Qwt User's Guide  6.1.1
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QwtPlotZoomer Class Reference

QwtPlotZoomer provides stacked zooming for a plot widget. More...

#include <qwt_plot_zoomer.h>

Inheritance diagram for QwtPlotZoomer:
Inheritance graph
[legend]

Public Slots

void moveBy (double x, double y)
 
virtual void moveTo (const QPointF &)
 
virtual void zoom (const QRectF &)
 Zoom in. More...
 
virtual void zoom (int up)
 Zoom in or out. More...
 
- Public Slots inherited from QwtPicker
void setEnabled (bool)
 En/disable the picker. More...
 

Signals

void zoomed (const QRectF &rect)
 
- Signals inherited from QwtPlotPicker
void selected (const QPointF &pos)
 
void selected (const QRectF &rect)
 
void selected (const QVector< QPointF > &pa)
 
void appended (const QPointF &pos)
 
void moved (const QPointF &pos)
 
- Signals inherited from QwtPicker
void activated (bool on)
 
void selected (const QPolygon &polygon)
 
void appended (const QPoint &pos)
 
void moved (const QPoint &pos)
 
void removed (const QPoint &pos)
 
void changed (const QPolygon &selection)
 

Public Member Functions

 QwtPlotZoomer (QWidget *, bool doReplot=true)
 Create a zoomer for a plot canvas. More...
 
 QwtPlotZoomer (int xAxis, int yAxis, QWidget *, bool doReplot=true)
 Create a zoomer for a plot canvas. More...
 
virtual void setZoomBase (bool doReplot=true)
 
virtual void setZoomBase (const QRectF &)
 Set the initial size of the zoomer. More...
 
QRectF zoomBase () const
 
QRectF zoomRect () const
 
virtual void setAxis (int xAxis, int yAxis)
 
void setMaxStackDepth (int)
 Limit the number of recursive zoom operations to depth. More...
 
int maxStackDepth () const
 
const QStack< QRectF > & zoomStack () const
 
void setZoomStack (const QStack< QRectF > &, int zoomRectIndex=-1)
 Assign a zoom stack. More...
 
uint zoomRectIndex () const
 
- Public Member Functions inherited from QwtPlotPicker
 QwtPlotPicker (QWidget *canvas)
 Create a plot picker. More...
 
virtual ~QwtPlotPicker ()
 Destructor.
 
 QwtPlotPicker (int xAxis, int yAxis, QWidget *)
 
 QwtPlotPicker (int xAxis, int yAxis, RubberBand rubberBand, DisplayMode trackerMode, QWidget *)
 
int xAxis () const
 Return x axis.
 
int yAxis () const
 Return y axis.
 
QwtPlotplot ()
 
const QwtPlotplot () const
 
QWidget * canvas ()
 
const QWidget * canvas () const
 
- Public Member Functions inherited from QwtPicker
 QwtPicker (QWidget *parent)
 
 QwtPicker (RubberBand rubberBand, DisplayMode trackerMode, QWidget *)
 
virtual ~QwtPicker ()
 Destructor.
 
void setStateMachine (QwtPickerMachine *)
 
const QwtPickerMachinestateMachine () const
 
QwtPickerMachinestateMachine ()
 
void setRubberBand (RubberBand)
 
RubberBand rubberBand () const
 
void setTrackerMode (DisplayMode)
 Set the display mode of the tracker. More...
 
DisplayMode trackerMode () const
 
void setResizeMode (ResizeMode)
 Set the resize mode. More...
 
ResizeMode resizeMode () const
 
void setRubberBandPen (const QPen &)
 
QPen rubberBandPen () const
 
void setTrackerPen (const QPen &)
 
QPen trackerPen () const
 
void setTrackerFont (const QFont &)
 
QFont trackerFont () const
 
bool isEnabled () const
 
bool isActive () const
 
virtual bool eventFilter (QObject *, QEvent *)
 Event filter. More...
 
QWidget * parentWidget ()
 Return the parent widget, where the selection happens.
 
const QWidget * parentWidget () const
 Return the parent widget, where the selection happens.
 
virtual QPainterPath pickArea () const
 
virtual void drawRubberBand (QPainter *) const
 
virtual void drawTracker (QPainter *) const
 
virtual QRegion rubberBandMask () const
 
QPoint trackerPosition () const
 
virtual QRect trackerRect (const QFont &) const
 
QPolygon selection () const
 
- Public Member Functions inherited from QwtEventPattern
 QwtEventPattern ()
 
virtual ~QwtEventPattern ()
 Destructor.
 
