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Refactor the selectScaleOption function, in Toolbar._updateUIState, to prevent any possible future display glitches

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Since the localization service is now asynchronous, depending on the load the browser is under, there's a small risk that the lookup of the 'page_scale_percent' string could be delayed slightly.
If the scale would change a couple of times in *very* quick succession, there's perhaps a *theoretical* possibility that the Zoom dropdown would display an incorrect value.

Consider the following, somewhat contrived, theoretical example of two zoom commands being executed *right* after one another:
```javascript
PDFViewerApplication.pdfViewer.currentScale = 1.23;
PDFViewerApplication.pdfViewer.currentScaleValue = 'page-width';
```

Only the `currentScale` call will currently trigger a l10n lookup in `selectScaleOption`. However, as far as I understand, there's no *guarantee* that the l10n string is resolved *before* `selectScaleOption` is called again as a result of the `currentScaleValue` call.

This thus has the possibility of putting the Zoom dropdown into an inconsistent state, since it's currently updated synchronously for one code-path and asynchronously for another.

To avoid these issues, I'm proposing that we *always* update the Zoom dropdown asynchronously, such that we can guarantee that the ordering is correct.
This commit is contained in:
Jonas Jenwald 2017-06-10 13:37:54 +02:00
parent 2971f522d4
commit 75edb859ce
1 changed files with 16 additions and 16 deletions
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32
web/toolbar.js
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@ -180,25 +180,25 @@ var Toolbar = (function ToolbarClosure() {
} }
let selectScaleOption = (value, scale) => { let selectScaleOption = (value, scale) => {
var options = items.scaleSelect.options; let customScale = Math.round(scale * 10000) / 100;
var predefinedValueFound = false; this.l10n.get('page_scale_percent', { scale: customScale, },
for (var i = 0, ii = options.length; i < ii; i++) { '{{scale}}%').then((msg) => {
var option = options[i]; let options = items.scaleSelect.options;
if (option.value !== value) { let predefinedValueFound = false;
option.selected = false; for (let i = 0, ii = options.length; i < ii; i++) {
continue; let option = options[i];
if (option.value !== value) {
option.selected = false;
continue;
}
option.selected = true;
predefinedValueFound = true;
} }
option.selected = true; if (!predefinedValueFound) {
predefinedValueFound = true;
}
if (!predefinedValueFound) {
var customScale = Math.round(scale * 10000) / 100;
this.l10n.get('page_scale_percent', { scale: customScale, },
'{{scale}}%').then((msg) => {
items.customScaleOption.textContent = msg; items.customScaleOption.textContent = msg;
items.customScaleOption.selected = true; items.customScaleOption.selected = true;
}); }
} });
}; };
var pageNumber = this.pageNumber; var pageNumber = this.pageNumber;