Contains operations and filters which apply to QImages. More...

#include <qgsimageoperation.h>

Classes
struct	DistanceTransformProperties
	Struct for storing properties of a distance transform operation. More...

Public Types
enum	FlipType { FlipHorizontal , FlipVertical }
	Flip operation types. More...

enum	GrayscaleMode { GrayscaleLightness , GrayscaleLuminosity , GrayscaleAverage , GrayscaleOff }
	Modes for converting a QImage to grayscale. More...

Static Public Member Functions
static void	adjustBrightnessContrast (QImage &image, int brightness, double contrast, QgsFeedback *feedback=nullptr)
	Alter the brightness or contrast of a QImage. More...

static void	adjustHueSaturation (QImage &image, double saturation, const QColor &colorizeColor=QColor(), double colorizeStrength=1.0, QgsFeedback *feedback=nullptr)
	Alter the hue or saturation of a QImage. More...

static void	convertToGrayscale (QImage &image, GrayscaleMode mode=GrayscaleLuminosity, QgsFeedback *feedback=nullptr)
	Convert a QImage to a grayscale image. More...

static QImage	cropTransparent (const QImage &image, QSize minSize=QSize(), bool center=false)
	Crop any transparent border from around an image. More...

static void	distanceTransform (QImage &image, const QgsImageOperation::DistanceTransformProperties &properties, QgsFeedback *feedback=nullptr)
	Performs a distance transform on the source image and shades the result using a color ramp. More...

static void	flipImage (QImage &image, FlipType type)
	Flips an image horizontally or vertically. More...

static QImage *	gaussianBlur (QImage &image, int radius, QgsFeedback *feedback=nullptr)
	Performs a gaussian blur on an image. More...

static void	multiplyOpacity (QImage &image, double factor, QgsFeedback *feedback=nullptr)
	Multiplies opacity of image pixel values by a factor. More...

static QRect	nonTransparentImageRect (const QImage &image, QSize minSize=QSize(), bool center=false)
	Calculates the non-transparent region of an image. More...

static void	overlayColor (QImage &image, const QColor &color)
	Overlays a color onto an image. More...

static void	stackBlur (QImage &image, int radius, bool alphaOnly=false, QgsFeedback *feedback=nullptr)
	Performs a stack blur on an image. More...

Detailed Description

Contains operations and filters which apply to QImages.

A set of optimised pixel manipulation operations and filters which can be applied to QImages. All operations only apply to ARGB32 format images, and it is left up to the calling procedure to ensure that any passed images are of the correct format.

Operations are written to either modify an image in place or return a new image, depending on which is faster for the particular operation.

Definition at line 46 of file qgsimageoperation.h.

Member Enumeration Documentation

◆ FlipType

enum QgsImageOperation::FlipType

Flip operation types.

Enumerator
FlipHorizontal	Flip the image horizontally.
FlipVertical	Flip the image vertically.

Definition at line 65 of file qgsimageoperation.h.

◆ GrayscaleMode

enum QgsImageOperation::GrayscaleMode

Modes for converting a QImage to grayscale.

Enumerator
GrayscaleLightness	Keep the lightness of the color, drops the saturation.
GrayscaleLuminosity	Grayscale by perceptual luminosity (weighted sum of color RGB components)
GrayscaleAverage	Grayscale by taking average of color RGB components.
GrayscaleOff	No change.

Definition at line 54 of file qgsimageoperation.h.

Member Function Documentation

◆ adjustBrightnessContrast()

void QgsImageOperation::adjustBrightnessContrast	(	QImage &	image,
		int	brightness,
		double	contrast,
		QgsFeedback *	feedback = `nullptr`
	)

static

Alter the brightness or contrast of a QImage.

Parameters

image	QImage to alter
brightness	brightness value, in the range -255 to 255. A brightness value of 0 indicates no change to brightness, a negative value will darken the image, and a positive value will brighten the image.
contrast	contrast value. Must be a positive or zero value. A value of 1.0 indicates no change to the contrast, a value of 0 represents an image with 0 contrast, and a value > 1.0 will increase the contrast of the image.
feedback	optional feedback object for responsive cancellation (since QGIS 3.22)

Definition at line 256 of file qgsimageoperation.cpp.

◆ adjustHueSaturation()

void QgsImageOperation::adjustHueSaturation	(	QImage &	image,
		double	saturation,
		const QColor &	colorizeColor = `QColor()`,
		double	colorizeStrength = `1.0`,
		QgsFeedback *	feedback = `nullptr`
	)

static

Alter the hue or saturation of a QImage.

Parameters

image	QImage to alter
saturation	double between 0 and 2 inclusive, where 0 = desaturate and 1.0 = no change
colorizeColor	color to use for colorizing image. Set to an invalid QColor to disable colorization.
colorizeStrength	double between 0 and 1, where 0 = no colorization and 1.0 = full colorization
feedback	optional feedback object for responsive cancellation (since QGIS 3.22)

Definition at line 280 of file qgsimageoperation.cpp.

◆ convertToGrayscale()

void QgsImageOperation::convertToGrayscale	(	QImage &	image,
		GrayscaleMode	mode = `GrayscaleLuminosity`,
		QgsFeedback *	feedback = `nullptr`
	)

static

Convert a QImage to a grayscale image.

