Bug 69739 – Loss of precision when converting from double to int and double to float in FrameView::zoomAnimatorTransformChanged()

• Component: Tools / Tests
• Status: RESOLVED FIXED

[Daniel Bates]

Bug #68035 (http://trac.webkit.org/changeset/97034) added the method FrameView::zoomAnimatorTransformChanged() which implicitly converts a double precision computation (64-bit) to an integer result (32-bit) and hence causes a warning on the Leopard Intel Debug bot:

[[
cc1plus: warnings being treated as errors
/Volumes/Big/WebKit-BuildSlave/leopard-intel-debug/build/Source/WebCore/page/FrameView.cpp: In member function 'virtual void WebCore::FrameView::zoomAnimatorTransformChanged(double, double, double, WebCore::ScrollableArea::ZoomAnimationState)':
/Volumes/Big/WebKit-BuildSlave/leopard-intel-debug/build/Source/WebCore/page/FrameView.cpp:1230: warning: implicit conversion shortens 64-bit value into a 32-bit value
/Volumes/Big/WebKit-BuildSlave/leopard-intel-debug/build/Source/WebCore/page/FrameView.cpp:1230: warning: implicit conversion shortens 64-bit value into a 32-bit value
/Volumes/Big/WebKit-BuildSlave/leopard-intel-debug/build/Source/WebCore/page/FrameView.cpp:1230: warning: implicit conversion shortens 64-bit value into a 32-bit value
]]
(http://build.webkit.org/builders/Leopard%20Intel%20Debug%20%28Build%29/builds/40404/steps/compile-webkit/logs/stdio)

[Daniel Bates]

I am unsure what's the best way to fix this issue at this time. For now, I explicitly converted the double precision results to an integers and landed this in <http://trac.webkit.org/changeset/97041>. We need to look into this some more.

[Daniel Bates]

Explicitly converted double precision result to single precision result and committed fix in <http://trac.webkit.org/changeset/97042>

[Daniel Bates]

From reading the patch (attachment #110142 [details]) the only caller of zoomAnimatorTransformChanged() passes floats for the arguments. So, it seems sufficient to modify the prototype of zoomAnimatorTransformChanged() to take floats instead of doubles. Then we can remove these casts. Is there a reason that zoomAnimatorTransformChanged() takes doubles?

[Simon Fraser (smfr)]

Who added it?

[W. James MacLean]

Created attachment 110504 [details]
Patch

[W. James MacLean]

(In reply to comment #4)
> Who added it?

I did. I have uploaded a patch to amend this.

[W. James MacLean]

Created attachment 110505 [details]
Patch

[W. James MacLean]

Revised to include BuiltInPDFView.h in WebKit2.

[Simon Fraser (smfr)]

Comment on attachment 110505 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=110505&action=review

> Source/WebCore/ChangeLog:8
> +        Reviewed by NOBODY (OOPS!).
> +
> +        Test coverage provided by existing zoom-animator tests.

Please say what the patch does here.

[W. James MacLean]

Created attachment 110518 [details]
Patch

[W. James MacLean]

(In reply to comment #10)
> Created an attachment (id=110518) [details]
> Patch

Revised changelog comments as per your suggestion ... let me know if they look OK.(In reply to comment #9)
> (From update of attachment 110505 [details])
> View in context: https://bugs.webkit.org/attachment.cgi?id=110505&action=review
> 
> > Source/WebCore/ChangeLog:8
> > +        Reviewed by NOBODY (OOPS!).
> > +
> > +        Test coverage provided by existing zoom-animator tests.
> 
> Please say what the patch does here.

Revised changelog comments as per your suggestion ... let me know if they look OK.

[WebKit Review Bot]

Comment on attachment 110518 [details]
Patch

Clearing flags on attachment: 110518

Committed r97188: <http://trac.webkit.org/changeset/97188>

[WebKit Review Bot]

All reviewed patches have been landed.  Closing bug.