ChrisKaczor.Wpf.Controls.Toolbar/SplitButton/SplitButton.cs

//  --------------------------------
//  Copyright (c) Huy Pham. All rights reserved.
//  This source code is made available under the terms of the Microsoft Public License (Ms-PL)
//  http://www.opensource.org/licenses/ms-pl.html
//  ---------------------------------

using System.Windows;
using System.Windows.Controls;
using System.Windows.Controls.Primitives;
using System.Windows.Data;
using System.Windows.Input;
using System.Windows.Media;

namespace ChrisKaczor.Wpf.Controls.Toolbar
{
    [TemplatePart(Name = "PART_Button", Type = typeof(ButtonBase))]
    public class SplitButton : ToggleButton
    {
        #region Dependency Properties

        public static readonly DependencyProperty DropDownContextMenuProperty = DependencyProperty.Register("DropDownContextMenu", typeof(ContextMenu), typeof(SplitButton), new UIPropertyMetadata(null));
        public static readonly DependencyProperty ImageProperty = DependencyProperty.Register("Image", typeof(ImageSource), typeof(SplitButton));
        public static readonly DependencyProperty TextProperty = DependencyProperty.Register("Text", typeof(string), typeof(SplitButton));
        public static readonly DependencyProperty TargetProperty = DependencyProperty.Register("Target", typeof(UIElement), typeof(SplitButton));
        public static readonly DependencyProperty MainButtonCommandProperty = DependencyProperty.Register("MainButtonCommand", typeof(ICommand), typeof(SplitButton), new FrameworkPropertyMetadata(null));
        public static readonly DependencyProperty DropDownButtonCommandProperty = DependencyProperty.Register("DropDownButtonCommand", typeof(ICommand), typeof(SplitButton), new FrameworkPropertyMetadata(null));
       
        #endregion

        #region Constructors

        public SplitButton()
        {
            // Bind the ToogleButton.IsChecked property to the drop-down's IsOpen property 
            var binding = new Binding("DropDownContextMenu.IsOpen") { Source = this };
            SetBinding(IsCheckedProperty, binding);

            Loaded += HandleSplitButtonLoaded;
        }

        void HandleSplitButtonLoaded(object sender, RoutedEventArgs e)
        {
            if (Parent is ToolBar)
            {
                Style style = (Style) TryFindResource("ToolBarSplitButtonStyle");
                if (style != null)
                    Style = style;
            }

            Loaded -= HandleSplitButtonLoaded;
        }

        #endregion

        #region Properties

        public ContextMenu? DropDownContextMenu
        {
            get => GetValue(DropDownContextMenuProperty) as ContextMenu;
            set => SetValue(DropDownContextMenuProperty, value);
        }

        public ImageSource? Image
        {
            get => GetValue(ImageProperty) as ImageSource;
            set => SetValue(ImageProperty, value);
        }

        public string? Text
        {
            get => GetValue(TextProperty) as string;
            set => SetValue(TextProperty, value);
        }

        public UIElement? Target
        {
            get => GetValue(TargetProperty) as UIElement;
            set => SetValue(TargetProperty, value);
        }

        public ICommand? MainButtonCommand
        {
            get => GetValue(MainButtonCommandProperty) as ICommand;
            set => SetValue(MainButtonCommandProperty, value);
        }

        public ICommand? DropDownButtonCommand
        {
            get => GetValue(DropDownButtonCommandProperty) as ICommand;
            set => SetValue(DropDownButtonCommandProperty, value);
        }

        #endregion

        #region Public Override Methods

        /// <summary>
        /// 
        /// </summary>
        public override void OnApplyTemplate()
        {
            base.OnApplyTemplate();
            SetMainButtonCommand();
        }

        #endregion

        #region Protected Override Methods

        protected override void OnPropertyChanged(DependencyPropertyChangedEventArgs e)
        {
            base.OnPropertyChanged(e);

            if (e.Property == MainButtonCommandProperty)
                SetMainButtonCommand();

            if (e.Property == DropDownButtonCommandProperty)
                Command = DropDownButtonCommand;
        }

        protected override void OnClick()
        {
            if (DropDownContextMenu == null) return;

            if (DropDownButtonCommand != null) 
                DropDownButtonCommand.Execute(null);

            // If there is a drop-down assigned to this button, then position and display it 
            DropDownContextMenu.PlacementTarget = this;
            DropDownContextMenu.Placement = PlacementMode.Bottom;
            DropDownContextMenu.IsOpen = !DropDownContextMenu.IsOpen;
        }

        #endregion

        #region Private Methods

        private void SetMainButtonCommand()
        {
            // Set up the event handlers
            if (Template != null)
            {
                var button = Template.FindName("PART_Button", this) as ButtonBase;
                if (button != null) button.Command = MainButtonCommand;
            }
        }

        #endregion
    }
}