QOpenGLWidget subclass to house a vtkGenericOpenGLRenderWindow in a Qt application. More...

#include <QVTKOpenGLNativeWidget.h>

Inherits QOpenGLWidget.

Collaboration diagram for QVTKOpenGLNativeWidget:

Signals
void	mouseEvent (QMouseEvent *event)
	This signal will be emitted whenever a mouse event occurs within the QVTK window. More...

Public Member Functions
	QVTKOpenGLNativeWidget (QWidget *parent=Q_NULLPTR, Qt::WindowFlags f=Qt::WindowFlags())

	~QVTKOpenGLNativeWidget () override

virtual QVTKInteractorAdapter *	GetInteractorAdapter ()
	Get the QEvent to VTK events translator. More...

virtual QVTKInteractor *	GetInteractor ()
	Get the QVTKInteractor that was either created by default or set by the user. More...

virtual void	setEnableHiDPI (bool enable)
	Enable or disable support for HiDPI displays. More...

virtual bool	enableHiDPI ()

void	setQVTKCursor (const QCursor &cursor)
	Set the cursor on this widget. More...


void	SetRenderWindow (vtkGenericOpenGLRenderWindow *win)
	Get/Set the currently used vtkGenericOpenGLRenderWindow. More...

void	SetRenderWindow (vtkRenderWindow *win)
	Get/Set the currently used vtkGenericOpenGLRenderWindow. More...

virtual vtkRenderWindow *	GetRenderWindow ()
	Get/Set the currently used vtkGenericOpenGLRenderWindow. More...

Static Public Member Functions
static void	copyFromFormat (const QSurfaceFormat &format, vtkRenderWindow *win)
	Sets up vtkRenderWindow ivars using QSurfaceFormat. More...

static void	copyToFormat (vtkRenderWindow *win, QSurfaceFormat &format)
	Using the vtkRenderWindow, setup QSurfaceFormat. More...

static QSurfaceFormat	defaultFormat ()
	Returns a typical QSurfaceFormat suitable for most applications using QVTKOpenGLNativeWidget. More...

Protected Slots
virtual void	cleanupContext ()
	Called as a response to `QOpenGLContext::aboutToBeDestroyed`. More...

Protected Member Functions
bool	event (QEvent *evt) Q_DECL_OVERRIDE

void	initializeGL () Q_DECL_OVERRIDE

void	resizeGL (int w, int h) Q_DECL_OVERRIDE

void	paintGL () Q_DECL_OVERRIDE

void	mousePressEvent (QMouseEvent *event) Q_DECL_OVERRIDE

void	mouseMoveEvent (QMouseEvent *event) Q_DECL_OVERRIDE

void	mouseReleaseEvent (QMouseEvent *event) Q_DECL_OVERRIDE

void	mouseDoubleClickEvent (QMouseEvent *event) Q_DECL_OVERRIDE

void	requireRenderWindowInitialization ()
	This method is called to indicate that vtkRenderWindow needs to reinitialize itself before the next render (done in QVTKOpenGLNativeWidget::paintGL). More...

virtual bool	renderVTK ()
	This method may be called in `paintGL` to request VTK to do a render i.e. More...

Protected Attributes
vtkSmartPointer< vtkGenericOpenGLRenderWindow >	RenderWindow

QVTKInteractorAdapter *	InteractorAdapter

bool	EnableHiDPI

int	OriginalDPI

Static Protected Attributes
static const double	DevicePixelRatioTolerance

Friends
class	QVTKOpenGLNativeWidgetObserver

Detailed Description

QOpenGLWidget subclass to house a vtkGenericOpenGLRenderWindow in a Qt application.

QVTKOpenGLNativeWidget extends QOpenGLWidget to make it work with a vtkGenericOpenGLRenderWindow. This is akin to QVTKWidget except it uses Qt to create and manage the OpenGL context using QOpenGLWidget (added in Qt 5.4).

While QVTKOpenGLNativeWidget is intended to be a replacement for QVTKWidget when using Qt 5, there are a few difference between QVTKOpenGLNativeWidget and QVTKWidget.

Unlike QVTKWidget, QVTKOpenGLNativeWidget only works with vtkGenericOpenGLRenderWindow. This is necessary since QOpenGLWidget wants to take over the window management as well as the OpenGL context creation. Getting that to work reliably with vtkXRenderWindow or vtkWin32RenderWindow (and other platform specific vtkRenderWindow subclasses) was tricky and fraught with issues.

Since QVTKOpenGLNativeWidget uses QOpenGLWidget to create the OpenGL context, it uses QSurfaceFormat (set using QOpenGLWidget::setFormat or QSurfaceFormat::setDefaultFormat) to create appropriate window and context. You can use QVTKOpenGLNativeWidget::copyToFormat to obtain a QSurfaceFormat appropriate for a vtkRenderWindow.

