Handles rendering text using rich formatting options, including drop shadows, buffers and background shapes. More...

#include <qgstextrenderer.h>

Public Types
enum	DrawMode { Rect = 0, Point, Label }
	Draw mode to calculate width and height. More...

enum	HAlignment { AlignLeft = 0, AlignCenter, AlignRight, AlignJustify }
	Horizontal alignment. More...

enum	TextPart { Text = 0, Buffer, Background, Shadow }
	Components of text. More...

enum	VAlignment { AlignTop = 0, AlignVCenter, AlignBottom }
	Vertical alignment. More...

Static Public Member Functions
static HAlignment	convertQtHAlignment (Qt::Alignment alignment)
	Converts a Qt horizontal alignment flag to a QgsTextRenderer::HAlignment value. More...

static VAlignment	convertQtVAlignment (Qt::Alignment alignment)
	Converts a Qt vertical alignment flag to a QgsTextRenderer::VAlignment value. More...

static Q_DECL_DEPRECATED void	drawPart (const QRectF &rect, double rotation, HAlignment alignment, const QStringList &textLines, QgsRenderContext &context, const QgsTextFormat &format, TextPart part, bool drawAsOutlines=true)
	Draws a single component of rendered text using the specified settings. More...

static Q_DECL_DEPRECATED void	drawPart (QPointF origin, double rotation, HAlignment alignment, const QStringList &textLines, QgsRenderContext &context, const QgsTextFormat &format, TextPart part, bool drawAsOutlines=true)
	Draws a single component of rendered text using the specified settings. More...

static void	drawText (const QRectF &rect, double rotation, HAlignment alignment, const QStringList &textLines, QgsRenderContext &context, const QgsTextFormat &format, bool drawAsOutlines=true, VAlignment vAlignment=AlignTop)
	Draws text within a rectangle using the specified settings. More...

static void	drawText (QPointF point, double rotation, HAlignment alignment, const QStringList &textLines, QgsRenderContext &context, const QgsTextFormat &format, bool drawAsOutlines=true)
	Draws text at a point origin using the specified settings. More...

static QFontMetricsF	fontMetrics (QgsRenderContext &context, const QgsTextFormat &format, double scaleFactor=1.0)
	Returns the font metrics for the given text format, when rendered in the specified render context. More...

static int	sizeToPixel (double size, const QgsRenderContext &c, QgsUnitTypes::RenderUnit unit, const QgsMapUnitScale &mapUnitScale=QgsMapUnitScale())
	Calculates pixel size (considering output size should be in pixel or map units, scale factors and optionally oversampling) More...

static double	textHeight (const QgsRenderContext &context, const QgsTextFormat &format, const QStringList &textLines, DrawMode mode=Point, QFontMetricsF *fontMetrics=nullptr)
	Returns the height of a text based on a given format. More...

static double	textHeight (const QgsRenderContext &context, const QgsTextFormat &format, QChar character, bool includeEffects=false)
	Returns the height of a character when rendered with the specified text format. More...

static double	textWidth (const QgsRenderContext &context, const QgsTextFormat &format, const QStringList &textLines, QFontMetricsF *fontMetrics=nullptr)
	Returns the width of a text based on a given format. More...

Static Public Attributes
static constexpr double	FONT_WORKAROUND_SCALE = 10
	Scale factor for upscaling font sizes and downscaling destination painter devices. More...

Friends
class	QgsLabelPreview

class	QgsVectorLayerLabelProvider

Detailed Description

Handles rendering text using rich formatting options, including drop shadows, buffers and background shapes.

Since: QGIS 3.0

Definition at line 36 of file qgstextrenderer.h.

Member Enumeration Documentation

◆ DrawMode

enum QgsTextRenderer::DrawMode

Draw mode to calculate width and height.

Enumerator
Rect	Text within rectangle draw mode.
Point	Text at point of origin draw mode.
Label	Label-specific draw mode.

Definition at line 41 of file qgstextrenderer.h.

◆ HAlignment

enum QgsTextRenderer::HAlignment

Horizontal alignment.

Enumerator
AlignLeft	Left align.
AlignCenter	Center align.
AlignRight	Right align.
AlignJustify	Justify align.

Definition at line 58 of file qgstextrenderer.h.

◆ TextPart

enum QgsTextRenderer::TextPart

Components of text.

Enumerator
Text	Text component.
Buffer	Buffer component.
Background	Background shape.
Shadow	Drop shadow.

Definition at line 49 of file qgstextrenderer.h.

◆ VAlignment

enum QgsTextRenderer::VAlignment

Vertical alignment.

Since: QGIS 3.16

Enumerator
AlignTop	Align to top.
AlignVCenter	Center align.
AlignBottom	Align to bottom.

Definition at line 78 of file qgstextrenderer.h.

