Download ComboBox TextWrapping Tutorial Project

Sometimes you just want stuff to work the way you want it to work. I want a property on the Silverlight ComboBox that says “WrapText”. But alas there is not one, so I have to do it myself.

So your ComboBox looks like this:

and you want it to look like this:

Let’s make that happen.

First, we need to make sure that the DataTemplate is going to act in such a way that it is compatible to having the data inside it wrap.

So… right-click on your ComboBox and go to: “Edit Additional Templates –> Edit Generated Items (Item Template) –> Edit Current”

If that option isn’t available, go to “Create Empty” The DataTemplate in my sample looks like this:

Hopefully, you have the binding information available for your data. If not, check out this post on creating sample data for the purpose of styling things. Make sure all the Widths and Heights (but especially the Widths) are set to “Auto”.

And make sure your TextBox or TextBlock has TextWrapping=”Wrap”

So now your ComboBox wraps in the main section… which is awesome, but you still have this happen when you open up the DropDown (PopUp)

If you want that to wrap as well, the solution isn’t hard so we’ll deal with it here instead of giving it another post.

First,change the HorizontalContentAlignment on the ComboBox to be “Stretch”.

Next, right click on the ComboBox and go to “Edit Additional Templates –> Edit Generated Item Container (ItemContainerStyle) –> Edit a Copy…”

What is happening is that the ItemContainerStyle element is requesting all the space in the world from it’s parent and since the parent with the ultimate authority is a PopUp, it sees no reason to constrict the ItemContainerStyle with irritating constraints, so the text element finds no reason to start wrapping. So, we’re going to tell the ItemContainerStyle that it can only request a certain amount of space. In this particular case, we’re going to set MaxWidth=”200”

And we get this:

And we’re happy.

Or at least I hope we’re happy. If you’re not happy, mention your problem in the comments and I’ll try to get back to you with any tweaks or updates you need.

Download ComboBox Styling Project Files

This post is meant to be a center point for topics related to styling the Silverlight 3 ComboBox. It will go over the basic about ComboBox styling and will also get updated with links to tutorials about common design problems with the ComboBox.

So, let’s get started…

If you want to change the look of the main ComboBox or the ComboBox drop down (popup),

you’re going to want to change the main template of the ComboBox.

As an aside, in order to make this as simple as possible, we’re not going to connect out ComboBox to any data… we’re just going to add a bunch of ComboBoxItems to it. To do this, click on the double-arrow at the bottom of the toolbar and type “combo” into the search field.

Click on the ComboBoxItem and draw it into the ComboBox a couple times. This will give your items some weird heights and widths, so change those if that bothers you. We now have enough items to be able to see the drop down for the purposes of styling it.

OK… let’s get started with actually working on the ComboBox template. Right click on the ComboBox and going to “Edit Template –> Edit a Copy…”

This will dump a copy of the default ComboBox style and template into your resources that you can play around with.

Let’s say we want to do something as simple as changing the corners in the main comboBox and the drop down to make them a little more rounded.

When we look at the template, we should see something that looks like this:

Let’s start with rounding the corners of the pop-up, since we can do that from right here. On the PopupBorder element, let’s change the CornerRadius to “0,0,16,16”. And let’s change the border color and thickness just cause we wanna. We end up with something like this:

Now, lets work on changing the corners on the rest of the ComboBox. As it turns out, most of the visual elements in the ComboBox are in the DropDownToggle ToggleButton and go to ControlTemplate by right clicking on it and going to “Edit Template –> Edit Current”

Now, we can see 8 rectangles that make up the design of the ComboBox. If you wanted to simplify the design, you could get rid of them and put something else in, but we’re going to assume for the moment that you just want to change the corners. Go through the rectangles and if RadiusX and RadiusY are 3, change them to 16 an if they are 2, change them to 15.

  becomes

And you have something that is… not that attractive, but it is definitely different.

