In the world of software development, creating a user-friendly and visually appealing interface is crucial. One of the key elements in achieving this is by using dialog boxes, also known as CDialogs in MFC (Microsoft Foundation Classes). These dialog boxes serve as a means for users to interact with the application, and it is essential to make them resizable to accommodate different screen sizes and user preferences. In this article, we will discuss how to create a resizable CDialog in MFC.
Before we dive into the steps, let us understand the concept of dialog boxes in MFC. A dialog box is a child window that appears on top of the main application window. It contains controls such as buttons, text boxes, checkboxes, etc., that users can interact with to perform certain tasks. In MFC, a CDialog class is used to create dialog boxes.
Now, let us move on to the steps to create a resizable CDialog in MFC.
Step 1: Creating a new project
The first step is to create a new MFC project in Visual Studio. Select the MFC Application template and give it a name. Click on the Next button and select Dialog based as the application type. Once the project is created, you will see a default dialog box in the resource view.
Step 2: Modifying the dialog template
To make the dialog resizable, we need to add a sizing border to the dialog template. In the resource view, double-click on the dialog template to open it in the dialog editor. Right-click on the dialog box and select Properties. In the properties window, set the Border style to Resizable and the Sizing border to Yes. This will add a sizing border to the dialog box.
Step 3: Enabling resizing in the CDialog class
Next, we need to enable resizing in the CDialog class. Open the header file of the dialog class and add the following line to the constructor:
this->SetWindowLong(this->m_hWnd, GWL_STYLE, GetStyle() | WS_THICKFRAME);
Step 4: Implementing the OnSize event handler
The OnSize event handler is responsible for resizing the controls in the dialog box when the size of the dialog changes. In the dialog class, add the following code to the OnSize event handler:
void CResizableDialog::OnSize(UINT nType, int cx, int cy)
{
CDialogEx::OnSize(nType, cx, cy);
// TODO: Add your message handler code here
CRect rect;
GetClientRect(rect);
HDWP hdwp = BeginDeferWindowPos(1);
if (hdwp)
{
DeferWindowPos(hdwp, this->GetDlgItem(IDC_STATIC)->m_hWnd, NULL, 0, 0, rect.Width(), rect.Height(), SWP_NOZORDER);
EndDeferWindowPos(hdwp);
}
}
This code will resize the static control in the dialog box, which acts as a placeholder for other controls.
Step 5: Handling the WM_NCHITTEST message
The WM_NCHITTEST message is responsible for handling the sizing of the dialog box. In the dialog class, add the following code:
BOOL CResizableDialog::OnNcHitTest(CPoint point)
{
// TODO: Add your message handler code here and/or call default
RECT rect;
GetClientRect(&rect);
ClientToScreen(&rect);
if (point.y >= rect.bottom - 10)
return HTBOTTOM;
if (point.x >= rect.right - 10)
return HTRIGHT;
return CDialogEx::OnNcHitTest(point);
}
This code will handle the mouse clicks on the sizing border, allowing the user to resize the dialog box.
Step 6: Testing the application
Now, we can test our application by running it and resizing the dialog box. You will notice that the controls in the dialog box also get resized, making the dialog box truly resizable.
In conclusion, creating a resizable CDialog in MFC is a straightforward process. By following the above steps, you can make your dialog boxes more user-friendly and visually appealing. As a developer, it is essential to pay attention to the user interface to provide a better user experience. We hope this article has helped you understand how to create a resizable CDialog in MFC.
