[Qt-interest] Does QGLWidget have to be manually released?

[Joe Liu]

2009/10/15 Donal O'Connor <donaloconnor at gmail.com>

> Does you're sub class pass the parent widget pointer to the QGLWidget
> superclass, QGLWidget?
>
> *//// Yes, MyGLWidget pass the parent window pointer to the QGLWidget in
its constructor;
*


> Also, you don't have a constructor in your MyGLWidget that accepts a
> pointer to a QWidget, not sure how it even compiles that way unless I'm
> missing something.
>

*//// it's a typing error; of course I have such a constructor which accepts
a pointer to the parent window; I just followed the sample code in Hello GL
coming with Qt. *

>
>
> On Thu, Oct 15, 2009 at 3:13 PM, Joe Liu <passer.by007gg at gmail.com> wrote:
>
>> Hi guys,
>>
>> I am writing some OpenGL programs based on QGLWidget;
>>
>> My program now is quite simple, its structure is generally like this:
>>
>> ===========================================================
>> *// my Qt gl widget class*
>> class *MyGLWidget *: public QGLWidget
>> {
>>     MyGLWidget ();
>>     ~MyGLWidget ();    // do nothing
>>
>>     // add some additional variables to manipulate the camera
>> };
>>
>> *// my main window class*
>> class *MyWindow *: public QMainWindow
>> {
>>     MyWindow(QWidget* parent);
>>     ~QMainWindow();
>>
>>     MyGLWidget* m_pGLWindow;
>> }
>>
>> *// how the GL widget is created and attached to the main window*
>> MyWindow::MyWindow(QWidget* parent)
>> : QMainWindow(parent)
>> {
>>     ui.setupUi(this);
>>
>>     *// set current main window as the parent of the gl widget***
>>     m_pGLWindow = new MyGLWidget (this);   **
>>     ui.glLayout->addWidget(m_pGLWindow);
>> }
>> ==================================================================
>>
>> At the beginning, everything works well; the GLWidget display a simple
>> quad in the scene;
>>
>> However, when i tried to add more variables to help manipulate the camera
>> states,
>> The program always crashed when closing the application window;
>>
>> the compiler outputs the message: Heap block at 013AB9C8 modified at
>> 013ABAE4 past requested size of 114
>>
>> Anyway, I tried to fix the problem by releasing QGLWidget object manually,
>> in this way:
>>
>> ==================================================================
>> MyWindow::~MyWIndow()
>> {
>>     m_pGLWindow->~MyGLWidget();  *// manually invoke the destructor of GL
>> widget*
>>
>> *    // delete m_pGLWindow;  does not work*
>> }
>> ==================================================================
>>
>> Then the program shut down correctly.
>>
>> So does Qt GL widget have to be manually released? It's very weird...
>>
>> My Qt: v4.5.2,
>> OS: Windows XP sp3
>> Compiler: VC++ 9.0
>>
>> Need some help, thanks~~
>>
>> Cheers,
>>
>>
>> Joe
>>
>> _______________________________________________
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>> Qt-interest at trolltech.com
>> http://lists.trolltech.com/mailman/listinfo/qt-interest
>>
>>
>
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