A typical usage for QVTKOpenGLNativeWidget is as follows:

// before initializing QApplication, set the default surface format.
QSurfaceFormat::setDefaultFormat(QVTKOpenGLNativeWidget::defaultFormat());
vtkNew<vtkGenericOpenGLRenderWindow> window;
QPointer<QVTKOpenGLNativeWidget> widget = new QVTKOpenGLNativeWidget(...);
widget->SetRenderWindow(window.Get());
// If using any of the standard view e.g. vtkContextView, then
// you can do the following.
vtkNew<vtkContextView> view;
view->SetRenderWindow(window.Get());
// You can continue to use `window` as a regular vtkRenderWindow
// including adding renderers, actors etc.

OpenGL Context

In QOpenGLWidget (superclass for QVTKOpenGLNativeWidget), all rendering happens in a framebuffer object. Thus, care must be taken in the rendering code to never directly re-bind the default framebuffer i.e. ID 0.

QVTKOpenGLNativeWidget creates an internal QOpenGLFramebufferObject, independent of the one created by superclass, for vtkRenderWindow to do the rendering in. This explicit double-buffering is useful in avoiding temporary back-buffer only renders done in VTK (e.g. when making selections) from destroying the results composed on screen.

Handling Render and Paint.

QWidget subclasses (including QOpenGLWidget and QVTKOpenGLNativeWidget) display their contents on the screen in QWidget::paint in response to a paint event. QOpenGLWidget subclasses are expected to do OpenGL rendering in QOpenGLWidget::paintGL. QWidget can receive paint events for various reasons including widget getting focus/losing focus, some other widget on the UI e.g. QProgressBar in status bar updating, etc.

In VTK applications, any time the vtkRenderWindow needs to be updated to render a new result, one call vtkRenderWindow::Render on it. vtkRenderWindowInteractor set on the render window ensures that as interactions happen that affect the rendered result, it calls Render on the render window.

Since paint in Qt can be called more often then needed, we avoid potentially expensive vtkRenderWindow::Render calls each time that happens. Instead, QVTKOpenGLNativeWidget relies on the VTK application calling vtkRenderWindow::Render on the render window when it needs to update the rendering. paintGL simply passes on the result rendered by the most render vtkRenderWindow::Render to Qt windowing system for composing on-screen.

There may still be occasions when we may have to render in paint for example if the window was resized or Qt had to recreate the OpenGL context. In those cases, QVTKOpenGLNativeWidget::paintGL can request a render by calling QVTKOpenGLNativeWidget::renderVTK.

Caveats

QVTKOpenGLNativeWidget only supports OpenGL2 rendering backend. QVTKOpenGLNativeWidget does not support stereo, please use QVTKOpenGLWidget if you need support for stereo rendering

QVTKOpenGLNativeWidget is targeted for Qt version 5.5 and above.

Definition at line 124 of file QVTKOpenGLNativeWidget.h.

Constructor & Destructor Documentation

QVTKOpenGLNativeWidget::QVTKOpenGLNativeWidget	(	QWidget *	parent = `Q_NULLPTR`,
		Qt::WindowFlags	f = `Qt::WindowFlags()`
	)

QVTKOpenGLNativeWidget::~QVTKOpenGLNativeWidget ( )

override

Member Function Documentation

void QVTKOpenGLNativeWidget::SetRenderWindow ( vtkGenericOpenGLRenderWindow * win )

Get/Set the currently used vtkGenericOpenGLRenderWindow.

GetRenderWindow() creates and returns a new vtkGenericOpenGLRenderWindow if it is not already provided.

void QVTKOpenGLNativeWidget::SetRenderWindow ( vtkRenderWindow * win )

Get/Set the currently used vtkGenericOpenGLRenderWindow.

GetRenderWindow() creates and returns a new vtkGenericOpenGLRenderWindow if it is not already provided.

virtual vtkRenderWindow* QVTKOpenGLNativeWidget::GetRenderWindow ( )

virtual

Get/Set the currently used vtkGenericOpenGLRenderWindow.

GetRenderWindow() creates and returns a new vtkGenericOpenGLRenderWindow if it is not already provided.

virtual QVTKInteractorAdapter* QVTKOpenGLNativeWidget::GetInteractorAdapter ( )

inlinevirtual

Get the QEvent to VTK events translator.

Definition at line 146 of file QVTKOpenGLNativeWidget.h.

virtual QVTKInteractor* QVTKOpenGLNativeWidget::GetInteractor ( )

virtual

Get the QVTKInteractor that was either created by default or set by the user.

static void QVTKOpenGLNativeWidget::copyFromFormat	(	const QSurfaceFormat &	format,
		vtkRenderWindow *	win
	)

static

Sets up vtkRenderWindow ivars using QSurfaceFormat.

static void QVTKOpenGLNativeWidget::copyToFormat	(	vtkRenderWindow *	win,
		QSurfaceFormat &	format
	)

static

Using the vtkRenderWindow, setup QSurfaceFormat.

static QSurfaceFormat QVTKOpenGLNativeWidget::defaultFormat ( )

static

Returns a typical QSurfaceFormat suitable for most applications using QVTKOpenGLNativeWidget.

