Common-VS2019/SacsMobileMaui/Maui/Controls/SamTabControl.cs

using Microsoft.Maui;
using Microsoft.Maui.Layouts;
using Sarand.Net.Mobile.Maui.App;
using Sarand.Net.Mobile.Maui.Layouts;
using Sarand.Net.Mobile.Maui.Panels;
using Sarand.Net.Mobile.Maui.Views;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Sarand.Net.Mobile.Maui.Controls
{
	public class SamTabControl : ContentView, ISamView
	{
		// --- Data Members ---

		private readonly List<SamTabPanel> tabPanels = new List<SamTabPanel>();
		private short currentTabIdx = -1;
		// Main layout to host header and body.
		private SamStackLayout mainLayout = new SamStackLayout() { Orientation = StackOrientation.Vertical };
		// Header layout - horizontal row.
		private SamFlexLayout headerPanel = new SamFlexLayout() { Direction = FlexDirection.Row, AlignItems = FlexAlignItems.Center, JustifyContent = FlexJustify.Start, HorizontalOptions = LayoutOptions.Start };
		// Body - Content view to host tab panel.
		private SamContentView bodyPanel = new SamContentView();

		// --- Construction ---

		public SamTabControl()
		{
			// --- Main layout ---

			VerticalOptions = LayoutOptions.FillAndExpand;
			mainLayout.VerticalOptions = LayoutOptions.FillAndExpand;
			mainLayout.Spacing = 2.0;
			Content = mainLayout;

			// --- Header panel ---

			headerPanel.BackgroundColor = Sam.Visuals.Form.TabControl.HeaderBackgroundColor;
			mainLayout.Children.Add(headerPanel);

			// --- Default font size ---

			DefaultHeaderFontSize = new Label().FontSize;
			HeaderFontSize = DefaultHeaderFontSize;

			// --- Body panel ---

			bodyPanel.HorizontalOptions = LayoutOptions.Fill;
			bodyPanel.VerticalOptions = LayoutOptions.FillAndExpand;
			bodyPanel.BackgroundColor = Sam.Visuals.Form.TabControl.BodyBackgroundColor;
			mainLayout.Children.Add(bodyPanel);
		}

		// --- Properties ---

		// Header.
		public Color HeaderBackgroundColor { get { return headerPanel.BackgroundColor; } set { headerPanel.BackgroundColor = value; } }
		public Color CaptionBackgroundColor { get; set; } = Sam.Visuals.Form.TabControl.CaptionBackgroundColor;
		public double DefaultHeaderFontSize { get; }
		public double HeaderFontSize { get; set; }
		public double HeaderMarginBottom
		{
			get { return mainLayout.Spacing; }
			set { if (mainLayout.Spacing == value) return; mainLayout.Spacing = value; }
		}
		public Thickness HeaderPadding
		{
			get { return mainLayout.Padding; }
			set { if (mainLayout.Padding == value) return; mainLayout.Padding = value; }
		}
		public Thickness HeaderCaptionPadding { get; set; } = new Thickness(12.0, 4.0);
		public double HeaderCaptionSpacing { get; set; } = 4.0;
		// Tab panels.
		public Color BodyBackgroundColor { get { return bodyPanel.BackgroundColor; } set { bodyPanel.BackgroundColor = value; } }
		public int PanelCount { get { return tabPanels.Count; } }
		public short TabPanelIndex
		{
			get { return currentTabIdx; }
			set { ChangeTabPanel(value); }
		}

		// --- Tab panels ---

		public void ClearPanels()
		{
			tabPanels.Clear();
			RefreshLayout();
		}
		public void AddPanel(String caption, SamContentView panel)
		{
			AddPanel(new SamTabPanel(caption, panel));
		}
		public void AddPanel(SamTabPanel tabPanel)
		{
			AddPanels(new List<SamTabPanel>() { tabPanel });
		}
		public void AddPanels(IEnumerable<SamTabPanel> tabPanels)
		{
			this.tabPanels.AddRange(tabPanels);
			RefreshLayout();
		}

		// --- Refresh layout ---

		private void RefreshLayout()
		{
			// Clear existing components.
			headerPanel.Children.Clear();
			bodyPanel.Content = null;

			// Add each Tab panel in turn.
			for (short tabPanelIdx = 0; tabPanelIdx < tabPanels.Count; tabPanelIdx++)
			{
				short tabPanelIdx_Local = tabPanelIdx; // Loop closure.
				SamTabPanel tabPanel = tabPanels[tabPanelIdx];

				// Header caption.
				SamContentView captionPanel = new SamContentView()
				{
					Padding = HeaderCaptionPadding,
					BackgroundColor = CaptionBackgroundColor,
					HorizontalOptions = LayoutOptions.FillAndExpand,
					VerticalOptions = LayoutOptions.FillAndExpand
				};
				if (tabPanelIdx > 0)
					captionPanel.Margin = new Thickness(HeaderCaptionSpacing, 0, 0, 0);
				SamLabel captionLabel = new SamLabel()
				{
					Text = tabPanel.Caption,
					FontSize = HeaderFontSize
				};
				captionPanel.Content = captionLabel;
				headerPanel.Children.Add(captionPanel);

				// Tap Gesture.
				var tapGestureRecognizer = new TapGestureRecognizer();
				tapGestureRecognizer.Tapped += (s, e) => { ChangeTabPanel(tabPanelIdx_Local); };
				captionPanel.GestureRecognizers.Add(tapGestureRecognizer);
			}
			// Current tab retains previous value if still valid (in panel range),
			// is restricted to the range 0 to number of panels - 1 if there are panels,
			// or -1 if no panels.
			currentTabIdx = (short)(tabPanels.Count > 0 ? Math.Max(0, Math.Min(tabPanels.Count - 1, currentTabIdx)) : -1);
			if (tabPanels.Count > 0)
				ChangeTabPanel(currentTabIdx);
		}

		// --- Change tab panel ---

		private void ChangeTabPanel(short tabPanelIdx)
		{
			// Validate requested panel index.
			if (tabPanelIdx < 0 || tabPanelIdx >= tabPanels.Count)
				throw new IndexOutOfRangeException("Tab panel index must be between 0 & " + (tabPanels.Count - 1) + ". Supplied value: " + tabPanelIdx);

			// Highlight selected tab panel header caption.
			for (short headerPanelIdx = 0; headerPanelIdx < headerPanel.Children.Count; headerPanelIdx++)
			{
				// View.
				View? headerPanelView = headerPanel.Children[headerPanelIdx] as View;
				// Label.
				Label? headerPanelLabel = (headerPanelView as Label);
				if (headerPanelLabel == null && headerPanelView is ContentView)
					headerPanelLabel = ((ContentView)headerPanelView).Content as Label;
				if (headerPanelLabel != null)
				{
					if (headerPanelIdx == tabPanelIdx)
						headerPanelLabel.FontAttributes = FontAttributes.Bold;
					else headerPanelLabel.FontAttributes = FontAttributes.None;
				}
			}

			// Display selected tab panel.
			bodyPanel.Content = tabPanels[tabPanelIdx];
			currentTabIdx = tabPanelIdx;
		}

		// --- Component state ---

		public void ConfigureComponents() { }
		public void SetControlActivity(bool enabled)
		{
			if (IsEnabled != enabled) IsEnabled = enabled;
			SetControlsReadOnly();
		}
		public void SetControlsReadOnly() { }

		// --- The End ---
	}
}