[vtkusers] Forward declaration of Foo enough for vtkNew<Foo> declaration?

[Elvis Stansvik]

2016-08-10 14:32 GMT+02:00 Elvis Stansvik <elvis.stansvik at orexplore.com>:

> Hi,
>
> The overview at
>
>     https://blog.kitware.com/a-tour-of-vtk-pointer-classes/
>
> seems to suggest that forward declaration of a class Foo should be enough
> to be able to declare a vtkNew<Foo> (e.g. see how vtkTable is used in the
> code example under "Use of Classes").
>
> But when I try e.g:
>
> class vtkCompositeTransferFunctionItem;
> ...
> vtkNew<vtkCompositeTransferFunctionItem> m_functionsItem;
>
> I get
>
>     error: invalid use of incomplete type ‘class
> vtkCompositeTransferFunctionItem’
>
> Do I really need to include vtkCompositeTransferFunctionItem.h to declare
> a vtkNew<vtkCompositeTransferFunctionItem> ?
>

To show more of the context where I'm trying this:

#pragma once

#include "VTKWidget.h"

#include <QObject>
#include <Qt>

#include <vtkNew.h>

#include <vtkChartXY.h>
#include <vtkContextView.h>
#include <vtkCompositeControlPointsItem.h>
#include <vtkCompositeTransferFunctionItem.h>

class QWidget;

class vtkColorTransferFunction;
// Apparently I can't just forward declare these.
//class vtkChartXY;
//class vtkCompositeTransferFunctionItem;
//class vtkCompositeControlPointsItem;
//class vtkContextView;
class vtkPiecewiseFunction;

class CompositeTransferFunctionEditor : public VTKWidget
{
    Q_OBJECT

public:
    enum Mode {
        EditColor,
        EditOpacity
    };
    Q_ENUM(Mode)

public:
    CompositeTransferFunctionEditor(vtkColorTransferFunction *colorFunction,
                                    vtkPiecewiseFunction *opacityFunction,
                                    Mode mode = EditColor,
                                    QWidget *parent = 0,
                                    Qt::WindowFlags flags =
Qt::WindowFlags());

    void setColorFunction(vtkColorTransferFunction *colorFunction);
    void setOpacityFunction(vtkPiecewiseFunction *opacityFunction);

signals:
    void functionsModified();

private:
    void editColorPoint();

private:
    vtkNew<vtkCompositeTransferFunctionItem> m_functionsItem;
    vtkNew<vtkCompositeControlPointsItem> m_pointsItem;
    vtkNew<vtkChartXY> m_chart;
    vtkNew<vtkContextView> m_contextView;
};

I had hoped I would only have to forward declare the types used in the
instantiations of vtkNew here, not include the full headers.

Elvis


> Thanks,
> Elvis
>
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