"""
Display Hooks for pycairo, cairocffi Surfaces and Contexts.
"""
from io import BytesIO
from IPython.core import display

def display_cairo_surface(surface):
    """Displayhook function for Surfaces Images, rendered as PNG."""
    b = BytesIO()

    surface.write_to_png(b)
    b.seek(0)
    data = b.read()

    ip_img = display.Image(data=data, format='png', embed=True)
    return ip_img._repr_png_()


def display_cairo_context(ctx):
    """Displayhook function for cairo Context Images, target is rendered as PNG."""
    surface = ctx.get_target()
    return display_cairo_surface(surface)



# register display func with PNG formatter:
png_formatter = get_ipython().display_formatter.formatters['image/png']
try:
    import cairo
    dpi = png_formatter.for_type(cairo.Surface, display_cairo_surface)
    dpi = png_formatter.for_type(cairo.Context, display_cairo_context)
except ImportError:
    pass

try:
    import cairocffi
    dpi = png_formatter.for_type(cairocffi.Surface, display_cairo_surface)
    dpi = png_formatter.for_type(cairocffi.Context, display_cairo_context)
except ImportError:
    pass


# Example cairo code.
import cairo

width, height = 100, 50


surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, width, height)

cr = cairo.Context(surface)
cr.set_source_rgb(0.7, 0.9, 0.0)
cr.rotate(-45)
cr.rectangle(0, 0, 40, 40)
cr.fill()

# The context will output in the cell
cr

# as wil surfaces
surface