#! /usr/bin/env python
import cairo
from math import pi, sqrt
class Diagram(object):
def __init__(self, filename, width, height):
self.surface = cairo.SVGSurface(filename + '.svg', width, height)
cr = self.cr = cairo.Context(self.surface)
cr.scale(width, height)
cr.set_line_width(0.01)
cr.rectangle(0, 0, 1, 1)
cr.set_source_rgb(1, 1, 1)
cr.fill()
self.draw_dest(cr)
cr.set_line_width( max(cr.device_to_user_distance(2, 2)) )
cr.set_source_rgb(0, 0, 0)
cr.rectangle(0, 0, 1, 1)
cr.stroke()
self.surface.write_to_png(filename + '.png')
cr.show_page()
self.surface.finish()
class SetSourceRGBA(Diagram):
def draw_dest(self, cr):
cr.set_source_rgb(0, 0, 0) #rgba
cr.move_to(0, 0) #rgba
cr.line_to(1, 1) #rgba
cr.move_to(1, 0) #rgba
cr.line_to(0, 1) #rgba
cr.set_line_width(0.2) #rgba
cr.stroke() #rgba
#rgba
cr.rectangle(0, 0, 0.5, 0.5) #rgba
cr.set_source_rgba(1, 0, 0, 0.80) #rgba
cr.fill() #rgba
#rgba
cr.rectangle(0, 0.5, 0.5, 0.5) #rgba
cr.set_source_rgba(0, 1, 0, 0.60) #rgba
cr.fill() #rgba
#rgba
cr.rectangle(0.5, 0, 0.5, 0.5) #rgba
cr.set_source_rgba(0, 0, 1, 0.40) #rgba
cr.fill() #rgba
class SetSourceGradient(Diagram):
def draw_dest(self, cr):
radial = cairo.RadialGradient(0.25, 0.25, 0.1, 0.5, 0.5, 0.5) #gradient
radial.add_color_stop_rgb(0, 1.0, 0.8, 0.8) #gradient
radial.add_color_stop_rgb(1, 0.9, 0.0, 0.0) #gradient
#gradient
for i in range(1, 10): #gradient
for j in range(1, 10): #gradient
cr.rectangle(i/10.0 - 0.04, j/10.0 - 0.04, 0.08, 0.08) #gradient
cr.set_source(radial) #gradient
cr.fill() #gradient
#gradient
linear = cairo.LinearGradient(0.25, 0.35, 0.75, 0.65) #gradient
linear.add_color_stop_rgba(0.00, 1, 1, 1, 0) #gradient
linear.add_color_stop_rgba(0.25, 0, 1, 0, 0.5) #gradient
linear.add_color_stop_rgba(0.50, 1, 1, 1, 0) #gradient
linear.add_color_stop_rgba(0.75, 0, 0, 1, 0.5) #gradient
linear.add_color_stop_rgba(1.00, 1, 1, 1, 0) #gradient
#gradient
cr.rectangle(0.0, 0.0, 1, 1) #gradient
cr.set_source(linear) #gradient
cr.fill() #gradient
class PathDiagram(Diagram):
def draw_dest(self, cr):
self.draw_dest_path(cr)
path = list(cr.copy_path_flat())
cr.set_line_width(max(cr.device_to_user_distance(3, 3)))
cr.set_source_rgb(0, 0.6, 0)
cr.stroke()
if len(path) and path[-1][0] != cairo.PATH_CLOSE_PATH:
x, y = path[0][1]
cr.arc(x, y, max(cr.device_to_user_distance(5, 5)), 0, 2*pi)
cr.set_source_rgba(0.0, 0.6, 0.0, 0.5)
cr.fill()
x, y = path[-1][1]
cr.arc(x, y, max(cr.device_to_user_distance(5, 5)), 0, 2*pi)
cr.set_source_rgba(0.0, 0.0, 0.75, 0.5)
cr.fill()
class PathDiagramMoveTo(PathDiagram):
def draw_dest_path(self, cr):
cr.move_to(0.25, 0.25) #moveto
class PathDiagramLineTo(PathDiagramMoveTo):
def draw_dest_path(self, cr):
PathDiagramMoveTo.draw_dest_path(self, cr)
cr.line_to(0.5, 0.375) #lineto
cr.rel_line_to(0.25, -0.125) #lineto
