From e6e2319dc3384cc9d9c728d67b1e367628cdabd5 Mon Sep 17 00:00:00 2001
From: Jumar Macato <hikari.netto23@gmail.com>
Date: Tue, 18 Aug 2020 19:00:19 +0800
Subject: [PATCH] add context menu

---
 samples/ControlCatalog/Pages/TextBoxPage.xaml | 74 +++++++++----------
 src/Avalonia.Controls/TextBox.cs              | 74 +++++++++++++++++--
 2 files changed, 104 insertions(+), 44 deletions(-)

diff --git a/samples/ControlCatalog/Pages/TextBoxPage.xaml b/samples/ControlCatalog/Pages/TextBoxPage.xaml
index 481a459159..88094c70f3 100644
--- a/samples/ControlCatalog/Pages/TextBoxPage.xaml
+++ b/samples/ControlCatalog/Pages/TextBoxPage.xaml
@@ -1,61 +1,57 @@
 <UserControl xmlns="https://github.com/avaloniaui"
-             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-             x:Class="ControlCatalog.Pages.TextBoxPage">
+  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" x:Class="ControlCatalog.Pages.TextBoxPage">
   <StackPanel Orientation="Vertical" Spacing="4">
+    <StackPanel.Resources>
+      <ContextMenu x:Key="DefaultTextBoxContextMenu">
+        <MenuItem Header="Cut" Command="{Binding $parent[TextBox].Cut}" IsEnabled="{Binding $parent[TextBox].CanCut}"/>
+        <MenuItem Header="Copy" Command="{Binding $parent[TextBox].Copy}" IsEnabled="{Binding $parent[TextBox].CanCopy}"/>
+        <MenuItem Header="Paste" Command="{Binding $parent[TextBox].Paste}" IsEnabled="{Binding $parent[TextBox].CanPaste}"/>
+      </ContextMenu>
+    </StackPanel.Resources>
+    <StackPanel.Styles>
+      <Style Selector=":is(TextBox)">
+        <Setter Property="ContextMenu" Value="{StaticResource DefaultTextBoxContextMenu}" />
+      </Style>
+    </StackPanel.Styles>
     <TextBlock Classes="h1">TextBox</TextBlock>
     <TextBlock Classes="h2">A control into which the user can input text</TextBlock>
 
-    <StackPanel Orientation="Horizontal"
-              Margin="0,16,0,0"
-              HorizontalAlignment="Center"
-              Spacing="16">
+    <StackPanel Orientation="Horizontal" Margin="0,16,0,0" HorizontalAlignment="Center" Spacing="16">
       <StackPanel Orientation="Vertical" Spacing="8">
         <TextBox Text="Lorem ipsum dolor sit amet, consectetur adipiscing elit." Width="200" />
         <TextBox Watermark="ReadOnly" IsReadOnly="True" Text="This is read only"/>
         <TextBox Width="200" Watermark="Watermark" />
-        <TextBox Width="200"
-                 Watermark="Floating Watermark"
-                 UseFloatingWatermark="True"
-                 Text="Lorem ipsum dolor sit amet, consectetur adipiscing elit."/>
+        <TextBox Width="200" Watermark="Floating Watermark" UseFloatingWatermark="True" Text="Lorem ipsum dolor sit amet, consectetur adipiscing elit."/>
 
-        <TextBox Width="200"
-                 Watermark="Password Box"
-                 Classes="revealPasswordButton"
-                 UseFloatingWatermark="True"
-                 PasswordChar="*"
-                 Text="Password" />
+        <TextBox Width="200" Watermark="Password Box" Classes="revealPasswordButton" UseFloatingWatermark="True" PasswordChar="*" Text="Password" />
         <TextBox Width="200" Text="Left aligned text" TextAlignment="Left" />
         <TextBox Width="200" Text="Center aligned text" TextAlignment="Center" />
         <TextBox Width="200" Text="Right aligned text" TextAlignment="Right" />
-        <TextBox Width="200" Text="Custom selection brush"
-                  SelectionStart="5" SelectionEnd="22"
-                  SelectionBrush="Green" SelectionForegroundBrush="Yellow"/>
+        <TextBox Width="200" Text="Custom selection brush" SelectionStart="5" SelectionEnd="22" SelectionBrush="Green" SelectionForegroundBrush="Yellow"/>
         <TextBox Width="200" Text="Custom caret brush" CaretBrush="DarkOrange"/>
       </StackPanel>
 