Super cool new thing I learned today. In WPF, we can make it so that the drop down (popup) on a ComboBox displays the data in a ListView. Because of the fact that I believe the DataGrid will eventually overtake the ListView as the gold standard for data display in WPF, we’ll do it both ways.

This tutorial is done entirely in Blend and without a line of code.

Step 0) (for the DataGrid only)

Go to Code Plex and download the WPF Toolkit. Extract to a convenient location.

Right-Click on the References folder in your project tab and click “Add Reference…”

Navigate to the location you extracted the WPFToolkit.dll file, select it and hit OK.

Step 1) Select the ComboBox you wish to change and edit the ControlTemplate by right-clicking and selecting “Edit Control Parts (Template) –> Edit a Copy…”

Step 2) Find the ItemsPresenter. This is what would normally display our ItemsSource.

We’re going to get rid of it. And the ScrollViewer for good measure.

Step 3) Where the ScrollViewer is, put in a ListView or a DataGrid, whichever one you’re using.

Now, go the properties of that ListView or DataGrid and click on the box to the right of “ItemsSource”

and, in the resulting menu, select “Template Binding –> ItemsSource”.

Set the DataContext of the ListView or DataGrid to the DataContext of the parent ComboBox using the same process.

And… you’re done! Open the ComboBox and you will see that you can select items in the ListView or DataGrid in the ComboBox dropdown and see those items change the selection of the ComboBox.

You’ll notice that this is probably not yet an ideal solution. For example, when we select an item, the dropdown doesn’t automatically close. Your best bet is to use the SelectionChanged event to trigger some logic to close the ComboBox dropdown.

Download code for this sample

I was reading Mike Snow’s blog and he had a recent Silverlight tutorial on creating a Zooming toolbar. I looked at it and said to myself, “I think I can do that without code in Blend!” So here’s a tutorial on exactly that.

End product :

Big bonuses to this XAML-only method include:

• Much smoother animation
• Midway animation (if you fly over a button, it doesn’t need to animate all the way up before it starts to animate back down)
• Really low overhead
• Can be done and maintained entirely by a designer in Blend without any code

1) create a new Silverlight project in either Visual Studio 2008 or Blend 2.5.

2) In Blend, add a new folder for our images by right-clicking on the project and selecting “Add New Folder”

3) Pull in our images by right-clicking on our new folder and selecting “Add Existing Item…” Navigate to the images you want to use and select “OK” to bring them into the project.

4) Create the button to which you want to add the image and then double-click it in the Obejcts and Timeline pane so that it has a yellow outline around it.

5) Now, go to the image you want to insert (in the Project panel), right click on it and select “Insert”

OK… so now we have a button with an image in it. Now it’s time to make the sucker zoom.

6) Right click on the button and select “Edit Control Parts (Template) -> Edit a Copy…”

Name your custom Template and hit OK

7) In the “States” pane, you see a set of “CommonStates” (Normal, MouseOver, Pressed, and Disabled). Click on the MouseOver state and a red box will surround your composition, indicating that any changes made will be changes to the “Mouse Over” state, not to the default control.

Recording state:

8] Click on the highest level item in the template (in my case, it is a “Grid”) and go to the “Transform” section in the “Properties” pane and select the “Scale” transformation tab. Change the X and Y scales to “1.5″

If you run the project now, you’ll notice that we get a cool zoom in effect on the mouse over, but our zoom out when the mouse leaves the button is basically a snap back to the original size. Let’s fix that now.

9) Click on the the arrow icon in the MouseOver state in the States pane and select the “MouseOver -> Normal”

In the “Transition Duration” box, type “.2″

10) Extra Designer Happiness Bonus Step! – If you’d like to have a zoom effect that isn’t strictly linear, open up the timeline view with the button on the right hand of the state recording box (seen below).

Click and drag the keyframe (the light gray oval below) to the point you want it. I put mine at .3 seconds.

With the keyframe selected, you should see an “Easing” pane on the right. The default easing is linear (aka. no easing), but you can change the easing curve by just dragging the yellow dots. Here is the easing curve I’ve found works pretty well for my apps.

