gf::Image Class Reference

Class for loading, manipulating and saving images. More...

#include <gf/Image.h>

Public Member Functions
	Image ()
	Default constructor. More...
	Image (Vector2i size)
	Create the image. More...
	Image (Vector2i size, Color4u color)
	Create the image and fill it with a unique color. More...
	Image (Vector2i size, Color3u color)
	Create the image and fill it with a unique color. More...
	Image (Vector2i size, const uint8_t *pixels, PixelFormat format=PixelFormat::Rgba32)
	Create the image from an array of pixels. More...
	Image (const Path &filename)
	Load the image from a file on disk. More...
	Image (Span< const uint8_t > content)
	Load the image from a file in memory. More...
	Image (InputStream &stream)
	Load the image from a custom stream. More...
	Image (const Image &)=default
	Default copy constructor. More...
Image &	operator= (const Image &)=default
	Default copy assignment. More...
	Image (Image &&)=default
	Default move constructor. More...
Image &	operator= (Image &&)=default
	Default move assignment. More...
bool	saveToFile (const Path &filename) const
	Save the image to a file on disk. More...
Image	subImage (const RectI &area) const
	Create a sub-image of the image from a defined area. More...
Vector2i	getSize () const
	Return the size (width and height) of the image. More...
void	createMaskFromColor (const Color4u &color, uint8_t alpha=0)
	Create a transparency mask from a specified color-key. More...
void	setPixel (Vector2i pos, const Color4u &color)
	Change the color of a pixel. More...
Color4u	getPixel (Vector2i pos) const
	Get the color of a pixel. More...
const uint8_t *	getPixelsPtr () const
	Get a read-only pointer to the array of pixels. More...
void	flipHorizontally ()
	Flip the pixels horizontally. More...

Detailed Description

Class for loading, manipulating and saving images.

gf::Image is an abstraction to manipulate images as bidimensional arrays of pixels. The class provides functions to load, read, write and save pixels, as well as many other useful functions.

gf::Image can handle a unique internal representation of pixels, which is RGBA 32 bits. This means that a pixel must be composed of 8 bits red, green, blue and alpha channels – just like a gf::Color4u.

All the functions that return an array of pixels follow this rule, and all parameters that you pass to gf::Image constructors must use this representation as well.

A gf::Image can be copied, but it is a heavy resource and if possible you should always use (const) references to pass or return them to avoid useless copies.

Usage example:

  // Load an image file from a file
  gf::Image background("background.jpg");
 
  // Create a 20x20 image filled with black color
  gf::Image image({ 20, 20 }, gf::Color4u{0xFF, 0xFF, 0xFF, 0xFF});
 
  // Make the top-left pixel transparent
  gf::Color4u color = image.getPixel({ 0, 0 });
  color.a = 0;
  image.setPixel({ 0, 0 }, color);
 
  // Save the image to a file
  if (!image.saveToFile("result.png")) {
    // error
    return;
  }

See also

gf::Texture

Constructor & Destructor Documentation

Image() [1/10]

gf::Image::Image

(

)

Default constructor.

Creates an empty image.

Image() [2/10]

gf::Image::Image

(

Vector2i

size

)

Create the image.

The initial color of the pixels is opaque white

Parameters

size	Size of the image

Image() [3/10]

gf::Image::Image	(	Vector2i	size,
		Color4u	color
	)

Create the image and fill it with a unique color.

Parameters

size	Size of the image
color	Fill color

Image() [4/10]

gf::Image::Image	(	Vector2i	size,
		Color3u	color
	)

Create the image and fill it with a unique color.

Parameters

size	Size of the image
color	Fill color

Image() [5/10]

gf::Image::Image	(	Vector2i	size,
		const uint8_t *	pixels,
		PixelFormat	format = PixelFormat::Rgba32
	)

Create the image from an array of pixels.

The pixels array is assumed to contain pixels with format given by format pixel format, and have the given size. If not, this is an undefined behavior.