       <StackPanel Orientation="Vertical" Spacing="8">
-        <TextBox AcceptsReturn="True" TextWrapping="Wrap" Width="200" Height="125"
-                 Text="Multiline TextBox with TextWrapping.&#xD;&#xD;Lorem ipsum dolor sit amet, consectetur adipiscing elit. Vivamus magna. Cras in mi at felis aliquet congue. Ut a est eget ligula molestie gravida. Curabitur massa. Donec eleifend, libero at sagittis mollis, tellus est malesuada tellus, at luctus turpis elit sit amet quam. Vivamus pretium ornare est." />
-        <TextBox AcceptsReturn="True" Width="200" Height="125"
-                 Text="Multiline TextBox with no TextWrapping.&#xD;&#xD;Lorem ipsum dolor sit amet, consectetur adipiscing elit. Vivamus magna. Cras in mi at felis aliquet congue. Ut a est eget ligula molestie gravida. Curabitur massa. Donec eleifend, libero at sagittis mollis, tellus est malesuada tellus, at luctus turpis elit sit amet quam. Vivamus pretium ornare est." />
-        
+        <TextBox AcceptsReturn="True" TextWrapping="Wrap" Width="200" Height="125" Text="Multiline TextBox with TextWrapping.&#xD;&#xD;Lorem ipsum dolor sit amet, consectetur adipiscing elit. Vivamus magna. Cras in mi at felis aliquet congue. Ut a est eget ligula molestie gravida. Curabitur massa. Donec eleifend, libero at sagittis mollis, tellus est malesuada tellus, at luctus turpis elit sit amet quam. Vivamus pretium ornare est." />
+        <TextBox AcceptsReturn="True" Width="200" Height="125" Text="Multiline TextBox with no TextWrapping.&#xD;&#xD;Lorem ipsum dolor sit amet, consectetur adipiscing elit. Vivamus magna. Cras in mi at felis aliquet congue. Ut a est eget ligula molestie gravida. Curabitur massa. Donec eleifend, libero at sagittis mollis, tellus est malesuada tellus, at luctus turpis elit sit amet quam. Vivamus pretium ornare est." />
+
         <TextBox Classes="clearButton" Text="Clear Content" Width="200" FontWeight="Normal" FontStyle="Normal" Watermark="Watermark" FontFamily="avares://ControlCatalog/Assets/Fonts#Source Sans Pro"/>
       </StackPanel>
-        <StackPanel Orientation="Vertical" Spacing="8">
-            <TextBlock Classes="h2">resm fonts</TextBlock>
-            <TextBox Width="200" Text="Custom font regular" FontWeight="Normal" FontStyle="Normal" FontFamily="resm:ControlCatalog.Assets.Fonts?assembly=ControlCatalog#Source Sans Pro"/>
-                <TextBox Width="200" Text="Custom font bold" FontWeight="Bold" FontStyle="Normal" FontFamily="resm:ControlCatalog.Assets.Fonts?assembly=ControlCatalog#Source Sans Pro"/>
-                <TextBox Width="200" Text="Custom font italic" FontWeight="Normal" FontStyle="Italic" FontFamily="resm:ControlCatalog.Assets.Fonts.SourceSansPro-Italic.ttf?assembly=ControlCatalog#Source Sans Pro"/>
-                <TextBox Width="200" Text="Custom font italic bold" FontWeight="Bold" FontStyle="Italic" FontFamily="resm:ControlCatalog.Assets.Fonts.SourceSansPro-*.ttf?assembly=ControlCatalog#Source Sans Pro"/>
