Render a saved whiteboard document to a small WebP blob.
Draws the active background page (if any) beneath the salvaged canvas
objects at their logical coordinates, then scales the result so its
longest edge is at most maxDimension pixels.
Returns undefined when the document has nothing to draw (no objects and
no background) or when rendering fails — absence of a thumbnail is not an
error condition.
Render a saved whiteboard document to a small WebP blob.
Draws the active background page (if any) beneath the salvaged canvas objects at their logical coordinates, then scales the result so its longest edge is at most
maxDimensionpixels.Returns
undefinedwhen the document has nothing to draw (no objects and no background) or when rendering fails — absence of a thumbnail is not an error condition.