.Net ramblings
# Wednesday, 26 May 2010
Compact Framework - Using the Treeview to replace the ListBox
As any compact framework developer will tell you, the out-of-the-box ListBox control is a bit crap because it doesn't support horizontal scrolling.  what were they thinking??
anyway, after several work-arounds to this problem, i finally realised that the treeview control does support horizontal scrolling, and you can load up a treeview to look just like a listbox, having all the nodes added at the top level, i.e. a "flat" treeview.
the extra bonus with this approach is that Windows Mobile 6.5 has a brilliant touch friendly Treeview control that you can finger-drag up and down and left and right (at least the HTC HD2 has this, i can't vouch for other devices).

i've included a "Chooser" class i wrote to make user selections easy to code for.  to use the class, use the following approach, the SelectedItem string is kept as a static variable in the Form so you can close and dispose the form straight away, and still catch the "return" value of the form. If you pass in the parameter to use Checkboxes, you can access the CheckedItems static property which is a List<string>.
Chooser c = new Chooser("Select Item", new string[]{"Option 1", "Option 2", "Option 3"}, true, true); 
DialogResult d = c.ShowDialog();
c.Dispose();
if(d != DialogResult.Cancel)
MessageBox.Show("You chose " + Chooser.SelectedItem);
here's the class then:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Threading;

namespace IbenzaMobileUtil
{
public partial class Chooser : Form
{
private MainMenu mainMenu1;
private MenuItem mmOK;
private MenuItem mmCancel;
private Label lblCaption;
public static string SelectedItem = null;
public static List<string> CheckedItems = null;
private TreeView treeView1;
private bool selectInvokesClose;


public Chooser()
{
InitializeComponent();
}

private Chooser(string Caption, bool FullScreen, bool SelectInvokesClose)
{
InitializeComponent();
CheckedItems = new List<string>();
SelectedItem = null;
this.selectInvokesClose = SelectInvokesClose;
this.lblCaption.Text = Caption;
this.mmOK.Enabled = false;

if (FullScreen)
{
this.WindowState = FormWindowState.Maximized;
this.FormBorderStyle = FormBorderStyle.None;
this.ControlBox = false;
this.MinimizeBox = false;
}
}

public Chooser(string Caption, string[] Items, bool FullScreen, bool SelectInvokesClose)
: this(Caption, FullScreen, SelectInvokesClose)
{
this.treeView1.BeginUpdate();
foreach (string s in Items)
this.treeView1.Nodes.Add(s);
this.treeView1.EndUpdate();
}

public Chooser(string Caption, string[] Items, bool FullScreen, bool CheckBoxes, bool SelectInvokesClose, bool CheckAll)
: this(Caption, Items, FullScreen, SelectInvokesClose)
{
this.treeView1.CheckBoxes = CheckBoxes;
if (CheckBoxes && CheckAll)
foreach (TreeNode node in this.treeView1.Nodes)
node.Checked = true;
if(CheckBoxes)
this.mmOK.Enabled = true; // don't require any user input
}

private void treeView1_AfterSelect(object sender, TreeViewEventArgs e)
{
this.mmOK.Enabled = true;
if (selectInvokesClose)
this.mmOK_Click(sender, EventArgs.Empty);
}

#region Windows Form Designer generated code

/// <summary>
/// Required designer variable.
/// </summary>
private System.ComponentModel.IContainer components = null;

/// <summary>
/// Clean up any resources being used.
/// </summary>
/// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
protected override void Dispose(bool disposing)
{
if (disposing && (components != null))
{
components.Dispose();
}
base.Dispose(disposing);
}


/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
private void InitializeComponent()
{
this.mainMenu1 = new System.Windows.Forms.MainMenu();
this.mmCancel = new System.Windows.Forms.MenuItem();
this.mmOK = new System.Windows.Forms.MenuItem();
this.lblCaption = new System.Windows.Forms.Label();
this.treeView1 = new System.Windows.Forms.TreeView();
this.SuspendLayout();
//
// mainMenu1
//
this.mainMenu1.MenuItems.Add(this.mmCancel);
this.mainMenu1.MenuItems.Add(this.mmOK);
//
// mmCancel
//
this.mmCancel.Text = "Cancel";
this.mmCancel.Click += new System.EventHandler(this.mmCancel_Click);
//
// mmOK
//
this.mmOK.Text = "OK";
this.mmOK.Click += new System.EventHandler(this.mmOK_Click);
//
// lblCaption
//
this.lblCaption.Dock = System.Windows.Forms.DockStyle.Top;
this.lblCaption.Font = new System.Drawing.Font("Tahoma", 10F, System.Drawing.FontStyle.Bold);
this.lblCaption.Location = new System.Drawing.Point(0, 0);
this.lblCaption.Name = "lblCaption";
this.lblCaption.Size = new System.Drawing.Size(240, 27);
this.lblCaption.Text = "...";
//
// treeView1
//
this.treeView1.Dock = System.Windows.Forms.DockStyle.Fill;
this.treeView1.Location = new System.Drawing.Point(0, 27);
this.treeView1.Name = "treeView1";
this.treeView1.ShowLines = false;
this.treeView1.ShowPlusMinus = false;
this.treeView1.ShowRootLines = false;
this.treeView1.Size = new System.Drawing.Size(240, 241);
this.treeView1.TabIndex = 12;
//
// Chooser
//
this.AutoScaleDimensions = new System.Drawing.SizeF(96F, 96F);
this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Dpi;
this.AutoScroll = true;
this.ClientSize = new System.Drawing.Size(240, 268);
this.ControlBox = false;
this.Controls.Add(this.treeView1);
this.Controls.Add(this.lblCaption);
this.KeyPreview = true;
this.Menu = this.mainMenu1;
this.MinimizeBox = false;
this.Name = "Chooser";
this.Text = "Choose Item";
this.Load += new System.EventHandler(this.Chooser_Load);
this.KeyDown += new System.Windows.Forms.KeyEventHandler(this.Chooser_KeyDown);
this.ResumeLayout(false);

}
#endregion

private void Chooser_KeyDown(object sender, KeyEventArgs e)
{
if ((e.KeyCode == System.Windows.Forms.Keys.Enter))
this.mmOK_Click(sender, EventArgs.Empty);
}

private void mmOK_Click(object sender, EventArgs e)
{
if (this.treeView1.SelectedNode != null)
Chooser.SelectedItem = this.treeView1.SelectedNode.Text;
if (this.treeView1.CheckBoxes)
foreach (TreeNode n in this.treeView1.Nodes)
if (n.Checked)
CheckedItems.Add(n.Text);

this.DialogResult = DialogResult.OK;
this.Close();
}

private void mmCancel_Click(object sender, EventArgs e)
{
this.DialogResult = DialogResult.Cancel;
this.Close();
}

private void Chooser_Load(object sender, EventArgs e)
{
this.treeView1.Focus();
this.treeView1.SelectedNode = null;
this.treeView1.AfterSelect += new TreeViewEventHandler(treeView1_AfterSelect);
}
}
}


Wednesday, 26 May 2010 15:51:34 (GMT Daylight Time, UTC+01:00)  #    Comments [0]  .Net Compact

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