Make sure buffer is a DataView

jupyterlab_widgets/src/manager.ts

@@ -133,14 +133,7 @@ export abstract class LabWidgetManager extends ManagerBase
             ) {
               const data = msg.content.data as any;
               const buffer_paths = data.buffer_paths || [];
-              // Make sure the buffers are DataViews
-              const buffers = (msg.buffers || []).map(b => {
-                if (b instanceof DataView) {
-                  return b;
-                } else {
-                  return new DataView(b instanceof ArrayBuffer ? b : b.buffer);
-                }
-              });
+              const buffers = msg.buffers || [];
               put_buffers(data.state, buffer_paths, buffers);
               info.resolve({ comm, msg });
             }

packages/base-manager/src/manager-base.ts

@@ -157,14 +157,7 @@ export abstract class ManagerBase implements IWidgetManager {
     }
     const data = (msg.content.data as unknown) as ISerializedState;
     const buffer_paths = data.buffer_paths || [];
-    // Make sure the buffers are DataViews
-    const buffers = (msg.buffers || []).map(b => {
-      if (b instanceof DataView) {
-        return b;
-      } else {
-        return new DataView(b instanceof ArrayBuffer ? b : b.buffer);
-      }
-    });
+    const buffers = msg.buffers || [];
     put_buffers(data.state, buffer_paths, buffers);
     return this.new_model(
       {

packages/base/src/utils.ts

@@ -100,18 +100,30 @@ export function reject(message: string, log: boolean) {
 export function put_buffers(
   state: Dict<BufferJSON>,
   buffer_paths: (string | number)[][],
-  buffers: DataView[]
+  buffers: (
+    | DataView
+    | ArrayBuffer
+    | ArrayBufferView
+    | { buffer: ArrayBuffer }
+  )[]
 ): void {
   for (let i = 0; i < buffer_paths.length; i++) {
     const buffer_path = buffer_paths[i];
-    // say we want to set state[x][y][z] = buffers[i]
+    // make sure the buffers are DataViews
+    let buffer = buffers[i];
+    if (!(buffer instanceof DataView)) {
+      buffer = new DataView(
+        buffer instanceof ArrayBuffer ? buffer : buffer.buffer
+      );
+    }
+    // say we want to set state[x][y][z] = buffer
     let obj = state as any;
     // we first get obj = state[x][y]
     for (let j = 0; j < buffer_path.length - 1; j++) {
       obj = obj[buffer_path[j]];
     }
-    // and then set: obj[z] = buffers[i]
-    obj[buffer_path[buffer_path.length - 1]] = buffers[i];
+    // and then set: obj[z] = buffer
+    obj[buffer_path[buffer_path.length - 1]] = buffer;
   }
 }
 

packages/base/src/widget.ts

@@ -216,15 +216,7 @@ export class WidgetModel extends Backbone.Model {
           .then(() => {
             const state = data.state;
             const buffer_paths = data.buffer_paths || [];
-            // Make sure the buffers are DataViews
-            const buffers = (msg.buffers || []).map(b => {
-              if (b instanceof DataView) {
-                return b;
-              } else {
-                return new DataView(b instanceof ArrayBuffer ? b : b.buffer);
-              }
-            });
-
+            const buffers = msg.buffers || [];
             utils.put_buffers(state, buffer_paths, buffers);
             return (this.constructor as typeof WidgetModel)._deserialize_state(
               state,