Common-VS2019/SacsStandardMob/Mobile/Forms/Controls/SaxTabControl.cs

using Sarand.Net.Standard.Mobile.Forms.Layouts;
using Sarand.Net.Standard.Mobile.Forms.Panels;
using Sarand.Net.Standard.Mobile.Forms.Views;
using System;
using System.Collections.Generic;
using System.Text;
using Xamarin.Forms;

namespace Sarand.Net.Standard.Mobile.Forms.Controls
{
	//=======================================================================
	public class SaxTabControl : ContentView
	{
		//-------------------------------------------------------------------
		// Definitions.

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

		//-------------------------------------------------------------------
		// Construction.
		public SaxTabControl ()
		{
			// Main layout - vertical stack with two rows.
			// 1. Header - tab panel captions.
			// 2. Body - current tab panel.
			VerticalOptions = LayoutOptions.FillAndExpand;
			//BackgroundColor = Color.LightSkyBlue;
			mainLayout.VerticalOptions = LayoutOptions.FillAndExpand;
			mainLayout.Spacing = 2.0;
			Content = mainLayout;

			// Header panel - tab captions.
			//headerPanel.HorizontalOptions = LayoutOptions.Fill;
			mainLayout.Children.Add(headerPanel);

			// Default label font size.
			DefaultHeaderFontSize = new Label().FontSize;
			HeaderFontSize = DefaultHeaderFontSize;

			// Body panel.
			bodyPanel.HorizontalOptions = LayoutOptions.Fill;
			bodyPanel.VerticalOptions = LayoutOptions.FillAndExpand;
			bodyPanel.BackgroundColor = Color.LightYellow;
			mainLayout.Children.Add(bodyPanel);
		}

		//-------------------------------------------------------------------
		// Properties.
		// Header.
		public Color HeaderBackgroundColor { get { return headerPanel.BackgroundColor; } set { headerPanel.BackgroundColor = value; } }
		public Color CaptionBackgroundColor { get; set; } = Color.Transparent;
		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); }
		}

		//-------------------------------------------------------------------
		//                        T a b   P a n e l s
		//-------------------------------------------------------------------
		public void ClearPanels ()
		{
			tabPanels.Clear();
			RefreshLayout();
		}
		public void AddPanel (String caption, SaxContentView panel)
		{
			AddPanel(new SaxTabPanel(caption, panel));
		}
		public void AddPanel (SaxTabPanel tabPanel)
		{
			AddPanels(new List<SaxTabPanel>() { tabPanel });
		}
		public void AddPanels (IEnumerable<SaxTabPanel> tabPanels)
		{
			this.tabPanels.AddRange(tabPanels);
			RefreshLayout();
		}

		//-------------------------------------------------------------------
		//                    R e f r e s h   L a y o u t
		//-------------------------------------------------------------------
		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.
				SaxTabPanel tabPanel = tabPanels[tabPanelIdx];

				// Header caption.
				SaxContentView captionPanel = new SaxContentView()
				{
					Padding = HeaderCaptionPadding,
					BackgroundColor = CaptionBackgroundColor,
					HorizontalOptions = LayoutOptions.FillAndExpand,
					VerticalOptions = LayoutOptions.FillAndExpand
				};
				if (tabPanelIdx > 0)
					captionPanel.Margin = new Thickness(HeaderCaptionSpacing, 0, 0, 0);
				SaxLabel captionLabel = new SaxLabel()
				{
					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);
		}

		//-------------------------------------------------------------------
		//                  C h a n g e   T a b   P a n e l
		//-------------------------------------------------------------------
		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 headerPanelView = headerPanel.Children[headerPanelIdx];
				Label headerPanelLabel = (headerPanelView as Label);
				if (headerPanelLabel == null && headerPanelView is ContentView)
					headerPanelLabel = ((headerPanelView as ContentView).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;
		}

		//-------------------------------------------------------------------
		//                    C o n t r o l   E v e n t s
		//-------------------------------------------------------------------

		//-------------------------------------------------------------------
	}
	//=======================================================================
}