beta tutorial 5 blend

8/6/2019 Beta Tutorial 5 Blend

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Silverlight 2 Beta 2 Tutorial Introducing Expression BlendForSilverlightDevelopers

ByJesse Liberty

Expression Blend For Developers

Beginning with version 2.5 (currently in Preview Edition) building Silverlight 2

applications, and especially assembling the User Interface components such as items

from the toolbox, and layout controls, is easier than ever.

A Note on This Tutorial. The history of the material for this tutorial isthat Scott Guthrie wrote a terrific introduction to this material at the

end of February, which he gave me permission to turn into a series of

videos, currently (or soon to be) available on Silverlight.NET. This

tutorial completes the circle by building on the videos and integrating

the material into the Silverlight Tutorial series.

The project were setting out to build is very similar to the Silverlight chat service built

by ScottGu, and is shown in Figure 5-1


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Figure 5-1. Completed Application

Getting StartedThe best way to get started is by opening Expression Blend.

This tutorial was written with Silverlight 2 Beta 2 and Expression

Blend 2.5 June Preview.

The first thing youll see is the New Project window. Choose Silverlight 2 Application,

set your language to Visual Basic and choose a location for your new project, which well

name BlendForSilverlight, as shown in Figure 6-2


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Figure 5-2. Creating the New Project

The Solution Files

Take a look in the upper right hand corner. The solution, project and other files created

by Blend are identical to the files created by Visual Studio 2008. In fact; there is no

exporting/importing between the two; you can open both development environments on

the same files simultaneously and they will both work perfectly (see figure 6-3)

Figure 5-3. Blend Files

A Very Quick Tour

The upper right hand corner not only contains the files, but also contains the properties

window, the resources window and, below these, the data window. The central area has


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the Art Board (the design surface and the Xaml (markup) which can be split as shown

in Figure 6-4

Figure 5-4. Design Surface in Split Mode

Ive added highlighting in the upper right hand corner to point out the controls that allow

you to switch among design, Xaml and split mode.

The upper left hand corner contains the Interaction panel and the toolbar. Many of the

tools in the tool bar have a small mark in the lower right hand corner indicating that they

can be expanded to find related tools. For example, expanding the grid tool displays all

the layout controls as shown in figure 6-5


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Figure 5-5. Expanding the Grid Tool

The Chevron tool allows access to all the controls, including any user controls, custom

controls or third party controls (be sure to click Show All) as shown in Figure 6-6

Figure 5-6. Chevron Expanded

Note that from within the Asset Library exposed by expanding the Chevron you can also

search for the control you want, and by clicking on the details radio button you can

determine which library a control is in.


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Chat Application First Steps

Begin by switching to design view, and then hold the control key and use the mouse

wheel to zoom out so that you can see the entire grid.

If your mouse doesnt have a wheel, you can zoom by picking a value

(or filling in an arbitrary value) at the bottom of the design window or

by using the menu choices ViewZoom In and ViewZoom Out

You can move the surface by clicking on the hand and then using the mouse to click and

drag or by using the scroll bars.

Take a look at the upper right hand corner of your grid, as shown in figure 6-7

Figure 5-7. Upper left corner of the grid

Hovering over the upper left hand corner will tell you if you are in grid layout mode or

Canvas layout mode. If you are in canvas layout, clicking will toggle you back to grid

layout mode.

You can create rows and columns just by sliding along the margins and clicking where

you want the rows and margins placed, as shown in figure 6-8

Figure 5-8. Creating a Row using The Mouse

Immediately after I click, an open lock appears above and below my new row line. Ill

add two lines, one for the top row and one for the bottom; thus implicitly creating a

middle row, and thus three locks as shown in figure 6-9.


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Figure 5-9. Creating the bottom row

Note that immediately after the row is created, not only are the locks shown but the

cursor changes shape to indicate that you can easily move, and thus resize the rows.

The open locks indicate that the rows will resize as the browser (inside of which your

Silverlight application will run) is resized. We want the middle row to do so, but we want

the top and bottom row to remain of fixed size, so click on the top and bottom lock, and

then click on split view to examine the effects on the XAML, as shown in figure 6-10.


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Figure 5-10. Middle Row has Star Sizing

Note that (on line 10) the middle row definition has its Height property set to * (star)

indicating that it will take up the remaining room after the other rows are allocated.

Creating the Columns

Lets create two columns, a smaller right column that has a fixed size and a larger

floating size left column. Try this yourself without additional help.

Creating the Background Color

Wed like to give the entire application a light blue background, but to make it a bit more

attractive, well use a linear gradient brush. To do this, please follow these numbered

steps, reflected in Figure 6-11.