Member Function Documentation

◆ convertQtHAlignment()

QgsTextRenderer::HAlignment QgsTextRenderer::convertQtHAlignment ( Qt::Alignment alignment )

static

Converts a Qt horizontal alignment flag to a QgsTextRenderer::HAlignment value.

See also: convertQtVAlignment()

Since: QGIS 3.16

Definition at line 40 of file qgstextrenderer.cpp.

◆ convertQtVAlignment()

QgsTextRenderer::VAlignment QgsTextRenderer::convertQtVAlignment ( Qt::Alignment alignment )

static

Converts a Qt vertical alignment flag to a QgsTextRenderer::VAlignment value.

See also: convertQtHAlignment()

Since: QGIS 3.16

Definition at line 55 of file qgstextrenderer.cpp.

◆ drawPart() [1/2]

void QgsTextRenderer::drawPart	(	const QRectF &	rect,
		double	rotation,
		HAlignment	alignment,
		const QStringList &	textLines,
		QgsRenderContext &	context,
		const QgsTextFormat &	format,
		QgsTextRenderer::TextPart	part,
		bool	drawAsOutlines = `true`
	)

static

Draws a single component of rendered text using the specified settings.

Parameters

rect	destination rectangle for text
rotation	text rotation
alignment	horizontal alignment
textLines	list of lines of text to draw
context	render context
format	text format
part	component of text to draw. Note that Shadow parts cannot be drawn individually and instead are drawn with their associated part (e.g., drawn together with the text or background parts)
drawAsOutlines	set to `false` to render text as text. This allows outputs to formats like SVG to maintain text as text objects, but at the cost of degraded rendering and may result in side effects like misaligned text buffers. This setting is deprecated and has no effect as of QGIS 3.4.3 and the text format should be set using QgsRenderContext::setTextRenderFormat() instead.

Deprecated:: Private API only, will be removed in 4.0

Definition at line 142 of file qgstextrenderer.cpp.

◆ drawPart() [2/2]

void QgsTextRenderer::drawPart	(	QPointF	origin,
		double	rotation,
		QgsTextRenderer::HAlignment	alignment,
		const QStringList &	textLines,
		QgsRenderContext &	context,
		const QgsTextFormat &	format,
		QgsTextRenderer::TextPart	part,
		bool	drawAsOutlines = `true`
	)

static

Draws a single component of rendered text using the specified settings.

Parameters

origin	origin for start of text. Y coordinate will be used as baseline.
rotation	text rotation
alignment	horizontal alignment
textLines	list of lines of text to draw
context	render context
format	text format
part	component of text to draw. Note that Shadow parts cannot be drawn individually and instead are drawn with their associated part (e.g., drawn together with the text or background parts)
drawAsOutlines	set to `false` to render text as text. This allows outputs to formats like SVG to maintain text as text objects, but at the cost of degraded rendering and may result in side effects like misaligned text buffers. This setting is deprecated and has no effect as of QGIS 3.4.3 and the text format should be set using QgsRenderContext::setTextRenderFormat() instead.

Deprecated:: Private API only, will be removed in 4.0

Definition at line 212 of file qgstextrenderer.cpp.

◆ drawText() [1/2]

void QgsTextRenderer::drawText	(	const QRectF &	rect,
		double	rotation,
		QgsTextRenderer::HAlignment	alignment,
		const QStringList &	textLines,
		QgsRenderContext &	context,
		const QgsTextFormat &	format,
		bool	drawAsOutlines = `true`,
		VAlignment	vAlignment = `AlignTop`
	)

static

Draws text within a rectangle using the specified settings.

Parameters

rect	destination rectangle for text
rotation	text rotation
alignment	horizontal alignment
textLines	list of lines of text to draw
context	render context
format	text format
drawAsOutlines	set to `false` to render text as text. This allows outputs to formats like SVG to maintain text as text objects, but at the cost of degraded rendering and may result in side effects like misaligned text buffers. This setting is deprecated and has no effect as of QGIS 3.4.3 and the text format should be set using QgsRenderContext::setTextRenderFormat() instead.
vAlignment	vertical alignment (since QGIS 3.16)

Definition at line 75 of file qgstextrenderer.cpp.

◆ drawText() [2/2]

void QgsTextRenderer::drawText	(	QPointF	point,
		double	rotation,
		QgsTextRenderer::HAlignment	alignment,
		const QStringList &	textLines,
		QgsRenderContext &	context,
		const QgsTextFormat &	format,
		bool	drawAsOutlines = `true`
	)

static

Draws text at a point origin using the specified settings.

Parameters

point	origin of text
rotation	text rotation
alignment	horizontal alignment
textLines	list of lines of text to draw
context	render context
format	text format
drawAsOutlines	set to `false` to render text as text. This allows outputs to formats like SVG to maintain text as text objects, but at the cost of degraded rendering and may result in side effects like misaligned text buffers. This setting is deprecated and has no effect as of QGIS 3.4.3 and the text format should be set using QgsRenderContext::setTextRenderFormat() instead.

