How to access methods of MDI Child from by MDI Parent Toolbar?

Question

Hi

How can I access the methods (Add, Save,Delete, Record navigation methods such first, previous, next & last) of a MDI child from when clicking on a toolbar positioned in the MDI parent form?

So on the MDI parent I have this toolbar. When clicking on a button on this toolbar it must call a method from the current MDI child form. I am running there are several types of MDI child forms with keeping recordsets, but each contains (the same) methods...

How can I write template class for this functions?

Does anybody has an example of how to do this in Visual C++ .NET?

Thanks,
Joseph TA
Tel: [phone]

Answer 1

If they all have the same methods, I think the easiest thing to do is to give all your MDI children the same base class, then override.  Alternately, you could create an interface they all implement.

Here's how:
Create a base form which has the methods, override the methods in your child forms, then from the MDIParent use the Form.ActiveMdiChild to obtain the currently active MDI child - cast to your base class, then call the method on it.

Here's pseudocode C# for it:

class MdiChildBaseForm : Form {
  protected virtual void MoveFirst() {
  }
}

class MdiChildForm1 : MdiChildForm {
   protected override void MoveFirst() { ... }
}

class MainForm : Form {
  private void  moveFirstToolStripButton_Clicked (object sender, EventArgs e) {
      MdiChildBaseForm f = this.ActiveMdiChild as MdiChildBaseForm;
      if (f != null) {
        f.MoveFirst();
     }
  }
}

Jessica

Answer 2

What's the best way to have the MDI Child access the toolbar on the parent form?  For example, if some of the buttons need to be disabled depending on the state of the child?

Answer 3

From the parent, you can use the MDIChildActivate event to detect when a new MDI child has become active, then refresh your button states based on the ActiveMdiChild.

Answer 4

Thanks for the reply. I hope this may give good result. But you written in second MdiChildForm is the parent class. Is correct or MdiChildBaseForm?

Thanks
Joseph TA

Answer 5

                                       Form
         MdiChildBaseForm                     MainForm
MdiChildForm1 MdiChildForm2

Where
   MainForm 
      is the MdiParent with the ToolBar
   MdiChildBaseForm
      is the base class for all your MDIChildren in the project.  
     It has virtual methods for MoveFirst, MoveLast, etc etc
   MdiChildForm1 - is the first child form with an implementation for MoveFirst 
      It would override MdiChildBaseForm's MoveFirst and control its own DataGrid etc.
   MdiChildForm2 - is the second child form with an implementation for MoveFirst 
      Similar to MdiChildForm1, it would override MdiChildBaseForm's MoveFirst and control its own DataGrid etc.

Answer 6

Thanks for the help. Realy its very useful and solved my problem through these logic. First I written one abstract base class with pure virtual function and inherated for all the childforms.

like this.

class MDIChildBaseForm : Form {
protected:
  virtual void NextRecord()=0;
  ...
}

class CustomerForm : MDIChildBaseForm {
private:
  virtual void NextRecord(){...}
}

class ProductForm : MDIChildBaseForm {
private:
  virtual void NextRecord(){...}
}

I hope it will work for my future software changes also.

Thanks
Jose
Tel: [phone]

Answer 7

 

Hi

Could please find why this problem occuring... while loading the Child Form in the design mode.

I couldn't find the problem why its happening. But when I changing the base class (MDIChildBaseForm) of child form to

System::Windows::Forms::Form its working fine. What problem with base class?

 

--------------------------
My MDIChildBaseForm code:
--------------------------

#pragma once

#include "stdafx.h"

using namespace System;
using namespace System::ComponentModel;
using namespace System::Collections;
using namespace System::Windows::Forms;
using namespace System::Data;
using namespace System::Drawing;

namespace SCS
{
 public __gc class MDIChildBaseForm : public System::Windows::Forms::Form
 {
 public:
  MDIChildBaseForm(void)
  {
   InitializeComponent();
  }
       
 protected:
  void Dispose(Boolean disposing)
  {
   if (disposing && components)
   {
    components->Dispose();
   }
   __super::Dispose(disposing);
  }
 public:
  virtual void FirstRecord()=0;
  virtual void PreviousRecord()=0;
  virtual void NextRecord()=0;
  virtual void LastRecord()=0;
 private:
  System::ComponentModel::Container* components;
  void InitializeComponent(void)
  {
   this->components = new System::ComponentModel::Container();
   this->Size = System::Drawing::Size(300,300);
   this->Text = S"MDIChildBaseForm";
  }  
 };
}

-----------------------------
My Inherited Child Form Code:
-----------------------------