class PathDiagramArcTo(PathDiagramLineTo):
def draw_dest_path(self, cr):
PathDiagramLineTo.draw_dest_path(self, cr)
cr.arc(0.5, 0.5, 0.25 * sqrt(2), -0.25 * pi, 0.25 * pi) #arc
class PathDiagramCurveTo(PathDiagramArcTo):
def draw_dest_path(self, cr):
if type(self) == PathDiagramCurveTo:
cr.save()
for x, y in ((0.5, 0.625), (0.5, 0.875)):
cr.new_sub_path()
cr.arc(x, y, max(cr.device_to_user_distance(3, 3)), 0, 2*pi)
cr.set_source_rgba(0.5, 0, 0, 0.5)
cr.fill()
for (x, y, w, h) in ((0.25, 0.75, 0.25, 0.125),
(0.75, 0.75, -0.25, -0.125)):
cr.move_to(x, y)
cr.rel_line_to(w, h)
cr.set_line_width(max(cr.device_to_user_distance(2, 2)))
cr.set_source_rgba(0.5, 0, 0, 0.25)
cr.stroke()
cr.restore()
PathDiagramArcTo.draw_dest_path(self, cr)
cr.rel_curve_to(-0.25, -0.125, -0.25, 0.125, -0.5, 0) #curveto
class PathDiagramClose(PathDiagramCurveTo):
def draw_dest_path(self, cr):
PathDiagramCurveTo.draw_dest_path(self, cr)
cr.close_path() #closepath
class TextExtents(Diagram):
def draw_dest(self, cr):
text = 'joy'
cr.select_font_face('Georgia', cairo.FONT_SLANT_NORMAL, cairo.FONT_WEIGHT_BOLD)
cr.set_font_size(0.5)
px = max(cr.device_to_user_distance(1, 1))
fascent, fdescent, fheight, fxadvance, fyadvance = cr.font_extents()
xbearing, ybearing, width, height, xadvance, yadvance = \
cr.text_extents(text)
x = 0.5 - xbearing - width / 2
y = 0.5 - fdescent + fheight / 2
# baseline, descent, ascent, height
cr.set_line_width(4 * px)
cr.set_dash([9 * px], 0)
cr.set_source_rgba(0, 0.6, 0, 0.5)
cr.move_to(x + xbearing, y)
cr.rel_line_to(width, 0)
cr.move_to(x + xbearing, y + fdescent)
cr.rel_line_to(width, 0)
cr.move_to(x + xbearing, y - fascent)
cr.rel_line_to(width, 0)
cr.move_to(x + xbearing, y - fheight)
cr.rel_line_to(width, 0)
cr.stroke()
# extents: width & height
cr.set_source_rgba(0, 0, 0.75, 0.5)
cr.set_line_width(1 * px)
cr.set_dash([3 * px], 0)
cr.rectangle(x + xbearing, y + ybearing, width, height)
cr.stroke()
# text
cr.move_to(x, y)
cr.set_source_rgb(0, 0, 0)
cr.show_text(text)
# bearing
cr.set_dash([], 0)
cr.set_line_width(2 * px)
cr.set_source_rgba(0, 0, 0.75, 0.5)
cr.move_to(x, y)
cr.rel_line_to(xbearing, ybearing)
cr.stroke()
# text's advance
cr.set_source_rgba(0, 0, 0.75, 0.5)
cr.arc(x + xadvance, y + yadvance, 5 * px, 0, 2 * pi)
cr.fill()
# reference point
cr.arc(x, y, 5 * px, 0, 2 * pi)
cr.set_source_rgba(0.75, 0, 0, 0.5)
cr.fill()
if __name__ == '__main__':
size = 120
SetSourceRGBA('setsourcergba', size, size)
SetSourceGradient('setsourcegradient', size, size)
PathDiagramMoveTo('path-moveto', size, size)
PathDiagramLineTo('path-lineto', size, size)
PathDiagramArcTo('path-arcto', size, size)
PathDiagramCurveTo('path-curveto', size, size)
PathDiagramClose('path-close', size, size)
TextExtents('textextents', size, size)
