drawCanvas enlarges when host is mobile and peer is on PC!?

As can be read in the DrawingCanvas manual article

Handling resizing and resolution

By default, the canvas uses the same display resolution as the game. However the display resolution usually changes when the window is resized. For example in letterbox scale mode, when the window is resized larger the game displays the same content but at a larger size (using more pixels). The Drawing canvas object automatically changes the resolution of its canvas when this happens. This is destructive, though: the next draw to the canvas will clear it, because internally the drawing surface is destroyed and recreated at the new resolution.

The reason it waits until the next draw to recreate the drawing surface is so that if you draw to it once, the same content is simply displayed stretched at the new resolution. This is often an acceptable result after drawing in On start of layout. Normally a better idea is to draw one-off content in the trigger On resolution changed - this also triggers on startup, and again any time the resolution changes, ensuring your content can increase in detail if the window is resized larger.

Alternatively if you clear and re-render the canvas in Every tick, since it is always redrawing it will always draw at the current resolution. This approach is similar to how the runtime itself renders, although you may want to stop drawing if nothing is changing in the game, which is also what the runtime does.

If you run in to a bug or issue in Construct 3, please post it to the GitHub issue tracker here:

github.com/Scirra/Construct-3-bugs

You must follow the bug report guidelines or your issue will be closed without investigation.

I appreciate the response.

So, what I'm hearing is...

Since a pc users window is larger, the fix is to... how do I avoid that unintentional stretch?

it seems to me that the snapshot is being loaded to large