dc3a8d88658 Mon Sep 17 00:00:00 2001
From: Andrey Antukh <niwi@niwi.nz>
Date: Wed, 20 Nov 2024 10:44:25 +0100
Subject: [PATCH] :sparkles: Add initial prototype for path content encoding

---
 common/src/app/common/svg/path.cljc     | 73 +++++++++++++++++++++++++
 frontend/src/app/render_wasm/shape.cljs |  1 +
 2 files changed, 74 insertions(+)

diff --git a/common/src/app/common/svg/path.cljc b/common/src/app/common/svg/path.cljc
index 5951002a1..ac89be9d0 100644
--- a/common/src/app/common/svg/path.cljc
+++ b/common/src/app/common/svg/path.cljc
@@ -40,3 +40,76 @@
              (map (fn [segment]
                     (.toPersistentMap ^js segment)))
              (parser/parse path-str)))))
+
+#?(:cljs
+   (defn content->buffer
+     "Converts the path content into binary format."
+     [content]
+     (let [total  (count content)
+           ssize  28
+           buffer (new js/ArrayBuffer (* total ssize))
+           dview  (new js/DataView buffer)]
+       (loop [index 0]
+         (when (< index total)
+           (let [segment (nth content index)
+                 offset  (* index ssize)]
+             (case (:command segment)
+               :move-to
+               (let [{:keys [x y]} (:params segment)]
+                 (.setInt16 dview   (+ offset 0) 1)
+                 (.setFloat32 dview (+ offset 20) x)
+                 (.setFloat32 dview (+ offset 24) y))
+               :line-to
+               (let [{:keys [x y]} (:params segment)]
+                 (.setInt16 dview   (+ offset 0) 2)
+                 (.setFloat32 dview (+ offset 20) x)
+                 (.setFloat32 dview (+ offset 24) y))
+               :curve-to
+               (let [{:keys [c1x c1y c2x c2y x y]} (:params segment)]
+                 (.setInt16 dview   (+ offset 0) 3)
+                 (.setFloat32 dview (+ offset 4) c1x)
+                 (.setFloat32 dview (+ offset 8) c1y)
+                 (.setFloat32 dview (+ offset 12) c2x)
+                 (.setFloat32 dview (+ offset 16) c2y)
+                 (.setFloat32 dview (+ offset 20) x)
+                 (.setFloat32 dview (+ offset 24) y))
+
+               :close-path
+               (.setInt16 dview (+ offset 0) 4))
+             (recur (inc index)))))
+       buffer)))
+
+#?(:cljs
+   (defn buffer->content
+     "Converts the a buffer to a path content vector"
+     [buffer]
+     (assert (instance? js/ArrayBuffer buffer) "expected ArrayBuffer instance")
+     (let [ssize  28
+           total  (/ (.-byteLength buffer) ssize)
+           dview  (new js/DataView buffer)]
+       (loop [index  0
+              result []]
+         (if (< index total)
+           (let [offset  (* index ssize)
+                 type    (.getInt16 dview (+ offset 0))
+                 command (case type
+                           1 :move-to
+                           2 :line-to
+                           3 :curve-to
+                           4 :close-path)
+                 params  (case type
+                           1 {:x (.getFloat32 dview (+ offset 20))
+                              :y (.getFloat32 dview (+ offset 24))}
+                           2 {:x (.getFloat32 dview (+ offset 20))
+                              :y (.getFloat32 dview (+ offset 24))}
+                           3 {:c1x (.getFloat32 dview (+ offset 4))
+                              :c1y (.getFloat32 dview (+ offset 8))
+                              :c2x (.getFloat32 dview (+ offset 12))
+                              :c2y (.getFloat32 dview (+ offset 16))
+                              :x   (.getFloat32 dview (+ offset 20))
+                              :y   (.getFloat32 dview (+ offset 24))}
+                           4 {})]
+             (recur (inc index)
+                    (conj result {:command command
+                                  :params params})))
+           result)))))
diff --git a/frontend/src/app/render_wasm/shape.cljs b/frontend/src/app/render_wasm/shape.cljs
index 39d5557a9..5082fbf3d 100644
--- a/frontend/src/app/render_wasm/shape.cljs
+++ b/frontend/src/app/render_wasm/shape.cljs
@@ -8,6 +8,7 @@
   (:require
    [app.common.transit :as t]
    [app.common.types.shape :as shape]
+   ;; [app.common.svg.path :as path]
    [app.render-wasm.api :as api]
    [clojure.core :as c]
    [cuerdas.core :as str]))