fix shortname

Author: tabatkins

compositing-2/Overview.bs

@@ -1,14 +1,14 @@
-<h1>Compositing and Blending Level 2</h1>
 <pre class='metadata'>
+Title: Compositing and Blending Level 2
+Group: fxtf
 Status: ED
 ED: https://drafts.fxtf.org/compositing-2/
 TR: https://www.w3.org/TR/compositing-2/
-Previous Version: 
-Shortname: compositing level 2
+Previous Version:
+Shortname: compositing
+Level: 2
 Link Defaults: css-color-3 (property) color, svg (property) mask
 Deadline: 2014-08-17
-Level: 2
-Group: fxtf
 Editor: Rik Cabanier, Adobe Systems Inc., cabanier@adobe.com
 Editor: Nikos Andronikos, Canon Information Systems Research Australia, Nikos.Andronikos@cisra.canon.com.au
 Abstract: Compositing describes how shapes of different elements are combined into a single image. There are various possible approaches for compositing. Previous versions of SVG and CSS used <a href="https://www.w3.org/TR/SVG11/masking.html#SimpleAlphaBlending">Simple Alpha Compositing</a>. In this model, each element is rendered into its own buffer and is then merged with its <a>backdrop</a> using the Porter Duff ''source-over'' operator. This specification will define a new compositing model that expands upon the Simple Alpha Compositing model by offering:
@@ -64,7 +64,7 @@ all properties defined in this specification also accept the <a
 href="https://www.w3.org/TR/CSS21/cascade.html#value-def-inherit">inherit</a>
 keyword as their property value. For readability it has not been repeated
 explicitly.
-   
+
 <h2 id="csscompositingandblending">Specifying Blending in CSS </h2>
 <h3 id="compositingandblendingorder">Order of graphical operations</h3>
 
@@ -117,7 +117,7 @@ Animatable: no
 The syntax of the property of <<blend-mode>> is given with:
 
 <pre class="blendmode"><dfn id="ltblendmodegt">&lt;blend-mode></dfn> = <a value>normal</a> | <a value>multiply</a> | <a value>screen</a> | <a value>overlay</a> | <a value>darken</a> | <a value>lighten</a> | <a value>color-dodge</a> |
-  <a value>color-burn</a> | <a value>hard-light</a> | <a value>soft-light</a> | <a value>difference</a> | <a value>exclusion</a> | <a value>hue</a> | 
+  <a value>color-burn</a> | <a value>hard-light</a> | <a value>soft-light</a> | <a value>difference</a> | <a value>exclusion</a> | <a value>hue</a> |
   <a value>saturation</a> | <a value>color</a> | <a value>luminosity</a></pre>
 
 Note: Applying a blendmode other than <a value>normal</a> to the element must establish a new <a spec="css21">stacking context</a> [[!CSS21]]. This group must then be blended and composited with the <a spec="css21">stacking context</a> that contains the element.
@@ -226,7 +226,7 @@ div { background-image: url('texture.png'); }
 }
 p {
   mix-blend-mode: overlay;
-  font-family: "Mythos Std" 
+  font-family: "Mythos Std"
 }
 </pre>
 
@@ -301,7 +301,7 @@ property for that element must be reset to its initial value.
 <p>And the following style rule:</p>
 <pre>
 body { background-color: lime; }
-div { 
+div {
   width: 200px;
   height: 200px;
   background-size: 200px 200px;
@@ -362,7 +362,7 @@ Where the graphic element is opaque, it obscures the backdrop and where the grap
 -->
 
 In the model described in this specification there are two steps to the overall compositing operation - <a href="#advancedcompositing">Porter-Duff compositing</a> and <a href="#blending">blending</a>.
-<!--Porter Duff compositing takes into account the overall shape of the graphic element and its opacity, as well as the opacity and shape of the backdrop, and 
+<!--Porter Duff compositing takes into account the overall shape of the graphic element and its opacity, as well as the opacity and shape of the backdrop, and
 determines where the backdrop is visible, where the graphic element is visible and where one is visible through the other.-->
 The blending step determines how the colors from the graphic element and the backdrop interact.
 
@@ -384,7 +384,7 @@ The formula for simple alpha compositing is
 co = Cs x αs + Cb x αb x (1 - αs)
 </pre>
 
-Where 
+Where
 
 <ul>
 <li>co: the premultiplied pixel value after compositing
@@ -399,10 +399,10 @@ Note: All values are between 0 and 1 inclusive.
 The pixel value after compositing (co) is given by adding the contributions from the source graphic element [Cs x αs] and the backdrop [Cb x αb x (1 - αs)].
 For both the graphic element and the backdrop, the color values are multiplied by the alpha to determine the amount of color that contributes.
 With zero alpha meaning that the color does not contribute and partial alpha means that some percentage of the color contributes.
-The contribution of the backdrop is further reduced based on the opacity of the graphic element. 
+The contribution of the backdrop is further reduced based on the opacity of the graphic element.
 Conceptually, (1 - αs) of the backdrop shows through the graphic element, meaning that if the graphic element is fully opaque (αs=1) then no backdrop shows through.
 