void initMousePattern (int numButtons)
 
void initKeyPattern ()
 
void setMousePattern (MousePatternCode, Qt::MouseButton button, Qt::KeyboardModifiers=Qt::NoModifier)
 
void setKeyPattern (KeyPatternCode, int keyCode, Qt::KeyboardModifiers modifierCodes=Qt::NoModifier)
 
void setMousePattern (const QVector< MousePattern > &)
 Change the mouse event patterns.
 
void setKeyPattern (const QVector< KeyPattern > &)
 Change the key event patterns.
 
const QVector< MousePattern > & mousePattern () const
 
const QVector< KeyPattern > & keyPattern () const
 
QVector< MousePattern > & mousePattern ()
 
QVector< KeyPattern > & keyPattern ()
 
bool mouseMatch (MousePatternCode, const QMouseEvent *) const
 Compare a mouse event with an event pattern. More...
 
bool keyMatch (KeyPatternCode, const QKeyEvent *) const
 Compare a key event with an event pattern. More...
 

Protected Member Functions

virtual void rescale ()
 
virtual QSizeF minZoomSize () const
 Limit zooming by a minimum rectangle. More...
 
virtual void widgetMouseReleaseEvent (QMouseEvent *)
 
virtual void widgetKeyPressEvent (QKeyEvent *)
 
virtual void begin ()
 
virtual bool end (bool ok=true)
 
virtual bool accept (QPolygon &) const
 Check and correct a selected rectangle. More...
 
- Protected Member Functions inherited from QwtPlotPicker
QRectF scaleRect () const
 
QRectF invTransform (const QRect &) const
 
QRect transform (const QRectF &) const
 
QPointF invTransform (const QPoint &) const
 
QPoint transform (const QPointF &) const
 
virtual QwtText trackerText (const QPoint &) const
 
virtual QwtText trackerTextF (const QPointF &) const
 Translate a position into a position string. More...
 
virtual void move (const QPoint &)
 
virtual void append (const QPoint &)
 
- Protected Member Functions inherited from QwtPicker
virtual QPolygon adjustedPoints (const QPolygon &) const
 Map the pickedPoints() into a selection() More...
 
virtual void transition (const QEvent *)
 
virtual void remove ()
 
virtual void reset ()
 
virtual void widgetMousePressEvent (QMouseEvent *)
 
virtual void widgetMouseDoubleClickEvent (QMouseEvent *)
 
virtual void widgetMouseMoveEvent (QMouseEvent *)
 
virtual void widgetWheelEvent (QWheelEvent *)
 
virtual void widgetKeyReleaseEvent (QKeyEvent *)
 
virtual void widgetEnterEvent (QEvent *)
 
virtual void widgetLeaveEvent (QEvent *)
 
virtual void stretchSelection (const QSize &oldSize, const QSize &newSize)
 
virtual void updateDisplay ()
 Update the state of rubber band and tracker label.
 
const QwtWidgetOverlayrubberBandOverlay () const
 
const QwtWidgetOverlaytrackerOverlay () const
 
const QPolygon & pickedPoints () const
 
- Protected Member Functions inherited from QwtEventPattern
virtual bool mouseMatch (const MousePattern &, const QMouseEvent *) const
 Compare a mouse event with an event pattern. More...
 
virtual bool keyMatch (const KeyPattern &, const QKeyEvent *) const
 Compare a key event with an event pattern. More...
 

Additional Inherited Members

- Public Types inherited from QwtPicker
enum  RubberBand {
  NoRubberBand = 0, HLineRubberBand, VLineRubberBand, CrossRubberBand,
  RectRubberBand, EllipseRubberBand, PolygonRubberBand, UserRubberBand = 100
}
 
enum  DisplayMode { AlwaysOff, AlwaysOn, ActiveOnly }
 Display mode. More...
 
enum  ResizeMode { Stretch, KeepSize }
 
- Public Types inherited from QwtEventPattern
enum  MousePatternCode {
  MouseSelect1, MouseSelect2, MouseSelect3, MouseSelect4,
  MouseSelect5, MouseSelect6, MousePatternCount
}
 Symbolic mouse input codes. More...
 
enum  KeyPatternCode {
  KeySelect1, KeySelect2, KeyAbort, KeyLeft,
  KeyRight, KeyUp, KeyDown, KeyRedo,
  KeyUndo, KeyHome, KeyPatternCount
}
 Symbolic keyboard input codes. More...
 

Detailed Description

QwtPlotZoomer provides stacked zooming for a plot widget.

QwtPlotZoomer selects rectangles from user inputs ( mouse or keyboard ) translates them into plot coordinates and adjusts the axes to them. The selection is supported by a rubber band and optionally by displaying the coordinates of the current mouse position.

