Layout engine for QwtPlot components. More...

#include <qwt_plot_layout_engine.h>

Classes
struct	Dimensions
	Structure holding dimension values for layout calculation. More...

class	LayoutData
	Data structure for layout calculation. More...

Public Member Functions
	QwtPlotLayoutEngine ()
	Default constructor for QwtPlotLayoutEngine.

QRectF	layoutLegend (int plotLayoutOptions, const LayoutData::LegendData &legendData, const QRectF &rect, const QSize &legendHint) const
	Calculate legend rectangle within available space.

QRectF	alignLegend (const QSize &legendHint, const QRectF &canvasRect, const QRectF &legendRect) const
	Align legend rectangle relative to canvas.

void	alignScales (int plotLayoutOptions, const LayoutData &layoutData, QRectF &canvasRect, QRectF scaleRect[QwtAxis::AxisPositions]) const
	Align scale rectangles with canvas.

void	alignScalesToCanvas (int plotLayoutOptions, const LayoutData &layoutData, const QRectF &canvasRect, QRectF scaleRect[QwtAxis::AxisPositions]) const
	Align scale rectangles to canvas boundaries.

Dimensions	layoutDimensions (int plotLayoutOptions, const LayoutData &layoutData, const QRectF &rect) const
	Iteratively calculate the layout dimensions for a QwtPlot.

void	setSpacing (unsigned int spacing)
	Set spacing value.

unsigned int	spacing () const
	Get spacing value.

void	setAlignCanvas (int axisPos, bool on)
	Set canvas alignment to scale for a specific axis position.

bool	alignCanvas (int axisPos) const
	Check if canvas is aligned to scale for a specific axis position.

void	setCanvasMargin (int axisPos, int margin)
	Set canvas margin for a specific axis position.

int	canvasMargin (int axisPos) const
	Get canvas margin for a specific axis position.

void	setLegendPos (QwtPlot::LegendPosition pos)
	Set the legend position.

QwtPlot::LegendPosition	legendPos () const
	Get the legend position.

void	setLegendRatio (double ratio)
	Set the legend ratio.

double	legendRatio () const
	Get the legend ratio.

Detailed Description

Layout engine for QwtPlot components.

Originally a private class in QwtPlotLayout, previously written as class LayoutEngine in qwt_plot_layout.cpp. It was extracted as a public class because other layouts need to use it.

Constructor & Destructor Documentation

◆ QwtPlotLayoutEngine()

QwtPlotLayoutEngine::QwtPlotLayoutEngine ( )

Default constructor for QwtPlotLayoutEngine.

Initializes the layout engine with default values: legend position Bottom, legend ratio 1.0, spacing 5 pixels.

Member Function Documentation

◆ alignCanvas()

bool QwtPlotLayoutEngine::alignCanvas ( int axisPos ) const

Check if canvas is aligned to scale for a specific axis position.

Parameters

[in] axisPos Axis position (0-3)

Returns: True if canvas is aligned to scale

◆ alignLegend()

QRectF QwtPlotLayoutEngine::alignLegend	(	const QSize &	legendHint,
		const QRectF &	canvasRect,
		const QRectF &	legendRect
	)		const

Align legend rectangle relative to canvas.

Adjusts the legend rectangle to be properly aligned with the canvas, ensuring it doesn't extend beyond the canvas boundaries when possible.

Parameters

[in]	legendHint	Preferred size hint for the legend
[in]	canvasRect	Canvas rectangle
[in]	legendRect	Initial legend rectangle

Returns: Aligned legend rectangle

◆ alignScales()

void QwtPlotLayoutEngine::alignScales	(	int	plotLayoutOptions,
		const LayoutData &	layoutData,
		QRectF &	canvasRect,
		QRectF	scaleRect[QwtAxis::AxisPositions]
	)		const

Align scale rectangles with canvas.

Adjusts the positions of scale rectangles to ensure proper alignment with the canvas, taking into account border distances and tick offsets. This function handles the complex layout calculation involving multiple axes and canvas spatial coordination.

Parameters

[in]	plotLayoutOptions	Layout options bitmask
[in]	layoutData	Precalculated layout data
[out]	canvasRect	Canvas rectangle (may be modified)
[out]	scaleRect	Array of scale rectangles (will be modified)

Initialize backbone offset First calculate the backbone offset for each axis, which consists of:

Add canvas margin if not aligning canvas to scale
Add canvas content margins if not ignoring frames

Handle the mutual influence of X and Y axes Iterate all axis positions and handle the spatial interaction between X and Y axes:

For X axes (horizontal): Check the influence of left and right Y axes Calculate left/right offsets, considering axis start/end distances and backbone offsets Adjust X axis rectangle position, and canvas rectangle if necessary

For Y axes (vertical): Check the influence of bottom and top X axes Calculate top/bottom offsets, considering axis start/end distances and backbone offsets Adjust Y axis rectangle position, and canvas rectangle if necessary

When the axis needs more space than available, the function adjusts the canvas rectangle

After mutual adjustment of all axes, the function performs final alignment to ensure axes are properly aligned with canvas edges

◆ alignScalesToCanvas()

void QwtPlotLayoutEngine::alignScalesToCanvas	(	int	plotLayoutOptions,
		const LayoutData &	layoutData,
		const QRectF &	canvasRect,
		QRectF	scaleRect[QwtAxis::AxisPositions]
	)		const

Align scale rectangles to canvas boundaries.

