Ticket #4030: cairo_rotate_example.py

#!/usr/bin/python

from __future__ import division
import gtk
import cairo
import math

IDENTITY = 0
ROTATE_90 = 1
SCALE = 2
ROTATE = 3

TRANSFORMS = [
    IDENTITY,
    ROTATE_90,
    SCALE,
    ROTATE
]

SOURCE_ALPHAS = [ False, True ]

FILTERS = [ cairo.FILTER_NEAREST, cairo.FILTER_BILINEAR ]

SOURCE_SIZE = 16
DEST_SIZE = 100
PAD = 10

TOTAL_SIZE = 4 * (DEST_SIZE + PAD) + PAD

transform = None
source_alpha = None
source_filter = None

def draw_sample(cr, x, y, transform, filter, source_alpha):
    cr.save()
    cr.translate(x, y)
    cr.rectangle(0, 0, DEST_SIZE, DEST_SIZE)
    cr.clip()

    if source_alpha:
        source = cairo.ImageSurface(cairo.FORMAT_ARGB32, SOURCE_SIZE, SOURCE_SIZE)
    else:
        source = cairo.ImageSurface(cairo.FORMAT_RGB24, SOURCE_SIZE, SOURCE_SIZE)
        
    source_cr = cairo.Context(source)
    source_cr.set_source_rgba(0, 0, 1)
    source_cr.paint()

    hole_x = hole_y = SOURCE_SIZE // 4
    hole_width = hole_height = SOURCE_SIZE // 2

    # Add some rectangles on the source image at the corners
    source_cr.rectangle(0, 0, hole_x, hole_y)
    source_cr.rectangle(hole_x + hole_width, 0, SOURCE_SIZE - (hole_x + hole_width), hole_y)
    source_cr.rectangle(0, hole_y + hole_height, hole_x, SOURCE_SIZE - (hole_y + hole_height))
    source_cr.rectangle(hole_x + hole_width, hole_y + hole_height, SOURCE_SIZE - (hole_x + hole_width), SOURCE_SIZE - (hole_y + hole_height))
    source_cr.set_source_rgba(0, 1, 0)
    source_cr.fill()
    
    if source_alpha:
        # Cut a whole out of the middle
        source_cr.set_operator(cairo.OPERATOR_DEST_OUT)
        source_cr.rectangle(hole_x, hole_y, hole_width, hole_height)
        source_cr.set_source_rgba(1, 1, 1)
        source_cr.fill()

    cr.translate(DEST_SIZE // 2, DEST_SIZE // 2)

    if transform == IDENTITY:
        pass
    elif transform == ROTATE_90:
        cr.rotate(math.pi / 2)
    elif transform == SCALE:
        cr.scale(11/3, 11/3)
    elif transform == ROTATE:
        cr.rotate(math.pi / 3)
        cr.scale(11/3, 11/3)

    cr.translate(- SOURCE_SIZE // 2, - SOURCE_SIZE // 2)
    
#     # Draw a shape in red under the bounds of the surface

#     cr.move_to(0, 0)
#     cr.line_to(SOURCE_SIZE, 0)
#     cr.line_to(SOURCE_SIZE, SOURCE_SIZE)
#     cr.line_to(0, SOURCE_SIZE)
#     cr.close_path()

#     if source_alpha:
#         # Cut the hole out of the shape
#         cr.move_to(hole_x, hole_y)
#         cr.line_to(hole_x, hole_y +  hole_height)
#         cr.line_to(hole_x + hole_height, hole_y + hole_height)
#         cr.line_to(hole_x + hole_height, hole_y)
#         cr.close_path()
        
#     cr.set_source_rgba(1, 0, 0)
#     cr.fill()

    # Draw the transformed surface

    cr.set_source_surface(source)
    cr.get_source().set_filter(filter)
#    cr.set_operator(cairo.OPERATOR_SOURCE)
    cr.paint()

    cr.restore()
        
def draw(cr):
    cr.set_source_rgba(1, 1, 1)
    cr.paint()

    y = PAD
    for source_alpha in SOURCE_ALPHAS:
        for filter in FILTERS:
            x = PAD
            for transform in TRANSFORMS:
                draw_sample(cr, x, y, transform, filter, source_alpha)
                x += DEST_SIZE + PAD
            y += DEST_SIZE + PAD
    
def on_expose(widget, event):
    cr = widget.window.cairo_create()
    draw(cr)

def dump_image():
    width, height = w.size_request()
    surface = cairo.ImageSurface(cairo.FORMAT_RGB24, width, height)
    cr = cairo.Context(surface)
    draw(cr)
    surface.write_to_png("/tmp/test-repeat-none-image.png")

def dump_pixmap():
    cmap = gtk.gdk.screen_get_default().get_rgb_colormap()
    out = gtk.gdk.Pixmap(None, TOTAL_SIZE, TOTAL_SIZE, cmap.get_visual().depth)
    out.set_colormap(cmap)
    cr = out.cairo_create()
    draw(cr)
    cr.get_target().write_to_png("/tmp/test-repeat-none-pixmap.png")
    
def reset():
    w.set_size_request(TOTAL_SIZE, TOTAL_SIZE)
    w.queue_draw()
    
def on_key_press(widget, event):
    if event.keyval in (gtk.keysyms.d, gtk.keysyms.D):
        dump_image()
        return True
    if event.keyval in (gtk.keysyms.p, gtk.keysyms.P):
        dump_pixmap()
        return True
    elif event.keyval in (gtk.keysyms.r, gtk.keysyms.R):
        reset()
        return True
    elif event.keyval in (gtk.keysyms.q, gtk.keysyms.Q):
        gtk.main_quit()
        return True
    elif event.keyval in (gtk.keysyms.Escape,):
        transform = None
        source_alpha = None
        filter = None
        reset()
        return True

    return False

w = gtk.Window()
w.set_app_paintable(True)
w.set_resizable(False)

reset()

w.connect('expose-event', on_expose)
w.connect('key-press-event', on_key_press)

w.show()
gtk.main()