ColorPickerButton.cs

// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Windows.UI;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;

namespace Microsoft.Toolkit.Uwp.UI.Controls
{
    /// <summary>
    /// A <see cref="DropDownButton"/> which displays a color as its <c>Content</c> and it's <c>Flyout</c> is a <see cref="ColorPicker"/>.
    /// </summary>
    [TemplatePart(Name = nameof(CheckeredBackgroundBorder), Type = typeof(Border))]
    public partial class ColorPickerButton : DropDownButton
    {
        /// <summary>
        /// Gets the <see cref="Controls.ColorPicker"/> instances contained by the <see cref="DropDownButton"/>.
        /// </summary>
        public ColorPicker ColorPicker { get; private set; }

        /// <summary>
        /// Gets or sets the <see cref="Style"/> for the <see cref="Controls.ColorPicker"/> control used in the button.
        /// </summary>
        public Style ColorPickerStyle
        {
            get
            {
                return (Style)GetValue(ColorPickerStyleProperty);
            }

            set
            {
                SetValue(ColorPickerStyleProperty, value);
            }
        }

        /// <summary>
        /// Identifies the <see cref="ColorPickerStyle"/> dependency property.
        /// </summary>
        public static readonly DependencyProperty ColorPickerStyleProperty = DependencyProperty.Register("ColorPickerStyle", typeof(Style), typeof(ColorPickerButton), new PropertyMetadata(default(Style)));

        /// <summary>
        /// Gets or sets the <see cref="Style"/> for the <see cref="FlyoutPresenter"/> used within the <see cref="Flyout"/> of the <see cref="DropDownButton"/>.
        /// </summary>
        public Style FlyoutPresenterStyle
        {
            get
            {
                return (Style)GetValue(FlyoutPresenterStyleProperty);
            }

            set
            {
                SetValue(FlyoutPresenterStyleProperty, value);
            }
        }

        /// <summary>
        /// Identifies the <see cref="FlyoutPresenterStyle"/> dependency property.
        /// </summary>
        public static readonly DependencyProperty FlyoutPresenterStyleProperty = DependencyProperty.Register("FlyoutPresenterStyle", typeof(Style), typeof(ColorPickerButton), new PropertyMetadata(default(Style)));

#pragma warning disable CS0419 // Ambiguous reference in cref attribute
        /// <summary>
        /// Gets or sets the selected <see cref="Windows.UI.Color"/> the user has picked from the <see cref="ColorPicker"/>.
        /// </summary>
#pragma warning restore CS0419 // Ambiguous reference in cref attribute
        public Color SelectedColor
        {
            get { return (Color)GetValue(SelectedColorProperty); }
            set { SetValue(SelectedColorProperty, value); }
        }

        /// <summary>
        /// Identifies the <see cref="SelectedColor"/> dependency property.
        /// </summary>
        public static readonly DependencyProperty SelectedColorProperty =
            DependencyProperty.Register(nameof(SelectedColor), typeof(Color), typeof(ColorPickerButton), new PropertyMetadata(null));

#pragma warning disable SA1306 // Field names should begin with lower-case letter
        //// Template Parts
        private Border CheckeredBackgroundBorder;
#pragma warning restore SA1306 // Field names should begin with lower-case letter

        /// <summary>
        /// Initializes a new instance of the <see cref="ColorPickerButton"/> class.
        /// </summary>
        public ColorPickerButton()
        {
            this.DefaultStyleKey = typeof(ColorPickerButton);
        }

        /// <inheritdoc/>
        protected override void OnApplyTemplate()
        {
            if (ColorPicker != null)
            {
                ColorPicker.ColorChanged -= ColorPicker_ColorChanged;
            }

            base.OnApplyTemplate();

            if (ColorPickerStyle != null)
            {
                ColorPicker = new ColorPicker() { Style = ColorPickerStyle };
            }
            else
            {
                ColorPicker = new ColorPicker();
            }

            ColorPicker.Color = SelectedColor;
            ColorPicker.ColorChanged += ColorPicker_ColorChanged;

            if (Flyout == null)
            {
                Flyout = new Flyout()
                {
                    // TODO: Expose Placement
                    Placement = Windows.UI.Xaml.Controls.Primitives.FlyoutPlacementMode.BottomEdgeAlignedLeft,
                    FlyoutPresenterStyle = FlyoutPresenterStyle,
                    Content = ColorPicker
                };
            }

            if (CheckeredBackgroundBorder != null)
            {
                CheckeredBackgroundBorder.Loaded -= this.CheckeredBackgroundBorder_Loaded;
            }

            CheckeredBackgroundBorder = GetTemplateChild(nameof(CheckeredBackgroundBorder)) as Border;

            if (CheckeredBackgroundBorder != null)
            {
                CheckeredBackgroundBorder.Loaded += this.CheckeredBackgroundBorder_Loaded;
            }
        }

        private void ColorPicker_ColorChanged(Microsoft.UI.Xaml.Controls.ColorPicker sender, Microsoft.UI.Xaml.Controls.ColorChangedEventArgs args)
        {
            SelectedColor = args.NewColor;
        }

        private async void CheckeredBackgroundBorder_Loaded(object sender, RoutedEventArgs e)
        {
            await ColorPickerRenderingHelpers.UpdateBorderBackgroundWithCheckerAsync(
                sender as Border,
                ColorPicker.CheckerBackgroundColor); // TODO: Check initialization
        }
    }
}