In some cases, an SDI can also have a toolbar and/or a status bar. Here is an example from Microsoft Works Spreadsheet:
All these features are left to the programmer to add and configure. Although Notepad is text-based, an SDI can be any type of application: text, graphics, spreadsheet, anything. Therefore, to create an SDI, start from a normal form, add a menu to it, and configure it to do what you want. To create a document using an SDI, the user launches the application. The SDI then presents a rectangular window with one frame and the inside is the document the user will use. In most cases, the application itself creates the document. The user can work on it and do whatever the application allows. To create another document of the same type, the user must open another instance of the application.
A multiple-document interface (MDI) is an application that primarily has a form and a menu. Some, if not most, MDIs also have one or more toolbars and/or a status bar. Here is an example:
Like a normal application, to use an MDI, the user must launch it. In some cases, when the application starts, it is empty; that is, no document is created and the title bar displays a caption, usually the name of the application. Usually, there are steps the user must follow to create a document. In some other cases, when the application is launched, it automatically creates a document. A document resides inside the parent frame of the application. That is, a child document can use only the area reserved for it. The child document has its own system icon, its own title bar, and its system buttons (Minimize, Maximize/Restore, and Close). To use the whole area, the user can maximize the child document. When this is done, the child merges its title bar with the parent's. The new caption of the title bar becomes made of the text of the parent, followed by -, and followed by the caption the child window was using. The system buttons of the child document display under those of the parent frame:
Once a document has been created, the user can use it. Normalement, the application must give the user the ability to create other documents while still using the application. If many documents have been created, all of them are confined in the frame of the Topic Applied:
The user can maximize the child forms. If so, the document that was in front occupies the whole area devoted to child documents. The other child forms stay in the back but become invisible. One of the differences between an SDI and an MDI is that, because the document and the application don't share a frame, the user can close the document and keep the application open.
As mentioned already, there is nothing magical with creating an SDI. You start with a form, add a menu to it, and specify what the application should allow a user to do with a document. As we will see, an MDI requires more steps. You start an MDI application with a normal form. You can create a Windows Forms Application using Microsoft Visual Studio or derive a class from Form. Here is an example: #include <windows.h>
#using <System.dll>
#using <System.Windows.Forms.dll>
using namespace System;
using namespace System::Windows::Forms;
public ref class CCommonParent : public Form
{
public:
CCommonParent()
{
InitializeComponent();
}
private:
void InitializeComponent()
{
Text = L"Exercise";
StartPosition = FormStartPosition::CenterScreen;
}
};
int APIENTRY WinMain(HINSTANCE hInstance,
HINSTANCE hPrevInstance,
LPSTR lpCmdLine,
int nCmdShow)
{
Application::Run(gcnew CCommonParent);
return 0;
}
The primary form of an MDI application is referred to as the parent or MDI container. It provides the frame inside of which the documents will reside. To provide this functionality, the Form class is equipped with a Boolean property named IsMdiContainer. Therefore, after creating the first form of your application, to indicate that it acts as the main frame, set this property to true. You can do this in the Properties window if you are visually creating your application, or programmatically. Here is an example: public ref class CCommonParent : public Form
{
public:
CCommonParent()
{
InitializeComponent();
}
private:
void InitializeComponent()
{
IsMdiContainer = true;
Text = L"Exercise";
StartPosition = FormStartPosition::CenterScreen;
}
};
This would produce:
The primary characteristic of an MDI is that it contains other forms. These forms must be created and made available to the parent. Each form can be created using a predefined form or you can programmatically create one by declaring an object of type Form. To allow you to specify that a form has a parent and will act as a child, the Form class is equipped with a property named MdiParent. This is a read-write property. The set accessor indicates what form acts as this one's parent. To provide this information, assign the main form this form's MdiParent. After doing this, you can display the form when you are ready, by calling its Show() member function. Here is an example: public ref class CCommonParent : public Form
{
public:
CCommonParent()
{
InitializeComponent();
}
private:
void InitializeComponent()
{
IsMdiContainer = true;
Form ^ frmChild = gcnew Form;
frmChild->MdiParent = this;
frmChild->Show();
Text = L"Exercise";
StartPosition = FormStartPosition::CenterScreen;
}
};
This would produce:
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Practical Learning: Introducing MDI Applications
and click the form
and click the form
and click the form
and click the form
and click the form
of the Properties window. Click the Click field and, on the right
side, select mnuFileNew_Click
to move and position it just above mnuHelp
