Yet another blog about WPF, Surface, SL, MVVM, NUI....





Tag - performance

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What ? Dynamic resources creates Memory leaks in WPF 3.5 (SP1) ???

27 March 2011

Everyone is told to not use DynamicResource during its childhood in WPF-(wonder)land. They are simply evil and they kill the app performance. Sometimes, we fall in the dark side of the force and use them effectively to be sure that the application will follow the trend and suits itself well. This is not as bad as it seems and it is in fact sometimes necessary and wanted.

 But today, while I was trying to improve the performance and the memory usage of a WPF application I work on, I discovered that they were also creating memory leaks! I felt betrayed. I was using them and they put a knife in my back while I trusted them to be useful. 

In this post we will see how it can happens, and how to solve this (little) issue.

Continue reading...


[Performance tips] Use the system shadows instead of your own

27 April 2010

Today a fast and easy tip about shadows and performance.

In a project I have recently made, we've told the designer not to use BitmapEffects because they are performance killer. He so decided to create it's own shadows by duplicating each shape and make them looks like shadows(designer magic, voodoo things, etc...). I was then surprised to see that it kills performance too !

There is still the shaders effect which came with the 3.5 SP1 framework but they will be available only on vista or greater plateforms and their performance will depend of your graphic cards.

But we have an another ace in you deck : the system shadow which are quite fast even on software rendering!

Using it is quite easy :

  1. Add the PresentationFramework.Aero reference to your project,
  2. Add the following XML namespace : ”clr-namespace:Microsoft.Windows.Themes;assembly=PresentationFramework.Aero”,
  3. Use the SystemDropShadowChrome element available with this namespace !

But there is a drawback : you can only produce squared shadows. But you can still play with the CornerRadius property to create simily round shadows.

Here is a little example of XAML code:

  <shadows:SystemDropShadowChrome Margin="25">
      <ListBoxItem Content="One item" />
      <ListBoxItem Content="Another item" />
      <ListBoxItem Content="Another third item" />
  </shadows:SystemDropShadowChrome >
  <shadows:SystemDropShadowChrome Margin="25" CornerRadius="800" Width="100" Height="100">
    <Ellipse Stroke="Black" Fill="White" />

Shadows screenshot

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Freeze brushes directly in the XAML to improve your application's performances

12 April 2010

When you read the MSDN guidelines to improve WPF's performances you can find that it's a good idea to freeze Freezable objects.

It's a quite easy thing to do via the code but it's quite harder to do it directly in the XAML. In this post we will see how to do so.

What are freezable objects

One upon a time, the MSDN said :

A Freezable is a special type of object that has two states: unfrozen and frozen. When unfrozen, a Freezable appears to behave like any other object. When frozen, a Freezable can no longer be modified.

A Freezable provides a Changed event to notify observers of any modifications to the object. Freezing a Freezable can improve its performance, because it no longer needs to spend resources on change notifications. A frozen Freezable can also be shared across threads, while an unfrozen Freezable cannot.

With this definition in mind, you surely had guess that it's a good thing to freeze them because and you surely want to do it... But how to do ?

Freeze freezable objects via the code

It's quite easy to do it in the code. The only thing do check is the property CanFreeze which tells you if you can or not freeze the Freezable object. You will then use this code :

if (myBrush.CanFreeze)
    // Makes the brush unmodifiable.

Freeze them (with ice) in XAML

The tips is to know the good XML Namespace

The use in the XAML is then quite easy :

<LinearGradientBrush ice:Freeze="True" 

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