Several months back, I was doing some work for a company that was using WPF for a stylus based application. One of the things that they found they needed was… Read More »How Do I Make a ListView or a ScrollViewer Left Handed?
This is a post that has taken months to complete, but addresses something that I don’t think I’ve seen sufficiently covered for anyone who is new to WPF. Resultantly, we’re… Read More »WPF Designers Guide to Styles And Templates
You can now check out all the MIX sessions, online. I attended the following sessions: Bringing Your Data to Life with Windows Presentation Foundation – Anson Tsao This is a great… Read More »MIX 08 Sessions Now Online
My brain is out of town while I’m working on our MIX Show Off Entry. In the meantime, I need to post some links so that I don’t forget them.… Read More »Special Leap Day Link-O-Rama
I was working on one of my projects today and I noticed that one of our popups displaying search results in a ListBox was having really serious performance problems. After determining that the problem was, in fact, on the WPF side of things, I was somewhat baffled. I wasn’t doing anything that I could think of that should be pushing the limit of what WPF could do.
Finally, I went looking online for an answer and discovered a list of possible performance killers for the ListView (and ListBox) on Mark Shurmer’s blog. Chief among his no-no’s:
Embedding the ListView inside a StackPanel
Which is exactly what I was doing.
Why is this a problem? To answer that question, let’s take a look at the ItemsPanel at runtime using Snoop. When I place my ListBox into a Grid, here is what my ItemsPanel looks like:
One of the questions I get most often from designers and almost never from developers is:
How can I get drop shadows into my application without killing my performance?
It is, of course, easy as punch and pie to get drop shadows into your application. You can just use the Bitmaps Effects panel in the Appearance section:
For the love of God, please do not use the Bitmap Effects in the Appearance section!
If any developers found out that I told you to use BitmapEffects, they would hunt me down and cut off my fingers. This is because, while the Bitmap Effects in WPF are all sorts of cool, they make your computer break down into uncontrollable sobbing. Bitmap Effects hog system resources by requiring software rendering for render-heavy effects. There is no better way to slow down a perfectly good application than to give every other element a drop shadow.
But, what if you really really want to?
This is actually a continuation of my post on getting the ComboBox items to accept text wrapping, so I’ll be working from that point forward. If you’re coming fresh into this, you won’t be missing anything… but that is my explaination for the pictures containing wrapping text.
When last we left our heroes, we has a couple problems. The first was that our items were either black text on a white background and ran together in a very un-designer-y way.
The second was that the selected item background makes your eyes bleed such a horrid blue color you’ll feel like Paul Atreides staring at a stone burner.
Was that a little too geek? My apologies.
The ComboBox is not the most complex of the WPF applications, but it can be a little tricky, so lets do a general overview post of it before we go into the specifics of how we’re going to make it work.
First of all, if you’re going to test your comboBox design, you should have it hooked up to an ItemsSource. Don’t have one? I have a tutorial in which I walk through attaching an RSS feed to your control. It was originally written for the ListView, but it will work fine for a ComboBox.
To start out… this is your standard ComboBox:
When working on a comboBox, you have a couple of options for the Items inside the ComboBox. If the options never change and are not data-driven, you can just toss come ComboBoxItems into it. Otherwise, you can connect it to some kind of ItemsSource (see the link above).
All of my examples are done with a data-driven ComboBoxes, but you should get the desired results if you run through the tutorials with ComboBoxItems.
First, a little bit about the structure of the comboBox.
I’ve been spending the past several days fighting with the ComboBox in an attempt to make it so something very simple: Wrap text inside the combo box. I’ve finally figured it out, so I thought I’d share.
OK, first of all, make sure that your ComboBox is hooked up to something, even if that something is some random RSS feed. I have a post that can help you with that over here. Bind your comboBox to the “Items” part of the New York Times RSS feed.
You need to do this because, if you do not, you will have to set the same data template to every single ComboBoxItem that you add to the ComboBox. And that’s just no fun.
Starting out, your ComboBox should look something like this:
Right click on your ComboBox and select “Edit Other Templates -> Edit Generated Items (ItemTemplate)-> Create Empty…” Give your new data template a name and Blend will take you into the Data Template design.
Read More »How Do I Wrap Text (or Add TextEllipsis) In The ComboBox?
OK, it’s really late and I want to get this done, so we’re going to go through the easy way, which will require some XAML, but I’ll try to keep it as Blend-y as possible.
So you have a column header and you want the text inside to wrap when the header space gets too short for the content. Your header probably looks something like this:
First, go to wherever your resources are being held and type the following in:
<Style x:Key=”CustomHeaderStyle” TargetType=”{x:Type GridViewColumnHeader}“>
</Style>