how to design a new tree view control
We recently need a special tree view control that included some Checkbox or Radio controls in some tree node in a VSTO project. Some of complex nodes included checkbox controls or radio controls but others nodes maybe only is a simply tree node in same TreeView control. If we set value of the property named Checkboxes is “true”, all of the node are included a Checkbox in the TreeView controls, otherwise it will have not any checkbox controls.
So I have to redesign a control to implements these features. I decided to inherit directly from the TreeView class instead of create a new class. I overwrite the method named ( OnPaint, WndProc, OnResize etc ) and add some new method that will draw a CheckBox control or Radio control in a tree node.
public
partial
class
BaseTreeView : TreeView
{
private define#region private define
private Bitmap internalBitmap = null; private Graphics internalGraphics = null; /**//// <summary> /// Indicates whether the OnMouseClick event is raised by expand or collapse a tree node.
/// </summary> private bool isExpandOrCollapseMouseClick; #endregion public BaseTreeView() { InitializeComponent(); } private method#region private method /**//// <summary> /// Dispose the internal object of treeview. /// </summary> private void DisposeInternalObject() { if (internalGraphics != null) { internalGraphics.Dispose(); } if (internalBitmap != null) { internalBitmap.Dispose(); } } #endregion public method#region public method protected override void OnAfterExpand(TreeViewEventArgs e) { isExpandOrCollapseMouseClick = true; } protected override void OnAfterCollapse(TreeViewEventArgs e) { isExpandOrCollapseMouseClick = true; //throw new Exception("The method or operation is not implemented."); } /**//// <summary> /// override the OnResize method /// </summary> /// <param name="e"></param> protected override void OnResize(EventArgs e) { if (internalBitmap == null || internalBitmap.Width != Width || internalBitmap.Height != Height) { if (Width != 0 && Height != 0) { DisposeInternalObject(); internalBitmap = new Bitmap(Width, Height); internalGraphics = Graphics.FromImage(internalBitmap); } } } /**//// <summary>Occurs when a Windows message is dispatched.</summary> /// <param name="message">Message to process.</param> /// <remarks>Overrides WM_PAINT, WM_ERASEBKGND.</remarks> protected override void WndProc(ref Message message) { const int WM_PAINT = 0x000F; const int WM_PRINTCLIENT = 0x0318; const int WM_ERASEBKGND = 0x0014; switch (message.Msg) { case WM_ERASEBKGND: //removes flicker return; case WM_PAINT: // The designer host does not call OnResize() if (internalGraphics == null) { OnResize(EventArgs.Empty); } //Set up Win32.RECT updateRect = new Win32.RECT(); if (Win32.GetUpdateRect(message.HWnd, ref updateRect, false) == 0) { break; } Win32.PAINTSTRUCT paintStruct = new Win32.PAINTSTRUCT(); IntPtr screenHdc = Win32.BeginPaint(message.HWnd, ref paintStruct); using (Graphics screenGraphics = Graphics.FromHdc(screenHdc)) { //Draw Internal Graphics IntPtr hdc = internalGraphics.GetHdc(); Message printClientMessage = Message.Create(Handle, WM_PRINTCLIENT, hdc, IntPtr.Zero); DefWndProc(ref printClientMessage); internalGraphics.ReleaseHdc(hdc); //Add the missing OnPaint() call OnPaint(new PaintEventArgs(internalGraphics, Rectangle.FromLTRB( updateRect.left, updateRect.top, updateRect.right, updateRect.bottom))); //Draw Screen Graphics screenGraphics.DrawImage(internalBitmap, 0, 0); } //Tear down Win32.EndPaint(message.HWnd, ref paintStruct); return; } base.WndProc(ref message); } /**//// <summary>Occurs when the control is redrawn.</summary> /// <remarks>Re enable browsing attributes for the Paint Event.</remarks> [ EditorBrowsableAttribute(EditorBrowsableState.Always), BrowsableAttribute(true) ] public new event PaintEventHandler Paint { add { base.Paint += value; } remove { base.Paint -= value; } } private void OnPaintChildNode(TreeNode parentNode, PaintEventArgs pe) { if (parentNode.Parent != null) { OptionTreeNode optionNode = parentNode.Parent as OptionTreeNode; OptionItemTreeNode optionItem = parentNode as OptionItemTreeNode; if (optionNode != null) { if (optionNode.IsOptionFolder ) { if ( optionItem != null) { Rectangle rect = new Rectangle(0, 0, 16, 16); Bitmap bitmap = new Bitmap(16, 16); Graphics graphics = Graphics.FromImage(bitmap); if (optionNode.IsCheckBox) { if (parentNode.Checked) { ControlPaint.DrawCheckBox(graphics, rect, ButtonState.Checked | ButtonState.Flat); } else { ControlPaint.DrawCheckBox(graphics, rect, ButtonState.Normal | ButtonState.Flat); } } else { if (parentNode.Checked) { ControlPaint.DrawRadioButton(graphics, rect, ButtonState.Checked | ButtonState.Flat); } else { ControlPaint.DrawRadioButton(graphics, rect, ButtonState.Normal | ButtonState.Flat); } } rect = parentNode.Bounds; rect.Y = rect.Y + 4; rect.Height = 16; rect.Width = 16; rect.X = rect.X - 40; pe.Graphics.DrawImage(bitmap, rect); } } } } if (parentNode.Nodes == null) { return; } foreach (TreeNode node in parentNode.Nodes) { OnPaintChildNode(node,pe); } } protected override void OnPaint(PaintEventArgs pe) { // TODO: Add custom paint code here foreach (TreeNode node in this.Nodes) { OnPaintChildNode(node,pe); } base.OnPaint(pe); } protected override void OnMouseClick(MouseEventArgs e) { if (isExpandOrCollapseMouseClick == true) { isExpandOrCollapseMouseClick = false; return; } TreeNode node = GetNodeAt(e.X, e.Y); if ((e.X > node.Bounds.Left) && (e.X < node.Bounds.Right) && (e.Y > node.Bounds.Top) && (e.Y < node.Bounds.Bottom)) return; if (node != null) { if (node.Parent != null) { OptionTreeNode optionNode = node.Parent as OptionTreeNode; if (optionNode != null) { if (optionNode.IsOptionFolder) { if (optionNode.IsCheckBox) { node.Checked = !node.Checked; } else { TreeNode parentNode = node.Parent; { foreach(TreeNode objNode in parentNode.Nodes) { if (node.Equals(objNode)) { objNode.Checked = !objNode.Checked; } else { objNode.Checked = false; } } } } } } } } } #endregion
}
If any question please reply me.