# -*- coding: utf-8 -*- # # libcaca Colour ASCII-Art library # Python language bindings # Copyright (c) 2010 Alex Foulon # All Rights Reserved # # This library is free software. It comes without any warranty, to # the extent permitted by applicable law. You can redistribute it # and/or modify it under the terms of the Do What The Fuck You Want # To Public License, Version 2, as published by Sam Hocevar. See # http://sam.zoy.org/wtfpl/COPYING for more details. # """ Libcaca Python bindings """ import ctypes from caca import _lib class _Canvas(object): """ Model for Canvas objects. """ def __init__(self): self._cv = 0 def from_param(self): """ Required by ctypes module to call object as parameter of a C function. """ return self._cv def __str__(self): return "" % (self.get_width(), self.get_height()) def __del__(self): if self._cv > 0: self._free() def _free(self): """ Free a libcaca canvas. """ _lib.caca_free_canvas.argtypes = [_Canvas] _lib.caca_free_canvas.restype = ctypes.c_int return _lib.caca_free_canvas(self) def get_width(self): raise CanvasError, "You can't use model canvas directly" def get_height(self): raise CanvasError, "You can't use model canvas directly" class Canvas(_Canvas): """ Canvas object, methods are libcaca functions with canvas_t as first parameter. """ def __init__(self, width=0, height=0): """ Canvas constructor. width -- the desired canvas width height -- the desired canvas height """ _lib.caca_create_canvas.argtypes = [ctypes.c_int, ctypes.c_int] self._cv = _lib.caca_create_canvas(width, height) if self._cv == 0: raise CanvasError, "Failed to create canvas" def set_size(self, width, height): """ Resize a canvas. width -- the desired canvas width height -- the desired canvas height """ _lib.caca_set_canvas_size.argtypes = [ _Canvas, ctypes.c_int, ctypes.c_int ] _lib.caca_set_canvas_size.restype = ctypes.c_int return _lib.caca_set_canvas_size(self, width, height) def get_width(self): """ Get the canvas width. """ _lib.caca_get_canvas_width.argtypes = [_Canvas] _lib.caca_get_canvas_width.restype = ctypes.c_int return _lib.caca_get_canvas_width(self) def get_height(self): """ Get the canvas height. """ _lib.caca_get_canvas_height.argtypes = [_Canvas] _lib.caca_get_canvas_height.restype = ctypes.c_int return _lib.caca_get_canvas_height(self) def get_chars(self): """ Get the canvas character array, return python list. """ chlist = [] #get canvas size w, h = self.get_width(), self.get_height() _lib.caca_get_canvas_chars.argtypes = [_Canvas] _lib.caca_get_canvas_chars.restype = \ ctypes.POINTER(ctypes.c_uint8 * (w * h)) plist = _lib.caca_get_canvas_chars(self) #build character list for item in plist.contents: if item != 0: chlist.append(chr(item)) return chlist def gotoxy(self, x, y): """ Set cursor position. x -- X cursor coordinate y -- Y cursor coordinate """ _lib.caca_gotoxy.argtypes = [_Canvas, ctypes.c_int] _lib.caca_gotoxy.restyoe = ctypes.c_int return _lib.caca_gotoxy(self, x, y) def wherex(self): """ Get X cursor position. """ _lib.caca_wherex.argtypes = [_Canvas] _lib.caca_wherex.restype = ctypes.c_int return _lib.caca_wherex(self) def wherey(self): """ Get Y cursor position. """ _lib.caca_wherey.argtypes = [_Canvas] _lib.caca_wherey.restype = ctypes.c_int return _lib.caca_wherey(self) def put_char(self, x, y, ch): """ Print an ASCII or Unicode character. x -- X coordinate y -- Y coordinate ch -- the character to print """ _lib.caca_put_char.argtypes = [ _Canvas, ctypes.c_int, ctypes.c_int, ctypes.c_uint32 ] _lib.caca_put_char.restype = ctypes.c_int return _lib.caca_put_char(self, x, y, ord(ch)) def get_char(self, x, y): """ Get the Unicode character