#cython: profile=False
# Copyright 2004-2012 Tom Rothamel <pytom@bishoujo.us>
#
# Permission is hereby granted, free of charge, to any person
# obtaining a copy of this software and associated documentation files
# (the "Software"), to deal in the Software without restriction,
# including without limitation the rights to use, copy, modify, merge,
# publish, distribute, sublicense, and/or sell copies of the Software,
# and to permit persons to whom the Software is furnished to do so,
# subject to the following conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

import collections
import pygame
import threading
import renpy
import gc

# We grab the blit lock each time it is necessary to blit
# something. This allows call to the pygame.transform functions to
# disable blitting, should it prove necessary.
blit_lock = threading.Condition()

# This is a dictionary containing all the renders that we know of. It's a
# map from displayable to dictionaries containing the render of that
# displayable.
render_cache = collections.defaultdict(dict)

# The queue of redraws. A list of (time, displayable) pairs.
redraw_queue = [ ]

# The render returned from render_screen.
screen_render = None

# A list of renders the system knows about, and thinks are still alive.
cdef list live_renders
live_renders = [ ]

# A copy of renpy.display.interface.frame_time, for speed reasons.
cdef double frame_time
frame_time = 0

def free_memory():
    """
    Frees memory used by the render system.
    """

    global screen_render    
    screen_render = None

    mark_sweep()

    render_cache.clear()

    # This can hang onto a render.
    renpy.display.interface.surftree = None
    

def check_at_shutdown():
    """
    This is called at shutdown time to check that everything went okay.
    The big thing it checks for is memory leaks.
    """

    if not renpy.config.developer:
        return

    free_memory()

    gc.collect()    
    l = gc.get_objects()

    count = 0
    objects = gc.get_objects()
    
    for i in objects:
        if isinstance(i, Render):
            count += 1

    if count:
        raise Exception("%d Renders are alive at shutdown. This is probably a memory leak bug in Ren'Py." % count)

    
    
cpdef render(d, object widtho, object heighto, double st, double at):
    """
    :doc: udd_utility
    :args: (d, width, height, st, at)
    
    Causes a displayable to be rendered, and a renpy.Render object to
    be returned.
    
    `d`
        The displayable to render.
        
    `width`, `height`
        The width and height available for the displayable to render into. 
        
    `st`, `at`
        The shown and animation timebases.

    Renders returned by this object may be cached, and should not be modified
    once they have been retrieved.
    """

    cdef float width, height
    cdef float orig_width, orig_height
    cdef tuple orig_wh, wh
    cdef dict render_cache_d
    cdef Render rv
    
    orig_wh = (widtho, heighto, frame_time-st, frame_time-at)

    render_cache_d = render_cache[d]
    rv = render_cache_d.get(orig_wh, None)

    if rv is not None:
        return rv

    orig_width = width = widtho
    orig_height = height = heighto
    
    style = d.style
    xmaximum = style.xmaximum
    ymaximum = style.ymaximum
    
    if xmaximum is not None:
        if isinstance(xmaximum, float):
            width = width * xmaximum
        else:
            width = min(xmaximum, width)

    if ymaximum is not None:
        if isinstance(ymaximum, float):
            height = height * ymaximum
        else:
            height = min(ymaximum, height)

    if width < 0:
        width = 0
    if height < 0:
        height = 0

    if orig_width != width or orig_height != height:        
        widtho = width
        heighto = height
        wh = (widtho, heighto, frame_time-st, frame_time-at)
        rv = render_cache_d.get(wh, None)

        if rv is not None:
            return rv

    else:
        wh = orig_wh
            
    rv = d.render(widtho, heighto, st, at)

    rv.render_of.append(d)

    if style.clipping:
        rv = rv.subsurface((0, 0, rv.width, rv.height), focus=True)
        rv.render_of.append(d)

    render_cache_d[wh] = rv

    if wh is not orig_wh:
        render_cache_d[orig_wh] = rv

    return rv


# This is true if something has been invalidated, and a redraw needs
# to occur. It's automatically cleared to False at the end of each
# redraw.
invalidated = False