Zooming can be repeated as often as possible, limited only by maxStackDepth() or minZoomSize(). Each rectangle is pushed on a stack.

The default setting how to select rectangles is a QwtPickerDragRectMachine with the following bindings:

To traverse the zoom stack the following bindings are used:

The setKeyPattern() and setMousePattern() functions can be used to configure the zoomer actions. The following example shows, how to configure the 'I' and 'O' keys for zooming in and out one position on the zoom stack. The "Home" key is used to "unzoom" the plot.

zoomer = new QwtPlotZoomer( plot );
zoomer->setKeyPattern( QwtEventPattern::KeyRedo, Qt::Key_I, Qt::ShiftModifier );
zoomer->setKeyPattern( QwtEventPattern::KeyUndo, Qt::Key_O, Qt::ShiftModifier );
zoomer->setKeyPattern( QwtEventPattern::KeyHome, Qt::Key_Home );

QwtPlotZoomer is tailored for plots with one x and y axis, but it is allowed to attach a second QwtPlotZoomer ( without rubber band and tracker ) for the other axes.

Note
The realtime example includes an derived zoomer class that adds scrollbars to the plot canvas.
See Also
QwtPlotPanner, QwtPlotMagnifier

Constructor & Destructor Documentation

QwtPlotZoomer::QwtPlotZoomer ( QWidget *  canvas,
bool  doReplot = true 
)
explicit

Create a zoomer for a plot canvas.

The zoomer is set to those x- and y-axis of the parent plot of the canvas that are enabled. If both or no x-axis are enabled, the picker is set to QwtPlot::xBottom. If both or no y-axis are enabled, it is set to QwtPlot::yLeft.

The zoomer is initialized with a QwtPickerDragRectMachine, the tracker mode is set to QwtPicker::ActiveOnly and the rubber band is set to QwtPicker::RectRubberBand

Parameters
canvasPlot canvas to observe, also the parent object
doReplotCall QwtPlot::replot() for the attached plot before initializing the zoomer with its scales. This might be necessary, when the plot is in a state with pending scale changes.
See Also
QwtPlot::autoReplot(), QwtPlot::replot(), setZoomBase()
QwtPlotZoomer::QwtPlotZoomer ( int  xAxis,
int  yAxis,
QWidget *  canvas,
bool  doReplot = true 
)
explicit

Create a zoomer for a plot canvas.

The zoomer is initialized with a QwtPickerDragRectMachine, the tracker mode is set to QwtPicker::ActiveOnly and the rubber band is set to QwtPicker;;RectRubberBand

Parameters
xAxisX axis of the zoomer
yAxisY axis of the zoomer
canvasPlot canvas to observe, also the parent object
doReplotCall QwtPlot::replot() for the attached plot before initializing the zoomer with its scales. This might be necessary, when the plot is in a state with pending scale changes.
See Also
QwtPlot::autoReplot(), QwtPlot::replot(), setZoomBase()

Member Function Documentation

bool QwtPlotZoomer::accept ( QPolygon &  pa) const
protectedvirtual

Check and correct a selected rectangle.

Reject rectangles with a height or width < 2, otherwise expand the selected rectangle to a minimum size of 11x11 and accept it.

Returns
true If the rectangle is accepted, or has been changed to an accepted one.

Reimplemented from QwtPicker.

void QwtPlotZoomer::begin ( )
protectedvirtual

Rejects selections, when the stack depth is too deep, or the zoomed rectangle is minZoomSize().

See Also
minZoomSize(), maxStackDepth()

Reimplemented from QwtPicker.

bool QwtPlotZoomer::end ( bool  ok = true)
protectedvirtual

Expand the selected rectangle to minZoomSize() and zoom in if accepted.

Parameters
okIf true, complete the selection and emit selected signals otherwise discard the selection.
See Also
accept(), minZoomSize()
Returns
True if the selection has been accepted, false otherwise

Reimplemented from QwtPlotPicker.

int QwtPlotZoomer::maxStackDepth ( ) const
Returns
Maximal depth of the zoom stack.
See Also
setMaxStackDepth()
QSizeF QwtPlotZoomer::minZoomSize ( ) const
protectedvirtual

Limit zooming by a minimum rectangle.

Returns
zoomBase().width() / 10e4, zoomBase().height() / 10e4
void QwtPlotZoomer::moveBy ( double  dx,
double  dy 
)
slot

Move the current zoom rectangle.

Parameters
dxX offset
dyY offset
Note
The changed rectangle is limited by the zoom base
void QwtPlotZoomer::moveTo ( const QPointF &  pos)
virtualslot

Move the the current zoom rectangle.

Parameters
posNew position
See Also
QRectF::moveTo()
Note
The changed rectangle is limited by the zoom base
void QwtPlotZoomer::rescale ( )
protectedvirtual

Adjust the observed plot to zoomRect()

Note
Initiates QwtPlot::replot()
void QwtPlotZoomer::setAxis ( int  xAxis,
int  yAxis 
)
virtual

Reinitialize the axes, and set the zoom base to their scales.

Parameters
xAxisX axis
yAxisY axis

Reimplemented from QwtPlotPicker.

void QwtPlotZoomer::setMaxStackDepth ( int  depth)

Limit the number of recursive zoom operations to depth.

A value of -1 set the depth to unlimited, 0 disables zooming. If the current zoom rectangle is below depth, the plot is unzoomed.

Parameters
depthMaximum for the stack depth
See Also
maxStackDepth()
Note
depth doesn't include the zoom base, so zoomStack().count() might be maxStackDepth() + 1.
void QwtPlotZoomer::setZoomBase ( bool  doReplot = true)
virtual

Reinitialized the zoom stack with scaleRect() as base.

Parameters
doReplotCall QwtPlot::replot() for the attached plot before initializing the zoomer with its scales. This might be necessary, when the plot is in a state with pending scale changes.
See Also
zoomBase(), scaleRect() QwtPlot::autoReplot(), QwtPlot::replot().
void QwtPlotZoomer::setZoomBase ( const QRectF &  base)
virtual

Set the initial size of the zoomer.

base is united with the current scaleRect() and the zoom stack is reinitialized with it as zoom base. plot is zoomed to scaleRect().

Parameters
baseZoom base
See Also
zoomBase(), scaleRect()
void QwtPlotZoomer::setZoomStack ( const QStack< QRectF > &  zoomStack,
int  zoomRectIndex = -1 
)

Assign a zoom stack.

In combination with other types of navigation it might be useful to modify to manipulate the complete zoom stack.

Parameters
zoomStackNew zoom stack
zoomRectIndexIndex of the current position of zoom stack. In case of -1 the current position is at the top of the stack.
Note
The zoomed signal might be emitted.
See Also
zoomStack(), zoomRectIndex()
void QwtPlotZoomer::widgetKeyPressEvent ( QKeyEvent *  ke)
protectedvirtual

Qt::Key_Plus zooms in, Qt::Key_Minus zooms out one position on the zoom stack, Qt::Key_Escape zooms out to the zoom base.

Changes the current position on the stack, but doesn't pop any rectangle.

Note
The keys codes can be changed, using QwtEventPattern::setKeyPattern: 3, 4, 5

Reimplemented from QwtPicker.

void QwtPlotZoomer::widgetMouseReleaseEvent ( QMouseEvent *  me)
protectedvirtual

Qt::MidButton zooms out one position on the zoom stack, Qt::RightButton to the zoom base.

Changes the current position on the stack, but doesn't pop any rectangle.

Note
The mouse events can be changed, using QwtEventPattern::setMousePattern: 2, 1

Reimplemented from QwtPicker.

void QwtPlotZoomer::zoom ( const QRectF &  rect)
virtualslot

Zoom in.

Clears all rectangles above the current position of the zoom stack and pushes the normalized rectangle on it.

Note
If the maximal stack depth is reached, zoom is ignored.
The zoomed signal is emitted.
void QwtPlotZoomer::zoom ( int  offset)
virtualslot

Zoom in or out.

Activate a rectangle on the zoom stack with an offset relative to the current position. Negative values of offset will zoom out, positive zoom in. A value of 0 zooms out to the zoom base.

Parameters
offsetOffset relative to the current position of the zoom stack.
Note
The zoomed signal is emitted.
See Also
zoomRectIndex()
QRectF QwtPlotZoomer::zoomBase ( ) const
Returns
Initial rectangle of the zoomer
See Also
setZoomBase(), zoomRect()
void QwtPlotZoomer::zoomed ( const QRectF &  rect)
signal

A signal emitting the zoomRect(), when the plot has been zoomed in or out.

Parameters
rectCurrent zoom rectangle.
QRectF QwtPlotZoomer::zoomRect ( ) const
Returns
Rectangle at the current position on the zoom stack.
See Also
zoomRectIndex(), scaleRect().
uint QwtPlotZoomer::zoomRectIndex ( ) const
Returns
Index of current position of zoom stack.
const QStack< QRectF > & QwtPlotZoomer::zoomStack ( ) const
Returns
The zoom stack. zoomStack()[0] is the zoom base, zoomStack()[1] the first zoomed rectangle.
See Also
setZoomStack(), zoomRectIndex()