自定义控件模板，显示和WPF

Question

I come from a Windows Forms background and I am a little confused on what would be considered the best practice for controlling the display of a control. I am working on a Control that I want some "Eye Candy" on. In WinForms I would override the Paint Event to do any kind of visual programming. I understand that the main reason WPF was conceived, is to separate the Action from the Display.

Here is the part that I am unsure about. Say I want to draw some simple lines in the "Background" of the Control. Would it be considered best practice to add the lines into the Template or do the Drawing of the Lines in the Code Behind as I would do in WinForms?

For Example say I am developing a Control named CustomControl1 and want to draw a line the entire width of the control that is centered vertically like:

Would it be better to do the line in the Code Behind or in the template?

I can do it entirely in xaml like so:

<Style TargetType="{x:Type local:CustomControl1}">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type local:CustomControl1}">
                    <Border Padding="{TemplateBinding Padding}"
                            Background="{TemplateBinding Background}"
                            BorderBrush="{TemplateBinding BorderBrush}"
                            BorderThickness="{TemplateBinding BorderThickness}">

                        <Grid HorizontalAlignment="Left" Width="{Binding ActualWidth}">

                            <Border HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Background="Aqua">
                                <Path Stretch="Fill" Stroke="Black" StrokeThickness="1" Data="M 0,0.5 H 1" />
                            </Border>

                            <TextBlock 
                                    HorizontalAlignment="Center"
                                    Text="Some Text" />
                        </Grid>
                    </Border>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

I am not sure if this is the "Best Practice" or if there another way that I should use all together? Is there one reason to use one over the other? Are there any performance gains/losses?

Answer 1

Anything static should be in the xaml. For example, if you know this line will always start at this position, with this size, put it in the xaml. But if the line is dynamic, like you can have one or many lines, with angles, curves, different colors ect... You might want to initialize it yourself and set properties in your user control.

Answer 2

IMO,your code is fine. No one would ever do " do the Drawing of the Lines in the Code Behind as I would do in WinForms" for this kind of requirements in WPF.

Controlling the display of control using ControlTemplate and Style is best and recommended approach in WPF. Also, if you need the Controls in code,you can get the Controls defined in ControlTemplate using GetTemplateChild method inside OnApplyTemplate override of your custom control.