[whatwg] new ImageData(w, h) proposal

Mathieu HENRI p01 at opera.com
Mon Mar 5 05:30:05 PST 2007


The ImageData [1] object used in Canvas should be instantiable like
HTMLImageElement are using the Image constructor [2,3]. I suggest to:

* Mention the ImageData constructor in [1]:

     Note: An instance of ImageData can be obtained using the ImageData

* Specify the ImageData constructor should go in Pixel
manipulation [4]:

     ImageData(in unsigned long w, in unsigned long h)

     Constructs an ImageData object. The new object's width and height
attributes must be set to respectively w and h. The new object's data is
set to transparent black, that is w*h*4 integers set to 0.

     If either w or h are non-positive an INDEX_SIZE_ERR exception must 
be raised.

This way developers will be able to create ImageData without using an
intermediary Canvas. The security model depicted at the end of [5]
applies and will prevent privacy and security issues.

Any objections or remarks ?


[1] http://www.whatwg.org/specs/web-apps/current-work/#imagedata
[2] http://www.whatwg.org/specs/web-apps/current-work/#htmlimageelement
[3] http://www.whatwg.org/specs/web-apps/current-work/#image0
[4] http://www.whatwg.org/specs/web-apps/current-work/#pixel
[5] http://www.whatwg.org/specs/web-apps/current-work/#the-canvas

Mathieu 'p01' HENRI
JavaScript developer, Opera Software ASA

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