--- name: "QwtPlotZoomer" section: "3" platform: "linux" package: "libqwt-doc" version: "6.1.4-2" release: "Debian 13 (Trixie)" platforms: ["linux"] url: "https://new.carta.tech/QwtPlotZoomer" --- # QwtPlotZoomer(3) QwtPlotZoomer provides stacked zooming for a plot widget. ## NAME QwtPlotZoomer - **QwtPlotZoomer** provides stacked zooming for a plot widget. ## SYNOPSIS `#include ` 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** (int **xAxis**, int **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 **setAxis** (int **xAxis**, int **yAxis**)\ 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 \*)\ virtual void **widgetKeyPressEvent** (QKeyEvent \*)\ virtual void **begin** ()\ virtual bool **end** (bool ok=true)\ virtual bool **accept** (QPolygon &) const\ 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** ## 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:** *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()** ### 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:** *xAxis* X axis of the zoomer \ *yAxis* 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()** ## Member Function Documentation ### bool QwtPlotZoomer::accept (QPolygon & pa) const` [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**. ### void QwtPlotZoomer::begin ()` [protected]`, ` [virtual]` 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`)` [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**. ### int QwtPlotZoomer::maxStackDepth () const **Returns:** Maximal depth of the zoom stack. **See also:** **setMaxStackDepth()** ### QSizeF QwtPlotZoomer::minZoomSize () const` [protected]`, ` [virtual]` 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:** *dx* X offset \ *dy* Y offset **Note:** The changed rectangle is limited by the zoom base ### 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 ### void QwtPlotZoomer::rescale ()` [protected]`, ` [virtual]` 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:** *xAxis* X axis \ *yAxis* Y 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:** *depth* Maximum 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:** *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()**. ### 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()** ### 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()** ### void QwtPlotZoomer::widgetKeyPressEvent (QKeyEvent \* ke)` [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**. ### void QwtPlotZoomer::widgetMouseReleaseEvent (QMouseEvent \* me)` [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**. ### 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. ### 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()** ### 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:** *rect* Current 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()** ## Author Generated automatically by Doxygen for Qwt User's Guide from the source code.