Method to achieve repositioning/resizing of child controls

First of all this is not a library. There is no associated DLL or LIB to link to. Secondly, it is not a class hierarchy. You don't have to derive your classes from classes exposing this functionality. Often, you already have a hierarchy of classes designed for a certain behavior. This behavior does not include repositioning/resizing of child controls, but you want to add it. Since the MFC doesn't let you use multiple inheritance when it comes to windows, you might wonder what is the solution. Well, the solution is templates. GEOMETRY is actually a collection of templates designed to make your windows to resize gracefully.

The interface to GEOMETRY is a single class template CGeometryWnd. You can use this class template with all your window classes including dialogs, forms, property sheets/property pages and splitter windows. Being a template library, GEOMETRY is contained in a single file Geometry.h. All you have to do is to include this file, to use CGeometryWnd and possibly a series of macros, in relation with your classes.

For example:

#include 
USE_GEOMETRY_TEMPLATES;
/////////////////////////////////////////////////////////////////////////////
// CAboutDlg dialog used for App About

class CAboutDlg : public CDialog
{
	DECLARE_GEOMETRY_RTSUPPORT()
public:
	CAboutDlg();

// Dialog Data
	//{{AFX_DATA(CAboutDlg)
	enum { IDD = IDD_ABOUTBOX };
	//}}AFX_DATA

	virtual BOOL OnInitDialog();
	//{{AFX_VIRTUAL(CAboutDlg)
	protected:
	virtual void DoDataExchange(CDataExchange* pDX);    // DDX/DDV support
	//}}AFX_VIRTUAL

// Implementation
protected:
	//{{AFX_MSG(CAboutDlg)
		// No message handlers
	//}}AFX_MSG
	DECLARE_MESSAGE_MAP()
};

CAboutDlg::CAboutDlg() : CDialog(CAboutDlg::IDD)
{
	//{{AFX_DATA_INIT(CAboutDlg)
	//}}AFX_DATA_INIT
}

void CAboutDlg::DoDataExchange(CDataExchange* pDX)
{
	CDialog::DoDataExchange(pDX);
	//{{AFX_DATA_MAP(CAboutDlg)
	//}}AFX_DATA_MAP
}

BEGIN_MESSAGE_MAP(CAboutDlg, CDialog)
	//{{AFX_MSG_MAP(CAboutDlg)
		// No message handlers
	//}}AFX_MSG_MAP
END_MESSAGE_MAP()

BOOL CAboutDlg::OnInitDialog()
{
	CDialog::OnInitDialog();

	AddConstraint(IDOK,CConstraint("X"));
	return TRUE;
}

// App command to run the dialog
void CTestPSGeoApp::OnAppAbout()
{
	CGeometryWnd aboutDlg;
	aboutDlg.DoModal();
}

CConstraint(LPCSTR lpOptions)	 and
CConstraint(float x,float y=0,float cx=0,float cy=0)

Option1[value]+Option2[value]+

Note:
To add the constraints at design time directly in resource editor you' ll gonna surround the controls sharing the same constraint options with invisible group boxes having the caption in the form "$Geometry:Option1[value]+Option2[value]+" w/o the quotes. Please note the $Geometry in front of the options string, this is not optional. Be careful with the capital/minor letters as they have different significance. Using this form of constraints specification you don't need DECLARE_GEOMETRY_RTSUPPORT() and AddConstraint() as previously displayed.

Using the second constructor you will specify the values between 0 and 1 that will be multiplied with the total resize amount of the parent. A value of 0 means don't move/resize a value of 1 means full movement/resizing. Please note that the values of movement/resizing on one axis added together must not be greater than 1 (otherwise the control will be clipped away from its parent).

AddConstraint(UINT nIDC,CConstraint& constraint) takes as parameters the control ID and a reference to a constraint object.

To achieve dynamic creation of windows MFC uses DECLARE_DYNCREATE(), IMPLEMENT_DYNCREATE() along with RUNTIME_CLASS() macros. For example the CFormView derived classes are usually created by the framework in this way. To accommodate this case GEOMETRY uses a set of macros of its own:

DECLARE_GEOMETRY_DYNCREATE(yourClass)
IMPLEMENT_GEOMETRY_DYNCREATE(yourClass)
GEOMETRY_RUNTIME_CLASS(yourClass)

For example:

#include 
USE_GEOMETRY_TEMPLATES;

class CTestPSGeoView : public CFormView
{
protected: // create from serialization only
	CTestPSGeoView();
	DECLARE_DYNCREATE(CTestPSGeoView)

};
DECLARE_GEOMETRY_DYNCREATE(CTestPSGeoView);

In the definition file of the CTestPSGeoView class and

IMPLEMENT_DYNCREATE(CTestPSGeoView,CFormView)
IMPLEMENT_GEOMETRY_DYNCREATE(CTestPSGeoView)

In the implementation file.

Also, there is necessary the substitution:

CMultiDocTemplate* pDocTemplate;
pDocTemplate = new CMultiDocTemplate(
	IDR_TESTPSTYPE,
	RUNTIME_CLASS(CTestPSGeoDoc),
	RUNTIME_CLASS(CChildFrame), // custom MDI child frame
	GEOMETRY_RUNTIME_CLASS(CTestPSGeoView));

Download demo project - 36 KB

Date Last Updated: April 4, 1999