1. Click on the grid (Layout Root) in the Interaction Panel2. Click on the properties panel and expose the Brushes subpanel. Click on the

Background brush

3. Click on the Gradient Brush button4.

Add stops along the gradient by clicking and then

5. manipulating the color bar and6. Moving the color dot for precise color choices


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Figure 5-11. Adding a Linear Gradient By the Numbers

Adding A Send Buton

The next step is to add a button to the lower right hand corner. Click on a button on the

toolbar, drag it to approximate size in the area and then click in the properties window.

Next, open the Layout subpanel and set the Width and Height to Auto and set a small

value (e.g., 4) for the Margin, all around. This will fill the area, but with a reasonable

margin from the edges of the column and row.

The value you put in a property box does not take effect until you leave

that box (e.g., using tab)

There are a few things to notice about the Layout Panel (figure 6-12)

Figure 5-12. Setting the Button Layout with the Layout Panel


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First, you can set the Width and/or Height to auto by pressing the button to the right of

the field. Second, when you set a specific (non-default) value next to a property, a white

dot appears (there are 5 white dots in Figure 6-12).

Take a look at the Xaml once you have these values set,

Blend has translated your choices into Xaml that will create the look youve chosen. We

have, however, forgotten to change the Content property from Button to Send. The

easiest way to do so is to type Content into the property Search box,

At co you will get back Column, Horizontal Content, Data Content and

Content as shown in Figure 6-13

Figure 5-13. Search with co

Refine your search just a bit further, and you reduce the complexity a bit, as shown in 6-

14,


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Figure 5-14. Refined Search

In any case, remove the word Button from the Content field and put in the word Search.

Your text task is to set the font size to 18 and the font family to Verdana. Oh, and set it to

Bold. (No cheating! Do this in design, not in Xaml!) (Youll find the image on the next

page)

Some (few) controls have a text property and most have a content

property. Those with a content property often fill that property with

text, but they are free to fill it with almost anything else, includingother controls. This is demonstrated in the Tutorial on Styles and

Templates


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Figure 5-15. Setting the Font Family and More


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Creating The Rounded Rectangle Input Area

Examining the finished application shown at the top of the tutorial reveals that the input

area has a rounded rectangle as shown in figure 6-16

Figure 5-16. Input Area is a Rounded Rectangle

This is slightly tricky to achieve since the TextBox does not have a setting for rounding

its corners. It turns out, however, that the Border control does.

Our tricky solution, therefore, is to put a TextBox within a border, and letting the Border

handle the look and feel and the TextBox mange the text handling!

Step one is to fill the grid square with a border. Click on the Grid pallet and expand it to

click on a border, and then drag out the border into the appropriate grid location (well

size it properly with the properties window).

Once in the grid, set its Width and Height to Auto, and its Margin to 4 all around, as

shown in figure 6-17

Figure 5-17. Sizing the Border in the Layout PanelLets set the background brush for the border, by setting the values in the Brushes

property window by hand to 255, 255, 255 with an Alpha (opacity) of 45%.I highly

recommend doing these one by one. AS you set the red value the background turns Red.

When you set the Green background to 255 as well, the background turns bright yellow.

Add 255 for Blue and the background turns bright white. Finally, knocking the Alpha

down to 45% gives us the pale shade were looking for, as shown in figure 6-18


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Figure 5-18. Setting the Background Brush

If you look carefully under the settings for RGBA youll find the hex value #72FFFFFF

which is the equivalent of setting the four values independently (with the alpha value

first).

Our Border control also needs its Border brush set (in 6-18 it is set to No Brush). The

values we want (which it may well default to) are Alpha of 100% and full black(00,00,00).

The Border brush wont appear unless we set its thickness (which defaults to zero); which

we can do in the Appearance panel. Lets set it to 2. This is also where we get to set the

rounded corners, which well set to 5 as shown in Figure 6-19.

Figure 5-19. Setting the Border Thickness and Rounded Corners

Placing the Text Box

The border has the rounded corners, but as noted above, a border cant accept text input.

For that we need a text box, but we dont want the text box to overwrite the background

we just carefully placed in the border.

Zap! All we need to do is make the text box reside within the border, and set it to

transparent!

To place the text box within the border, double click on the border in the Interaction

panel, signaling to Blend that it is now the container for the next control. That is, the next

control we add will not be a sibling, but a child of the border. The yellow rectangle will

jump from Layout Root to the Border as feedback that it is now the active container.

When you drag the text box in, it will be placed inside the text box, as shown in figure 6-

20, both from a design view and a Xaml view.


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Figure 5-20. Text Box Nested within Border

Review of key points

There are a few new concepts all put together in this one construct, so a quick review is

in order:

The border is set with a background color and the rounded corners The text box is nested fully within the border, and the text boxs background

opacity is set to 0 (making it transparent). That allows the text box to pick up

the background color and rounded corners of the border

In order to ensure that the text box will be nested within the border, double clickon the border in the Interaction panel surrounding the border with a yellow box

and thus indicating that it is now the container.

