generativepy.bitmap module

The bitmap module provides the ability to paint bitmap images and save them as either PNG images or frames.

The module is based on the popular PIL Python imaging library. This provides many functions for manipulating bitmap images, such as colour manipulation, filters, enhancement, morphing, colour channel operations, and pixel access. It also provides drawing operations (rectangles, ellipses, text etc), but these are not as powerful as the vector methods available via Pycairo in the generativepy.drawing module.

generativepy actually uses the Pillow library, which is a fork of PIL. That is because Pillow is actively maintained whereas PIL is not. The Pillow library is compatible, and is still imported using the name PIL. We will refer to is as PIL in the documentation.

make_bitmap

Used to create a single PNG image.

generativepy.bitmap.make_bitmap(outfile, paint, pixel_width, pixel_height, channels=3)

make_bitmap creates a PIL Image object, then calls the user supplied paint function to fill the image.

The paint function must have the following signature:

paint(image, pixel_width, pixel_height, frame_no, frame_count)

frame_no and frame_count only apply to functions that create a sequence of images. The make_bitmap function only ever creates one image, so the frame_no will always be 0 and the frame_count will always be 1.

make_bitmaps

Used to create a sequence of PNG images. These can be combined into an animated GIF or video.

generativepy.bitmap.make_bitmaps(outfile, paint, pixel_width, pixel_height, count, channels=3)

make_bitmap creates a PIL Image object, then calls the user supplied paint function to fill the image.

The outfile parameter should be a base filepath. For example:

C:/temp/image

In this case the files will be created in the folder C:/temp, and their names will be based on the base name "image":

image00000000.png
image00000001.png
image00000002.png
etc

Once the images have been created, you can use an external program to convert them into an animated GIF or movie.

The paint function has the same signature as for make_bitmap. In this case though, it will be called count times. The frame_count will always be set to count, and the frame_no will increment each time draw is called. You can use the frame_no value to draw a different image each time, to create animation.

make_bitmap_frame

Used to create a single PNG image.

generativepy.bitmap.make_bitmap_frame(paint, pixel_width, pixel_height, channels=3)

This works in a simlar way to make_bitmap, but instead of saving the image to a file, it returns a frame.

make_bitmap_frames

Used to create a sequence of PNG images. These can be combined into an animated GIF or video.

generativepy.bitmap.make_bitmap_frames(paint, pixel_width, pixel_height, count, channels=3)

This works in a similar way to make_bitmaps, but instead of saving the images to a set of files, it returns a lazy sequence of frames.

get_mode

Convert the number of channels into a PIL mode string.

generativepy.bitmap.get_mode(channels)

Returns a string:

• 'L' if channels is 1.
• 'RGBA' if channels is 4.
• 'RGB' in all other cases.

Scaler class

A PIL Image object always works in pixels. Unlike a Pycairo context used by make_image and similar functions, Image has no concept of a user space.

However, it is sometimes useful to be able to calculate values in a user space and convert them to image pixels (device space), or vice versa.

The Scaler class provides this functionality. You can create a scaler object with the dimensions of the image and the required user space. The scaler object can then be used to convert coordinates from one space to another. See the user space tutorial for more details.

Scaler constructor

Creates an Scaler object.

Scaler(self, pixel_width, pixel_height, width=None, height=None, startx=0, starty=0)

device_to_user

Converts a device coordinate to user space.

device_to_user(self, device_x, device_y)

Returns float (x, y), a tuple of the equivalent coordinates in user space.

user_to_device

Converts a user coordinate to device space.

user_to_device(self, user_x, user_y)

Returns int (x, y), a tuple of the equivalent coordinates in device space.

For an example, see the user space tutorial.

See also

• generativepy.analytics module
• generativepy.color module
• generativepy.drawing module
• generativepy.drawing3d module
• generativepy.formulas module
• generativepy.geometry module
• generativepy.geometry3d module
• generativepy.gif module
• generativepy.graph module
• generativepy.math module
• generativepy.movie module
• generativepy.nparray module
• generativepy.shape2d module
• generativepy.table module
• generativepy.tween module
• generativepy.utils module