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QwtPlotZoomer(3) Qwt User's Guide QwtPlotZoomer(3)

NAME

QwtPlotZoomer - QwtPlotZoomer provides stacked zooming for a plot widget.

SYNOPSIS

#include <qwt_plot_zoomer.h>

Inherits QwtPlotPicker.

Public Slots


void moveBy (double dx, double dy)
virtual void moveTo (const QPointF &)
virtual void zoom (const QRectF &)
Zoom in. virtual void zoom (int offset)
Zoom in or out.

Signals


void zoomed (const QRectF &rect)

Public Member Functions


QwtPlotZoomer (QWidget *, bool doReplot=true)
Create a zoomer for a plot canvas. QwtPlotZoomer (QwtAxisId xAxis, QwtAxisId yAxis, QWidget *, bool doReplot=true)
Create a zoomer for a plot canvas. virtual void setZoomBase (bool doReplot=true)
virtual void setZoomBase (const QRectF &)
Set the initial size of the zoomer. QRectF zoomBase () const
QRectF zoomRect () const
virtual void setAxes (QwtAxisId xAxis, QwtAxisId yAxis) override
void setMaxStackDepth (int)
Limit the number of recursive zoom operations to depth. int maxStackDepth () const
const QStack< QRectF > & zoomStack () const
void setZoomStack (const QStack< QRectF > &, int zoomRectIndex=-1)
Assign a zoom stack. uint zoomRectIndex () const

Protected Member Functions


virtual void rescale ()
virtual QSizeF minZoomSize () const
Limit zooming by a minimum rectangle. virtual void widgetMouseReleaseEvent (QMouseEvent *) override
virtual void widgetKeyPressEvent (QKeyEvent *) override
virtual void begin () override
virtual bool end (bool ok=true) override
virtual bool accept (QPolygon &) const override
Check and correct a selected rectangle.

Additional Inherited Members

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:

  • QwtEventPattern::MouseSelect1
    The first point of the zoom rectangle is selected by a mouse press, the second point from the position, where the mouse is released.
  • QwtEventPattern::KeySelect1
    The first key press selects the first, the second key press selects the second point.
  • QwtEventPattern::KeyAbort
    Discard the selection in the state, where the first point is selected.

To traverse the zoom stack the following bindings are used:

  • QwtEventPattern::MouseSelect3, QwtEventPattern::KeyUndo
    Zoom out one position on the zoom stack
  • QwtEventPattern::MouseSelect6, QwtEventPattern::KeyRedo
    Zoom in one position on the zoom stack
  • QwtEventPattern::MouseSelect2, QwtEventPattern::KeyHome
    Zoom to the zoom base

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

Definition at line 79 of file qwt_plot_zoomer.h.

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 QwtAxis::XBottom. If both or no y-axis are enabled, it is set to QwtAxis::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

canvas Plot canvas to observe, also the parent object
doReplot Call 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()

Definition at line 109 of file qwt_plot_zoomer.cpp.

QwtPlotZoomer::QwtPlotZoomer (QwtAxisId xAxisId, QwtAxisId yAxisId, 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

xAxisId X axis of the zoomer
yAxisId Y axis of the zoomer
canvas Plot canvas to observe, also the parent object
doReplot Call 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()

Definition at line 133 of file qwt_plot_zoomer.cpp.

Member Function Documentation

bool QwtPlotZoomer::accept (QPolygon & pa) const [override], [protected], [virtual]

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.

Definition at line 567 of file qwt_plot_zoomer.cpp.

void QwtPlotZoomer::begin () [override], [protected], [virtual]

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

See also

minZoomSize(), maxStackDepth()

Reimplemented from QwtPicker.

Definition at line 609 of file qwt_plot_zoomer.cpp.

bool QwtPlotZoomer::end (bool ok = true) [override], [protected], [virtual]

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

Parameters

ok If 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.

Definition at line 643 of file qwt_plot_zoomer.cpp.

int QwtPlotZoomer::maxStackDepth () const

Returns

Maximal depth of the zoom stack.

