gizeh 0.1.09

Surfaces

A Surface is a rectangle of fixed dimensions (in pixels), on which you will draw elements, and that you can save or export as an image:

import gizeh

# initialize surface
surface = gizeh.Surface(width=320, height=260) # in pixels

# Now make a shape and draw it on the surface
circle = gizeh.circle(r=30, xy= [40,40], fill=(1,1,1))
circle.draw(surface)

# Now export the surface
surface.get_npimage() # returns a (width x height x 3) numpy array
surface.write_to_png("circle.png")

Elements

Basic elements are circles, rectangles, lines, texts, etc., that you can draw on a surface using my_element.draw(surface). You can specify the properties and coordinates of these elements at creation time:

• xy : coordinates of the center of the object. At rendering time (in function surface.write_to_png) you can set the parameter y_origin to top (default) or bottom. If you leave it to top, (0,0) corresponds to the upper left corner of the final picture, and the bottom right corner has coordinates (width, height). If you choose y_origin=bottom, (0,0) will be at the bottom left of the picture (like in a standard plot) and (width, height) will be at the upper right corner.

• angle : angle (in radians) of the rotation of the element around its center xy.

• fill : what will fill the element (default is no fill). Can be a color (R,G,B), a color gradient, an image, etc. See section below.

• stroke : What will fill the element’s contour. Same rules as for fill.

• stroke_width : the width (in pixels) of the element’s contour. Default is 0 (no stroke).

Examples of elements:

Pi = 3.14
circ = gizeh.circle(r=30, xy=(50,50), fill=(1,1,1))
rect = gizeh.rectangle(lx=60.3, ly=45, xy=(60,70), fill=(0,1,0), angle=Pi/8)
sqr = gizeh.square(l=20, stroke=(1,1,1), stroke_width= 1.5)
arc = gizeh.arc(r=20, a1=Pi/4, a2=3*Pi/4, fill=(1,1,1))
text = gizeh.text("Hello world", fontfamily="Impact",  fontsize=40,
                  fill=(1,1,1), xy=(100,100), angle=Pi/12)
polygon = gizeh.polygon(r=40, n=5, angle=np.pi/4, xy=[40,50], fill=(1,0,1))
line = gizeh.polyline(points=[(0,0), (20,30), (40,40), (0,10)], stroke_width=3,
                     stroke=(1,0,0), fill=(0,1,0))

Transformations

Any element can be tranformed (translated, rotated or scaled). All transformations are outplace: they do not modify the original element, they create a modified version of it.

Examples:

square_1 = gizeh.square(l=20, xy = [30,35], fill=(1,0,0))
square_2 = square_1.rotate(Pi/8) # rotation around [0,0] by default
square_3 = square_2.rotate(Pi/4, center=[10,15]) # rotation around a center
square_4 = square_1.scale(2) # two times bigger
square_5 = square1.scale(sx=2, sy=3) # width times 2, height times 3
square_6 = square_1.scale(2, center=[30,30]) # zoom: scales around a center
square_7 = square_1.translate(xy=[5,15]) # translation

Groups

A Group is a collection of elements which will be transformed and drawn together. The elements can be a basic element (square, circle…) or even groups.

Examples:

square = gizeh.square(l=20, fill=(1,0,0), xy=(40,40))
circle = gizeh.circle(r=20, fill=(1,2,0), xy=(50,30))
group_1 = gizeh.Group([square, circle])
group_2 = group.translate(xy=[30,30]).rotate(Pi/4)
group_3 = gizeh.Group([circle, group_1])

surface = gizeh.Surface(width=300,height=200)
group.draw(surface)
group_1.draw(surface)
group_2.draw(surface)
group_3.draw(surface)
surface.write_to_png("my_masterwork.png")

That’s all folks !

That’s about all there is to know. To go further, see the examples in the examples folder or (wishful thinking) on the Web.