Creating the Top RowWell do the same thing on the top row, except that instead of using a TextBox well use

a textblock, setting the text inside to a font family of Comic Sans MS, a font size of 48

and the text of your own name.

To set the upper right hand corner, begin by double clicking on the LayoutRoot to make

it the container, then click on an Image Control in the Chevron. Set the source property to

point to any image file on your disk.

Creating the Conversation Area

The final part of our IM application is the middle: the conversation area, which will in

fact be a list box. Well place that in a border that will stretch across both columns. You

can place that manually, just by stretching a border across both columns using the mouse.Youll notice as you go to refine the placement in the Layout panel that the ColumnSpan

has been set to 2, and all you need do is fix the Margins to make the border fit snugly

(e.g., with a margin of 4 all around.)


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Youll want to set the background to a solid color ( FF03588D works nicely) and once

again well set the corners to a radius of 5 all around, as well as setting the border to

black and a thickness of 2.

Once again, double click on the new border, and drag a list box (from the chevron) inside

the new border, and set it to fill the border.

Adding dummy data

It is convenient to have dummy data to fill the list box, and the easiest way to do that is in

Xaml. This is a good opportunity to switch to Visual Studio, so save all the files in Blend

but leave blend open and switch over to the project in Visual Studio 2008.

If your project was already open, youll be notified that it has changed, say yes to accept

the changes, and you should find that all the files are shown and your Page.xaml looks

impressively similar to what you just saw in Blend.

Figure 5-21. Examining the Project in Visual Studio

You can now easily populate your list box with dummy list items,


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Save your file and switch back to Blend (no need to close Visual Studio 2008). When you

do, Blend lets you know the files were modified,

Figure 5-22. Blend letting you know the files were modified

Click yes, and your dummy data should be visible.

You can press F5 to run the program as an interim check. Youll find that the image

doesnt appear unless you place a copy of the image file in the bin/debug directory as

well. Thats not a big problem, however, as well be binding to the source for the image

file.

Building the Business Layer

To support the exchange of instant messages, we will build (or, to be more honest, stubout) a service that will identify the remote users name, image and that will manage the

messaging.

Because we are more interested in Silverlight than in building the service (at least for the

purposes of this tutorial) well simplify this by creating a ChatSession class that will

stand in for all the networking, sockets and other plumbing, and which will maintain

instead a collection of Message objects. As you can guess, well also create, therefore, a

Message class to represent each message transmitted by the service.

Because Visual Studio 2008 is better suited to programming than is Blend, well do this

work in Visual Studio 2008 but well get there by right clicking on the solution in Blend

and choosing Edit In Visual Studio, as shown in figure 6-23


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Figure 5-23. Moving to Visual Studio from Blend

Once in Visual Studio 2008 right click on the project and choose Add Class. In the new

items dialog select class and name your new class ChatMessage as shown in figure 6-24

Figure 5-24. Adding the Chat Message Class

The Chat Message class is pretty straight forward, consisting only of two properties,

PublicClass ChatMessage

Private privateUserName AsString


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PublicProperty UserName() AsString

Get

Return privateUserName

EndGet

Set(ByVal value AsString)

privateUserName = value

EndSet

EndProperty

Private privateText AsString

PublicProperty Text() AsString

Get

Return privateText

EndGet


privateText = value

EndSet

EndProperty

EndClass

The ChatSession is somewhat more complex, but well simplify greatly by stubbing out

all the difficult parts.

We begin by marking the class as implementing INotifyPropertyChanged, which as noted

in the DataBinding Tutorial ensures that the UI fields will be updated as the data changes.

PublicClass ChatSession

Implements INotifyPropertyChanged

This interface requires only that we provide a PropertyChangedEventHandler that

implements the PropertyChanged event,

PublicEvent PropertyChanged As PropertyChangedEventHandler Implements

INotifyPropertyChanged.PropertyChanged

The class has two straight forward public properties: one for the users name, and one for

the URL of the users Avitar (image),

Private privateRemoteUserName AsString

PublicProperty RemoteUserName() AsString

Get

Return privateRemoteUserName

EndGet


privateRemoteUserName = value

EndSet

EndProperty

Private privateRemoteAvatarUrl AsString

PublicProperty RemoteAvatarUrl() AsString

Get

Return privateRemoteAvatarUrl

EndGet

FriendSet(ByVal value AsString)

privateRemoteAvatarUrl = value

EndSet

EndProperty

Next we want to create a collection of the ChatMessages. What we want, however, is to

raise an event each time the collection changes (e.g., a message is added) and we want

the list box to respond to that event. We could create all of that, but the framework makes


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it easy. Listbox already knows to respond to PropertyChanged events, and there is a

special collection type ObservableCollection(of) that fires exactly that event every time

the collection is changed. This makes life a walk in the park,

Private privateMessageHistory As ObservableCollection(Of ChatMessage)

