Rounding error in HiDPI canvas.

Rounding error in HiDPI canvas.

Rounding is not appropriate if the scaling factor is not an integer.
(And if it is an integer, it's not necessary.)

BUG=149881
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=208331

[girard, 2013-06-21 00:19:58]

Rounding errors caused the omnibox to quiver as it was repeatedly rendered.

[Ben Goodger (Google), 2013-06-24 17:04:29]

lgtm


On Thu, Jun 20, 2013 at 5:19 PM, <girard@chromium.org> wrote:

> Reviewers: Ben Goodger (Google),
>
> Message:
> Rounding errors caused the omnibox to quiver as it was repeatedly rendered.
>
> Description:
> Rounding error in HiDPI canvas.
>
> Rounding is not appropriate if the scaling factor is not an integer.
> (And if it is an integer, it's not necessary.)
>
> BUG=149881
>
> Please review this at
https://chromiumcodereview.**appspot.com/17505003/<https://chromiumcodereview...
>
> SVN Base:
http://git.chromium.org/**chromium/src.git@master<http://git.chromium.org/chr...
>
> Affected files:
>   M ui/gfx/canvas_paint_win.h
>
>
> Index: ui/gfx/canvas_paint_win.h
> diff --git a/ui/gfx/canvas_paint_win.h b/ui/gfx/canvas_paint_win.h
> index 520bdcc482de1001fe59fa2f17b304**ce56e35679..**
> 613641ad5cd7d65213d397092c858a**e9b3ae8719 100644
> --- a/ui/gfx/canvas_paint_win.h
> +++ b/ui/gfx/canvas_paint_win.h
> @@ -121,8 +121,8 @@ class UI_EXPORT CanvasSkiaPaint : public Canvas {
>      // This will bring the canvas into the screen coordinate system for
> the
>      // dirty rect
>      canvas->translate(
> -        SkScalarRoundToInt(-ps_.**rcPaint.left/ui::win::**
> GetDeviceScaleFactor()),
> -        SkScalarRoundToInt(-ps_.**rcPaint.top/ui::win::**
> GetDeviceScaleFactor()));
> +        -ps_.rcPaint.left/ui::win::**GetDeviceScaleFactor(),
> +        -ps_.rcPaint.top/ui::win::**GetDeviceScaleFactor());
>    }
>
>    // If true, this canvas was created for a BeginPaint.
>
>
>

[commit-bot: I haz the power, 2013-06-24 17:56:21]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/girard@chromium.org/17505003/1

[commit-bot: I haz the power, 2013-06-25 00:56:14]

Change committed as 208331