That’s it. Now you can just assign this template to a button and you’ll have this zooming functionality all set up.

Update: Project files for the Silverlight Mac ScrollViewer have been uploaded.

 Just because we’re working in Microsoft technologies doesn’t mean we can’t throw a bone to our Mac friends. After all, they are the people we love, our cousins and our neighbors, and that irritating guy who is dating our daughter and can’t seem to shut up about how awesome his Mac is even though he’ll be long out of his program in musical costume design before he ever pays off his laptop …

Issues? I don’t have issues. Why do you ask?

Anyway, since Silverlight is a semi-ubiquitous technology, it would be nice if we could cater to all platforms and not make anyone feel left out. And nothing makes people feel more left out than when they expect their application to work one way and it doesn’t.

So, here’s a picture of what we’re going for.

As far as I’m concerned (and therefore as far as this tutorial is concerned) the important stuff is to make sure that the incremental buttons (the arrow buttons in the bottom right) are in the right place. We can deal with the color later.

OK, so let create our ScrollViewer (I’ll be using Blend exclusively for this). I tossed a button in it and made it small so we can see both of the ScrollBars.

Right click on the ScrollViewer in the “Objects and Timeline” section and go down to “Edit Control Parts (Template) -> Edit a Copy…”

You should have something that looks like this:

Let’s do the VerticalScrollBar first. Right click on it and go to “Edit Control Parts (Template) -> Edit a Copy…” Name it something memorable and you should get something like this:

This is actually easier than it looks. The unnamed rectangles and the path lay down the basic visual backbone for the ScrollBar and the rest of it runs like this:

VerticalSmallDecrease – The up button
VerticalLargeDecrease – The space between the up button and the VerticalThumb

VerticalThumb – The interface element that allows the dragging interaction of the scrollbar
VerticalLargeIncrease – The space between the down button and the VerticalThumb

VerticalSmallIncrease – The down button

The horizontal root in this template is strikingly similar.

So, let’s start by moving the VerticalSmallDecrease button down to the bottom above the VerticalSmallIncrease button. The magic here will happen in the VerticalRoot grid. (I highly recommend the Design/XAML split view for this one.) In the design view, our grid looks like this:

Ugly. However, in the XAML, it looks like this:

<Grid.RowDefinitions>
      <RowDefinition Height=”Auto”/>
      <RowDefinition Height=”Auto”/>
      <RowDefinition Height=”Auto”/>
      <RowDefinition Height=”*”/>
      <RowDefinition Height=”Auto”/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
      <ColumnDefinition/>
      <ColumnDefinition/>
</Grid.ColumnDefinitions>

Much easier. For the purposes of maintaining a coherent structure, drag the VerticalSmallDecrease in Objects and Timeline pane until it is between the VerticalSmallIncrease and the VerticalLargeIncrease. Next, change the third RowDefinition to “*”. You can do this in the XAML or by clicking on the “Auto” icon until it becomes a “*” icon. Change the fourth RowDefinition from “*” to “Auto”. When you do this, it won’t immediately act like an “Auto”. This is because Blend gives it an automatic “MinHeight” of whatever the current Height is. You can change that in the XAML (easiest move) or you can highlight that row by clicking just below the “Auto” icon until the row highlights in a semitransparent gray like so.

You may need to zoom in to do this. Once highlighted, the properties of the Row will show up in the Properties tab on the right. Change the MinHeight to 0.

Now we’ll need to change the Grid.Row properties of almost everything. Click on the items in the Objects and Timeline and change the Row property in the Layout section of the Properties tab like so:

VerticalLargeDecrease -> Row = 0
VerticalThumb -> Row = 1
VerticalLargeIncrease -> Row = 2
VerticalSmallDecrease -> Row = 3
VerticalSmallIncrease -> Row = 4

You’re done. With the Vertical part of the ScrollBar at least. You can do the same thing with the Horizontal part of it. Just move around the buttons, change the ColumnDefinitions and update the Column assignments. My best recommendation is to go back to the ScrollViewer template and assign your new ScrollBar template to the HorizontalScrollBar and then go back to editing the template from there.

