QGIS API Documentation  2.18.3-Las Palmas (77b8c3d)
Classes | Public Types | Static Public Member Functions | List of all members
QgsImageOperation Class Reference

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, const int brightness, const double contrast)
 Alter the brightness or contrast of a QImage. More...
 
static void adjustHueSaturation (QImage &image, const double saturation, const QColor &colorizeColor=QColor(), const double colorizeStrength=1.0)
 Alter the hue or saturation of a QImage. More...
 
static void convertToGrayscale (QImage &image, const GrayscaleMode mode=GrayscaleLuminosity)
 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 DistanceTransformProperties &properties)
 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 QImagegaussianBlur (QImage &image, const int radius)
 Performs a gaussian blur on an image. More...
 
static void multiplyOpacity (QImage &image, const double factor)
 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, const int radius, const bool alphaOnly=false)
 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.

Note
Added in version 2.7

Definition at line 41 of file qgsimageoperation.h.

Member Enumeration Documentation

Flip operation types.

Enumerator
FlipHorizontal 

flip the image horizontally

FlipVertical 

flip the image vertically

Definition at line 58 of file qgsimageoperation.h.

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 48 of file qgsimageoperation.h.

Member Function Documentation

void QgsImageOperation::adjustBrightnessContrast ( QImage image,
const int  brightness,
const double  contrast 
)
static

Alter the brightness or contrast of a QImage.

Parameters
imageQImage to alter
brightnessbrightness 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.
contrastcontrast 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.

Definition at line 246 of file qgsimageoperation.cpp.

void QgsImageOperation::adjustHueSaturation ( QImage image,
const double  saturation,
const QColor colorizeColor = QColor(),
const double  colorizeStrength = 1.0 
)
static

Alter the hue or saturation of a QImage.

Parameters
imageQImage to alter
saturationdouble between 0 and 2 inclusive, where 0 = desaturate and 1.0 = no change
colorizeColorcolor to use for colorizing image. Set to an invalid QColor to disable colorization.
colorizeStrengthdouble between 0 and 1, where 0 = no colorization and 1.0 = full colorization

Definition at line 269 of file qgsimageoperation.cpp.

void QgsImageOperation::convertToGrayscale ( QImage image,
const GrayscaleMode  mode = GrayscaleLuminosity 
)
static

Convert a QImage to a grayscale image.

Alpha channel is preserved.

Parameters
imageQImage to convert
modemode to use during grayscale conversion

Definition at line 186 of file qgsimageoperation.cpp.

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

Crop any transparent border from around an image.

Parameters
imagesource image
minSizeminimum size for cropped image, if desired. If the cropped image is smaller than the minimum size, it will be centered in the returned image.
centercropped image will be centered on the center of the original image if set to true
Note
added in QGIS 2.9

Definition at line 849 of file qgsimageoperation.cpp.

void QgsImageOperation::distanceTransform ( QImage image,
const DistanceTransformProperties properties 
)
static

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

Parameters
imageQImage to alter
propertiesDistanceTransformProperties object with parameters for the distance transform operation

Definition at line 372 of file qgsimageoperation.cpp.

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

Flips an image horizontally or vertically.

Parameters
imageQImage to flip
typetype of flip to perform (horizontal or vertical)

Definition at line 794 of file qgsimageoperation.cpp.

QImage * QgsImageOperation::gaussianBlur ( QImage image,
const int  radius 
)
static

Performs a gaussian blur on an image.

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

Parameters
imageQImage to blur
radiusblur radius in pixels
Returns
blurred image
Note
for fastest operation, ensure the source image is ARGB32_Premultiplied

Definition at line 630 of file qgsimageoperation.cpp.

void QgsImageOperation::multiplyOpacity ( QImage image,
const double  factor 
)
static

Multiplies opacity of image pixel values by a factor.

Parameters
imageQImage to alter
factorfactor to multiple pixel's opacity by

Definition at line 323 of file qgsimageoperation.cpp.

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

Calculates the non-transparent region of an image.

Parameters
imagesource image
minSizeminimum 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.
centerreturn rectangle will be centered on the center of the original image if set to true
Note
added in QGIS 2.9
See also
cropTransparent

Definition at line 800 of file qgsimageoperation.cpp.

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
imageQImage to alter
colorcolor to overlay (any alpha component of the color is ignored)

Definition at line 357 of file qgsimageoperation.cpp.

void QgsImageOperation::stackBlur ( QImage image,
const int  radius,
const bool  alphaOnly = false 
)
static

Performs a stack blur on an image.

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

Parameters
imageQImage to blur
radiusblur radius in pixels, maximum value of 16
alphaOnlyset to true to blur only the alpha component of the image
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 559 of file qgsimageoperation.cpp.


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