[Qt] Make tiled backing store more configurable

[Antti Koivisto]

Make tile size, tile creation delay and tiling area dynamically configurable.

[Antti Koivisto]

Created attachment 57321 [details]
trivial webcore patch and qt api using dynamic properties

[WebKit Review Bot]

Attachment 57321 [details] did not pass style-queue:

Failed to run "['WebKitTools/Scripts/check-webkit-style', '--no-squash']" exit_code: 1
WARNING: File exempt from style guide. Skipping: "WebKit/qt/Api/qwebpage.cpp"
WebCore/platform/graphics/TiledBackingStore.h:62:  Place brace on its own line for function definitions.  [whitespace/braces] [4]
Total errors found: 1 in 5 files


If any of these errors are false positives, please file a bug against check-webkit-style.

[Viatcheslav Ostapenko]

Cool!
I like it! I need it!

[Antti Koivisto]

http://trac.webkit.org/changeset/60350

[WebKit Review Bot]

http://trac.webkit.org/changeset/60350 might have broken Qt Linux Release minimal

[Antti Koivisto]

..and http://trac.webkit.org/changeset/60352

[Simon Hausmann]

<cherry-pick-for-backport: r60350>

[Simon Hausmann]

<cherry-pick-for-backport: r60352>

[Simon Hausmann]

Revision r60350 cherry-picked into qtwebkit-2.0 with commit a65262d9e153242fcbe8b95a69d6b260abcf0eed
Revision r60352 cherry-picked into qtwebkit-2.0 with commit b9be716cfede8047581969927fc49736fddf4414

[Antti Koivisto]

To configure the backing store, do something along the lines of

webView->page()->setProperty("_q_TiledBackingStoreTileSize", QSize(256, 256));
webView->page()->setProperty("_q_TiledBackingStoreTileCreationDelay", 25);
webView->page()->setProperty("_q_TiledBackingStoreCoverAreaMultiplier", QSizeF(1.5, 1.5));
webView->page()->setProperty("_q_TiledBackingStoreKeepAreaMultiplier", QSizeF(2., 2.5));

for a page. 

The settings above would set tile size to (256, 256) and add 25ms delay between constructing individual tiles. The settings would try to cache an area 1.5x width and 1.5x height of the current viewport (centered to the viewport) with tiles and would drop tiles after they are outside an area 2x the width and 2.5x the height of the viewport.

[Kenneth Rohde Christiansen]

should we document our private api on the wiki?