def invalidate(d):
    """
    Removes d from the render cache. If we're not in a redraw, triggers
    a redraw to start.
    """

    global invalidated
    
    if d in render_cache:
        for v in render_cache[d].values():
            v.kill_cache()

        invalidated = True

        
def process_redraws():
    """
    Called to determine if any redraws are pending. Returns true if we
    need to redraw the screen now, false otherwise.
    """

    global redraw_queue
    
    redraw_queue.sort()

    now = renpy.display.core.get_time()
    rv = invalidated

    new_redraw_queue = [ ]
    seen = set()

    for t in redraw_queue:
        when, d = t

        if d in seen:
            continue

        seen.add(d)

        if d not in render_cache:
            continue
        
        if when <= now:
            # Remove this displayable and all its parents from the
            # render cache. But don't kill them yet, as that will kill the
            # children that we want to reuse.

            for v in render_cache[d].values():
                v.kill_cache()

            rv = True

        else:
            new_redraw_queue.append(t)

        redraw_queue = new_redraw_queue

        
    return rv


def redraw_time():
    """
    Returns the time at which the next redraw is scheduled.
    """

    if redraw_queue:
        return redraw_queue[0][0]

    return None
    

def redraw(d, when):
    """
    :doc: udd_utility
    
    Causes the displayable `d` to be redrawn after `when` seconds have
    elapsed.
    """

    if not renpy.game.interface:
        return

    redraw_queue.append((when + renpy.game.interface.frame_time, d))
    

cdef class Matrix2D:
    """
    This represents a 2d matrix that can be used to transform
    points and things like that.
    """

    def __getstate__(self):
        return dict(
            xdx = self.xdx,
            xdy = self.xdy,
            ydx = self.ydx,
            ydy = self.ydy)

    def __setstate__(self, state):
        self.xdx = state['xdx']
        self.xdy = state['xdy']
        self.ydx = state['ydx']
        self.ydy = state['ydy']
        
    def __init__(Matrix2D self, double xdx, double xdy, double ydx, double ydy):
        self.xdx = xdx
        self.xdy = xdy
        self.ydx = ydx
        self.ydy = ydy

    cpdef tuple transform(Matrix2D self, double x, double y):
        return (x * self.xdx + y * self.xdy), (x * self.ydx + y * self.ydy)

    def __mul__(Matrix2D self, Matrix2D other):
        return Matrix2D(
            other.xdx * self.xdx + other.xdy * self.ydx,
            other.xdx * self.xdy + other.xdy * self.ydy,
            other.ydx * self.xdx + other.ydy * self.ydx,
            other.ydx * self.xdy + other.ydy * self.ydy)

    def __repr__(self):
        return "Matrix2D(xdx=%f, xdy=%f, ydx=%f, ydy=%f)" % (self.xdx, self.xdy, self.ydx, self.ydy)
    
IDENTITY = Matrix2D(1, 0, 0, 1)

def take_focuses(focuses):
    """
    Adds a list of rectangular focus regions to the focuses list.
    """

    screen_render.take_focuses(
        0, 0, screen_render.width, screen_render.height,
        IDENTITY, 0, 0, focuses)

# The result of focus_at_point for a modal render. This overrides any
# specific focus from below us.
Modal = object()
    
def focus_at_point(x, y):
    """
    Returns a focus object corresponding to the uppermost displayable
    at point, or None if nothing focusable is at point.
    """

    if screen_render is None:
        return None
    
    cf = screen_render.focus_at_point(x, y)
    if cf is None or cf is Modal:
        return None
    else:
        d, arg = cf
        return renpy.display.focus.Focus(d, arg, None, None, None, None)

    
def mutated_surface(surf):
    """
    Called to indicate that the given surface has changed. 
    """

    renpy.display.draw.mutated_surface(surf)


def render_screen(root, width, height):
    """
    Renders `root` (a displayable) as the root of a screen with the given
    `width` and `height`.
    """


    
    global old_screen_render
    global screen_render
    global invalidated
    global frame_time

