NPP_DrawImage NPAPI proposal.

Antoine Labour piman at google.com
Thu Apr 8 13:23:39 PDT 2010


On Thu, Apr 8, 2010 at 12:27 PM, Oleg Romashin <romaxa at gmail.com> wrote:

> Hi,
>
> On https://wiki.mozilla.org/Plugins:NPP_DrawImageNPAPI
> I'm proposing new NPP_DrawImage  API,  which some sort of improved version
> for NPImageExpose
>
> Can we get it as part of official NPAPI ?
>
> Here is the bug with this API implementation, non-IPC + IPC parts:
> https://bugzilla.mozilla.org/show_bug.cgi?id=554270
>
> Br, Oleg
>

A few comments, that I think should be addressed before making this an
official component of the spec.
- how does a plugin opt-in to this new drawing model ?
- who decides the pixel format ? Is it negotiated (how?) between the plugin
and the browser, or is just the browser's choice and the plugin needs to
support everything the browser throws at it ?
- x,y,width,height: in which coordinates are they (page, window, plugin) ?
- translateX, translateY, scaleX, scaleY: what do they mean ?
- data: where does byte 0 point to ? (0,0) in the page coordinates ? (0,0)
in the window coordinates ? (0,0) in the plugin coordinates ? (0,0) in the
clip rect coordinates ?
- is alpha premultiplied or not ?
- the usage sample suggests that the underlying pixels already exists in
data when this function gets called, and that the plugin is responsible for
doing the compositing itself. While this is similar to the existing drawing
model, we found it to be a major performance bottleneck with out-of-process
plugins because it means the page painting and the plugin painting need to
be synchronized.

Another point: significant work has already been invested into the platform
independent NPAPI to redefine 2D drawing into something that works better
for untrusted and OOP plugins, and that work is supported by 2 browser
vendors and 1 major plugin vendor (see
https://wiki.mozilla.org/Plugins:PlatformIndependentNPAPI#2D_Rendering ), so
I would suggest bringing your thoughts into the design there, rather than
bringing a 3rd drawing model to the table.

Antoine




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