#pragma once

#include "stdafx.h"
#include "MDIChildBaseForm.h"

using namespace System;
using namespace System::ComponentModel;
using namespace System::Collections;
using namespace System::Windows::Forms;
using namespace System::Data;
using namespace System::Drawing;

namespace SCS
{
  public __gc class frmCurrency : public SCS::MDIChildBaseForm
  {
  public:
    frmCurrency(void)
    {
      InitializeComponent();
    }
       
    protected:
      void Dispose(Boolean disposing)
      {
 if (disposing && components)
 {
   components->Dispose();
 }
 __super::Dispose(disposing);
      }
    private:
      System::Windows::Forms::Label *  label1;
      System::Windows::Forms::TextBox *  txtCurrencyID;
      System::Windows::Forms::Label *  label2;
      System::Windows::Forms::TextBox *  txtCurrencyName;
      System::ComponentModel::Container* components;

    void InitializeComponent(void)
    {
      this->label1 = new System::Windows::Forms::Label();
      this->txtCurrencyID = new System::Windows::Forms::TextBox();
      this->label2 = new System::Windows::Forms::Label();
      this->txtCurrencyName = new System::Windows::Forms::TextBox();
      this->SuspendLayout();
      //
      // label1
      //
      this->label1->Location = System::Drawing::Point(96, 64);
      this->label1->Name = S"label1";
      this->label1->TabIndex = 0;
      this->label1->Text = S"&Currency ID:";
      this->label1->TextAlign = System::Drawing::ContentAlignment::MiddleRight;
      //
      // txtCurrencyID
      //
      this->txtCurrencyID->Location = System::Drawing::Point(200, 64);
      this->txtCurrencyID->Name = S"txtCurrencyID";
      this->txtCurrencyID->TabIndex = 1;
      this->txtCurrencyID->Text = S"txtCurrencyID";
      //
      // label2
      //
      this->label2->Location = System::Drawing::Point(96, 104);
      this->label2->Name = S"label2";
      this->label2->TabIndex = 2;
      this->label2->Text = S"Currency &Name:";
      this->label2->TextAlign = System::Drawing::ContentAlignment::MiddleRight;
      //
      // txtCurrencyName
      //
      this->txtCurrencyName->Location = System::Drawing::Point(200, 104);
      this->txtCurrencyName->Name = S"txtCurrencyName";
      this->txtCurrencyName->TabIndex = 3;
      this->txtCurrencyName->Text = S"txtCurrencyName";
      //
      // frmCurrency
      //
      this->AutoScaleBaseSize = System::Drawing::Size(5, 13);
      this->ClientSize = System::Drawing::Size(528, 374);
      this->Controls->Add(this->txtCurrencyName);
      this->Controls->Add(this->label2);
      this->Controls->Add(this->txtCurrencyID);
      this->Controls->Add(this->label1);
      this->Name = S"frmCurrency";
      this->Text = S"Currency";
      this->Load += new System::EventHandler(this, frmCurrency_Load);
      this->ResumeLayout(false);
    }  
  
    System::Void frmCurrency_Load(System::Object *  sender, System::EventArgs *  e)
    {
      ...
    }

    System::Void btnPrevious_Click(System::Object *  sender, System::EventArgs *  e)
    {
       PreviousRecord();
    }

    System::Void btnFirst_Click(System::Object *  sender, System::EventArgs *  e)
    {
       FirstRecord();
    }

    System::Void btnNext_Click(System::Object *  sender, System::EventArgs *  e)
    {
       NextRecord();
    }

    System::Void btnLast_Click(System::Object *  sender, System::EventArgs *  e)
    {
 LastRecord();
    }
  public:
    virtual System::Void FirstRecord()
    {
 ...
    }
    virtual System::Void LastRecord()
    {
 ...
    }
    virtual System::Void NextRecord()
    {
 ...
    }
    virtual System::Void PreviousRecord()
    {
 ...
    }
  };
}

-----------------------------------------------------------------------------
While loading form in the Microsoft Visual Studio .NET IDE giving this error:
-----------------------------------------------------------------------------

An error occurred while loading the document. Fix the error, and then try loading the document again. The error message

follows:

The designer could not be shown for this file because none of the classes within it can be designed. The designer inspected

the following classes in the file:

frmCurrency --- The base class 'SoficomCollectionSystem.MDIChildBaseForm' could not be loaded. Ensure the assembly has been

referenced or built if it is part of the project.

Thanks
Jose

 

Answer 8

Did you ever have the frmCurrency class inheriting from the MDIChildBaseForm class and loading in the designer?  Or did you have this working and then made a change? 

Can you get this to work in the simple case of creating a new project and adding two forms with the second inheriting from the first?

thanks
 - mike

Answer 9

Hi

I didn't try with new project so far. Before I want to know why this problem happening while designing my form so that I can fix and continue my work without work. Because I am going to develop lot of forms with that base class.

Could you find the problem? How I can solve? Please who have knowledge in this area help me.

Thanks in advance.
Jose