W3C home > Mailing lists > Public > public-html@w3.org > February 2013

Re: Adding the imageSmoothingEnabled back into 2dContext Level 2 spec.

From: Rik Cabanier <cabanier@gmail.com>
Date: Fri, 8 Feb 2013 23:25:24 +1100
Message-ID: <CAGN7qDAf_tBWfhD=EogOpQ_TrZzCkSNk0ijY+FfMa-N7XP+L0w@mail.gmail.com>
To: Jay Munro <jaymunro@microsoft.com>
Cc: "public-html@w3.org" <public-html@w3.org>, "public-canvas-api@w3.org" <public-canvas-api@w3.org>, whatwg@whatwg.org
I agree we should bring it back.

Personally, it would be nice that have a more formal definition of what
smoothing actually means so user agents can implement it similarly.

Rik

On Tue, Feb 5, 2013 at 7:14 AM, Jay Munro <jaymunro@microsoft.com> wrote:

> For CR, we took the imageSmoothingEnable feature out because it hadn't
> been given a chance to be discussed by the working group. For level 2, I'm
> adding it back in, but asking for any discussion that needs to be made
> first.
>
> Silence will be taken to mean there is no objection, but positive
> responses are encouraged.  If I don't hear any objections by Monday Feb 11,
> I'll check it in.
>
> The following is the pending check in:
>
>
> @@ -40677,6 +40677,10 @@ dictionary <dfn>TrackEventInit</dfn> :
> <span>EventInit</span> {
>    // compositing
>             attribute unrestricted double <span
> title="dom-context-2d-globalAlpha">globalAlpha</span>; // (default 1.0)
>             attribute DOMString <span
> title="dom-context-2d-globalCompositeOperation">globalCompositeOperation</span>;
> // (default source-over)
> +
> +  // image smoothing
> +           attribute boolean <span
> title="dom-context-2d-imageSmoothingEnabled">imageSmoothingEnabled</span>;
> // (default true)
> +
>  <!--
>    // v7 we've also received requests for:
>    - turning off antialiasing to avoid seams when patterns are painted
> next to each other
> @@ -40945,7 +40949,8 @@ interface <dfn>Path</dfn> {
>
> title="dom-context-2d-globalCompositeOperation">globalCompositeOperation</code>,
> <code
>     title="dom-context-2d-font">font</code>, <code
>     title="dom-context-2d-textAlign">textAlign</code>, <code
> -   title="dom-context-2d-textBaseline">textBaseline</code>.</li>
> +   title="dom-context-2d-textBaseline">textBaseline</code>, <code
> +
> title="dom-context-2d-imageSmoothingEnabled">imageSmoothingEnabled</code>.</li>
>    </ul>
>
>    <p class="note">The <span>current default path</span> and the
> @@ -43416,10 +43421,16 @@ try {
>
>    <p>If the original image data is a bitmap image, the value painted
>    at a point in the area of the repetitions is computed by filtering
> -  the original image data. The user agent may use any filtering
> +  the original image data. If the <code
> +
>  title="dom-context-2d-imageSmoothingEnabled">imageSmoothingEnabled</code>
> +  then the user agent may use any filtering
>    algorithm (for example bilinear interpolation or nearest-neighbor).
> -  When the filtering algorithm requires a pixel value from outside the
> -  original image data, it must instead use the value from wrapping the
> +  If the <code
> +
>  title="dom-context-2d-imageSmoothingEnabled">imageSmoothingEnabled</code>
> +  attribute is set to false, the image must be rendered using
> +  nearest-neighbor interpolation. When such the filtering algorithm
> +  requires a pixel value from outside the original image data, it
> +  must instead use the value from wrapping the
>    pixel's coordinates to the original image's dimensions. (That is,
>    the filter uses 'repeat' behavior, regardless of the value of
>    <var title="">repetition</var>.)
> @@ -44539,6 +44550,18 @@ v6DVT (also check for '- -' bits in the part
> above) -->
>    <p class="note">This specification does not define the algorithm to
>    use when scaling the image, if necessary.</p>
>
> +  <p>If the <code
> +
>  title="dom-context-2d-imageSmoothingEnabled">imageSmoothingEnabled</code>
> +  attribute is set to true, then the user agent should attempt to
> +  apply a smoothing algorithm to the image data when it is scaled.
> +  Otherwise, the image must be rendered using nearest-neighbor
> +  interpolation.</p>
> +
> +  <p class="note">This specification does not define the precise
> +  algorithm to use when scaling an image when the <code
> +
>  title="dom-context-2d-imageSmoothingEnabled">imageSmoothingEnabled</code>
> +  attribute is set to true.</p>
> +
>    <p class="note">When a canvas is drawn onto itself, the <span>drawing
>    model</span> requires the source to be copied before the image is drawn
>    back onto the canvas, so it is possible to copy parts of a canvas
> @@ -46040,6 +46063,36 @@ function AddCloud(data, x, y) { ... }</pre>
>
>    </div>
>
> +  <h6>Image smoothing</h6>
> +
> +  <dl class="domintro">
> +
> +   <dt><var title="">context</var> . <code
> title="dom-context-2d-imageSmoothingEnabled">imageSmoothingEnabled</code> [
> = <var title="">value</var> ]</dt>
> +
> +   <dd>
> +
> +    <p>Returns whether pattern fills and the <code
> +    title="dom-context-2d-drawImage">drawImage()</code> method will
> +    attempt to smooth images if they have to rescale them (as opposed
> +    to just rendering the images with "big pixels").</p>
> +
> +    <p>Can be set, to change whether images are smoothed (true) or not
> +    (false).</p>
> +
> +   </dd>
> +
> +  </dl>
> +
> +  <div class="impl">
> +
> +  <p>The <dfn
> +
>  title="dom-context-2d-imageSmoothingEnabled"><code>imageSmoothingEnabled</code></dfn>
> +  attribute, on getting, must return the last value it was set to. On
> +  setting, it must be set to the new value. When the
> +  <code>CanvasRenderingContext2D</code> object is created, the
> +  attribute must be set to true.</p>
> +
> +  </div>
>
>
>
>
>
>
>
Received on Friday, 8 February 2013 12:25:51 UTC

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