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Re: Proposal: getStyleAs(property, primitiveValue)

From: Garrett Smith <dhtmlkitchen@gmail.com>
Date: Sat, 2 Jan 2010 22:50:02 -0800
Message-ID: <c9e12661001022250p7dec5d8bgf046f1d17c2d98c7@mail.gmail.com>
To: Giovanni Campagna <scampa.giovanni@gmail.com>
Cc: Patrick Garies <pgaries@fastmail.us>, Travis Leithead <travil@microsoft.com>, www-style <www-style@w3.org>
Was this unclear or confusing?

Does Microsoft intend to provide an API to read styles for IE9?


On Tue, Dec 22, 2009 at 12:57 PM, Garrett Smith <dhtmlkitchen@gmail.com> wrote:
> On Tue, Dec 22, 2009 at 4:53 AM, Giovanni Campagna
> <scampa.giovanni@gmail.com> wrote:
>> On Tue, Dec 22, 2009 at 10:30 AM, Patrick Garies <pgaries@fastmail.us> wrote:
>>> On 9/22/2009 8:08 PM, Garrett Smith wrote:
>>>>>
>>>>> I also assume that getStyleAs can return a plethora of possible values
>>>>> from strings to other interfaces...
>>>>>
>>>>
>>>> I was thinking it would return a string although |asNumber| param
>>>> might a possibility:-
>>>>
>>>> x.getStyleAs("length", "px", "number");
>>>>
>>>> Returns a number representing the length, in css pixels.
>>>
>
> Ah, no, there is no "length" /property/.
>
> How about "width" for an element.
>
> // Read el's computed width, in px, but as a number.
>  el.getStyleAs("width", "px", "number");
>
> On second glance, the method returning either string or number is
> complex and inconsistent. The extra - valueType - argument is
> responsible for this problem. It should be omitted and the method
> should return a string. And so that leaves:
>
>  el.getStyleAs("width", "px")
>
> - which is already complicated enough.
>
> This fulfills the goal of reading a computed style.
>
> This does not allow for reading/parsing of numbers, nor does it allow
> for value object.
>
>>> For some reason, I'm thinking Travis was wondering what all the types of
>>> returnable values are. So far, pixels, integers, and RGBA seem to be covered
>>> based upon your examples. |rgb| is also mentioned, but it's not clear if
>>> that's a reference to the hexadecimal or functional notation.
>>>
>
> The string "rgb" would get an RGB functional notation string
>
> el.getStyleAs("color", "rgb");
> => "rgb(0, 0, 0)";
>
> el.getStyleAs("color", "rgba");
> => "rgba(0,0,0,1)"
>
> el.getStyleAs("color", "#");
> => "#000000"
>
> Other situations will want an Object or number: getStyleObject, getStyleNumber.
>
> var c = el.getStyleObject("color", "rgb");
> [c.r, c.g, c.b] + "";
> => "0, 0, 0"
>
> And for the number case, something like:
>
> var c = el.getStyleNumber("color", "rgb");
> => 0
>
> The idea of style.width.px++ wont be compatible with the web today and
> 2++ would be an error. However, parts of the idea could be used for a
> different object.
>
> Another proposal to read computedStyle on an HTMLElement that is not
> disconnected, call it "ElementComputedStyle". Example:
>
> el.computedStyle.color+ ""
> => "inherit";
>
> el.computedStyle.color.rgb.r
> => 0
>
> el.computedStyle.width.r
> => undefined
>
> As you can see, the object returned from the css property name varies.
> If it is a css length type of property, the object will have a - px -
> property. If it is a CSS Color object, it will have an - r- property.
>
> A setter for the computedStyle object would not make sense because it
> is a *computed* style.
>
> For setting values on an element, the element's style object could be
> used. Example:
>
> el.style.width  = el.computedStyle.width.percent + "%";
>
> Finally, a third idea is "LiveStyle".
>
> LiveStyle mixes computedStyle (for getting), overrideStyle (for
> setting), and cascaded style, for default value in toString, into one
> object. The object would have a toString function that returns the
> *cascaded* style. The LiveStyle interface implements CSS2Properties,
> but each CSS2Property of a LiveStyle has a new DynamicStyle properties
> that implements CSS2Properties
>
> interface LiveStyle : CSS2Properties {
>  string toString()
> }
>
> Interface DynamicStyle : CSSStyleDeclaration {
>  string toString()
>  long valueOf()
> }
>
> The properties for a DynamicStyle depend on the property in question.
> For RGBColor, an - r - property would be present, but for width, no r
> property would be present. For property values that read a
> computedStyle and set an overrideStyle. The liveStyle value itself
> serializes the cascaded style.
>
> el.liveStyle + "";
> => "color: red; width: auto"
>
> el.liveStyle.width + ""; // cascaded style, as declared.
> "auto";
>
> el.liveStyle.width.px; // computed style, in px
> => 10
>
> el.liveStyle.width.px++; // Read computedStyle in px, add 1, and set
> override Style, in px
> => 11
>
> el.liveStyle.color;
> => "inherit"
>
> el.liveStyle.color.r += 10;
> => 255
>
> Shorthand properties such as margin, pading, borderWidth, etc add
> complexity with multiple CSS value types for both proposals. The
> complexity of shorthand properties have to be considered to either
> ignore, or consider handling iff is the property takes a length and
> all values are equal.
>
> // Shorthand, but risky.
> el.style.margin = el.computedStyle.margin + "px";
>
> There are the three proposals.
> 1) getStyleAs - reads a computed style, returns a string
> 2) ElementComputedStyle - reads computed style from non-disconnected element.
> 3) LiveStyle reads cascade style, computed style, sets override style.
>
> Aside from it would be useful to have a standard specify conversion of
> ToString for the setter of style property. So that setting a style
> property to an object would result in calling the internal ToString
> for the assigned value.
>
> // Assign a string value.
> el.style.width = "10px"; Standard.
>
> // Proposed:
> // Leverage ECMAScript internal [[ToString]]
> anotherEl.style.width = { toString: function(){ return "10px"; }};
>
> Garrett
>
Received on Sunday, 3 January 2010 06:50:35 GMT

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