Alpha channel is preserved.

Parameters

image	QImage to convert
mode	mode to use during grayscale conversion
feedback	optional feedback object for responsive cancellation (since QGIS 3.22)

Definition at line 195 of file qgsimageoperation.cpp.

◆ cropTransparent()

QImage QgsImageOperation::cropTransparent	(	const QImage &	image,
		QSize	minSize = `QSize()`,
		bool	center = `false`
	)

static

Crop any transparent border from around an image.

Parameters

image	source image
minSize	minimum size for cropped image, if desired. If the cropped image is smaller than the minimum size, it will be centered in the returned image.
center	cropped image will be centered on the center of the original image if set to `true`

Definition at line 955 of file qgsimageoperation.cpp.

◆ distanceTransform()

void QgsImageOperation::distanceTransform	(	QImage &	image,
		const QgsImageOperation::DistanceTransformProperties &	properties,
		QgsFeedback *	feedback = `nullptr`
	)

static

Performs a distance transform on the source image and shades the result using a color ramp.

Parameters

image	QImage to alter
properties	DistanceTransformProperties object with parameters for the distance transform operation
feedback	optional feedback object for responsive cancellation (since QGIS 3.22)

Definition at line 387 of file qgsimageoperation.cpp.

◆ flipImage()

void QgsImageOperation::flipImage	(	QImage &	image,
		QgsImageOperation::FlipType	type
	)

static

Flips an image horizontally or vertically.

Parameters

image	QImage to flip
type	type of flip to perform (horizontal or vertical)

Definition at line 843 of file qgsimageoperation.cpp.

◆ gaussianBlur()

QImage * QgsImageOperation::gaussianBlur	(	QImage &	image,
		int	radius,
		QgsFeedback *	feedback = `nullptr`
	)

static

Performs a gaussian blur on an image.

Gaussian blur is slower but results in a high quality blur.

Parameters

image	QImage to blur
radius	blur radius in pixels
feedback	optional feedback object for responsive cancellation (since QGIS 3.22)

Returns: blurred image

Note: for fastest operation, ensure the source image is ARGB32_Premultiplied

Definition at line 651 of file qgsimageoperation.cpp.

◆ multiplyOpacity()

void QgsImageOperation::multiplyOpacity	(	QImage &	image,
		double	factor,
		QgsFeedback *	feedback = `nullptr`
	)

static

Multiplies opacity of image pixel values by a factor.

Parameters

image	QImage to alter
factor	factor to multiple pixel's opacity by
feedback	optional feedback object for responsive cancellation (since QGIS 3.22)

Definition at line 335 of file qgsimageoperation.cpp.

◆ nonTransparentImageRect()

QRect QgsImageOperation::nonTransparentImageRect	(	const QImage &	image,
		QSize	minSize = `QSize()`,
		bool	center = `false`
	)

static

Calculates the non-transparent region of an image.

Parameters

image	source image
minSize	minimum size for returned region, if desired. If the non-transparent region of the image is smaller than this minimum size, it will be centered in the returned rectangle.
center	return rectangle will be centered on the center of the original image if set to `true`

See also: cropTransparent

Definition at line 850 of file qgsimageoperation.cpp.

◆ overlayColor()

void QgsImageOperation::overlayColor	(	QImage &	image,
		const QColor &	color
	)

static

Overlays a color onto an image.

This operation retains the alpha channel of the original image, but replaces all image pixel colors with the specified color.

Parameters

image	QImage to alter
color	color to overlay (any alpha component of the color is ignored)

Definition at line 371 of file qgsimageoperation.cpp.

◆ stackBlur()

void QgsImageOperation::stackBlur	(	QImage &	image,
		int	radius,
		bool	alphaOnly = `false`,
		QgsFeedback *	feedback = `nullptr`
	)

static

Performs a stack blur on an image.

Stack blur represents a good balance between speed and blur quality.

Parameters

image	QImage to blur
radius	blur radius in pixels, maximum value of 16
alphaOnly	set to `true` to blur only the alpha component of the image
feedback	optional feedback object for responsive cancellation (since QGIS 3.22)

Note: for fastest operation, ensure the source image is ARGB32_Premultiplied if alphaOnly is set to false, or ARGB32 if alphaOnly is true

Definition at line 585 of file qgsimageoperation.cpp.

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

/build/qgis-3.37.0+git20240325+fdefdf9c27f+17bookworm/src/core/effects/qgsimageoperation.h
/build/qgis-3.37.0+git20240325+fdefdf9c27f+17bookworm/src/core/effects/qgsimageoperation.cpp

Classes

Public Types

Static Public Member Functions

Detailed Description

Member Enumeration Documentation

◆ FlipType

◆ GrayscaleMode

Member Function Documentation

◆ adjustBrightnessContrast()

◆ adjustHueSaturation()

◆ convertToGrayscale()

◆ cropTransparent()

◆ distanceTransform()

◆ flipImage()

◆ gaussianBlur()

◆ multiplyOpacity()

◆ nonTransparentImageRect()

◆ overlayColor()

◆ stackBlur()