feat: improve map and upload experience

src/lib/canvas.ts

@@ -0,0 +1,37 @@
+const PATCH_FLAG = '__openCloudWillReadFrequentlyPatched__'
+
+type CanvasLikePrototype = {
+  getContext?: (contextId: string, options?: unknown) => unknown
+  [PATCH_FLAG]?: boolean
+}
+
+function patch2DContextOptions(ctor: typeof HTMLCanvasElement | typeof OffscreenCanvas | undefined) {
+  const prototype = ctor?.prototype as CanvasLikePrototype | undefined
+  if (!prototype?.getContext || prototype[PATCH_FLAG]) return
+
+  const originalGetContext = prototype.getContext
+
+  prototype.getContext = function getContextWithReadHint(contextId: string, options?: unknown) {
+    if (contextId === '2d') {
+      const nextOptions =
+        options && typeof options === 'object'
+          ? { ...options as Record<string, unknown>, willReadFrequently: true }
+          : { willReadFrequently: true }
+
+      return originalGetContext.call(this, contextId, nextOptions)
+    }
+
+    return originalGetContext.call(this, contextId, options)
+  }
+
+  prototype[PATCH_FLAG] = true
+}
+
+export function enableCanvasReadbackHint() {
+  if (typeof window === 'undefined') return
+
+  patch2DContextOptions(window.HTMLCanvasElement)
+  if (typeof window.OffscreenCanvas !== 'undefined') {
+    patch2DContextOptions(window.OffscreenCanvas)
+  }
+}