Pygame.image learning notes

Now I am learning how to use Pygame to read, write and store a surface.

http://www.pygame.org/docs/ref/image.html

pygame.image

pygame.image

pygame module for image transfer

pygame.image.load	—	load new image from a file
pygame.image.save	—	save an image to disk
pygame.image.get_extended	—	test if extended image formats can be loaded
pygame.image.tostring	—	transfer image to string buffer
pygame.image.fromstring	—	create new Surface from a string buffer
pygame.image.frombuffer	—	create a new Surface that shares data inside a string buffer

The image module contains functions for loading and saving pictures, as well as transferring Surfaces to formats usable by other packages. .

Note that there is no Image class; an image is loaded as a Surface object. The Surface class allows manipulation (drawing lines, setting pixels, capturing regions, etc.).

The image module is a required dependency of Pygame, but it only optionally supports any extended file formats. By default it can only load uncompressed BMP images. When built with full image support, the pygame.image.load() function can support the following formats.

• JPG
• PNG
• GIF (non animated)
• BMP
• PCX
• TGA (uncompressed)
• TIF
• LBM (and PBM)
• PBM (and PGM, PPM)
• XPM

Saving images only supports a limited set of formats. You can save to the following formats.

• BMP
• TGA
• PNG
• JPEG

PNG, JPEG saving new in pygame 1.8.

pygame.image.load()

load new image from a file

load(filename) -> Surface

load(fileobj, namehint=”“) -> Surface

Load an image from a file source. You can pass either a filename or a Python file-like object.

Pygame will automatically determine the image type (e.g., GIF or bitmap) and create a new Surface object from the data. In some cases it will need to know the file extension (e.g., GIF images should end in “.gif”). If you pass a raw file-like object, you may also want to pass the original filename as the namehint argument.

The returned Surface will contain the same color format, colorkey and alpha transparency as the file it came from. You will often want to call Surface.convert() with no arguments, to create a copy that will draw more quickly on the screen.

For alpha transparency, like in .png images use the convert_alpha() method after loading so that the image has per pixel transparency.

Pygame may not always be built to support all image formats. At minimum it will support uncompressed BMP. If pygame.image.get_extended() returns ‘True’, you should be able to load most images (including png, jpg and gif).

You should use os.path.join() for compatibility.

eg. asurf = pygame.image.load(os.path.join('data', 'bla.png'))

pygame.image.save()

save an image to disk

save(Surface, filename) -> None

This will save your Surface as either a BMP, TGA, PNG, or JPEG image. If the filename extension is unrecognized it will default to TGA. Both TGA, and BMP file formats create uncompressed files.

PNG, JPEG saving new in pygame 1.8.

pygame.image.get_extended()

test if extended image formats can be loaded

get_extended() -> bool

If pygame is built with extended image formats this function will return True. It is still not possible to determine which formats will be available, but generally you will be able to load them all.

pygame.image.tostring()

transfer image to string buffer

tostring(Surface, format, flipped=False) -> string

Creates a string that can be transferred with the ‘fromstring’ method in other Python imaging packages. Some Python image packages prefer their images in bottom-to-top format (PyOpenGL for example). If you pass True for the flipped argument, the string buffer will be vertically flipped.

The format argument is a string of one of the following values. Note that only 8bit Surfaces can use the “P” format. The other formats will work for any Surface. Also note that other Python image packages support more formats than Pygame.

• P, 8bit palettized Surfaces
• RGB, 24bit image
• RGBX, 32bit image with unused space
• RGBA, 32bit image with an alpha channel
• ARGB, 32bit image with alpha channel first
• RGBA_PREMULT, 32bit image with colors scaled by alpha channel
• ARGB_PREMULT, 32bit image with colors scaled by alpha channel, alpha channel first

pygame.image.fromstring()

create new Surface from a string buffer

fromstring(string, size, format, flipped=False) -> Surface

This function takes arguments similar to pygame.image.tostring(). The size argument is a pair of numbers representing the width and height. Once the new Surface is created you can destroy the string buffer.

The size and format image must compute the exact same size as the passed string buffer. Otherwise an exception will be raised.

See the pygame.image.frombuffer() method for a potentially faster way to transfer images into Pygame.

pygame.image.frombuffer()

create a new Surface that shares data inside a string buffer

frombuffer(string, size, format) -> Surface

Create a new Surface that shares pixel data directly from the string buffer. This method takes the same arguments as pygame.image.fromstring(), but is unable to vertically flip the source data.

This will run much faster than pygame.image.fromstring()create new Surface from a string buffer, since no pixel data must be allocated and copied.

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