CODEWITHSUNDEEP
c#wpfxamlpropertiesdependencies
AidanH
AidanH

Reputation: 522

WPF Dependency Property

I'm struggling to get my head around dependency properties in WPF, maybe because the use case I'm looking for is very specific and not well documented.

What I have is a custom control that looks like this (please do ignore all the terrible code, it is temporary!):

<UserControl x:Class="HydroAccessory.Controls.FillGraph"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
         xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
         xmlns:local="clr-namespace:HydroAccessory.Controls"
         mc:Ignorable="d"
         SizeChanged="FillGraph_SizeChanged"
         d:DesignHeight="200" d:DesignWidth="300">
<Grid>

    <TextBlock x:Name="PercentageTB" Text="Fill Percentage: 0%" />

</Grid>

I call it inside my main window like this:

<controls:FillGraph x:Name="HydroModel" />

and the code inside the control is as follows:

using System;
using System.Windows;
using System.Windows.Controls;

namespace HydroAccessory.Controls
{
public partial class FillGraph : UserControl
{
    private float percentage;
    public float Percentage
    {
        get
        {
            return percentage;
        }
        set
        {
            percentage = value;
            PercentageTB.Text = String.Format("Fill Percentage: {0}", percentage.ToString() + "%");
        }
    }

    public FillGraph()
    {
        InitializeComponent();
    }
}
}

All that I want to be able to do is say in my custom control call in the main window:

<controls:FillGraph x:Name="HydroModel" Percentage="{Binding FillPercentage}" />

(Where FillPercentage is something in another script that you don't need to worry about). The control will be expanded, so it needs to stay as a custom control. I understand I may need dependency properties, but after trying many different ways I cannot figure out how to do this seemingly simple task. Help is appreciated.

Upvotes: 3

Views: 2328

Answers (1)

15ee8f99-57ff-4f92-890c-b56153
15ee8f99-57ff-4f92-890c-b56153

Reputation: 37060

There isn't a dependency property in your code.

This is a dependency property:

public partial class FillGraph : UserControl
{
    public FillGraph()
    {
        InitializeComponent();
    }

    public float Percentage
    {
        get { return (float)GetValue(PercentageProperty); }
        set { SetValue(PercentageProperty, value); }
    }

    //  Using a DependencyProperty as the backing store for Percentage.  This 
    //  enables animation, styling, binding, etc...
    public static readonly DependencyProperty PercentageProperty =
        DependencyProperty.Register("Percentage", typeof(float), 
                typeof(FillGraph), new PropertyMetadata(0.0f));
}

Upvotes: 7

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