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The MFC unclickable button ported to Managed C++

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23 May 2002CPOL1 min read 128.1K   1.4K   18   14
This article presents a port of the MFC Trick button to .NET using Managed C++ and Windows Forms

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

MC++
// MCTrickButton.h

#pragma once

using namespace System::Windows::Forms;

namespace CodeProject
{
    namespace WinForms
    {
        public __gc class MCTrickButton : public Button
        {
            // Constructor
        public:
            MCTrickButton();

            // Properties
        public:
            __property int get_JumpDistance()            
                                    { return m_nJumpDistance; }
            __property void set_JumpDistance(int value) 
                                    { m_nJumpDistance = value; }
        
            // Member variables
        protected:
            int m_nJumpDistance; // Pixels to jump

        protected:
            virtual void OnMouseMove(MouseEventArgs* e);
            virtual void WndProc(Message *pmsg);
        };
    }
}

Implementation

MC++
#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;
}

// Called when the mouse moves over the button
void MCTrickButton::OnMouseMove(MouseEventArgs* e)
{
    // Get the current mouse position from the MouseEventArgs
    // object and convert to screen coords    
    Point point(e->X,e->Y);
    point = PointToScreen(point);

    // All pixels are used in parent client coordinates
    // So convert screen coords parent relative coords 
    Control *pParent = Parent;
    if (pParent != NULL)
        point = pParent->PointToClient(point);

    // Get the client area of the parent (so we know the bounds
    // of movement for the button
    Drawing::Rectangle ParentRect;
    if (pParent == NULL)
    {
        // use the current screen if no parent
        Screen *currentScreen = Screen::FromPoint(point);
        ParentRect = currentScreen->WorkingArea;
    }
    else
        ParentRect = pParent->ClientRectangle;

    // Get the dimensions of this button and convert to parent
    // coords
    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);


    // We now check where the mouse is relative to the center
    // of the button. We need to know from which direction the 
    // mouse is coming from so we can move the button away from 
    // the mouse

    Drawing::Rectangle NewButtonRect = ButtonRect;

    // mouse attack from the right side
    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;
        }
    }
    // mouse attack from the left
    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;
        }
    }
    // mouse attack from below
    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;
        }
    }
    // attack from above
    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;
        }
    }

    // now we move the button to the new point
    Location = Point(NewButtonRect.X, NewButtonRect.Y);

    Button::OnMouseMove(e);
}

void MCTrickButton::WndProc(Message *pMsg)
{
     // Call the base class function first
    Button::WndProc(pMsg);

    // If the button is recieving the focus then pass
    // it back to the window that gave it the focus
    if (pMsg->Msg == WM_SETFOCUS)
    {
        Control *pOldWnd = FromHandle(pMsg->WParam); 
        if (pOldWnd != NULL) 
            pOldWnd->Focus(); //set focus to previous control
    } 
}

A sample app

C#
using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;

using CodeProject.WinForms;

namespace TrickButtonDemo
{
    /// Summary description for Form1.
    public class Form1 : System.Windows.Forms.Form
    {
        private System.Windows.Forms.Button QuitButton;
        private CodeProject.WinForms.MCTrickButton TrickButton;

        /// Required designer variable.
        private System.ComponentModel.Container components = null;

        public Form1()
        {
            InitializeComponent();
        }

        /// Clean up any resources being used.
        protected override void Dispose( bool disposing )
        {
            if( disposing )
            {
                if (components != null) 
                {
                    components.Dispose();
                }
            }
            base.Dispose( disposing );
        }

        #region Windows Form Designer generated code
        /// <summary>
        /// Required method for Designer support - do not modify
        /// the contents of this method with the code editor.
        /// </summary>
        private void InitializeComponent()
        {
            this.QuitButton = new System.Windows.Forms.Button();
            this.TrickButton = new CodeProject.WinForms.MCTrickButton();
            this.SuspendLayout();
            // 
            // QuitButton
            // 
            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);
            // 
            // TrickButton
            // 
            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);
            // 
            // Form1
            // 
            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

        /// <summary>
        /// The main entry point for the application.
        /// </summary>
        [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!");
        }
    }
}

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


Written By
Founder CodeProject
Canada Canada
Chris Maunder is the co-founder of CodeProject and ContentLab.com, and has been a prominent figure in the software development community for nearly 30 years. Hailing from Australia, Chris has a background in Mathematics, Astrophysics, Environmental Engineering and Defence Research. His programming endeavours span everything from FORTRAN on Super Computers, C++/MFC on Windows, through to to high-load .NET web applications and Python AI applications on everything from macOS to a Raspberry Pi. Chris is a full-stack developer who is as comfortable with SQL as he is with CSS.

