Wand alpha() function in Python

The alpha() function is identical to the wand color() function. Similar to color() function, alpha() function draws a color on the image using current fill color, starting at specified position & method. Uses same arguments as color() method.

Syntax: wand.drawing.alpha(x, y, method) Parameters :

Parameter	Input Type	Description
x	numbers.Integer	start of filling color
y	numbers.Integer	end of filling color
method	basestring	method from PAINT_METHOD_TYPES

The following are the PAINT_METHOD_TYPES:

• ‘point’ alters a single pixel.
• ‘replace’ swaps on color for another. Threshold is influenced by fuzz.
• ‘floodfill’ fills area of a color influenced by fuzz.
• ‘filltoborder’ fills area of a color until border defined by border_color.
• ‘reset’ replaces the whole image to a single color.

Note: This method replaces matte() in ImageMagick version 7. An AttributeError will be raised if attempting to call on a library without DrawAlpha support. Example #1:

Python3

# Import required objects from wand modules
from wand.image import Image
from wand.drawing import Drawing
from wand.color import Color

# generate object for wand.drawing
with Drawing() as draw:
    draw.alpha(100, 100, 'point')
    with Image(width = 200,
               height = 200) as img:

        # draw shape on image using draw() function
        draw.draw(img)
        img.save(filename ='color.png')

Output: A pixel is visible at center of transparent image here is the zoomed image. Example #2: Filling color using a flood-fill algorithm. 

Python3

# Import required objects from wand modules
from wand.image import Image
from wand.drawing import Drawing
from wand.color import Color

# generate object for wand.drawing
with Drawing() as draw:
    draw.fill_color = Color('blue')
    draw.alpha(10, 35, 'floodfill')
    with Image(width = 200,
               height = 200,
               background = Color('white')) as img:

        # draw shape on image using draw() function
        draw.draw(img)
        img.save(filename ='color2.png')

Output: