LocationColorMap class

Translate the finger location into a code, according to a BMP image. The image is not displayed, but the class can tell you the color of a certain image pixel had it been displayed on screen.

This is a very flexible method for defining several different regions on the screen.

Using this class

  • Create an image file. The file format should be a bitmap (image.bmp) in 24-bit format (which means that each pixel is specified as an RGB combination).

    The file doesn’t have to be of the same size as the screen.

  • Create the LocationColorMap object

  • Get the colors of pixels using get_color_at()

  • In this simplest configuration, get_color_at() will tell you the RGB color of the pixel indicated.

    You can also define colormap to map each RGB color to any value (e.g., to make get_color_at() will return meaningful values).

    When using a color map, make sure to set use_mapping to True.

Methods and properties:

class trajtracker.misc.LocationColorMap(image, position=None, use_mapping=False, colormap=None)
__init__(image, position=None, use_mapping=False, colormap=None)

Constructor - invoked when you create a new object by writing LocationColorMap()

Parameters:
  • image – Name of a BMP file, or the actual image (rectangular matrix of colors)
  • position – See position
  • use_mapping – See use_mapping
  • colormap – See colormap
available_colors

Return a set with all colors that exist in the image

colormap

Mapping of each color in the image to another value. This mapping will be used when calling get_color_at(use_mapping=True)

Valid values:

  • None (default): no mapping; calling get_color_at(use_mapping=True)
  • “RGB”: Each color is assigned the RGB code - a number between 0 and 65535 (0xFFFFFF)
  • “DEFAULT”: Each color is assigned a unique code (0, 1, 2, etc.). Codes are assigned by order of RGB codes.
  • or a dictionary that maps each color in the image (RGB tuple) to a value
get_color_at(x_coord, y_coord, use_mapping=None)

Return the color at a given coordinate

Parameters:
  • x_coord –
  • y_coord –
  • use_mapping –
Returns:

The color in the given place, or None if the coordinate is out of the image range
log_level

Logging level of this object: trajtracker.log_none, log_error (default), log_warn, log_info, log_debug, log_trace

position

The coordinate of the image provided in the constructor (middle of the image) - an (x,y) tuple/list If position=(a,b), then get_color_at() with arguments (a,b) will return the color of the middle of the image.

use_mapping

The default value of the ‘use_mapping’ argument in get_color_at()

Type:bool