In the late 1990s, he and his business partner David Cunningham recognized the need for a platform that would facilitate knowledge-sharing among developers, leading to the establishment of CodeProject.com in 1999. Chris's expertise in programming and his passion for fostering a collaborative environment have played a pivotal role in the success of CodeProject.com. Over the years, the website has grown into a vibrant community where programmers worldwide can connect, exchange ideas, and find solutions to coding challenges. Chris is a prolific contributor to the developer community through his articles and tutorials, and his latest passion project, CodeProject.AI.

In addition to his work with CodeProject.com, Chris co-founded ContentLab and DeveloperMedia, two projects focussed on helping companies make their Software Projects a success. Chris's roles included Product Development, Content Creation, Client Satisfaction and Systems Automation.

Written By
United States United States
Nish Nishant is a technology enthusiast from Columbus, Ohio. He has over 20 years of software industry experience in various roles including Chief Technology Officer, Senior Solution Architect, Lead Software Architect, Principal Software Engineer, and Engineering/Architecture Team Leader. Nish is a 14-time recipient of the Microsoft Visual C++ MVP Award.

Nish authored C++/CLI in Action for Manning Publications in 2005, and co-authored Extending MFC Applications with the .NET Framework for Addison Wesley in 2003. In addition, he has over 140 published technology articles on CodeProject.com and another 250+ blog articles on his WordPress blog. Nish is experienced in technology leadership, solution architecture, software architecture, cloud development (AWS and Azure), REST services, software engineering best practices, CI/CD, mentoring, and directing all stages of software development.

Nish's Technology Blog : voidnish.wordpress.com

Comments and Discussions

 
GeneralYour code ported to C# Pin
georani21-Apr-05 10:55
georani21-Apr-05 10:55 
GeneralYour Code Ported to VB (It works) Pin
georani21-Apr-05 9:18
georani21-Apr-05 9:18 
GeneralI want to ask a question! Pin
Member 39655012-Jun-03 2:40
Member 39655012-Jun-03 2:40 
GeneralWindows.Forms.Control in Browser: Pin
Anonymous29-Mar-03 21:30
Anonymous29-Mar-03 21:30 
GeneralVC++ Pin
Ayman Rabee1-Aug-02 0:04
sussAyman Rabee1-Aug-02 0:04 
GeneralRe: VC++ Pin
Nish Nishant1-Aug-02 0:08
sitebuilderNish Nishant1-Aug-02 0:08 
GeneralActually... Pin
Tim Smith24-May-02 8:50
Tim Smith24-May-02 8:50 
This is an interesting concept.

Take a basic but non-trivial subject and provide different implementations for each of the common platform. For example, this in MFC/WTL(ATL)/Managed C/C#.



Tim Smith

I know what you're thinking punk, you're thinking did he spell check this document? Well, to tell you the truth I kinda forgot myself in all this excitement. But being this here's CodeProject, the most powerful forums in the world and would blow your head clean off, you've got to ask yourself one question, Do I feel lucky? Well do ya punk?
GeneralRe: Actually... Pin
Nish Nishant24-May-02 17:15
sitebuilderNish Nishant24-May-02 17:15 
QuestionThe quit button should be unclickable ? Pin
Daniel Turini24-May-02 8:36
Daniel Turini24-May-02 8:36 
AnswerRe: The quit button should be unclickable ? Pin
Nish Nishant24-May-02 17:16
sitebuilderNish Nishant24-May-02 17:16 
GeneralA request from users ... Pin
24-May-02 7:36
suss24-May-02 7:36 
GeneralRe: A request from users ... Pin
Shog924-May-02 11:59
sitebuilderShog924-May-02 11:59 
GeneralRe: A request from users ... Pin
Brian Olej24-May-02 15:03
Brian Olej24-May-02 15:03 
GeneralRe: A request from users ... Pin
Shog924-May-02 16:24
sitebuilderShog924-May-02 16:24 

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