Parameters

size	Size of the image
pixels	Array of pixels to copy to the image
format	Format of the pixels

Image() [6/10]

gf::Image::Image

(

const Path &

filename

)

Load the image from a file on disk.

The supported image formats are bmp, png, tga, jpg, gif, psd, hdr and pic. Some format options are not supported, like progressive jpeg. If this function fails, the image is left unchanged.

Parameters

filename

Path of the image file to load

Image() [7/10]

gf::Image::Image

(

Span< const uint8_t >

content

)

Load the image from a file in memory.

The supported image formats are bmp, png, tga, jpg, gif, psd, hdr and pic. Some format options are not supported, like progressive jpeg. If this function fails, the image is left unchanged.

Parameters

content

Content of the file data in memory

Image() [8/10]

gf::Image::Image

(

InputStream &

stream

)

Load the image from a custom stream.

The supported image formats are bmp, png, tga, jpg, gif, psd, hdr and pic. Some format options are not supported, like progressive jpeg. If this function fails, the image is left unchanged.

Parameters

stream

Source stream to read from

Image() [9/10]

gf::Image::Image ( const Image &  )

default

Default copy constructor.

Image() [10/10]

gf::Image::Image ( Image &&  )

default

Default move constructor.

Member Function Documentation

createMaskFromColor()

void gf::Image::createMaskFromColor	(	const Color4u &	color,
		uint8_t	alpha = 0
	)

Create a transparency mask from a specified color-key.

This function sets the alpha value of every pixel matching the given color to alpha (0 by default), so that they become transparent.

Parameters

color	Color to make transparent
alpha	Alpha value to assign to transparent pixels

flipHorizontally()

void gf::Image::flipHorizontally

(

)

Flip the pixels horizontally.

This function is needed internally. But you can use it if you want.

getPixel()

Color4u gf::Image::getPixel

(

Vector2i

pos

)

const

Get the color of a pixel.

This function doesn't check the validity of the pixel coordinates, using out-of-range values will result in an undefined behavior.

Parameters

pos	Coordinate of pixel to get

Returns

Color of the pixel at coordinates (x, y)

See also

setPixel

getPixelsPtr()

const uint8_t * gf::Image::getPixelsPtr

(

)

const

Get a read-only pointer to the array of pixels.

The returned value points to an array of RGBA pixels made of 8 bits integers components. The size of the array is width * height * 4. Warning: the returned pointer may become invalid if you modify the image, so you should never store it for too long. If the image is empty, a null pointer is returned.

Returns

Read-only pointer to the array of pixels

getSize()

Vector2i gf::Image::getSize

(

)

const

Return the size (width and height) of the image.

Returns

Size of the image, in pixels

operator=() [1/2]

Image & gf::Image::operator= ( const Image &  )

default

Default copy assignment.

operator=() [2/2]

Image & gf::Image::operator= ( Image &&  )

default

Default move assignment.

saveToFile()

bool gf::Image::saveToFile

(

const Path &

filename

)

const

Save the image to a file on disk.

The format of the image is automatically deduced from the extension. The supported image formats are bmp, png and tga. The destination file is overwritten if it already exists. This function fails if the image is empty.

Parameters

filename

Path of the file to save

Returns

true if saving was successful

setPixel()

void gf::Image::setPixel	(	Vector2i	pos,
		const Color4u &	color
	)

Change the color of a pixel.

This function doesn't check the validity of the pixel coordinates, using out-of-range values will result in an undefined behavior.

Parameters

pos	Coordinate of pixel to change
color	New color of the pixel

See also

getPixel

subImage()

Image gf::Image::subImage

(

const RectI &

area

)

const

Create a sub-image of the image from a defined area.

If the area doesn't contain the image, an empty image is returned. If the area is bigger than the size of the image, the image itself is returned.

Parameters

area	Sub-area of the image

Returns

The sub-image of the image