[whatwg] Adding features needed for WebGL to ImageBitmap

Justin Novosad junov at google.com
Thu Jul 18 11:00:52 PDT 2013

To help us iterate further, I've attempted to capture the essence of this
thread on the whatwg wiki, using the problem solving template.
I tried to capture the main ideas that we seem to agree on so far and I
started to think about how to handle special cases.



On Thu, Jul 18, 2013 at 1:22 PM, Justin Novosad <junov at google.com> wrote:

> On Thu, Jul 18, 2013 at 5:45 AM, Mark Callow <callow.mark at artspark.co.jp>wrote:
>> On 2013/07/18 16:34, K. Gadd wrote:
>> >
>> > I understand the rationale behind gregg's suggestion for flipY, but
>> > ultimately don't know if that one makes any sense in a HTML5 context. It
>> > basically only exists because of the annoying disagreement between APIs
>> > like OpenGL and other APIs like HTML5 Canvas or Direct3D, specifically
>> > about which direction the Y axis goes.
>> It exists because of the annoying disagreement between the orientation
>> of the data in most image file formats and the default orientation for
>> textures images in OpenGL. There are a some image file formats that have
>> a bottom left orientation and there is one, extremely common, format,
>> EXIF, that includes metadata giving the visual orientation of the image.
>> The flipY item in the proposed dictionary could be handily extended to
>> an enum. E.g.,
>>   * "none" - leave orientation alone
>>   * "flipY" - ignore the EXIF orientation, just flip in Y
>>   * "topLeftEXIF" - identify visual orientation from EXIF data and
>>     re-order data so top-down, left-to-right processing for display
>>     results in correct visual orientation
>>   * "bottomRightEXIF" - as above but ordered for bottom-up,
>>     left-to-right processing
>> Regards
>>     -Mark
> EXIF, may be a defacto standard in some image formats we use today, but I
> think we should probably be more general and just refer to this as image
> media meta-data.  What should the default be? I hesitate between 'topLeft'
> and 'none'.

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