Introduction
This article presents a port of the MFC unclickable button to .NET using Managed
C++ and Windows Forms. Nish did the original 1:1 port of the original MFC
control to Managed C++ to demonstrate how easy it was to port. Chris then took
this, rounded off some of the corners and wrapped the control up in an assembly
in order to demonstrate the class in use in a C# application.
Porting to .NET
The MCTrickButton
class is a fully managed Windows Form class derived
from System::Windows::Forms::Button.
. Moving from MFC to Windows
Forms was relatively painless - and in some cases positively sweet. There were a
couple of issues though
As in the original we override the
OnMouseMove
method. Initially an attempt
was made to override OnSetFocus
as well, but
the .NET OnSetFocus
won't tell you what the previous control was which
had the focus. Thus WndProc
has been overridden and WM_SETFOCUS
has been handled directly. The source code is commented and mostly self-explanatory.
There were also small
changes such as having the desktop window be a Screen
object instead of a
Control
(the analogy to Win32 being that the desktop is just another HWND)
meant a minor change to the code but apart from that it was smooth sailing
The control has been compiled to an assembly "CodeProject.WinForms"
(CodeProject.WinForms.dll)
Issues
Our Managed C++ WinForms control does not work inside the VS.NET Forms designer.
I'm not sure if that's simply a case of C++ not having RAD support or if it's merely
a problem with our code. Suggestions welcome.
TrickButton Source listing
Header
#pragma once
using namespace System::Windows::Forms;
namespace CodeProject
{
namespace WinForms
{
public __gc class MCTrickButton : public Button
{
public:
MCTrickButton();
public:
__property int get_JumpDistance()
{ return m_nJumpDistance; }
__property void set_JumpDistance(int value)
{ m_nJumpDistance = value; }
protected:
int m_nJumpDistance;
protected:
virtual void OnMouseMove(MouseEventArgs* e);
virtual void WndProc(Message *pmsg);
};
}
}
Implementation
#include "StdAfx.h"
using namespace System;
using namespace System::ComponentModel;
using namespace System::Drawing;
using namespace System::Windows::Forms;
using namespace System::Runtime::InteropServices;
#include "MCTrickButton.h"
using namespace CodeProject::WinForms;
MCTrickButton::MCTrickButton()
{
m_nJumpDistance = 5;
TabStop = false;
}
void MCTrickButton::OnMouseMove(MouseEventArgs* e)
{
Point point(e->X,e->Y);
point = PointToScreen(point);
Control *pParent = Parent;
if (pParent != NULL)
point = pParent->PointToClient(point);
Drawing::Rectangle ParentRect;
if (pParent == NULL)
{
Screen *currentScreen = Screen::FromPoint(point);
ParentRect = currentScreen->WorkingArea;
}
else
ParentRect = pParent->ClientRectangle;
Drawing::Rectangle ButtonRect = RectangleToScreen(ClientRectangle);
if (pParent != NULL)
ButtonRect = pParent->RectangleToClient(ButtonRect);
Drawing::Point Center((ButtonRect.Right+ButtonRect.Left)/2,
(ButtonRect.Bottom+ButtonRect.Top)/2);
Drawing::Rectangle NewButtonRect = ButtonRect;
if (point.X > Center.X)
{
if (ButtonRect.Left > ParentRect.Left + ButtonRect.Width +
m_nJumpDistance)
{
NewButtonRect.X -= ButtonRect.Right - point.X +
m_nJumpDistance;
}
else
{
NewButtonRect.X += point.X - ButtonRect.Left +
m_nJumpDistance;
}
}
else if (point.X < Center.X)
{
if (ButtonRect.Right < ParentRect.Right - ButtonRect.Width -
m_nJumpDistance)
{
NewButtonRect.X += point.X - ButtonRect.Left +
m_nJumpDistance;
}
else
{
NewButtonRect.X -= ButtonRect.Right - point.X +
m_nJumpDistance;
}
}
if (point.Y > Center.Y)
{
if (ButtonRect.Top > ParentRect.Top + ButtonRect.Height +
m_nJumpDistance)
{
NewButtonRect.Y -= ButtonRect.Bottom - point.Y +
m_nJumpDistance;
}
else
{
NewButtonRect.Y += point.Y - ButtonRect.Top +
m_nJumpDistance;
}
}
else if (point.Y < Center.Y)
{
if (ButtonRect.Bottom < ParentRect.Bottom - ButtonRect.Height -
m_nJumpDistance)
{
NewButtonRect.Y += point.Y - ButtonRect.Top +
m_nJumpDistance;
}
else
{
NewButtonRect.Y -= ButtonRect.Bottom - point.Y +
m_nJumpDistance;
}
}
Location = Point(NewButtonRect.X, NewButtonRect.Y);
Button::OnMouseMove(e);
}
void MCTrickButton::WndProc(Message *pMsg)
{
Button::WndProc(pMsg);
if (pMsg->Msg == WM_SETFOCUS)
{
Control *pOldWnd = FromHandle(pMsg->WParam);
if (pOldWnd != NULL)
pOldWnd->Focus();
}
}
A sample app
using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
using CodeProject.WinForms;
namespace TrickButtonDemo
{
public class Form1 : System.Windows.Forms.Form
{
private System.Windows.Forms.Button QuitButton;
private CodeProject.WinForms.MCTrickButton TrickButton;
private System.ComponentModel.Container components = null;
public Form1()
{
InitializeComponent();
}
protected override void Dispose( bool disposing )
{
if( disposing )
{
if (components != null)
{
components.Dispose();
}
}
base.Dispose( disposing );
}
#region Windows Form Designer generated code
private void InitializeComponent()
{
this.QuitButton = new System.Windows.Forms.Button();
this.TrickButton = new CodeProject.WinForms.MCTrickButton();
this.SuspendLayout();
this.QuitButton.Location = new System.Drawing.Point(208, 128);
this.QuitButton.Name = "QuitButton";
this.QuitButton.TabIndex = 0;
this.QuitButton.Text = "Quit";
this.QuitButton.Click +=
new System.EventHandler(this.QuitButton_Click);
this.TrickButton.Location = new System.Drawing.Point(100, 60);
this.TrickButton.Name = "TrickButton";
this.TrickButton.Text = "Click Me!";
this.TrickButton.Click +=
new System.EventHandler(this.TrickButton_Click);
this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
this.ClientSize = new System.Drawing.Size(292, 165);
this.Controls.AddRange(new System.Windows.Forms.Control[] {
this.TrickButton, this.QuitButton });
this.Name = "Form1";
this.Text = "Form1";
this.ResumeLayout(false);
}
#endregion
[STAThread]
static void Main()
{
Application.Run(new Form1());
}
private void QuitButton_Click(object sender, System.EventArgs e)
{
Close();
}
private void TrickButton_Click(object sender, System.EventArgs e)
{
System.Windows.Forms.MessageBox.Show("You clicked me!");
}
}
}