-The simple alpha compositing formula listed above gives a resultant color which is the result of the 
+The simple alpha compositing formula listed above gives a resultant color which is the result of the
 weighted average of the backdrop color and graphic element color, with the weighting determined by the backdrop and
 graphic element alphas.
 The resultant alpha value of the composite is simply the sum of the contributed alpha of the composited elements.
@@ -412,7 +412,7 @@ The formula for the resultant alpha of the composite is
 αo = αs + αb x (1 - αs)
 </pre>
 
-Where 
+Where
 
 <ul>
 <li>αo: the alpha value of the composite
@@ -428,7 +428,7 @@ The pre-multiplied value is given by
 <pre>
 cs = Cs x αs
 </pre>
-with 
+with
 <ul>
 <li>cs: the pre-multiplied value
 <li>Cs: the color value
@@ -769,7 +769,7 @@ The area of each region can be calculated with the following equations:
 The figure above represents coverage of 0.5 for both source and destination.
 
 <pre>
-Both = 0.5 x 0.5 = 0.25 
+Both = 0.5 x 0.5 = 0.25
 Source Only = 0.5 (1 – 0.5) = 0.25
 Destination Only = 0.5(1 – 0.5) = 0.25
 None = (1 – 0.5)(1 – 0.5) = 0.25
@@ -900,7 +900,7 @@ Destination which overlaps the source, replaces the source.
 </div>
 <pre>
     Fa = 0; Fb = αs
-    co = αb x Cb x αs 
+    co = αb x Cb x αs
     αo = αb x αs
 </pre>
 
@@ -1001,8 +1001,8 @@ Display the sum of the source image and destination image. It is defined in the
 <!--<h4 id="groupcompositingisolation">Isolated groups and Porter Duff modes</h4>-->
 
 When compositing the elements within an isolated group, the elements are composited over a transparent black initial backdrop. If the bottom element in the group uses a Porter Duff compositing operator
-which is dependent on the backdrop, such as <a href="#porterduffcompositingoperators_dst">destination</a>, <a href="#porterduffcompositingoperators_srcin">source-in</a>, 
-<a href="#porterduffcompositingoperators_dstin">destination-in</a>, <a href="#porterduffcompositingoperators_dstout">destination-out</a> or <a href="#porterduffcompositingoperators_srcatop">source-atop</a>, 
+which is dependent on the backdrop, such as <a href="#porterduffcompositingoperators_dst">destination</a>, <a href="#porterduffcompositingoperators_srcin">source-in</a>,
+<a href="#porterduffcompositingoperators_dstin">destination-in</a>, <a href="#porterduffcompositingoperators_dstout">destination-out</a> or <a href="#porterduffcompositingoperators_srcatop">source-atop</a>,
 then the result of the composite will be empty. Subsequent elements within the group are composited with the result of the first composite.
 
 <!--
@@ -1116,7 +1116,7 @@ This is the default attribute which specifies no blending. The blending formula
 
 <h4 id="blendingmultiply"><dfn dfn-type="value" dfn-for="<blend-mode>">multiply</dfn> blend mode</h4>
 
-The source color is multiplied by the destination color and replaces the destination. 
+The source color is multiplied by the destination color and replaces the destination.
 
 The resultant color is always at least as dark as either the source or destination color. Multiplying any color with black results in black. Multiplying any color with white preserves the original color.
 
@@ -1237,7 +1237,7 @@ Multiplies or screens the colors, depending on the source color value. The effec
     if(Cs <= 0.5)
         B(Cb, Cs) = Multiply(Cb, 2 x Cs)
     else
-        B(Cb, Cs) = Screen(Cb, 2 x Cs -1)	
+        B(Cb, Cs) = Screen(Cb, 2 x Cs -1)
 </pre>
 
 See the definition of <a value>multiply</a> and <a value>screen</a> for their formulas.
@@ -1311,28 +1311,28 @@ The nonseparable blend mode formulas make use of several auxiliary functions:
 
 <pre>
     Lum(C) = 0.3 x Cred + 0.59 x Cgreen + 0.11 x Cblue
-    
+
     ClipColor(C)
         L = Lum(C)
         n = min(Cred, Cgreen, Cblue)
         x = max(Cred, Cgreen, Cblue)
         if(n < 0)
             C = L + (((C - L) * L) / (L - n))
-                      
+
         if(x > 1)
             C = L + (((C - L) * (1 - L)) / (x - L))
-        
+
         return C
-    
+
     SetLum(C, l)
         d = l - Lum(C)
         Cred = Cred + d
         Cgreen = Cgreen + d
         Cblue = Cblue + d
         return ClipColor(C)
-        
+
     Sat(C) = max(Cred, Cgreen, Cblue) - min(Cred, Cgreen, Cblue)
-        
+
 The subscripts min, mid, and max in the next function refer to the color
 components having the minimum, middle, and maximum values upon entry to the function.
 
@@ -1422,8 +1422,8 @@ If this rule is not followed, an attacker could infer information and mount a ti
 <p>A timing attack is a method of obtaining information about content that
    is otherwise protected, based on studying the amount of time it takes for
    an operation to occur. If, for example, red pixels took longer to
-   draw than green pixels, one might be able to reconstruct a rough image of 
-   the element being rendered, without ever having access to the content 
+   draw than green pixels, one might be able to reconstruct a rough image of
+   the element being rendered, without ever having access to the content
    of the element.</p>
 </div>
 
@@ -1459,11 +1459,11 @@ Working draft of 10 October 2013</a>:
 The following changes were made relative to the <a
 href="https://www.w3.org/TR/2013/WD-compositing-1-20130625/" >Working
 Draft of 2013-06-25</a>:
- 
+
  <ul>
- <li>clipping was removed as one of the operators that 
+ <li>clipping was removed as one of the operators that
  creates an isolated group in SVG
- <li>background-blend-mode was changed so it matches 
+ <li>background-blend-mode was changed so it matches
  repeating behavior of other background syntaxes.
  <li>The mix-composite property was removed
  <li>all open issues were resolved