2010: CacheMode for ListViewItem?

Question

Hello,

it just occurs to me that in my problematic ListView (40 items long, scrolling a LOT downward as data drops in on the top - a LOT)... I may actually win a lot by caching the indivisual lines (ListViewItems) with the CacheMode property introduced in 4.0 ;) It would mean after a scroll the line could only be redrawrn from bitmap, not from the elements... may make sense ;)

Setting CacheMode on the complete list is not good, as it scrolls down, so it invalidates completely every time.

Anyone can help me out how to set that?

I dont define a complete style so far - I am more than happy with the standard. I define an ItemCntainerStyle, but it basically sets HorizontalContentAlignment AND has a lot of datatrigger color changes.

Is there a way to access the CacheMode property of the ListViewItem at the ItemContainerStyle? Or how else (yeah, willing to learn) can I do that?

Answer 1

I suppose I don't understand the problem here.  ListViewItem is a Control, which is a UIElement, so you should be able to set the property just like you would any other.  Setting this style as a ListBox's ItemContainerStyle worked fine for me.

<Style TargetType="ListBoxItem" x:Key="ContainerStyle">
    <Setter Property="CacheMode" Value="BitmapCache"/>
</Style>

Answer 2

THe problem is mostly one of me still getting my hands wet in WPF ;) I totally overlooked that - including the lttle fact that I even did have the style already defined in my XAML code ;) Nice ;)

THe final part of the question then is - how do I set parameters in there?

If I want to have

  <BitmapCache EnableClearType="True" RenderAtScale="1" SnapsToDevicePixels="False" />

What would be the equivalent? I am particularly interested in EnableClearType - the text now is fast but looks blurry ;)

Answer 3

If you enable ClearType you'll also want to set SnapsToDevicePixels to true.  Snapping the cache to pixels should make everything less blurry, including the text.  The example XAML I gave you cheated a bit since we added a TypeConverter that creates a default-valued BitmapCache if you use the shorthand notation I used.  The verbose way that allows you to specify all the properties would look like this:

<Style TargetType="ListBoxItem" x:Key="ContainerStyle">
    <Setter Property="CacheMode">
        <Setter.Value>
            <BitmapCache EnableClearType="True" SnapsToDevicePixels="True"/>
        </Setter.Value>
    </Setter>
</Style>

Answer 4

Thanks ;) Will try ;) I still am stumbling like mad with the WPF delicacies ;)

Funny how performance went up with caching (and text quality down) ;) Still not good enough, though ;) Will have to open another post with some concrete scenario.

THanks for the help here ;) This Bitmap Caching is a great addition ;)