    frame_time = renpy.display.interface.frame_time
    
    rv = render(root, width, height, 0, 0)
    screen_render = rv
    
    invalidated = False

    rv.is_opaque()
    
    return rv

def mark_sweep():
    """
    This performs mark-and-sweep garbage collection on the live_renders
    list.
    """

    global live_renders

    cdef list worklist
    cdef int i
    cdef Render r, j
    
    worklist = [ ]

    if screen_render is not None:
        worklist.append(screen_render)

    i = 0

    while i < len(worklist):
        r = worklist[i]

        for j in r.depends_on_list:
            if not j.mark:
                j.mark = True
                worklist.append(j)

        i += 1

    for r in live_renders:
        if not r.mark:
            r.kill_cache()
        else:
            r.mark = False

    live_renders = worklist

def compute_subline(sx0, sw, cx0, cw):
    """
    Given a source line (start sx0, width sw) and a crop line (cx0, cw),
    return three things:

    * The offset of the portion of the source line that overlaps with
      the crop line, relative to the crop line.
    * The offset of the portion of the source line that overlaps with the
      the crop line, relative to the source line.
    * The length of the overlap in pixels. (can be <= 0) 
    """

    sx1 = sx0 + sw
    cx1 = cx0 + cw

    if sx0 > cx0:
        start = sx0
    else:
        start = cx0

    offset = start - cx0
    crop = start - sx0

    if sx1 < cx1:
        width = sx1 - start
    else:
        width = cx1 - start

        
    return offset, crop, width

    


# Possible operations that can be done as part of a render.
BLIT = 0
DISSOLVE = 1
IMAGEDISSOLVE = 2
PIXELLATE = 3

cdef class Render:

    def __init__(Render self, float width, float height, draw_func=None, layer_name=None, bint opaque=None): #@DuplicatedSignature
        """
        Creates a new render corresponding to the given widget with
        the specified width and height.

        If `layer_name` is given, then this render corresponds to a
        layer.
        """

        # The mark bit, used for mark/sweep-style garbage collection of
        # renders.
        self.mark = False

        # Is has this render been removed from the cache?
        self.cache_killed = False
        
        
        self.width = width
        self.height = height

        self.layer_name = layer_name

        # A list of (surface/render, xoffset, yoffset, focus, main) tuples, ordered from
        # back to front.
        self.children = [ ]

        # The set of renders that either have us as children, or depend on
        # us.
        self.parents = set()

        # The renders we depend on, including our children.
        self.depends_on_list = [ ]
        
        # The operation we're performing. (BLIT, DISSOLVE, OR IMAGE_DISSOLVE)
        self.operation = BLIT

        # The fraction of the operation that is complete.
        self.operation_complete = 0.0

        # Should the dissolve operations preserve alpha?
        self.operation_alpha = False
        
        # The parameter to the operation. 
        self.operation_parameter = 0
        
        # Forward is used to transform from screen coordinates to child
        # coordinates.
        # Reverse is used to transform from child coordinates to screen
        # coordinates.
        # 
        # For performance reasons, these aren't used to transform the
        # x and y offsets found in self.children. Those offsets should
        # be of the (0, 0) point in the child coordinate space.
        self.forward = None
        self.reverse = None

        # This is used to adjust the alpha of children of this render.
        self.alpha = 1
        
        # A list of focus regions in this displayable.
        self.focuses = None

        # Other renders that we should pass focus onto.
        self.pass_focuses = None
        
        # The displayable(s) that this is a render of. (Set by render)
        self.render_of = [ ]

        # If set, this is a function that's called to draw this render
        # instead of the default.
        self.draw_func = draw_func

        # Is this displayable opaque? (May be set on init, or later on
        # if we have opaque children.) This may be True, False, or None
        # to indicate we don't know yet.
        self.opaque = opaque

        # A list of our visible children. (That is, children above and
        # including our uppermost opaque child.) If nothing is opaque,
        # includes all children.
        self.visible_children = self.children
        
        # Should children be clipped to a rectangle?
        self.clipping = False

        # Caches of the texture created by rendering this surface.
        self.surface = None
        self.alpha_surface = None

        # Cache of the texture created by rendering this surface at half size.
        # (This is set in gldraw.)
        self.half_cache = None

