Rename ComboBox to DropDownBox;

Introduce actual ComboBox with text input nad proposals;

ImGui.Forms/Controls/ComboBox.cs

@@ -1,24 +1,40 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Numerics;
+using System.Runtime.InteropServices;
 using ImGui.Forms.Controls.Base;
-using ImGui.Forms.Localization;
 using ImGui.Forms.Models;
 using ImGui.Forms.Resources;
+using ImGuiNET;
 using Veldrid;
 
+// Initial code: https://github.com/ocornut/imgui/issues/2057
+
 namespace ImGui.Forms.Controls
 {
     public class ComboBox<TItem> : Component
     {
+        private string _input = string.Empty;
+
         public IList<ComboBoxItem<TItem>> Items { get; } = new List<ComboBoxItem<TItem>>();
 
         public ComboBoxItem<TItem> SelectedItem { get; set; }
 
         public SizeValue Width { get; set; } = SizeValue.Content;
 
-        #region Events
+        /// <summary>
+        /// Get or set the max count of characters allowed in the input.
+        /// </summary>
+        public uint MaxCharacters { get; set; } = 256;
 
+        /// <summary>
+        /// Get or set the max count of items in the drop down.
+        /// </summary>
+        public uint MaxShowItems { get; set; } = 10;
+
+        #region Events
+
         public event EventHandler SelectedItemChanged;
 
         #endregion
@@ -34,47 +50,138 @@ public override Size GetSize()
             return new Size(width, height);
         }
 
-        protected override void UpdateInternal(Rectangle contentRect)
+        protected override unsafe void UpdateInternal(Rectangle contentRect)
         {
-            ImGuiNET.ImGui.SetNextItemWidth(contentRect.Width);
+            //Check if both strings matches
+            uint maxShowItems = MaxShowItems;
+            if (maxShowItems == 0)
+                maxShowItems = (uint)Items.Count;
+
+            ImGuiNET.ImGui.PushID(Id);
 
-            var selectedName = SelectedItem?.Name ?? string.Empty;
-            if (ImGuiNET.ImGui.BeginCombo($"##combo{Id}", selectedName))
+            bool isFinal = ImGuiNET.ImGui.InputText("##in", ref _input, MaxCharacters, ImGuiInputTextFlags.CallbackAlways | ImGuiInputTextFlags.EnterReturnsTrue, Propose);
+            if (isFinal)
             {
-                for (var i = 0; i < Items.Count; i++)
+                ComboBoxItem<TItem> selectedItem = Items.FirstOrDefault(i => i.Name == _input);
+                if (SelectedItem != selectedItem)
                 {
-                    if (ImGuiNET.ImGui.Selectable(Items[i].Name, SelectedItem == Items[i]))
-                    {
-                        var hasChanged = SelectedItem != Items[i];
-                        SelectedItem = Items[i];
+                    SelectedItem = selectedItem;
+                    OnSelectedItemChanged();
+                }
+            }
 
-                        if (hasChanged)
-                            OnSelectedItemChanged();
+            ImGuiNET.ImGui.OpenPopupOnItemClick("combobox"); // Enable right-click
+            Vector2 pos = ImGuiNET.ImGui.GetItemRectMin();
+            Vector2 size = ImGuiNET.ImGui.GetItemRectSize();
+
+            ImGuiNET.ImGui.SameLine(0, 0);
+            if (ImGuiNET.ImGui.ArrowButton("##openCombo", ImGuiDir.Down))
+            {
+                ImGuiNET.ImGui.OpenPopup("combobox");
+            }
+            ImGuiNET.ImGui.OpenPopupOnItemClick("combobox"); // Enable right-click
+
+            pos.Y += size.Y;
+            size.X += ImGuiNET.ImGui.GetItemRectSize().Y;
+            size.Y += 5 + size.Y * maxShowItems;
+            ImGuiNET.ImGui.SetNextWindowPos(pos);
+            ImGuiNET.ImGui.SetNextWindowSize(size);
+            if (ImGuiNET.ImGui.BeginPopup("combobox", ImGuiWindowFlags.NoMove))
+            {
+                ImGuiNET.ImGui.Text("Select an item");
+                ImGuiNET.ImGui.Separator();
+                foreach (ComboBoxItem<TItem> item in Items)
+                {
+                    if (!ImGuiNET.ImGui.Selectable(item.Name)) 
+                        continue;
+
+                    _input = item.Name;
+
+                    if (SelectedItem != item)
+                    {
+                        SelectedItem = item;
+                        OnSelectedItemChanged();
                     }
                 }
 
-                ImGuiNET.ImGui.EndCombo();
+                ImGuiNET.ImGui.EndPopup();
             }
+
+            ImGuiNET.ImGui.PopID();
         }
 
         private void OnSelectedItemChanged()
         {
-            SelectedItemChanged?.Invoke(this, new EventArgs());
+            SelectedItemChanged?.Invoke(this, EventArgs.Empty);
         }
-    }
-
-    public class ComboBoxItem<TItem>
-    {
-        public TItem Content { get; }
 
-        public LocalizedString Name { get; }
-
-        public ComboBoxItem(TItem content, LocalizedString name = default)
+        private bool Identical(string buf, string item)
         {
-            Content = content;
-            Name = name.IsEmpty ? (LocalizedString)content.ToString() : name;
+            //Check if the item length is shorter or equal --> exclude
+            if (buf.Length >= item.Length)
+                return false;
+
+            for (var i = 0; i < buf.Length; ++i)
+                // set the current pos if matching or return the pos if not
+                if (buf[i] != item[i])
+                    return false;
+
+            // Complete match
+            // and the item size is greater --> include
+            return true;
         }
 
