Clear_output: Animation & widget related changes.

[jdfreder]

• No more delay when calling clear_output
• Removed ability to clear stderr and stdout individually.
• Output div height is unmodified
• New wait flag prevents clear_output from being executed until new output is available

Animation flickering also mentioned in #1563

Some of the behaviors that were unwanted can be seen in this YouTube video.

[minrk]

review from dev meeting: remove the height-fixing when wait=False

[jdfreder]

remove the height-fixing when wait=False

Thanks, changes made ^

[ellisonbg]

The code looks great, but can you update our example notebook that shows how to use this stuff:

https://github.com/ipython/ipython/blob/master/examples/notebooks/Animations%20Using%20clear_output.ipynb

[jdfreder]

@ellisonbg thanks, changes made ^

[ellisonbg]

A few other places where we should probably use wait=True:

./IPython/parallel/client/asyncresult.py:
   26 : from IPython.core.display import clear_output, display, display_pretty
  394 :             clear_output()

./examples/parallel/InteractiveMPI-publish-data.ipynb:
  237 :       "from IPython.display import display, clear_output\n",
  248 :       "        By default it calls clear_output so that new plots replace old ones.  Set\n",
  274 :       "            clear_output()\n",
  336 :       "        clear_output()\n",

./examples/parallel/InteractiveMPI.ipynb:
  252 :       "from IPython.display import clear_output\n",
  261 :       "        By default it calls clear_output so that new plots replace old ones.  Set\n",
  284 :       "        clear_output()\n",
  380 :       "        clear_output()\n",

You will need MPI to run those last two notebooks - don't worry about that - just update the code.

[ellisonbg]

This PR should also add an entry in the what's new in /docs/source/whatsnew.

[jdfreder]

@ellisonbg thanks, changes made again ^

[ellisonbg]

put wait in double backticks here.

[jdfreder]

Thanks @ellisonbg , changes made

[ellisonbg]

OK everything is done, merging.

[minrk]

is this auto height the right behavior, or was that a remnant from the previous implementation?

[jdfreder]

It still measures/sets the height if wait=True, this line is supposed to reset that. So yes & yes.

If parsing javascript threadlocks the browser's render function, this is pointless since it wont redraw in between clear_output and the append operation. Do you have insight to whether or not this is the case?

[Carreau]

Ahhhhhhhh !!!!!

this.element.height('auto');

I cannot have output that scroll now.... the scoll area cannot be smaller than the output anymooooooooooore

run

for i in range(1000):
    print i

and now... suffer !

[jdfreder]

I cannot have output that scroll now....

Shoot, that's a problem... If I put a conditional around the auto-height that should be enough to fix the problem. I doubt you want scrolling output for rapid animations, right?