CODEWITHSUNDEEP
javascriptcanvas
mckurt
mckurt

Reputation: 154

Chrome canvas becomes blank after waking up from standby mode

Our application downloads about 15meg of images and displays them in a html canvas. We are doing a bit of stress testing and have found that after we have about 10 tabs open if we put the computer in sleep mode, when it comes back the canvas is blank - it just shows plain white (this doesn't happen every time, but very frequently).

We hold the images in JavaScript Image objects, and I have inspected the memory in those and they still appear to be valid. I've tried to use the Chrome memory analysis by taking a snap shot before and after the error occurs, in some cases less memory is being used, in other cases more, so that didn't seem to tell me much.

I am curious if anyone has seen this before, and even if not, does anyone have pointers about debugging something similar. It would be perfectly sufficient if there was a way for us to determine if the error had occurred so we could trigger a reload of the images, but I'm afraid until I figure out what is causing it, I won't even know what to try and inspect.

Upvotes: 3

Views: 1685

Answers (2)

user1002346
user1002346

Reputation: 67

There are major canvas issues in Chrome 29.

You may want to check out and star this issue: https://code.google.com/p/chromium/issues/detail?id=280153

(This stress test is failing too and may be related)

Upvotes: 1

mckurt
mckurt

Reputation: 154

@rtpg - the draw loop was continuing to run, but it would not display anything

For some reason the canvas would no longer update. I was unable to determine when the problem occurred but did figure out how to get the canvas to start displaying the images again. It was required that I resize the canvas (I change the width by one pixel) and then redraw (it's embarrassingly hackish). I current have it set to run every 30 seconds through setTimeout, but will probably change to window.onfocus once I can verify that gets called when coming out of sleep mode.

Upvotes: 2

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