See also

setMaxStackDepth()

Definition at line 201 of file qwt_plot_zoomer.cpp.

QSizeF QwtPlotZoomer::minZoomSize () const [protected], [virtual]

Limit zooming by a minimum rectangle.

Returns

zoomBase().width() / 10e4, zoomBase().height() / 10e4

Definition at line 597 of file qwt_plot_zoomer.cpp.

void QwtPlotZoomer::moveBy (double dx, double dy) [slot]

Move the current zoom rectangle.

Parameters

dx X offset
dy Y offset

Note

The changed rectangle is limited by the zoom base

Definition at line 520 of file qwt_plot_zoomer.cpp.

void QwtPlotZoomer::moveTo (const QPointF & pos) [virtual], [slot]

Move the the current zoom rectangle.

Parameters

pos New position

See also

QRectF::moveTo()

Note

The changed rectangle is limited by the zoom base

Definition at line 534 of file qwt_plot_zoomer.cpp.

void QwtPlotZoomer::rescale () [protected], [virtual]

Adjust the observed plot to zoomRect()

Note

Initiates QwtPlot::replot()

Definition at line 416 of file qwt_plot_zoomer.cpp.

void QwtPlotZoomer::setAxes (QwtAxisId xAxisId, QwtAxisId yAxisId) [override], [virtual]

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

Parameters

xAxisId X axis
yAxisId Y axis

Reimplemented from QwtPlotPicker.

Definition at line 455 of file qwt_plot_zoomer.cpp.

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

depth Maximum for the stack depth

See also

maxStackDepth()

Note

depth doesn't include the zoom base, so zoomStack().count() might be maxStackDepth() + 1.

Definition at line 174 of file qwt_plot_zoomer.cpp.

void QwtPlotZoomer::setZoomBase (bool doReplot = true) [virtual]

Reinitialized the zoom stack with scaleRect() as base.

Parameters

doReplot Call 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().

Definition at line 235 of file qwt_plot_zoomer.cpp.

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

base Zoom base

See also

zoomBase(), scaleRect()

Definition at line 261 of file qwt_plot_zoomer.cpp.

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

zoomStack New zoom stack
zoomRectIndex Index 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()

Definition at line 383 of file qwt_plot_zoomer.cpp.

void QwtPlotZoomer::widgetKeyPressEvent (QKeyEvent * ke) [override], [protected], [virtual]

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.

Definition at line 497 of file qwt_plot_zoomer.cpp.

void QwtPlotZoomer::widgetMouseReleaseEvent (QMouseEvent * me) [override], [protected], [virtual]

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.

Definition at line 474 of file qwt_plot_zoomer.cpp.

void QwtPlotZoomer::zoom (const QRectF & rect) [virtual], [slot]

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.

Definition at line 310 of file qwt_plot_zoomer.cpp.

void QwtPlotZoomer::zoom (int offset) [virtual], [slot]

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

offset Offset relative to the current position of the zoom stack.

Note

The zoomed signal is emitted.

See also

zoomRectIndex()

Definition at line 347 of file qwt_plot_zoomer.cpp.

QRectF QwtPlotZoomer::zoomBase () const

Returns

Initial rectangle of the zoomer

See also

setZoomBase(), zoomRect()

Definition at line 221 of file qwt_plot_zoomer.cpp.

void QwtPlotZoomer::zoomed (const QRectF & rect) [signal]

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

Parameters

rect Current zoom rectangle.

QRectF QwtPlotZoomer::zoomRect () const

Returns

Rectangle at the current position on the zoom stack.

See also

zoomRectIndex(), scaleRect().

Definition at line 287 of file qwt_plot_zoomer.cpp.

uint QwtPlotZoomer::zoomRectIndex () const

Returns

Index of current position of zoom stack.

Definition at line 295 of file qwt_plot_zoomer.cpp.

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()

Definition at line 212 of file qwt_plot_zoomer.cpp.

Author

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Sun Jul 18 2021 Version 6.2.0