#!/usr/bin/env python3

import math

import cairo

import gi
gi.require_version('Pango', '1.0')
gi.require_version('PangoCairo', '1.0')
from gi.repository import Pango, PangoCairo

surface = cairo.SVGSurface('test.svg', 480, 480)
ctx = cairo.Context(surface)
ctx.set_source_rgb(1, 1, 1)
ctx.rectangle(0, 0, 480, 480)
ctx.fill()

layout = PangoCairo.create_layout(ctx)
# Size is relative to surface units.  An ImageSurface will get nominally
# 45 pixel tall text.  An SVGSurface will get 45 point text.
#
# The comma is necessary because otherwise Pango will think you mean the
# Roman variation of a font named "Times New".
#
# Linux users without Microsoft fonts installed might want to use
# Liberation Serif instead of Times New Roman.
font_description = Pango.font_description_from_string('Times New Roman, 45')
layout.set_font_description(font_description)

# Set the origin a little ways into the canvas to give some margin
ctx.translate(16, 16)
# Needed whenever the Cairo context's transformation (or target surface) changes.
PangoCairo.update_layout(ctx, layout)

# Make a function to draw text and the bounds around the text, so we can
# do this a few times in a row.  The function will assume that the context
# has been translated so the text will be placed at the current origin.
# The function returns the text's logical bounds so we can place
# additional text without overlapping anything.
def draw_text_and_bounds(ctx, layout, text):
    """Returns the text's logical rectangle."""
    layout.set_text(text)

    # The ink_rect gives the bounds of the glyphs in aggregate.  The
    # logical_rect covers the total area of the font; basically the full line.
    #
    # As with all Pango measurements, these are scaled integers.  You need to
    # divide them by Pango.SCALE to get Cairo units.
    ink_rect, logical_rect = layout.get_extents()
    baseline = layout.get_baseline()

    ctx.set_line_width(2)

    # Baseline in orange.  Offset to account for stroke thickness.
    ctx.set_source_rgb(1, 0.5, 0.25)
    ctx.move_to(-8, baseline / Pango.SCALE + 1)
    ctx.line_to((logical_rect.x + logical_rect.width) / Pango.SCALE + 8,
                baseline / Pango.SCALE + 1)
    ctx.stroke()
    
    # logical rect in red
    ctx.set_source_rgb(0.75, 0, 0)
    ctx.rectangle(logical_rect.x / Pango.SCALE - 1,
                  logical_rect.y / Pango.SCALE - 1,
                  logical_rect.width / Pango.SCALE + 2,
                  logical_rect.height / Pango.SCALE + 2)
    ctx.stroke()

    # ink rect in blue
    ctx.set_source_rgb(0, 0, 0.75)
    ctx.rectangle(ink_rect.x / Pango.SCALE - 1,
                  ink_rect.y / Pango.SCALE - 1,
                  ink_rect.width / Pango.SCALE + 2,
                  ink_rect.height / Pango.SCALE + 2)
    ctx.stroke()

    # Origin in dark blue
    ctx.set_source_rgb(0, 0, 0.5)
    ctx.arc(0, 0, 2 * math.sqrt(2), 0, 2 * math.pi)
    ctx.fill()

    # Output the text
    ctx.set_source_rgb(0, 0, 0)
    # Since the origin was changed via translation, the text just goes in
    # at (0, 0).
    ctx.move_to(0, 0)
    PangoCairo.show_layout(ctx, layout)

    return logical_rect
    
logical_rect = draw_text_and_bounds(ctx, layout, 'Aa Ee Rr  ')

ctx.translate(0, 16 + logical_rect.height / Pango.SCALE)
PangoCairo.update_layout(ctx, layout)

font_description = Pango.font_description_from_string('Times New Roman, Italic 45')
layout.set_font_description(font_description)

# Note that the ink rectangle for this text actually has a negative x
# value (with Times New Roman as the font).  Logically, the text starts at
# the origin, but the serif on the "B" sticks out a little to the left.
logical_rect = draw_text_and_bounds(ctx, layout, 'Bb Gg Jj')

ctx.translate(0, 16 + logical_rect.height / Pango.SCALE)
PangoCairo.update_layout(ctx, layout)

# Alternate way of accessing fonts.
font_map = PangoCairo.font_map_get_default()
font_family = font_map.get_family('Times New Roman')
if font_family is None:
    print('No font found.  Fonts on the system:')
    for family in font_map.list_families():
        print(family.get_name())
    exit(1)
font_face = font_family.get_face('Italic')
if font_face is None:
    print('No face found.  "{}" faces on the system:'.format(font_family.get_name()))
    for face in font_family.list_faces():
        print(face.get_face_name())
    exit(1)
font_description = font_face.describe()
font_description.set_size(45 * Pango.SCALE)
layout.set_font_description(font_description)

logical_rect = draw_text_and_bounds(ctx, layout, 'אָלֶף־בֵּית עִבְרִי')

surface.finish()
surface.flush()