        # Are we modal?
        self.modal = False
        
        live_renders.append(self)
        
    def __repr__(self): #@DuplicatedSignature
        return "<Render %x of %r>" % (id(self), self.render_of)

    def __getstate__(self): #@DuplicatedSignature
        if renpy.config.developer:
            raise Exception("Can't pickle a Render.")
        else:
            return { }
        
    def __setstate__(self, state): #@DuplicatedSignature
        return

    cpdef int blit(Render self, source, tuple pos, object focus=True, object main=True, object index=None):
        """
        Blits `source` (a Render or Surface) to this Render, offset by
        xo and yo.

        If `focus` is true, then focuses are added from the child to the
        parent.

        This will only blit on integer pixel boundaries.
        """

        (xo, yo) = pos
        
        if source is self:
            raise Exception("Blitting to self.")
        
        xo = int(xo)
        yo = int(yo)

        if index is None:
            self.children.append((source, xo, yo, focus, main))
        else:
            self.children.insert(index, (source, xo, yo, focus, main))
                    
        if isinstance(source, Render):
            self.depends_on_list.append(source)
            source.parents.add(self)

        return 0
        
    cpdef int subpixel_blit(Render self, source, tuple pos, object focus=True, object main=True, object index=None):
        """
        Blits `source` (a Render or Surface) to this Render, offset by
        xo and yo.

        If `focus` is true, then focuses are added from the child to the
        parent.

        This blits at fractional pixel boundaries.
        """

        (xo, yo) = pos
        
        xo = float(xo)
        yo = float(yo)
        
        if index is None:
            self.children.append((source, xo, yo, focus, main))
        else:
            self.children.insert(index, (source, xo, yo, focus, main))
                        
        if isinstance(source, Render):
            self.depends_on_list.append(source)
            source.parents.add(self)

        return 0
            
    def get_size(self):
        """
        Returns the size of this Render, a mostly ficticious value
        that's taken from the inputs to the constructor. (As in, we
        don't clip to this size.)
        """

        return self.width, self.height

    
    def render_to_texture(self, alpha=True):
        """
        Returns a texture constructed from this render. This may return
        a cached textue, if one has already been rendered.

        `alpha` is a hint that controls if the surface should have
        alpha or not.
        """        

        if alpha:
            if self.alpha_surface is not None:
                return self.alpha_surface
        else:
            if self.surface is not None:
                return self.surface
            
        rv = None

        opaque = self.is_opaque()

        # If we can, reuse a child's texture.
        if opaque or alpha:

            if not self.forward and len(self.children) == 1:
                child, x, y, focus, main = self.children[0]
                cw, ch = child.get_size()
                if x <= 0 and y <= 0 and cw + x >= self.width and ch + y >= self.height:
                    # Our single child overlaps us.
                    if isinstance(child, Render):
                        child = child.render_to_texture(alpha)

                    if x != 0 or y != 0 or cw != self.width or ch != self.height:
                        rv = child.subsurface((-x, -y, self.width, self.height))
                    else:
                        rv = child

        # Otherwise, render to a texture.
        if rv is None:
            # is_opaque has already been called.
            rv = renpy.display.draw.render_to_texture(self, alpha)
            
        # Stash and return the surface.
        if alpha:
            self.alpha_surface = rv
        else:
            self.surface = rv
            
        return rv
    
    pygame_surface = render_to_texture
    
    def subsurface(self, rect, focus=False):
        """
        Returns a subsurface of this render. If `focus` is true, then
        the focuses are copied from this render to the child.
        """

        (x, y, w, h) = rect
        rv = Render(w, h)

        reverse = self.reverse
        
        # This doesn't actually make a subsurface, as we can't easily do
        # so for non-rectangle-aligned renders.
        if (reverse is not None) and (
            reverse.xdx != 1.0 or
            reverse.xdy != 0.0 or
            reverse.ydx != 0.0 or
            reverse.ydy != 1.0):

            rv.clipping = True
            rv.blit(self, (-x, -y), focus=focus, main=True)            
            return rv

