[Laszlo-dev] anybody recall why we changed how LzTextSprite.getTextWidth works from 4.2 ?
P T Withington
ptw at pobox.com
Thu Apr 1 13:32:17 PDT 2010
Before I did this, I would _really_ want to understand why it was changed. It seems this was the end result of a _lot_ of discussion related to:
You, Max, and André all had input on this.
getTextWidth is a Kernel API, which is used by the LFC. So, it needs to have a contract that is the _same_ for all platforms.
I changed this and left a note as to why:
* Calculates the current width of the text held by the text field.
* @devnote NOTE: [2009-03-01 ptw] this is _not_ the clip textWidth, which
* "when autoSize is true is always 4 pixels less than _width" (which
* is why we have to add 4 pixels for emulate_flash_font_metrics
* in the DHTML version of this method, and why Henry used to add
* PAD_TEXTWIDTH to the textWidth!)
* @devnote NOTE: [2009-03-28 ptw] But if the text is empty, we return
* 0. <sigh />
The way I read that, when we split the LFC to have platform kernels we screwed up the abstraction and left part of the platform-specific stuff (this 4px offset from the Flash API) in the general part of the kernel. This change fixes that, so that _all_ the kernels are measuring the same thing.
You clearly cannot just change the Flash kernel, because then it would be skewed from the other kernels.
On 2010-04-01, at 14:08, Henry Minsky wrote:
> We used to measure text width in LzTextSprite by looking at the Flash
> 'TextField.textWidth' property (and adding
> 4 pixels of padding because it clipped otherwise).
> At some point that method was changed to look at the TextField._width
> instead, which gives different values (slightly larger ones).
> Anyone remember what the thinking there was? I'm inclined to revert that, so
> that we're compatible with the
> 4.2 text width in swf8.
> r13517 by ptw has the last assignment according to svn blame
> " Fixed getTextWidth, getTextHeight, getTextfieldHeight,
> to obey kernel API contract."
> Henry Minsky
> Software Architect
> hminsky at laszlosystems.com
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