PublicProperty MessageHistory() As ObservableCollection(Of ChatMessage)

Get

Return privateMessageHistory

EndGet

FriendSet(ByVal value As ObservableCollection(Of ChatMessage))

privateMessageHistory = value

EndSet

EndProperty

Sending a message is now as simple as adding a new Chat message where the text is

taken from the message box and the user name is taken from the current users name (for

now, hard coded to Me)

PublicSub SendMessage(ByVal message AsString)

' Todo: Send to remote chat server over sockets

MessageHistory.Add(New ChatMessage With {.Text = message, .UserName = "Me"})

EndSub

We leave it as an exercise for the reader to actually send the message

across the network

Before we can send messages, however, we must connect with the remote user,

obtaining the remote users name, avatar and initializing the observable collection of

messages,

PublicSub ConnectWithRemoteUser(ByVal remoteUserName AsString)

' Todo: 1) Wire-Up socket stack to receive notifications of received messages

' 2) Wire-Up to a remote avatar service instead of hard-coding my picture

RemoteUserName = remoteUserNameRemoteAvatarUrl = "jesse.jpg"

MessageHistory = New ObservableCollection(Of ChatMessage)()

' Notify any listeners of property changes

RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs("RemoteUserName"))

RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs("RemoteAvatarUrl"))

RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs("MessageHistory"))

EndSub

Finally, well add a method we can call that will simulate an exchange of IMs (but well

only call this method when were in design mode; not when the program is actually

running)

PrivateSub PopulateWithDummyData()

RemoteUserName = "BillG"

RemoteAvatarUrl = "billg.jpg"

MessageHistory = New ObservableCollection(Of ChatMessage)()

MessageHistory.Add(New ChatMessage With

{.UserName = "BillG", .Text = "How is your video going?"})

MessageHistory.Add(New ChatMessage With

{.UserName = "BillG", .Text = "Hmmm....you there?"})


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MessageHistory.Add(New ChatMessage With {.UserName = "BillG", .Text =

"Hello???"})

MessageHistory.Add(New ChatMessage With {.UserName = "Jesse", .Text = "Sorry

Bill - working on a video..."})

MessageHistory.Add(New ChatMessage With {.UserName = "BillG", .Text = "Oh -

ok."})

EndSub

To ensure that this dummy data is in place during design mode, well test in the

constructor of ChatSession,

PublicSubNew()

If HtmlPage.IsEnabled = FalseThen

PopulateWithDummyData()

EndIf

EndSub

DataBindingWith these classes in place (you did build to make sure all is well, yes?) were ready to

data bind. Lets do that in Blend (!)

Make sure youve saved all your files in Visual Studio 2008 but dont close it, just switch

over to Blend. Say yes to the something has changed when I wasnt looking dialog

(your wording may vary). Under the project panel you should see a Data panel, within

which is a tab marked CLR Object. Click on that and Hey! Presto! You will see Blend for

Silverlight that will open up to show a dialog that lets you add any CLR object as a data

source. Notice that ChatMessage and ChatSession are listed. Click on Chat session and

click OK and Chat SessionDS appears in your Data list, as shown in Figure 6-25.

Figure 5-25. Adding Chat Session as a Data Source

Now, this is really scary how easy this is; click on RemoteUserName, and drag it onto the

name field at the top of the design and let go, as shown in figure 6-26


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Figure 5-26. Binding the RemoteUserName to the TextBlock by Dragand Drop

When you let go, Blend recognizes that you are binding the data, and asks first which

field youd like to bind to (guessing youd like to bind to Text) and then offers (if you

expand the dialog) additional options, such as two-way binding (so that if the UI is

updated, the changes will be written back to the data source), as shown in figure 6-27

Figure 5-27. Creating the Data Binding

When you click OK the UI is immediately updated with the bound data.


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Figure 5-28. Bound Data

Unfortunately, your list box does not know how to display a Chat Message (why would

it?). We can fix that, of course, by using a Data template,

This teaches the ListBox how to display each of the list items, specifying that each will

be dislayed with three TextBlocks, aligned horizontally by a stack panel, as shown in

figure 6-29


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Figure 5-29. Data Template at work

Adding Templates

The Listbox and especially the Start Button dont quite look the way wed like. In the

previous version of this tutorial we fixed them with hand-written templates, but Blend

now offers a far better solution, which we will introduce in the next tutorial, so were

going to leave this as it is for now (not quite done, but a good way towards a solid

introduction to using Blend and Visual Studio together for programming an application).

Better not to finish, than to show you what amounts to an obsolete and inferior way ofsolving the problem. In the interim, both Tim Heurer and I and many others will be

blogging about the new approach to Templates, and well have the full tutorial out within

a few weeks.

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