at the given coordinates. x -- X coordinate y -- Y coordinate """ _lib.caca_get_char.argtypes = [ _Canvas, ctypes.c_int, ctypes.c_int ] _lib.caca_get_char.restype = ctypes.c_uint32 return _lib.caca_get_char(self, x, y) def put_str(self, x, y, s): """ Print a string. x -- X coordinate y -- Y coordinate s -- the string to print """ _lib.caca_put_str.argtypes = [ _Canvas, ctypes.c_int, ctypes.c_int, ctypes.c_char_p ] _lib.caca_put_str.restype = ctypes.c_int return _lib.caca_put_str(self, x, y, s) def printf(self, x, y, fmt, *args): """ Print a formated string. x -- X coordinate y -- Y coordinate fmt -- the format string to print args -- Arguments to the format string """ _lib.caca_printf.argtypes = [ _Canvas, ctypes.c_int, ctypes.c_int, ctypes.c_char_p ] _lib.caca_printf.restype = ctypes.c_int return _lib.caca_printf(self, x, y, fmt, *args) def clear(self): """ Clear the canvas. """ _lib.caca_clear_canvas.argtypes = [_Canvas] _lib.caca_clear_canvas.restype = ctypes.c_int return _lib.caca_clear_canvas(self) def set_handle(self, x, y): """ Set cursor handle. Blitting method will use the handle value to put the canvas at the proper coordinates. x -- X handle coordinate y -- Y handle coordinate """ _lib.caca_set_canvas_handle.argtypes = [ _Canvas, ctypes.c_int, ctypes.c_int ] _lib.caca_set_canvas_handle.restype = ctypes.c_int return _lib.caca_set_canvas_handle(self, x, y) def get_handle_x(self): """ Get X handle position. """ _lib.caca_get_canvas_handle_x.argtypes = [_Canvas] _lib.caca_get_canvas_handle_x.restype = ctypes.c_int return _lib.caca_get_canvas_handle_x(self) def get_handle_y(self): """ Get Y handle position. """ _lib.caca_get_canvas_handle_y.argtypes = [_Canvas] _lib.caca_get_canvas_handle_y.restype = ctypes.c_int return _lib.caca_get_canvas_handle_y(self) def blit(self, x, y, cv, mask): """ Blit canvas onto another one. x -- X coordinate y -- Y coordinate cv -- the source canvas mask -- the mask canvas """ _lib.caca_blit.argtypes = [ _Canvas, ctypes.c_int, ctypes.c_int, _Canvas, _Canvas ] _lib.caca_blit.restype = ctypes.c_int return _lib.caca_blit(self, x, y, cv, mask) def set_boundaries(self, x, y, width, height): """ Set a canvas' new boundaries. x -- X coordinate of the top-left corner y -- Y coordinate of the top-left corner width -- width of the box height -- height of the box """ _lib.caca_set_canvas_boundaries.argtypes = [ _Canvas, ctypes.c_int, ctypes.c_int, ctypes.c_int, ctypes.c_int ] _lib.caca_set_canvas_boundaries.restype = ctypes.c_int return _lib.caca_set_canvas_boundaries(self, x, y, width, height) def disable_dirty_rect(self): """ Disable dirty rectangles. """ _lib.caca_disable_dirty_rect.argtypes = [_Canvas] _lib.caca_disable_dirty_rect.restype = ctypes.c_int return _lib.caca_disable_dirty_rect(self) def enable_dirty_rect(self): """ Enable dirty rectangles. """ _lib.caca_enable_dirty_rect.argtypes = [_Canvas] _lib.caca_enable_dirty_rect.restype = ctypes.c_int return _lib.caca_enable_dirty_rect(self) def get_dirty_rect_count(self): """ Get the number of dirty rectangles in the canvas. """ _lib.caca_get_dirty_rect_count.argtypes = [_Canvas] _lib.caca_get_dirty_rect_count.restype = ctypes.c_int return _lib.caca_get_dirty_rect_count(self) def get_dirty_rect(self, idx): """ Get a canvas's dirty rectangle. idx -- the requested rectangle index """ x = ctypes.POINTER(ctypes.c_int) y = ctypes.POINTER(ctypes.c_int) w = ctypes.POINTER(ctypes.c_int) h = ctypes.POINTER(ctypes.c_int) _lib.caca_get_dirty_rect.argtypes = [ _Canvas, ctypes.c_int, ctypes.POINTER(ctypes.c_int), ctypes.POINTER(ctypes.c_int), ctypes.POINTER(ctypes.c_int), ctypes.POINTER(ctypes.c_int) ] _lib.caca_get_dirty_rect.restype = ctypes.c_int _lib.caca_get_dirty_rect(self, idx, x, y, w, h) return [x.contents.value, y.contents.value, w.contents.value, h.contents.value] def add_dirty_rect(self, x, y, width, height): """ Add an area to the canvas's dirty rectangle list. x -- the leftmost edge of the additional dirty rectangle y -- the topmost edge of the additional dirty rectangle width -- the width of the additional dirty rectangle height -- the height of the additional dirty rectangle """ _lib.caca_add_dirty_rect.argtypes = [ _Canvas, ctypes.c_int, ctypes.c_int, ctypes.c_int, ctypes.c_int ] _lib.caca_add_dirty_rect.restype = ctypes.c_int return _lib.caca_add_dirty_rect(self, x, y, width, height) def remove_dirty_rect(self, x, y, width, height): """ Remove an area from the dirty rectangle list. x -- the leftmost edge of the additional dirty rectangle y -- the topmost edge of the additional dirty rectangle width -- the width of the additional rectangle height -- the height of the additional dirty rectangle """ _lib.caca_remove_dirty_rect.argtypes = [ _Canvas, ctypes.c_int, ctypes.c_int, ctypes.c_int, ctypes.c_int ] _lib.caca_remove_dirty_rect.restype = ctypes.c_int return _lib.caca_remove_dirty_rect(self, x, y, height, width) def clear_dirty_rect_list(self): """ Clear a canvas's dirty rectangle list. """ _lib.caca_clear_dirty_rect_list.argtypes = [_Canvas] _lib.caca_clear_dirty_rect_list.restype = ctypes.c_int return _lib.caca_clear_dirty_rect_list(self) def invert(self): """ Invert a canvas' colours. """ _lib.caca_invert.argtypes = [_Canvas] _lib.caca_invert.restype = ctypes.c_int return _lib.caca_invert(self) def flip(self): """ Flip a canvas horizontally. """ _lib.caca_flip.argtypes = [_Canvas] _lib.caca_flip.restype = ctypes.c_int return _lib.caca_flip(self) def flop(self): """ Flip a canvas vertically. """ _lib.caca_flop.argtypes = [_Canvas] _lib.caca_flop.restype = ctypes.c_int return _lib.caca_flop(self) def rotate_180(self): """ Rotate a canvas. """ _lib.caca_rotate_180.argtypes = [_Canvas] _lib.caca_rotate_180.restype = ctypes.c_int return _lib.caca_rotate_180(self) def rotate_left(self): """ Rotate a canvas, 90 degrees counterclockwise. """ _lib.caca_rotate_left.argtypes = [_Canvas] _lib.caca_rotate_left.restype = ctypes.c_int return _lib.caca_rotate_left(self) def rotate_right(self): """ Rotate a canvas, 90 degrees clockwise. """ _lib.caca_rotate_right.argtypes = [_Canvas] _lib.caca_rotate_right.restype = ctypes.c_int return _lib.caca_rotate_right(self) def stretch_left(self): """ Rotate and stretch a canvas, 90 degrees counterclockwise. """ _lib.caca_stretch_left.argtypes = [_Canvas] _lib.caca_stretch_left.restype = ctypes.c_int return _lib.caca_stretch_left(self) def stretch_right(self): """ Rotate and stretch a canvas, 90 degrees clockwise. """ _lib.caca_stretch_right.argtypes = [_Canvas] _lib.caca_stretch_right.restype = ctypes.c_int return _lib.caca_stretch_right(self) def get_attr(self, x, y): """ Get the text attribute at the given coordinates. x -- X coordinate y -- Y coordinate """ _lib.caca_get_attr.argtypes = [_Canvas, ctypes.c_int, ctypes.c_int] _lib.caca_get_attr.restype = ctypes.c_uint32 return _lib.caca_get_attr(self, x, y) def set_attr(self, attr): """ Set the default character attribute. attr -- the requested attribute value """ _lib.caca_set_attr.argtypes = [_Canvas, ctypes.c_uint32] _lib.caca_set_attr.restype = ctypes.c_int return _lib.caca_set_attr(self, attr) def put_attr(self, x, y, attr): """ Set the character attribute at the given coordinates. x -- X coordinate y -- Y coordinate attr -- the requested attribute value """ _lib.caca_put_attr.argtypes = [ _Canvas, ctypes.c_int, ctypes.c_int, ctypes.c_uint32 ] _lib.caca_put_attr.restype = ctypes.c_int return _lib.caca_put_attr(self, x, y, attr) def set_color_ansi(self, fg, bg): """ Set the default colour pair for text (ANSI version). fg -- the requested ANSI foreground colour. bg -- the requested ANSI background colour. """ _lib.caca_set_color_ansi.argtypes = [_Canvas, ctypes.c_uint8, ctypes.c_uint8] _lib.caca_set_color_ansi.restype = ctypes.c_int return _lib.caca_set_color_ansi(self, fg, bg) def set_color_argb(self, fg, bg): """ Set the default colour pair for text (truecolor version). fg -- the requested ARGB foreground colour. bg -- the requested ARGB background colour. """ _lib.caca_set_color_argb.argtypes = [ _Canvas, ctypes.c_uint16, ctypes.c_uint16 ] _lib.caca_set_color_argb.restype = ctypes.c_int return _lib.caca_set_color_argb(self, fg, bg) def draw_line(self, x1, y1, x2, y2, ch): """ Draw a line on the canvas using the given character. x1 -- X coordinate of the first point y1 -- Y coordinate of the first point x2 -- X coordinate of the second point y2 -- Y coordinate of the second point ch -- character to be used to draw the line """ _lib.caca_draw_line.argtypes = [ _Canvas, ctypes.c_int, ctypes.c_int, ctypes.c_int, ctypes.c_int, ctypes.c_uint32 ] _lib.caca_draw_line.restype = ctypes.c_int return _lib.caca_draw_line(self, x1, y1, x2, y2, ord(ch)) def draw_polyline(self, array_x, array_y, n, ch): """ Draw a polyline. array_x -- Array of X coordinates, must have n+1 elements array-y -- Array of Y coordinates, must have n+1 elements n -- Number of lines to draw ch -- character to be used to draw the line """ _lib.caca_draw_polyline.argtypes = [ _Canvas, ctypes.c_int * n, ctypes.c_int * n, ctypes.c_int, ctypes.c_uint32 ] _lib.caca_draw_polyline.restype = ctypes.c_int return _lib.caca_draw_polyline(self, array_x, array_y, n, ord(ch)) def draw_thin_line(self, x1, y1, x2, y2): """ Draw a thin line on the canvas, using ASCII art. x1 -- X coordinate of the first point y1 -- Y coordinate of the first point x2 -- X coordinate of the second point y2 -- Y coordinate of the second point """ _lib.caca_draw_thin_line.argtypes = [ _Canvas, ctypes.c_int, ctypes.c_int, ctypes.c_int, ctypes.c_int ] _lib.caca_draw_thin_line.restype = ctypes.c_int return _lib.caca_draw_thin_line(self, x1, y1, x2, y2) def draw_thin_polyline(self, array_x, array_y, n): """ Draw an ASCII art thin polyline. array_x -- Array of X coordinates, must have n+1 elements array_y -- Array of Y coordinates, must have n+1 elements n -- Number of lines to draw """ _lib.caca_draw_thin_polyline.argtypes = [ Canvas, ctypes.c_int * n, ctypes.c_int * n, ctypes.c_int ] _lib.caca_draw_thin_polyline.restype = ctypes.c_int return _lib.caca_draw_thin_polyline(self, array_x, array_y, n) def draw_circle(self, x, y, r, ch): """ Draw a circle on the canvas using the given character. x -- center X coordinate y -- center Y coordinate r -- circle radius ch -- the UTF-32 character to be used to draw the circle outline """ _lib.caca_draw_circle.argtypes = [ _Canvas, ctypes.c_int, ctypes.c_int, ctypes.c_int, ctypes.c_uint32 ] _lib.caca_draw_circle.restype = ctypes.c_int return _lib.caca_draw_circle(self, x, y, r, ord(ch)) def draw_ellipse(self, xo, yo, a, b, ch): """ Draw an ellipse on the canvas using the given character. xo -- center X coordinate yo -- center Y coordinate a -- ellipse x radius b -- ellipse y radius ch -- UTF-32 character to be used to draw the ellipse outline """ _lib.caca_draw_ellipse.argtypes = [ _Canvas, ctypes.c_int, ctypes.c_int, ctypes.c_int, ctypes.c_int, ctypes.c_uint32 ] _lib.caca_draw_ellipse.restype = ctypes.c_int return _lib.caca_draw_ellipse(self, xo, yo, a, b, ord(ch)) def draw_thin_ellipse(self, xo, yo, a, b): """ Draw a thin ellipse on the canvas. xo -- center X coordinate yo -- center Y coordinate a -- ellipse X radius b -- ellipse Y radius """ _lib.caca_draw_thin_ellipse.argtypes = [ _Canvas, ctypes.c_int, ctypes.c_int, ctypes.c_int, ctypes.c_int ] _lib.caca_draw_thin_ellipse.restype = ctypes.c_int return _lib.caca_draw_thin_ellipse(self, xo, yo, a, b) def fill_ellipse(self, xo, yo, a, b, ch): """ Fill an ellipse on the canvas using the given character. xo -- center X coordinate yo -- center Y coordinate a -- ellipse X radius b -- ellipse Y radius ch -- UTF-32 character to be used to fill the ellipse """ _lib.caca_fill_ellipse.argtypes = [ _Canvas, ctypes.c_int, ctypes.c_int, ctypes.c_int, ctypes.c_int, ctypes.c_uint32 ] _lib.caca_fill_ellipse.restype = ctypes.c_int return _lib.caca_fill_ellipse(self, xo, yo, a, b, ord(ch)) def draw_box(self, x, y, width, height, ch): """ Draw a box on the canvas using the given character. x -- X coordinate of the upper-left corner of the box y -- Y coordinate of the upper-left corner of the box width -- width of the box height -- height of the box ch -- character to be used to draw the box """ _lib.caca_draw_box.argtypes = [ Canvas, ctypes.c_int, ctypes.c_int, ctypes.c_int, ctypes.c_int, ctypes.c_uint32 ] _lib.caca_draw_box.restype = ctypes.c_int return _lib.caca_draw_box(self, x, y, width, height, ord(ch)) def draw_thin_box(self, x, y, width, height): """ Draw a thin box on the canvas. x -- X coordinate of the upper-left corner of the box y -- Y coordinate of the upper-left corner of the box width -- width of the box height -- height of the box """ _lib.caca_draw_thin_box.argtypes = [ _Canvas, ctypes.c_int, ctypes.c_int, ctypes.c_int, ctypes.c_int ] _lib.caca_draw_thin_box.restype = ctypes.c_int return _lib.caca_draw_thin_box(self, x, y, width, height) def draw_cp437_box(self, x, y, width, height): """ Draw a box on the canvas using CP437 characters. x -- X coordinate of the upper-left corner box y -- Y coordinate of the upper-left corner box width -- width of the box height -- height of the box """ _lib.caca_draw_cp437_box.argtypes = [ _Canvas, ctypes.c_int, ctypes.c_int, ctypes.c_int, ctypes.c_int ] _lib.caca_draw_cp437_box.restype = ctypes.c_int return _lib.caca_draw_cp437_box(self, x, y, width, height) def fill_box(self, x, y, width, height, ch): """ Fill a box on the canvas using the given character. x -- X coordinate of the upper-left corner of the box y -- Y coordinate of the upper-left corner of the box width -- width of the box height -- height of the box ch -- UFT-32 character to be used to fill the box """ _lib.caca_fill_box.argtypes = [ _Canvas, ctypes.c_int, ctypes.c_int, ctypes.c_int, ctypes.c_int, ctypes.c_uint32 ] _lib.caca_fill_box.restype = ctypes.c_int return _lib.caca_fill_box(self, x, y, width, height, ord(ch)) def draw_triangle(self, x1, y1, x2, y2, x3, y3, ch): """ Draw a triangle on the canvas using the given character. x1 -- X coordinate of the first point y1 -- Y coordinate of the first point x2 -- X coordinate of the second point y2 -- Y coordinate of the second point x3 -- X coordinate of the third point y3 -- Y coordinate of the third point ch -- UTF-32 character to be used to draw the triangle outline """ _lib.caca_draw_triangle.argtypes = [ _Canvas, ctypes.c_int, ctypes.c_int, ctypes.c_int, ctypes.c_int, ctypes.c_int, ctypes.c_int, ctypes.c_uint32 ] _lib.caca_draw_triangle.restype = ctypes.c_int return _lib.caca_draw_triangle(self, x1, y1, x2, y2, x3, y3, ord(ch)) def draw_thin_triangle(self, x1, y1, x2, y2, x3, y3): """ Draw a thin triangle on the canvas. """ _lib.caca_draw_thin_triangle.argtypes = [ _Canvas, ctypes.c_int, ctypes.c_int, ctypes.c_int, ctypes.c_int, ctypes.c_int, ctypes.c_int ] _lib.caca_draw_thin_triangle.restype = ctypes.c_int return _lib.caca_draw_thin_triangle(self, x1, y1, x2, y2, x3, y3) def fill_triangle(self, x1, y1, x2, y2, x3, y3, ch): """ Fill a triangle on the canvas using the given character. x1 -- X coordinate of the first point y1 -- Y coordinate of the first point x2 -- X coordinate of the second point y2 -- Y coordinate of the second point x3 -- X coordinate of the second point y3 -- Y coordinate of the second point ch -- UTF-32 character to be used to fill the triangle """ _lib.caca_fill_triangle.argtypes = [ _Canvas, ctypes.c_int, ctypes.c_int, ctypes.c_int, ctypes.c_int, ctypes.c_int, ctypes.c_int ] _lib.caca_fill_triangle.restype = ctypes.c_int return _lib.caca_fill_triangle(self, x1, y1, x2, y2, x3, y3, ord(ch)) def fill_triangle_textured(self, coords, tex, uv): """ Fill a triangle on the canvas using an arbitrary-sized texture. coords -- coordinates of the triangle (3{x,y}) tex -- the handle of the canvas texture uv -- coordinates of the texture (3{u,v}) """ _lib.caca_fill_triangle_textured.argtypes = [ _Canvas, ctypes.c_int * 6, _Canvas, ctypes.c_int * 6 ] _lib.caca_fill_triangle_textured.restype = ctypes.c_int return _lib.caca_fill_triangle_textured(self, coords, tex, uv) def get_frame_count(self): """ Get the number of frames in a canvas. """ _lib.caca_get_frame_count.argtypes = [_Canvas] _lib.caca_get_frame_count.restype = ctypes.c_int return _lib.caca_get_frame_count(self) def set_frame(self, idx): """ Activate a given canvas frame. idx -- the canvas frame to activate """ _lib.caca_set_frame.argtypes = [_Canvas, ctypes.c_int] _lib.caca_set_frame.restype = ctypes.c_int return _lib.caca_set_frame(self, idx) def get_frame_name(self): """ Get the current frame's name. """ _lib.caca_get_frame_name.argtypes = [_Canvas] _lib.caca_get_frame_name.restype = ctypes.c_char_p return _lib.caca_get_frame_name(self) def set_frame_name(self, name): """ Set the current frame's name. name -- the name to give to the current frame """ _lib.caca_set_frame_name.argtypes = [_Canvas, ctypes.c_char_p] _lib.caca_set_frame_name.restype = ctypes.c_int return _lib.caca_set_frame_name(self, name) def create_frame(self, idx): """ Add a frame to a canvas. idx -- the index where to insert the new frame """ _lib.caca_create_frame.argtypes = [_Canvas, ctypes.c_int] _lib.caca_create_frame.restype = ctypes.c_int return _lib.caca_create_frame(self, idx) def free_frame(self, idx): """ Remove a frame from a canvas. idx -- the index of the frame to delete """ _lib.caca_free_frame.argtypes = [_Canvas, ctypes.c_int] _lib.caca_free_frame.restype = ctypes.c_int return _lib.caca_free_frame(self, idx) def import_from_memory(self, data, length, fmt): """ Import a memory buffer into the given libcaca canvas's current frame. The current frame is resized accordingly and its contents are replaced with the imported data. data -- a memory area containing the data to be loaded into the canvas length -- the size in bytes of the memory area fmt -- a string describing the input format """ _lib.caca_import_canvas_from_memory.argtypes = [ Canvas, ctypes.c_char_p, ctypes.c_int, ctypes.c_char_p ] _lib.caca_import_canvas_from_memory.restype = ctypes.c_int return _lib.caca_import_canvas_from_memory(self, data, length, fmt) class NullCanvas(_Canvas): """ Represent a NULL canvas_t, eg to use as canvas mask for blit operations. """ def __str__(self): return "" class CanvasError(Exception): pass