436254 - Lens implementation based on canvas works not smooth enough on N810

Status: RESOLVED WONTFIX

(Core :: Graphics: Canvas2D, defect)

Description

[Oleg Romashin (:romaxa)]

I have some implementation of "movable lens" based on <canvas> for N810.

But it works not very fast and smooth,
and performance is very different for different content on the page.

I think it should be possible to optimize canvas/RenderDocument for smooth redrawing of scaled parts of page on each mousemove event.

Comment 1

[Oleg Romashin (:romaxa)]

Attachment: canvas playground extension

c++ extension example.

Canvas "lens" rectangle appears on mouseclick event.
Each mousemove event will move canvas rect to new position and redraw canvas window.

Comment 2

[Oleg Romashin (:romaxa)]

Attachment: plain text extension version (for fast reading)

Comment 3

[Oleg Romashin (:romaxa)]

Attachment: plain profile for simple image scaling

Profile data with lens moving on big image page:
http://www.gnu.org/graphics/o_espirito_da_liberdade.fondo.big.png

Comment 4

[Oleg Romashin (:romaxa)]

Attachment: plain profile for lens on text page

Profile data from text page:
'data:text/html,<h1>212klsdfjklasjdklajdlkasjdlashdio22131231231231231231231231233</h1>(repeat)'

Comment 5

[Oleg Romashin (:romaxa)]

Also while it moving there are ASSERTION in debug build:
........
###!!! ASSERTION: cannot call GetUsedBorder on a dirty frame not currently being reflowed: 'nsLayoutUtils::sDisableGetUsedXAssertions || !NS_SUBTREE_DIRTY(this) || (GetStateBits() & NS_FRAME_IN_REFLOW)', file mozilla/layout/generic/nsFrame.cpp, line 560
...........

Comment 6

[Oleg Romashin (:romaxa)]

Also attached sources is buggy:

This need to be changed:
-NSIntPixelsToAppUnits(mX+aWidth, nsIDeviceContext::AppUnitsPerCSSPixel()),
-NSIntPixelsToAppUnits(mY+aHeight, nsIDeviceContext::AppUnitsPerCSSPixel()));
+NSIntPixelsToAppUnits(aWidth/2,nsIDeviceContext::AppUnitsPerCSSPixel()),
+NSIntPixelsToAppUnits(aHeight/2, nsIDeviceContext::AppUnitsPerCSSPixel()));

Comment 7

[Oleg Romashin (:romaxa)]

Oh, still one problem

-gfxASurface *surface = nsnull;
-cx->GetThebesSurface(&surface);
-nsRefPtr<gfxContext> ctx = new gfxContext(surface);
+nsRefPtr<gfxASurface> surface;
+cx->GetThebesSurface(getter_AddRefs(surface));

Comment 8

[Benoit Girard (:BenWa)]

This bug hasn't been touched in 3 years. Can we close it romaxa?