        # This is the path that executes for rectangle-aligned surfaces,
        # making an actual subsurface.

        for child, cx, cy, cfocus, cmain in self.children:

            cw, ch = child.get_size()            
            xo, cx, cw = compute_subline(cx, cw, x, w)
            yo, cy, ch = compute_subline(cy, ch, y, h)
            
            if cw <= 0 or ch <= 0:
                continue

            crop = (cx, cy, cw, ch)
            offset = (xo, yo)

            if isinstance(child, Render):
                newchild = child.subsurface(crop, focus=focus)
                newchild.render_of = child.render_of[:]
            else:
                newchild = child.subsurface(crop)
                renpy.display.draw.mutated_surface(newchild)
                
            rv.blit(newchild, offset, focus=cfocus, main=cmain)

        if focus and self.focuses:

            for (d, arg, xo, yo, fw, fh, mx, my, mask) in self.focuses:

                if xo is None:
                    rv.add_focus(d, arg, xo, yo, fw, fh, mx, my, mask)
                    continue

                xo, cx, fw = compute_subline(xo, fw, x, w)
                yo, cy, fh = compute_subline(yo, fh, y, h)

                if cw <= 0 or ch <= 0:
                    continue
                
                if mx is not None:

                    mw, mh = mask.get_size()

                    mx, mcx, mw = compute_subline(mx, mw, x, w) 
                    my, mcy, mh = compute_subline(my, mh, y, h)
                    
                    if mw <= 0 or mh <= 0:
                        mx = None
                        my = None
                        mask = None
                    else:
                        mask = mask.subsurface((mcx, mcy, mw, mh))

                rv.add_focus(d, arg, xo, yo, fw, fh, mx, my, mask)

        rv.depends_on(self)
        rv.alpha = self.alpha
        rv.operation = self.operation
        rv.operation_alpha = self.operation_alpha
        rv.operation_complete = self.operation_complete
        
        return rv
    
        
    def depends_on(self, source, focus=False):
        """
        Used to indicate that this render depends on another
        render. Useful, for example, if we use pygame_surface to make
        a surface, and then blit that surface into another render.
        """

        if source is self:
            raise Exception("Render depends on itself.")

        self.depends_on_list.append(source)
        source.parents.add(self)
        
        if focus:
            if self.pass_focuses is None:
                self.pass_focuses = [ source ]
            else:            
                self.pass_focuses.append(source)

        
    def kill_cache(self):
        """
        Removes this render and its transitive parents from the cache.
        """

        if self.cache_killed:
            return

        self.cache_killed = True

        for i in self.parents:
            i.kill_cache()

        self.parents.clear()
                
        for i in self.depends_on_list:
            if not i.cache_killed:
                i.parents.discard(self)

        for ro in self.render_of:
            cache = render_cache[ro]
            for k, v in cache.items():
                if v is self:
                    del cache[k]
                    
            if not cache:
                del render_cache[ro]

    def kill(self):
        """
        Retained for compatibility.
        """
                
    def add_focus(self, d, arg=None, x=0, y=0, w=None, h=None, mx=None, my=None, mask=None):
        """
        This is called to indicate a region of the screen that can be
        focused.

        `d` - the displayable that is being focused.
        `arg` - an argument.

        The rest of the parameters are a rectangle giving the portion of
        this region corresponding to the focus. If they are all None, than
        this focus is assumed to be the singular full-screen focus.
        """

        if mask is not None and mask is not self:
            self.depends_on(mask)

        t = (d, arg, x, y, w, h, mx, my, mask)
            
        if self.focuses is None:
            self.focuses = [ t ]
        else:
            self.focuses.append(t)

    def take_focuses(self, cminx, cminy, cmaxx, cmaxy, reverse, x, y, focuses): #@DuplicatedSignature
        """
        This adds to focuses Focus objects corresponding to the focuses
        added to this object and its children, transformed into screen
        coordinates.

