1 Basics

XML Basics

General Rules

• XML is case sensitive, so <Button> and <button> are different tags.
• All tags must be closed, either with a closing tag or self-closing tag. for example, <Button></Button> and <Button /> are valid, but <Button> is not valid.
• All attributes must be quoted, either with single or double quotes. For example, <Button Content="Click Me" /> is valid, but <Button Content=Click Me /> is not valid.
• XML have only one root tag, so you can have only one top level tag. For example, <Button /><TextBlock /> is not valid, but <StackPanel><Button /><TextBlock /></StackPanel> is valid.
• XML is hierarchical, so you can have nested tags. For example, <Button><TextBlock Text="Click Me" /></Button> is valid

Close tag without children

• For tag without children you can use either of the following syntax

  <!-- Open and Close tag -->
  <Button Content="Click Me"></Button>
  

  <!-- Self Closing tag -->
  <Button Content="Click Me" />
  

• This is more readable and preferred way to write XML tag without children

Close tag with children

• You must follow this syntax to close tag with children

  <Button>
      <Button.Content>
          Click Me
      </Button.Content>
  </Button>
  

Namespaces matter in XML

• WPF uses XML namespaces to differentiate between different types of controls and elements. For example, the Button control is defined in the http://schemas.microsoft.com/winfx/2006/xaml/presentation namespace, while the TextBlock control is defined in the http://schemas.microsoft.com/winfx/2006/xaml/presentation namespace.
• If namespaces are wrong, controls may not be recognized.

Sample WPF Form

<Window x:Class="WpfApp.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:local="clr-namespace:WpfApp" mc:Ignorable="d" Title="MainWindow" Height="450" Width="800">
    <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*"/>
            <ColumnDefinition Width="200"/>
        </Grid.ColumnDefinitions>
        <!-- Add Stack Panel in first column -->
        <StackPanel Grid.Column="0" Background="White">
            <!-- Add List View with 3 columns -->
            <TextBlock Name="NameTextBlock" Text="Name" FontWeight="Bold" Margin="10"/>
            <TextBox Name="NameTextBox" Margin="10"/>
            <TextBlock Name="AgeTextBlock" Text="Age" FontWeight="Bold" Margin="10"/>
            <TextBox Name="AgeTextBox" Margin="10"/>
            <TextBlock Name="BalanceTextBlock" Text="Balance" FontWeight="Bold" Margin="10"/>
            <TextBox Name="BalanceTextBox" Margin="10"/>

        </StackPanel>
        <!-- Add Stack Panel in second  column -->
        <StackPanel Grid.Column="1" Background="LightGray">
            <Button 
                Name="RunButton" Content="Run" Click="RunButton_Click"
                Margin="10"/>
        </StackPanel>
    </Grid>
</Window>

 public partial class MainWindow : Window
 {
     public MainWindow()
     {
         InitializeComponent();

     }
     private void RunButton_Click(object sender, RoutedEventArgs e)
     {
         MessageBox.Show($"Name: {NameTextBox.Text}\nAge: {AgeTextBox.Text}\nBalance: {BalanceTextBox.Text}");
     }
 }

Calling WPF form from console APP

using System;
using System.Windows;

namespace ConsoleApp
{
    internal static class Program
    {
        [STAThread]
        private static void Main()
        {
            // Initialize WPF Application
            var app = new Application();

            var frm = new AboutForm();
            frm.ShowDialog();
        }
    }
}

To Add WPF Form to existing project

• Add this references

  <Reference Include="System.Xaml">
    <RequiredTargetFramework>4.0</RequiredTargetFramework>
  </Reference>
  <Reference Include="PresentationCore" />
  <Reference Include="PresentationFramework" />
  <Reference Include="WindowsBase" />