Later on…

After a bunch of color tweaking, I have a scroll viewer in silverlight that looks like this:

I’m feeling OK with it. I’ve embedded what I have at this point below.

This is just a quick note on creating a ListView style with the appropriate GridView style and template assignments.

Normally, I’ve been creating listviews that look like this:

<ListView x:Name=”MyListView”
               ItemContainerStyle=”{DynamicResource MyListViewItemContainerStyle}”>
    <ListView.View>
         <GridView ColumnHeaderContainerStyle=”{DynamicResource MyListViewHeaderStyle}”
                         ColumnHeaderTemplate=”{DynamicResource MyGridColumnHeaderTemplate}”> 

I did this because I didn’t know exactly how to assign these styles and templates to the ListView Style. In the style, ColumnHeaderContainerStyle and ColumnHeaderTemplate are not properties of the ListView, they are properties of the GridView… which you can’t create a style for.

Instead, you can encapsulate all the information above in the following style.

<Style x:Key=”CustomListViewStyle” TargetType=”{x:Type ListView}”>
      <Setter Property=”GridView.ColumnHeaderContainerStyle” Value=”{DynamicResource MyListViewHeaderStyle}” />
      <Setter Property=”GridView.ColumnHeaderTemplate” Value=”{DynamicResource MyGridColumnHeaderTemplate}” />
      <Setter Property=”ItemContainerStyle” Value=”{DynamicResource MyListViewItemContainerStyle}” />
</Style>

Problem solved.

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 going to go through it slowly and I’m officially begging for additional questions at the end.

Part of the problem with styles and templates in WPF stems from the fact that Blend allows a wonderfully simply way of creating a copy of a template:

It then gives you something that looks like this:

<Style x:Key=”My_Template” TargetType=”{x:Type Button}“>
      <Setter Property=”Template“>
            <Setter.Value>
                  <ControlTemplate TargetType=”{x:Type Button}“>
                        <!– blah blah blah –>

So, from a usability point of view… I told it to create a Template and it created a style. I judged from this that styles and templates were roughly the same thing.

And I was confused.

So, first, I’ll try to explain styles and templates by explaining how they work and then I’ll draw an analogy that I hope is helpful.

Let’s say you have a button.

You can change all sorts of properties of that button… visibility, background, width, height, margins, border thickness, alignment, font, whatever.

If you have a dozen buttons and you want them all to have the same properties, you can create a button style that specifies those properties and assigns them across the board. You can edit a style in Blend by selecting your control, clicking in the menu: “Objects -> Edit Style -> Edit a Copy…“.

Style editing in the objects tab will look like this.

As you can see, there are no objects in the visual tree to play with… only properties to assign in the properties tab.

When you assign a property in Blend, your styles will save that assignment as setters and values. Let’s say we wanted all of our buttons to have green 18 point font  bold text. We could create a style that looked like this:

<Style x:Key=”GreenBorderButton” TargetType=”{x:Type Button}“>
      <Setter Property=”Foreground” Value=”#FF00FF00” />
      <Setter Property=”FontSize” Value=”18“ />
      <Setter Property=”FontWeight” Value=”Bold” />
</Style>

The styles can only define properties that belong to the control type that they are styling (which is defined in the “TargetType“). Also, styles can only give information for properties the control already has and only in the way that the control is already set up. For example, because there is no property for changing the corner radius of a button, you can’t change the corner radius of a button using a button style.

However, what if we want to change something about the button that we can’t change with the given properties? For example, let’s say we wanted to see all the text show up twice.

In order to do this, we need to make what I’m going to call “structural changes” to our control. Structural changes are changes in the actual guts of the control, changes to the base elements that make up the control. For this we need a control template.