-        </StackPanel>
-        
-        <StackPanel Orientation="Vertical" Spacing="8">
-            <TextBlock Classes="h2">res fonts</TextBlock>
-            <TextBox Width="200" Text="Custom font regular" FontWeight="Normal" FontStyle="Normal" FontFamily="avares://ControlCatalog/Assets/Fonts#Source Sans Pro"/>
-            <TextBox Width="200" Text="Custom font bold" FontWeight="Bold" FontStyle="Normal" FontFamily="avares://ControlCatalog/Assets/Fonts#Source Sans Pro"/>
-            <TextBox Width="200" Text="Custom font italic" FontWeight="Normal" FontStyle="Italic" FontFamily="/Assets/Fonts/SourceSansPro-Italic.ttf#Source Sans Pro"/>
-            <TextBox Width="200" Text="Custom font italic bold" FontWeight="Bold" FontStyle="Italic" FontFamily="/Assets/Fonts/SourceSansPro-*.ttf#Source Sans Pro"/>
-        </StackPanel>
+      <StackPanel Orientation="Vertical" Spacing="8">
+        <TextBlock Classes="h2">resm fonts</TextBlock>
+        <TextBox Width="200" Text="Custom font regular" FontWeight="Normal" FontStyle="Normal" FontFamily="resm:ControlCatalog.Assets.Fonts?assembly=ControlCatalog#Source Sans Pro"/>
+        <TextBox Width="200" Text="Custom font bold" FontWeight="Bold" FontStyle="Normal" FontFamily="resm:ControlCatalog.Assets.Fonts?assembly=ControlCatalog#Source Sans Pro"/>
+        <TextBox Width="200" Text="Custom font italic" FontWeight="Normal" FontStyle="Italic" FontFamily="resm:ControlCatalog.Assets.Fonts.SourceSansPro-Italic.ttf?assembly=ControlCatalog#Source Sans Pro"/>
+        <TextBox Width="200" Text="Custom font italic bold" FontWeight="Bold" FontStyle="Italic" FontFamily="resm:ControlCatalog.Assets.Fonts.SourceSansPro-*.ttf?assembly=ControlCatalog#Source Sans Pro"/>
+      </StackPanel>
+
+      <StackPanel Orientation="Vertical" Spacing="8">
+        <TextBlock Classes="h2">res fonts</TextBlock>
+        <TextBox Width="200" Text="Custom font regular" FontWeight="Normal" FontStyle="Normal" FontFamily="avares://ControlCatalog/Assets/Fonts#Source Sans Pro"/>
+        <TextBox Width="200" Text="Custom font bold" FontWeight="Bold" FontStyle="Normal" FontFamily="avares://ControlCatalog/Assets/Fonts#Source Sans Pro"/>
+        <TextBox Width="200" Text="Custom font italic" FontWeight="Normal" FontStyle="Italic" FontFamily="/Assets/Fonts/SourceSansPro-Italic.ttf#Source Sans Pro"/>
+        <TextBox Width="200" Text="Custom font italic bold" FontWeight="Bold" FontStyle="Italic" FontFamily="/Assets/Fonts/SourceSansPro-*.ttf#Source Sans Pro"/>
       </StackPanel>
+    </StackPanel>
   </StackPanel>
 </UserControl>
diff --git a/src/Avalonia.Controls/TextBox.cs b/src/Avalonia.Controls/TextBox.cs
index 559932bf80..d803d03258 100644
--- a/src/Avalonia.Controls/TextBox.cs
+++ b/src/Avalonia.Controls/TextBox.cs
@@ -1,3 +1,4 @@
+using System.Windows.Input;
 using Avalonia.Input.Platform;
 using System;
 using System.Collections.Generic;
@@ -103,6 +104,21 @@ namespace Avalonia.Controls
 
