ITブログ時々なんでもブログ

using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows.Input;
using UIKit;
using CoreGraphics;
using Xamarin.Forms;
using Xamarin.Forms.Platform.iOS;
using AppName.iOS.Renderer;
[assembly: ExportRenderer(typeof(Page), typeof(CustomPageRenderer))]

namespace AppName.iOS.Renderer
{
    public class CustomPageRenderer : PageRenderer
    {
        List<ToolbarItem> _primaryItems;
        readonly Dictionary<UIButton, ICommand> _buttonPrimaryCommands = new Dictionary<UIButton, ICommand>();

        protected override void OnElementChanged(VisualElementChangedEventArgs e)
        {
            var page = e.NewElement as Page;
            if (page != null)
            {
                //プライマリ
                //プライマリメニューバーは（3, 2, 1）というように右から並ぶため、Order by Desc で逆に並び替える
                _primaryItems = page.ToolbarItems.Where(i => i.Order == ToolbarItemOrder.Primary).OrderByDescending(r => r.Priority).ToList();
                _primaryItems.ForEach(t => page.ToolbarItems.Remove(t));
            }
            base.OnElementChanged(e);

        }

        public override void ViewWillAppear(bool animated)
        {
            //プライマリ
            if (_primaryItems != null && _primaryItems.Count > 0)
            {
                var tools = new List<UIBarButtonItem>();

                //スペース調整を追加（その１）
                UIBarButtonItem sideMarginSpaceAdjustment1 = new UIBarButtonItem();
                sideMarginSpaceAdjustment1.Width = -16.0f;
                tools.Add(sideMarginSpaceAdjustment1);

                _buttonPrimaryCommands.Clear();
                foreach (var tool in _primaryItems)
                {
                    tool.PropertyChanged += this.ToolPropertyChanged;

                    //UIButtonの設定
                    UIButton button = new UIButton();
                    button.SetImage(UIImage.FromFile(tool.Icon), UIControlState.Normal);
                    button.SizeToFit();
                    button.TintColor = UIColor.White;
                    button.TouchDown += this.ToolPrimaryClicked;

                    //UIBarButtonItemの設定
                    UIBarButtonItem buttonItem = new UIBarButtonItem(button);
                    buttonItem.Title = tool.Text;
                    buttonItem.Style = UIBarButtonItemStyle.Plain;
                    buttonItem.TintColor = UIColor.White;

                    _buttonPrimaryCommands.Add(button, tool.Command);
                    tools.Add(buttonItem);

                    //スペース調整を追加（その２）
                    UIBarButtonItem sideMarginSpaceAdjustment2 = new UIBarButtonItem();
                    sideMarginSpaceAdjustment2.Width = -16.0f;
                    tools.Add(sideMarginSpaceAdjustment2);
                }

                var navigationItem = this.NavigationController.TopViewController.NavigationItem;
                if (navigationItem != null)
                {
                    //ツールバーを再作成
                    navigationItem.RightBarButtonItems = tools.ToArray();   //逆順でセットされている
                }
            }

            base.ViewWillAppear(animated);
        }

        /// <summary>
        /// ツールバーアイテムが変更になった場合に外観を変更する
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="args"></param>
        void ToolPropertyChanged(object sender, EventArgs args)
        {
            var navigationItem = this.NavigationController.TopViewController.NavigationItem;
            if (navigationItem != null)
            {
                var tool = sender as ToolbarItem;
                int cnt = navigationItem.RightBarButtonItems.Count() - 1;   //逆順でセットされている為、メニューアイテム数から減算する為
                int index = cnt - (tool.Priority + tool.Priority / 2);    //sideMarginSpaceAdjustmentを入れた分だけindexを加算する

                var button = (UIButton)(navigationItem.RightBarButtonItems[index].CustomView);
                if (button != null)
                {
                    //メニューアイコンを変更
                    if (tool.Icon != null)
                    {
                        button.SetImage(UIImage.FromFile(tool.Icon), UIControlState.Normal);
                        button.SizeToFit();
                    }
                }
                //メニュータイトル文字列を変更
                navigationItem.RightBarButtonItems[index].Title = tool.Text;
            }
        }

        /// <summary>
        /// プライマリメニューのコマンドを実行する
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="args"></param>
        void ToolPrimaryClicked(object sender, EventArgs args)
        {
            var tool = sender as UIButton;
            var command = _buttonPrimaryCommands[tool];
            command.Execute(null);
        }

        /// <summary>
        /// 終了処理
        /// </summary>
        /// <param name="animated"></param>
        public override void ViewWillDisappear(bool animated)
        {
            if (_primaryItems != null && _primaryItems.Count > 0)
            { 
                NavigationController.SetToolbarHidden(true, animated);
                this.NavigationItem.RightBarButtonItems = null;
                _buttonPrimaryCommands.Clear();
            }
            base.ViewWillDisappear(animated);
        }
    }
}