-        public static implicit operator ComboBoxItem<TItem>(TItem o) => new(o);
+        private unsafe int Propose(ImGuiInputTextCallbackData* data)
+        {
+            var dataPtr = new ImGuiInputTextCallbackDataPtr(data);
+
+            // We don't want to "preselect" anything
+            if (dataPtr.BufTextLen == 0)
+                return 0;
+
+            // We need to give the user a chance to remove wrong input
+            if (dataPtr.EventKey == ImGuiKey.Backspace)
+            {
+                // We delete the last char automatically, since it is what the user wants to delete, but only if there is something (selected/marked/hovered)
+                // FIXME: This worked fine, when not used as helper function
+                if (data->SelectionEnd == data->SelectionStart)
+                    return 0;
+
+                if (data->BufTextLen <= 0)
+                    return 0; //...and the buffer isn't empty
+
+                if (data->CursorPos > 0) //...and the cursor not at pos 0
+                    dataPtr.DeleteChars(data->CursorPos - 1, 1);
+
+                return 0;
+            }
+
+            if (dataPtr.EventKey == ImGuiKey.Delete)
+                return 0;
+
+            string bufferString = Marshal.PtrToStringUTF8(dataPtr.Buf);
+            foreach (ComboBoxItem<TItem> item in Items)
+            {
+                if (!Identical(bufferString, item.Name))
+                    continue;
+
+                int cursor = data->CursorPos;
+
+                //Insert the first match
+                dataPtr.DeleteChars(0, data->BufTextLen);
+                dataPtr.InsertChars(0, item.Name);
+
+                //Reset the cursor position
+                data->CursorPos = cursor;
+
+                //Select the text, so the user can simply go on writing
+                data->SelectionStart = cursor;
+                data->SelectionEnd = data->BufTextLen;
+
+                break;
+            }
+
+            return 0;
+        }
     }
 }

ImGui.Forms/Controls/DropDownBox.cs

@@ -0,0 +1,80 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using ImGui.Forms.Controls.Base;
+using ImGui.Forms.Localization;
+using ImGui.Forms.Models;
+using ImGui.Forms.Resources;
+using Veldrid;
+
+namespace ImGui.Forms.Controls
+{
+    public class DropDownBox<TItem> : Component
+    {
+        public IList<ComboBoxItem<TItem>> Items { get; } = new List<ComboBoxItem<TItem>>();
+
+        public ComboBoxItem<TItem> SelectedItem { get; set; }
+
+        public SizeValue Width { get; set; } = SizeValue.Content;
+
+        #region Events
+
+        public event EventHandler SelectedItemChanged;
+
+        #endregion
+
+        public override Size GetSize()
+        {
+            var maxWidth = Items.Select(x => FontResource.GetCurrentLineWidth(x.Name)).DefaultIfEmpty(0).Max() + (int)ImGuiNET.ImGui.GetStyle().ItemInnerSpacing.X * 2;
+            var arrowWidth = 20;
+
+            SizeValue width = Width.IsContentAligned ? maxWidth + arrowWidth : Width;
+            var height = FontResource.GetCurrentLineHeight() + (int)ImGuiNET.ImGui.GetStyle().ItemInnerSpacing.Y * 2;
+
+            return new Size(width, height);
+        }
+
+        protected override void UpdateInternal(Rectangle contentRect)
+        {
+            ImGuiNET.ImGui.SetNextItemWidth(contentRect.Width);
+
+            var selectedName = SelectedItem?.Name ?? string.Empty;
+            if (ImGuiNET.ImGui.BeginCombo($"##combo{Id}", selectedName))
+            {
+                for (var i = 0; i < Items.Count; i++)
+                {
+                    if (ImGuiNET.ImGui.Selectable(Items[i].Name, SelectedItem == Items[i]))
+                    {
+                        var hasChanged = SelectedItem != Items[i];
+                        SelectedItem = Items[i];
+
+                        if (hasChanged)
+                            OnSelectedItemChanged();
+                    }
+                }
+
+                ImGuiNET.ImGui.EndCombo();
+            }
+        }
+
+        private void OnSelectedItemChanged()
+        {
+            SelectedItemChanged?.Invoke(this, new EventArgs());
+        }
+    }
+
+    public class ComboBoxItem<TItem>
+    {
+        public TItem Content { get; }
+
+        public LocalizedString Name { get; }
+
+        public ComboBoxItem(TItem content, LocalizedString name = default)
+        {
+            Content = content;
+            Name = name.IsEmpty ? (LocalizedString)content.ToString() : name;
+        }
+
+        public static implicit operator ComboBoxItem<TItem>(TItem o) => new(o);
+    }
+}

ImGui.Forms/ImGui.Forms.nuspec

@@ -2,7 +2,7 @@
 <package >
   <metadata>
     <id>Imgui.Forms</id>
-    <version>1.0.60</version>
+    <version>1.0.61</version>
     <description>A WinForms-inspired object-oriented framework around Dear ImGui (https://github.com/ocornut/imgui)</description>
 
     <authors>onepiecefreak</authors>