         public static readonly StyledProperty<bool> RevealPasswordProperty =
             AvaloniaProperty.Register<TextBox, bool>(nameof(RevealPassword));
+        
+        public static readonly DirectProperty<TextBox, bool> CanCutProperty =
+                    AvaloniaProperty.RegisterDirect<TextBox, bool>(
+                        nameof(CanCut),
+                        o => o.CanCut);
+
+        public static readonly DirectProperty<TextBox, bool> CanCopyProperty =
+            AvaloniaProperty.RegisterDirect<TextBox, bool>(
+                nameof(CanCopy),
+                o => o.CanCopy);
+
+        public static readonly DirectProperty<TextBox, bool> CanPasteProperty =
+                    AvaloniaProperty.RegisterDirect<TextBox, bool>(
+                        nameof(CanPaste),
+                        o => o.CanPaste);
 
         struct UndoRedoState : IEquatable<UndoRedoState>
         {
@@ -126,6 +142,9 @@ namespace Avalonia.Controls
         private UndoRedoHelper<UndoRedoState> _undoRedoHelper;
         private bool _isUndoingRedoing;
         private bool _ignoreTextChanges;
+        private bool _canCut;
+        private bool _canCopy;
+        private bool _canPaste;
         private string _newLine = Environment.NewLine;
         private static readonly string[] invalidCharacters = new String[1] { "\u007f" };
 
@@ -378,6 +397,33 @@ namespace Avalonia.Controls
             SelectionStart = SelectionEnd = CaretIndex;
         }
 
+        /// <summary>
+        /// Property for determining if the Cut command can be executed.
+        /// </summary>
+        public bool CanCut
+        {
+            get { return _canCut; }
+            private set { SetAndRaise(CanCutProperty, ref _canCut, value); }
+        }
+
+        /// <summary>
+        /// Property for determining if the Copy command can be executed.
+        /// </summary>
+        public bool CanCopy
+        {
+            get { return _canCopy; }
+            private set { SetAndRaise(CanCopyProperty, ref _canCopy, value); }
+        }
+
+        /// <summary>
+        /// Property for determining if the Paste command can be executed.
+        /// </summary>
+        public bool CanPaste
+        {
+            get { return _canPaste; }
+            private set { SetAndRaise(CanPasteProperty, ref _canPaste, value); }
+        }
+
         protected override void OnApplyTemplate(TemplateAppliedEventArgs e)
         {
             _presenter = e.NameScope.Get<TextPresenter>("PART_TextPresenter");
@@ -395,9 +441,19 @@ namespace Avalonia.Controls
             if (change.Property == TextProperty)
             {
                 UpdatePseudoclasses();
+                UpdateCommandStates();
             }
         }
 
+        private void UpdateCommandStates()
+        {
+            var text = GetSelection();
+            var b1 = string.IsNullOrEmpty(text);
+            CanCopy = !b1;
+            CanCut = !b1;
+            CanPaste = !IsReadOnly;
+        }
+
         protected override void OnGotFocus(GotFocusEventArgs e)
         {
             base.OnGotFocus(e);
@@ -412,6 +468,8 @@ namespace Avalonia.Controls
                 SelectAll();
             }
 
+            UpdateCommandStates();
+
             _presenter?.ShowCaret();
         }
 
@@ -425,6 +483,8 @@ namespace Avalonia.Controls
                 RevealPassword = false;
             }
 
+            UpdateCommandStates();
+
             _presenter?.HideCaret();
         }
 
@@ -469,6 +529,9 @@ namespace Avalonia.Controls
 
         public async void Cut()
         {
+            var text = GetSelection();
+            if (text is null) return;
+
             _undoRedoHelper.Snapshot();
             Copy();
             DeleteSelection();
@@ -477,17 +540,18 @@ namespace Avalonia.Controls
 
         public async void Copy()
         {
+            var text = GetSelection();
+            if (text is null) return;
+
             await ((IClipboard)AvaloniaLocator.Current.GetService(typeof(IClipboard)))
-                .SetTextAsync(GetSelection());
+                .SetTextAsync(text);
         }
 
         public async void Paste()
         {
             var text = await ((IClipboard)AvaloniaLocator.Current.GetService(typeof(IClipboard))).GetTextAsync();
-            if (text == null)
-            {
-                return;
-            }
+
+            if (text is null) return;
 
             _undoRedoHelper.Snapshot();
             HandleTextInput(text);