Boiled down to their essence, templates are little chunks of XAML that are inserted whenever you use your control. When you right click on something and go to  “Edit Control Parts (Template) -> Edit a Copy…“, Blend takes the default XAML that makes up your control and places it in the resources so that you can change it at your whim.

You can get to the Control Template using the right-click method described at the top of this post. Your basic button template will look something like this:

<Style x:Key=”MyButtonStyle” TargetType=”{x:Type Button}“>
      <Setter Property=”Template” Value=”{DynamicResource MyButtonTemplate}” />
</Style>

<ControlTemplate x:Key=”MyButtonTemplate” TargetType=”{x:Type Button}” >
      <Microsoft_Windows_Themes:ButtonChrome x:Name=”Chrome” >
            <ContentPresenter />
      </Microsoft_Windows_Themes:ButtonChrome>
</ControlTemplate>

We can go in and add an additional ContentPresenter in here, like so:

<ControlTemplate x:Key=”MyButtonTemplate” TargetType=”{x:Type Button}” >
      <Microsoft_Windows_Themes:ButtonChrome x:Name=”Chrome” >
            <Grid>
                  <Grid.RowDefinitions>
                        <RowDefinition Height=”.5*” />
                        <RowDefinition Height=”.5*” />
                  <Grid.RowDefinitions>
                  <ContentPresenter Grid.Row=”0” />
                  <ContentPresenter Grid.Row=”1” />
            </Grid>
      </Microsoft_Windows_Themes:ButtonChrome>
</ControlTemplate>

And now our button shows all the content twice, one right on top of another.

The best way I’ve found to think about it is to think of your control as a car.

The dealer give the buyer a list of things that they can change about the car… interior color, leather or fabric seats, 4 or 6 cylinder engine… these are properties of the car… defined in the car “style”. (Basically, you can think of everything that you’re allowed to tweak at this website as the style of the car.)

<Style x:Name=”MySpecialCar” TargetType=”{x:Type Camry}” >
      <Setter Property=”ExteriorColor” Value=”Blue” />
      <Setter Property=”TransmissionType” Value=”5SpeedManual” />
</Style>

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But let’s say that the buyer doesn’t want a normal seat… she wants a big comfy chair in place of the regular drivers seat. This is something outside of the scope of the list of things she was allowed to choose from, so they have to draw up new blueprints for making this new car. They have to create a new car “template”.

If our normal Camry blueprint looks like this:

<ControlTemplate x:Key=”MySpecialCarBlueprint” TargetType=”{x:Type Camry}“>
      <CamryFrame x:Name=”CamryFrame” >
            <Seat Type=”Drivers ” />
            <Seat Type=”FrontPassenger” />
            <Seat Type=”BackBench” />
      </CamryFrame>
</ControlTemplate>

We can go in and replace :

<Seat Type=”Drivers ” />

With

<Seat Type=”ComfyChair” />

You may also notice that, with this model we could get rid of all the other seats except the drivers seat or we could add 12 new rows of seats. We can change anything about the car because we’re down into the original car blueprint.

This is the basic difference between styles and templates.

• A style is a list of properties that can be assigned in bulk to a control.
• A template goes a big step further and actually defines the underlying structure of the control.

You may be asking: “So how do these two work together? And what is this Data Template think I keep hearing about?”

Given that this post is getting dangerously long already, I’m going to address those issues in a couple more posts on styles and templates.

I’ll end on this note: if you are working in WPF and you’re having trouble with styles and templates, please read all of these posts (as I get to them) and ask questions in the comments section. I’m pretty good about getting to the comments questions and if the question is big enough, I’ll write a whole post on it. There are few things more vital to a WPF developer/designer than to have a firm grasp on styles and templates. It is in this understanding that the power of WPF really comes out.

• Who’s The Boss? Property Priority in Styles and Templates (coming soon)
• Create Conditional Styles and Templates (With the Magic of Triggers) (coming soon)
• So How Do Data Templates Fit Into All This? (coming soon)