[L2Ork-dev] Excalibur Bug

[Jonathan Wilkes]

One addition-- I've tried whittling pd_canvas.html down to nothing but
a single SVG, to no avail.

-Jonathan

On Fri, Jun 12, 2020 at 1:15 AM Jonathan Wilkes <jon.w.wilkes at gmail.com> wrote:
>
> Hi list,
>
> If anyone here can wrest the following bug from the guts of our
> codebase I'll immediately add you as a maintainer of Purr Data.
> (Careful, though-- there's some Tom Sawyer style mischief going on in
> that offer... :)
>
> You start your quest armed with three snippets:
>
> 1. Trusty menu:
>
> // Create an empty menubar
> var menu = new nw.Menu({type: 'menubar'});
>
> // Create a submenu as the 2nd level menu
> var submenu = new nw.Menu();
> submenu.append(new nw.MenuItem({ label: 'Item A' }));
> submenu.append(new nw.MenuItem({ label: 'Item B' }));
>
> // Create and append the 1st level menu to the menubar
> menu.append(new nw.MenuItem({
>   label: 'First Menu',
>   submenu: submenu
> }));
>
> // Assign it to `window.menu` to get the menu displayed
> nw.Window.get().menu = menu;
>
> End trusty menu
>
> 2. SVG-spawning potion
>
> var w = document.documentElement.clientWidth;
> var h = document.documentElement.clientHeight;
> document.body.style.padding = "0px";
> document.body.style.margin = "0px";
> var svg_string = ['<svg width="', w, '" height="', h, '"><rect
> width="20" height="20"/></svg>'].join("");
> document.body.innerHTML = svg_string;
>
> End SVG-spawning potion
>
> 3. Lightning bolt
>
> document.body.innerHTML = '';
>
> End lightning bolt
>
> Ok, let's go:
>
> 1. Run nw directly to get the demo app (~/purr-data/pd/nw/nw/nw)
> 2. Right click and choose "Inspect"
> 3. Click the "Console" tab
> 4. Paste the lightning bolt to erase the demo
> 5. Paste your SVG-spawning potion in the console and hit <Enter>
>
> Notice that the SVG fills the entire viewport of the document
> *without* creating scrollbars. You can click the "Elements" tab and
> make the SVG height/width one pixel larger and that will trigger the
> scrollbars. Change them back and boom-- no scrollbars anymore. Simple,
> deterministic behavior which works exactly the same in any version of
> Chromium.
>
> Next:
>
> 1. Run nw directly to get the demo app
> 2. Right click and choose "Inspect"
> 3. Click the "Console" tab
> 4. Paste the lightning bolt to erase the demo
> 5. Paste the trusty menu
> 6. Paste your SVG-spawning potion in the console
>
> Again-- notice that the viewport is is covered completely by the SVG
> without spawning any scrollbars. Again you can change width/height
> values to watch scrollbars appear/disappear.
>
> Okay, now some fun:
>
> 1. Run nw directly to get the demo app
> 2. Right click and choose "Inspect"
> 3. Click the "Console" tab
> 4. Paste the lightning bolt to erase the demo
> 5. Paste your SVG-spawning potion in the console
> 6. Paste the trusty menu
>
> Ah, now we get some scrollbars because the menu takes up some of our
> viewport and pushes the SVG down.
>
> But fear not-- we can go to the console and do this to get the new
> height of the viewport minus that menubar:
>
> window.innerHeight;
>
> Now type that value into the height for the SVG in the "Elements" tab
> and poof-- scrollbars disappear. Predictable, consistent behavior.
>
> And now, Excalibur:
>
> 1. Run Purr Data
> 2. Open a new Patch
> 3. Click "Help" then "Show DevTools" and click the "Console" tab
> 4. Paste the lightning bolt
> 5. Paste you SVG-spawning potion
>
> Oops, now we have scrollbars.
>
> Same GUI toolkit, but different behavior here.
>
> What is responsible for the difference, and how can we get the
> predictable, consistent behavior we witnessed when running the nw
> demo?
>
> Btw-- I'm on Debian Stretch on an older version of nw.js. But I've
> tested the consistent, predictable behavior in a Chromium browser
> and it works. Browsers obviously know how to fill a cavity with
> content in 2020.
>
> That means that somewhere in our codebase we are setting
> some state that causes the window to shift the content down,
> but I don't know what it could be.
>
> Good luck on your quest,
> Jonathan