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#378 fix strategy none semantics

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This commit is contained in:
Leo Horie 2014-12-10 22:34:20 -05:00
parent cbdbdd7c60
commit 09b25cb803
2 changed files with 19 additions and 4 deletions
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10
docs/mithril.redraw.md
View file

@ -122,7 +122,7 @@ Note that the redraw strategy is a global setting that affects the entire templa
### Preventing redraws on events
Sometimes you only care about a particular condition in an event and want to ignore it if this condition is not met.
Sometimes you only care about a particular condition in an event and want the event to not trigger a redraw if this condition is not met.
For example, you might only be interested in running a redraw if a user presses the space bar, and you might not want to waste a redraw if the user presses any other key. In that case, it's possible to skip redrawing altogether by calling `m.redraw.strategy("none")`
```javascript
@ -132,6 +132,14 @@ m("input", {onkeydown: function(e) {
}})
```
There are some important semantic caveats for `m.redraw.strategy("none")` that you should be aware of: Setting the strategy to `"none"` only affects **synchronous** redraws. As soon as the event handler returns, the strategy is set back to "diff".
If you set strategy to `"none"` but then proceed to trigger a redraw asynchronously, either via `start/endComputation`, `m.redraw` or `m.request`, a redraw *will* occur, using the `"diff"` strategy.
Additionally, calling `m.redraw` synchronously after calling `m.redraw.strategy("none")` resets the strategy to `"diff"`.
Lastly, be aware that if a user action triggers more than one event handler (for example, oninput and onkeypress, or an event bubbling up to event handlers in multiple ancestor elements), every event triggers a redraw by default. Setting strategy to none in any one of those handlers will not affect the redrawing strategy of other handlers (and remember that `strategy("none")` has no effect on asynchronous redraws).
---
### Forcing redraw

13
mithril.js
View file

@ -409,7 +409,7 @@ var m = (function app(window, undefined) {
m.startComputation();
try {return callback.call(object, e)}
finally {
m.endComputation()
endFirstComputation()
}
}
}
@ -499,7 +499,7 @@ var m = (function app(window, undefined) {
controllers[index] = controller;
modules[index] = module
}
m.endComputation();
endFirstComputation();
return controllers[index]
}
};
@ -523,7 +523,7 @@ var m = (function app(window, undefined) {
function redraw() {
var mode = m.redraw.strategy();
for (var i = 0, root; root = roots[i]; i++) {
if (controllers[i] && mode != "none") {
if (controllers[i]) {
m.render(root, modules[i].view(controllers[i]), mode === "all")
}
}
@ -543,6 +543,13 @@ var m = (function app(window, undefined) {
pendingRequests = Math.max(pendingRequests - 1, 0);
if (pendingRequests === 0) m.redraw()
};
var endFirstComputation = function() {
if (m.redraw.strategy() == "none") {
pendingRequests--
m.redraw.strategy("diff")
}
else m.endComputation();
}
m.withAttr = function(prop, withAttrCallback) {
return function(e) {