Note that this is not the QSurfaceFormat that gets used if none is specified. That is set using QSurfaceFormat::setDefaultFormat.

virtual void QVTKOpenGLNativeWidget::setEnableHiDPI ( bool enable )

virtual

Enable or disable support for HiDPI displays.

virtual bool QVTKOpenGLNativeWidget::enableHiDPI ( )

inlinevirtual

Definition at line 174 of file QVTKOpenGLNativeWidget.h.

void QVTKOpenGLNativeWidget::setQVTKCursor ( const QCursor & cursor )

Set the cursor on this widget.

void QVTKOpenGLNativeWidget::mouseEvent ( QMouseEvent * event )

signal

This signal will be emitted whenever a mouse event occurs within the QVTK window.

virtual void QVTKOpenGLNativeWidget::cleanupContext ( )

protectedvirtualslot

Called as a response to QOpenGLContext::aboutToBeDestroyed.

This may be called anytime during the widget lifecycle. We need to release any OpenGL resources allocated in VTK work in this method.

bool QVTKOpenGLNativeWidget::event ( QEvent * evt )

protected

void QVTKOpenGLNativeWidget::initializeGL ( )

protected

void QVTKOpenGLNativeWidget::resizeGL	(	int	w,
		int	h
	)

protected

void QVTKOpenGLNativeWidget::paintGL ( )

protected

void QVTKOpenGLNativeWidget::mousePressEvent ( QMouseEvent * event )

protected

void QVTKOpenGLNativeWidget::mouseMoveEvent ( QMouseEvent * event )

protected

void QVTKOpenGLNativeWidget::mouseReleaseEvent ( QMouseEvent * event )

protected

void QVTKOpenGLNativeWidget::mouseDoubleClickEvent ( QMouseEvent * event )

protected

void QVTKOpenGLNativeWidget::requireRenderWindowInitialization ( )

protected

This method is called to indicate that vtkRenderWindow needs to reinitialize itself before the next render (done in QVTKOpenGLNativeWidget::paintGL).

This is needed when the context gets recreated or the default FrameBufferObject gets recreated, for example.

virtual bool QVTKOpenGLNativeWidget::renderVTK ( )

protectedvirtual

This method may be called in paintGL to request VTK to do a render i.e.

trigger render on the render window via its interactor.

It will return true if render (or an equivalent action) was performed to update the frame buffer made available to VTK for rendering with latest rendering.

Default implementation never returns false. However, subclasses can return false to indicate to QVTKOpenGLNativeWidget that it cannot generate a reasonable image to be displayed in QVTKOpenGLNativeWidget. In which case, the paintGL call will return leaving the defaultFramebufferObject untouched.

Since by default QOpenGLWidget::UpdateBehavior is set to QOpenGLWidget::PartialUpdate, this means whatever was rendered in the frame buffer in most recent successful call will be preserved, unless the widget was forced to recreate the FBO as a result of resize or screen change.

See also: Section Handling Render and Paint..

Friends And Related Function Documentation

friend class QVTKOpenGLNativeWidgetObserver

friend

Definition at line 277 of file QVTKOpenGLNativeWidget.h.

Member Data Documentation

vtkSmartPointer<vtkGenericOpenGLRenderWindow> QVTKOpenGLNativeWidget::RenderWindow

protected

Definition at line 256 of file QVTKOpenGLNativeWidget.h.

QVTKInteractorAdapter* QVTKOpenGLNativeWidget::InteractorAdapter

protected

Definition at line 257 of file QVTKOpenGLNativeWidget.h.

bool QVTKOpenGLNativeWidget::EnableHiDPI

protected

Definition at line 259 of file QVTKOpenGLNativeWidget.h.

int QVTKOpenGLNativeWidget::OriginalDPI

protected

Definition at line 260 of file QVTKOpenGLNativeWidget.h.

const double QVTKOpenGLNativeWidget::DevicePixelRatioTolerance

staticprotected

Definition at line 262 of file QVTKOpenGLNativeWidget.h.

The documentation for this class was generated from the following file:

/home/demarle/Source/VTK/release/8.2/build/Utilities/Doxygen/dox/GUISupport/Qt/QVTKOpenGLNativeWidget.h

Signals

Public Member Functions

Static Public Member Functions

Protected Slots

Protected Member Functions

Protected Attributes

Static Protected Attributes

Friends

Detailed Description

OpenGL Context

Handling Render and Paint.

Caveats

Constructor & Destructor Documentation

Member Function Documentation

Friends And Related Function Documentation

Member Data Documentation