Definition at line 98 of file qgstextrenderer.cpp.

◆ fontMetrics()

QFontMetricsF QgsTextRenderer::fontMetrics	(	QgsRenderContext &	context,
		const QgsTextFormat &	format,
		double	scaleFactor = `1.0`
	)

static

Returns the font metrics for the given text format, when rendered in the specified render context.

The font metrics will take into account all scaling required by the render context.

The optional scaleFactor argument can specify a font size scaling factor. It is recommended to set this to QgsTextRenderer::FONT_WORKAROUND_SCALE and then manually scale painter devices or calculations based on the resultant font metrics. Failure to do so will result in poor quality text rendering at small font sizes.

Since: QGIS 3.2

Definition at line 261 of file qgstextrenderer.cpp.

◆ sizeToPixel()

int QgsTextRenderer::sizeToPixel	(	double	size,
		const QgsRenderContext &	c,
		QgsUnitTypes::RenderUnit	unit,
		const QgsMapUnitScale &	mapUnitScale = `QgsMapUnitScale()`
	)

static

Calculates pixel size (considering output size should be in pixel or map units, scale factors and optionally oversampling)

Parameters

size	size to convert
c	rendercontext
unit	size units
mapUnitScale	a mapUnitScale clamper

Returns: font pixel size

Definition at line 70 of file qgstextrenderer.cpp.

◆ textHeight() [1/2]

double QgsTextRenderer::textHeight	(	const QgsRenderContext &	context,
		const QgsTextFormat &	format,
		const QStringList &	textLines,
		DrawMode	mode = `Point`,
		QFontMetricsF *	fontMetrics = `nullptr`
	)

static

Returns the height of a text based on a given format.

Parameters

context	render context
format	text format
textLines	list of lines of text to calculate width from
mode	draw mode
fontMetrics	font metrics

Definition at line 567 of file qgstextrenderer.cpp.

◆ textHeight() [2/2]

double QgsTextRenderer::textHeight	(	const QgsRenderContext &	context,
		const QgsTextFormat &	format,
		QChar	character,
		bool	includeEffects = `false`
	)

static

Returns the height of a character when rendered with the specified text format.

Parameters

context	render context
format	text format
character	character to determine height of. If character is invalid, then the maximum character height will be returned.
includeEffects	if `true`, then the size of formatting effects such as buffers and shadows will be considered in the returned height. If `false`, then the returned size considers the character only.

Since: QGIS 3.16

Definition at line 579 of file qgstextrenderer.cpp.

◆ textWidth()

double QgsTextRenderer::textWidth	(	const QgsRenderContext &	context,
		const QgsTextFormat &	format,
		const QStringList &	textLines,
		QFontMetricsF *	fontMetrics = `nullptr`
	)

static

Returns the width of a text based on a given format.

Parameters

context	render context
format	text format
textLines	list of lines of text to calculate width from
fontMetrics	font metrics

Definition at line 496 of file qgstextrenderer.cpp.

Friends And Related Function Documentation

◆ QgsLabelPreview

friend class QgsLabelPreview

friend

Definition at line 383 of file qgstextrenderer.h.

◆ QgsVectorLayerLabelProvider

friend class QgsVectorLayerLabelProvider

friend

Definition at line 382 of file qgstextrenderer.h.

Member Data Documentation

◆ FONT_WORKAROUND_SCALE

constexpr double QgsTextRenderer::FONT_WORKAROUND_SCALE = 10

staticconstexpr

Scale factor for upscaling font sizes and downscaling destination painter devices.

Using this scale factor and manually adjusting any font metric based calculations results in more stable font metrics and sizes for small font sizes.

Since: QGIS 3.16

Definition at line 240 of file qgstextrenderer.h.

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

/build/qgis-3.16.0+99unstable/src/core/textrenderer/qgstextrenderer.h
/build/qgis-3.16.0+99unstable/src/core/textrenderer/qgstextrenderer.cpp

Public Types

Static Public Member Functions

Static Public Attributes

Friends

Detailed Description

Member Enumeration Documentation

◆ DrawMode

◆ HAlignment

◆ TextPart

◆ VAlignment

Member Function Documentation

◆ convertQtHAlignment()

◆ convertQtVAlignment()

◆ drawPart() [1/2]

◆ drawPart() [2/2]

◆ drawText() [1/2]

◆ drawText() [2/2]

◆ fontMetrics()

◆ sizeToPixel()

◆ textHeight() [1/2]

◆ textHeight() [2/2]

◆ textWidth()

Friends And Related Function Documentation

◆ QgsLabelPreview

◆ QgsVectorLayerLabelProvider

Member Data Documentation

◆ FONT_WORKAROUND_SCALE