Setting up and using a GLDisplayListWidget

Set-up:

Download the GLDisplayListWidget repository from 157support

From within Qt Designer:

• Design/create your interface and use the Graph View widget as a placeholder widget for the graphical display window.
• Promote the Graph View widget to a GLDisplayListWidget (instructions). After you have promoted the Graph View widget, save your user interface to effect the changes.

Outside of Qt Designer

• Add entries in your *.pro project file to support a GLDisplayListWidget.
  
  In order for the correct code to be created from the user interface file, a project (*.pro) file must now include a path to the QtGLgraphics directory, a specification of the headers and source files for GLDisplayListWidget and QtGLgraphics, and a specifcation that opengl is to be used. Also, you will want _CRT_SECURE_NO_WARNINGS and _CRT_SECURE_NO_DEPRECATE to be defined so that Visual Studio doesn't issue so many warnings.
  
  Assuming that the GLDisplayListWidget are located in the relative location, ..\QtGLgraphics, the additional entries to the *.pro file would be
  
  QT += opengl
DEFINES += _CRT_SECURE_NO_WARNINGS
DEFINES += _CRT_SECURE_NO_DEPRECATE
INCLUDEPATH += ../QtGLgraphics

HEADERS += ../QtGLgraphics/GLDisplayListWidget.h
HEADERS += ../QtGLgraphics/GLDriverQt.h

SOURCES += ../QtGLgraphics/GLDisplayListWidget.cpp
SOURCES += ../QtGLgraphics/GLDriverQt.cpp
  
  
• Re-run qmake after adding these entries and then rebuild your project.

GLDisplayListWidget Usage

The GLDisplayListWidget class implements a Qt based OpenGL widget that renders UCdriver and UCdriverEx graphics calls. This class is derived from QGLWidget. See the Qt reference guide for information about member functions associated with QGLwidget.

The UCdriver (UCdriverEx) interface is provided by an internal instance of a GLDriverQt. Access to this interface is through a pointer obtained with the getGLDriverQtPtr() member function.

When a code in which the user interface (*.ui) contains a GLDisplayListWidget is built, a data member is made in the corresponding user interface header file that points to the GLDisplayListWidget in the interface. The following code samples assume that the GLDisplayListWidget object is named glWidget. If you don't know the name of the GLDisplayListWidget pointer in your program, you can look af the user interface header file.

A sample code snippet where the GLDriverQt pointer is used to call UCdriver or UCdriverEx routines whose output will be displayed in the graphics window.

//
//  In a response function in the window class that implements the plotting...

//
//  Capture the GLDriverQt pointer  
//
    GLDriverQt* Gldriver = glWidget->getGLDriverQtPtr(); 

//  Use the  start() to open up a GL display list and then create
//  graphics by calling UCdriver or UCdriverEx methods. Close
//  the list and induce a repaint of glWidget by calling frame(). 

    Gldriver->start();
     
    Gldriver->point(...);          //           
    Gldriver->lines(...);          // UCdriver or UCdriverEx calls
    Gldriver->pointEx(...);        //

    Gldriver->frame();

//
//  In a response function in the window class that implements the plotting...

//
//  Extract the pointer to the low level driver (can be used in any class expecting a 
//  UCdriver or UCdriverEx pointer).
// 
    GLDriverQt* Gldriver = glWidget->getGLDriverQtPtr();
//
//  A collection of GLDriverQt calls must be 
//  prefaced by a start(..) call when using the OpenGL based 
//  driver. 
//
    Gldriver->start();
//
//  read f(x) value (as a Qstring)
//
    QString fxText = fxTextEdit->text();
//
//  create symbolic function, if in error then close frame and set error message
 
    DoubleSymbolicFunction symfun;
    int ierr = symfun.initialize(fxText.toStdString());
    if(ierr == 1)
    {
        Gldriver->frame(); 
        fxTextEdit->setText("Function Error");
        return;
	}
//
//  Create an instance of the PlotFunction class
//
    PlotData Plot;
    Plot.setGraphicsDriver(Gldriver);
//
//  Plot the function 
//
    Plot.plot(symfun,xMin,xMax,yMin,yMax);
//
//  Draw a frame around the plot
//
    Plot.drawFrame();
//
//  Call frame to display the plot and close the display list
//
    Gldriver->frame();