If you really wanted to slow things down, you would make it really
abstract:
<view bgcolor="${mouse.over == this ? blue : red}" />
The constraint system would have to be really sophisticated to
realize that if only had to evaluate the constraint on mouse.over on
the views it was leaving and entering, rather than every view.
I actually like that abstraction, but we have to be practical.
Your straw implementation introduces an additional layer of events,
so will slow things down. That could be crushed out by sending the
event directly in the mouse handler with only the overhead of an
extra call.
On 19 Dec 2005, at 21:55, Oliver Steele wrote:
I'd like to be able to write rollover effects more declaratively.
For example, instead of writing something like this:
<view bgcolor="red" onmouseover="this.bgcolor=blue"
onmouseout="this.bgcolor=red"/>
I'd like to be able to use a constraint:
<view bgcolor="${this.mouseisover ? blue : red}"/>
Or more realistically, for a view that has a more radically
different appearance in its rollover and non-rollover states, I'd
like to be able to do something like this:
<view>
<state apply="${!this.mouseisover}">
...normal state...
</state>
<state apply="${this.mouseisover}">
....rollover state...
</state>
</view>
I can get this if I add these lines to LzModeManager.handleMouseEvent:
if (eventStr == "onmouseover") view.setAttribute
('mouseisover', true);
if (eventStr == "onmouseout") view.setAttribute('mouseisover',
false);
if (eventStr == "onmousedown") view.setAttribute
('mouseisdown', true);
if (eventStr == "onmouseup") view.setAttribute('mouseisup',
false);
Does this sound reasonable? I don't want to write a performance
test to see if this is credible, so I thought I'd run it by your
intuition instead.
---
Notes:
LzView.mouseover would be a better name for this, but for the
constraint system to work, onmouseover would have to be sent when
it changed its value from true to false, which would be an
incompatible (and confusing) change.
LzView.mouse.over and LzView.mouse.down would also be more elegant
names than LzView.mouseover and LzView.mousedown, but this would
require an extra node for each view, to register the delegates on,
and I was worried about the effect on memory footprint and
instantiation time if I added an extra Object to every LzView.
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