Simplify TemplateBindings #1695
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Rather than just use a standard `Binding`, make `TemplateBinding` a lightweight binding in the case where the binding is simply to a property on the templated parent.
Can just use TemplateBinding directly.
| @@ -139,7 +139,7 @@ public object Load(Uri uri, Uri baseUri = null, object rootInstance = null) | |||
| { | |||
| uriString = new Uri(baseUri, uri).AbsoluteUri; | |||
| } | |||
| throw new XamlLoadException("Error loading xaml at " + uriString, e); | |||
| throw new XamlLoadException("Error loading xaml at " + uriString + ": " + e.Message, e); | |||
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Also fixed the annoying problem where the XAML exception message didn't actually include the description of what went wrong.
| @@ -72,8 +72,7 @@ | |||
| <Style Selector="Slider /template/ Track#PART_Track"> | |||
| <Setter Property="Minimum" Value="{TemplateBinding Minimum}"/> | |||
| <Setter Property="Maximum" Value="{TemplateBinding Maximum}"/> | |||
| <Setter Property="Value" Value="{TemplateBinding Path=Value, Mode=TwoWay}"/> | |||
| <Setter Property="Orientation" Value="{TemplateBinding Orientation}"/> | |||
| <Setter Property="Value" Value="{TemplateBinding Value, Mode=TwoWay}"/> | |||
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This setter was both unnecessary and caused problems in that it was binding to Track.Orientation instead of Slider.Orientation which are actually different AvaloniaPropertys (#1696). This was resulting in the Slider getting messed up.
| public class AvaloniaPropertyTypeConverter : TypeConverter | ||
| { | ||
| private static readonly Regex regex = new Regex(@"^\(?(\w*)\.(\w*)\)?|(.*)$"); |
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This allows attached properties to be optionally specified with braces surrounding the property, as in a standard Binding.
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Is there a way we can do this without using regular expressions? Regex uses lot of memory for us just checking if the string starts and ends with parentheses.
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Yeah definitely! I looked at using StringTokenizer for this, but it wasn't suitable, and I didn't want to introduce another string tokenizer in this PR. Wasn't sure if we should make StringTokenizer more general purpose, or just manually parse the string here, so I just used Regex for the time being.
This shouldn't happen normally as `InpcPropertyAcessorPlugin` matches everything.
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As this is part of #1703 and it was tested so this PR is also tested 👍
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Other than the regex, this looks good! I'll merge it in! |
Previously a
TemplateBindingjust created a normalBindingwith aRelativeSourceMode.TemplatedParent. This PR changesTemplateBindingto a simple binding class in its own right, with aPropertyinstead of aPath(note that this is also howTemplateBindingworks in WPF and UWP).Implementing
TemplateBindinglike this means that for the common case of binding to anAvaloniaPropertyon the template parent, no allocations need to be made other than subscribing to a couple ofPropertyChangedevents: theTemplateBindingclass itself is reused for the instantiated binding in the common case that it is bound to a single property.In WPF and UWP, two-way bindings are not supported by
TemplateBinding. Here they are: there was no downside to allowing this and it makes it more broadly usable.Breaking Changes
TemplateBindings which specifyPath=will stop working, as the property is now calledProperty. Simply remove thePath=qualifierTemplateBindings which don't simply bind to a property on the templated parent will need to be changed to regularBindings withRelativeSourceMode.TemplatedParentMemory Usage
Memory usage was measured via the VS2017 diagnostic tools by running ControlCatalog in Release mode, opening all pages and then taking a memory snapshot:
Note that this PR depends on #1694:
On #1694:
This PR:
Depends on #1694