Adjusts the positions of scale rectangles to align with canvas boundaries, taking into account border distances and tick offsets. Unlike alignScales, this function does not modify the canvas rectangle.

Parameters

[in]	plotLayoutOptions	Layout options bitmask
[in]	layoutData	Precalculated layout data
[in]	canvasRect	Canvas rectangle
[out]	scaleRect	Array of scale rectangles (will be modified)

Initialize backbone offset First calculate the backbone offset for each axis, which consists of:

Add canvas margin if not aligning canvas to scale
Add canvas content margins if not ignoring frames

Handle the mutual influence of X and Y axes Iterate all axis positions and handle the spatial interaction between X and Y axes:

For X axes (horizontal): Check the influence of left and right Y axes Calculate left/right offsets, considering axis start/end distances and backbone offsets Adjust X axis rectangle position, and canvas rectangle if necessary

For Y axes (vertical): Check the influence of bottom and top X axes Calculate top/bottom offsets, considering axis start/end distances and backbone offsets Adjust Y axis rectangle position, and canvas rectangle if necessary

After mutual adjustment of all axes, the function performs final alignment to ensure axes are properly aligned with canvas edges

◆ canvasMargin()

int QwtPlotLayoutEngine::canvasMargin ( int axisPos ) const

Get canvas margin for a specific axis position.

Parameters

[in] axisPos Axis position (0-3)

Returns: Canvas margin value

◆ layoutDimensions()

QwtPlotLayoutEngine::Dimensions QwtPlotLayoutEngine::layoutDimensions	(	int	plotLayoutOptions,
		const LayoutData &	layoutData,
		const QRectF &	rect
	)		const

Iteratively calculate the layout dimensions for a QwtPlot.

Determines the exact space (in pixels) that every visual component of a QwtPlot—title, footer, and the four axes—needs inside a given rectangle. Because the required size of one component affects the available space for all others, the algorithm loops until the dimensions stabilize.

Parameters

[in]	plotLayoutOptions	Layout options bitmask
[in]	layoutData	Precalculated layout data
[in]	rect	Available rectangle for layout

Returns: Dimensions structure with calculated sizes

◆ layoutLegend()

QRectF QwtPlotLayoutEngine::layoutLegend	(	int	plotLayoutOptions,
		const LayoutData::LegendData &	legendData,
		const QRectF &	rect,
		const QSize &	legendHint
	)		const

Calculate legend rectangle within available space.

Determines the optimal position and size for the legend based on the specified legend position and ratio constraints.

Parameters

[in]	plotLayoutOptions	Layout options bitmask
[in]	legendData	Precalculated legend data
[in]	rect	Available rectangle for layout
[in]	legendHint	Preferred size hint for the legend

Returns: Calculated legend rectangle

◆ legendPos()

QwtPlot::LegendPosition QwtPlotLayoutEngine::legendPos ( ) const

Get the legend position.

Returns: Current legend position

◆ legendRatio()

double QwtPlotLayoutEngine::legendRatio ( ) const

Get the legend ratio.

Returns: Current legend ratio value

◆ setAlignCanvas()

void QwtPlotLayoutEngine::setAlignCanvas	(	int	axisPos,
		bool	on
	)

Set canvas alignment to scale for a specific axis position.

Parameters

[in]	axisPos	Axis position (0-3)
[in]	on	True to align canvas to scale

◆ setCanvasMargin()

void QwtPlotLayoutEngine::setCanvasMargin	(	int	axisPos,
		int	margin
	)

Set canvas margin for a specific axis position.

Parameters

[in]	axisPos	Axis position (0-3)
[in]	margin	New canvas margin value

◆ setLegendPos()

void QwtPlotLayoutEngine::setLegendPos ( QwtPlot::LegendPosition pos )

Set the legend position.

Parameters

[in] pos New legend position

◆ setLegendRatio()

void QwtPlotLayoutEngine::setLegendRatio ( double ratio )

Set the legend ratio.

Parameters

[in] ratio New legend ratio value

◆ setSpacing()

void QwtPlotLayoutEngine::setSpacing ( unsigned int spacing )

Set spacing value.

Parameters

[in] spacing New spacing value in pixels

◆ spacing()

unsigned int QwtPlotLayoutEngine::spacing ( ) const

Get spacing value.

Returns: Current spacing value in pixels

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

/home/runner/work/QWT/QWT/src/plot/qwt_plot_layout_engine.h
/home/runner/work/QWT/QWT/src/plot/qwt_plot_layout_engine.cpp

Classes

Public Member Functions

Detailed Description

Constructor & Destructor Documentation

◆ QwtPlotLayoutEngine()

Member Function Documentation

◆ alignCanvas()

◆ alignLegend()

◆ alignScales()

◆ alignScalesToCanvas()

◆ canvasMargin()

◆ layoutDimensions()

◆ layoutLegend()

◆ legendPos()

◆ legendRatio()

◆ setAlignCanvas()

◆ setCanvasMargin()

◆ setLegendPos()

◆ setLegendRatio()

◆ setSpacing()

◆ spacing()