        `cminx`, `cminy`, `cmaxx`, `cmaxy` - The clipping rectangle.
        `reverse` - The transform from render to screen coordinates.
        `x`, `y` - The offset of the upper-left corner of the render.
        `focuses` - The list of focuses to add to.
        """
        
        if self.modal:
            focuses[:] = [ ]
            
        if self.reverse:
            reverse = reverse * self.reverse

        if self.focuses:

            for (d, arg, xo, yo, w, h, mx, my, mask) in self.focuses:

                if xo is None:
                    focuses.append(renpy.display.focus.Focus(d, arg, None, None, None, None)) 
                    continue

                x1, y1 = reverse.transform(xo, yo)
                x2, y2 = reverse.transform(xo + w, yo + h)

                minx = min(x1, x2) + x
                miny = min(y1, y2) + y
                maxx = max(x1, x2) + x
                maxy = max(y1, y2) + y

                minx = max(minx, cminx)
                miny = max(miny, cminy)
                maxx = min(maxx, cmaxx)
                maxy = min(maxy, cmaxy)

                if minx >= maxx or miny >= maxy:
                    continue

                focuses.append(renpy.display.focus.Focus(d, arg, minx, miny, maxx - minx, maxy - miny)) 

        if self.clipping:
            cminx = max(cminx, x)
            cminy = max(cminy, y)
            cmaxx = min(cmaxx, x + self.width)
            cmaxy = min(cmaxx, x + self.height)

        for child, xo, yo, focus, main in self.children:
            if not focus or not isinstance(child, Render):
                continue

            xo, yo = reverse.transform(xo, yo)
            child.take_focuses(cminx, cminy, cmaxx, cmaxy, reverse, x + xo, y + yo, focuses)

        if self.pass_focuses:
            for child in self.pass_focuses:
                child.take_focuses(cminx, cminy, cmaxx, cmaxy, reverse, x, y, focuses)
        
    def focus_at_point(self, x, y): #@DuplicatedSignature
        """
        This returns the focus of this object at the given point.
        """

        if self.clipping:
            if x < 0 or x >= self.width or y < 0 or y >= self.height:
                return None
        
        rv = None

        if self.focuses:
            for (d, arg, xo, yo, w, h, mx, my, mask) in self.focuses:

                if xo is None:
                    continue

                elif mx is not None:
                    cx = x - mx
                    cy = y - my

                    if self.forward:
                        cx, cy = self.forward.transform(cx, cy)

                    if mask.is_pixel_opaque(cx, cy):
                        rv = d, arg

                elif xo <= x < xo + w and yo <= y < yo + h:
                    rv = d, arg
            
        for child, xo, yo, focus, main in self.children:

            if not focus or not isinstance(child, Render):
                continue
            
            cx = x - xo
            cy = y - yo

            if self.forward:
                cx, cy = self.forward.transform(cx, cy)

            cf = child.focus_at_point(cx, cy)
            if cf is not None:
                rv = cf

        if self.pass_focuses:
            for child in self.pass_focuses:
                cf = child.focus_at_point(x, y)
                if cf is not None:
                    rv = cf

        if rv is None and self.modal:
            rv = Modal
                
        return rv
        
            
    def main_displayables_at_point(self, x, y, layers, depth=None):
        """
        Returns the displayable at `x`, `y` on one of the layers in
        the set or list `layers`.
        """

        rv = [ ]

        if x < 0 or y < 0 or x >= self.width or y >= self.height:
            return rv

        if depth is not None:
            for d in self.render_of:
                rv.append((depth, self.width, self.height, d))
                depth += 1
        elif self.layer_name in layers:
            depth = 0

        for (child, xo, yo, focus, main) in self.children:
            if not main or not isinstance(child, Render):
                continue

            cx = x - xo
            cy = y - yo

            if self.forward:
                cx, cy = self.forward.transform(cx, cy)

            cf = child.main_displayables_at_point(cx, cy, layers, depth)
            rv.extend(cf)            

        return rv
        

    def is_opaque(self):
        """
        Returns true if this displayable is opaque, or False otherwise.
        Also sets self.visible_children.
        """

        if self.opaque is not None:
            return self.opaque

        # A rotated image is never opaque. (This isn't actually true, but it
        # saves us from the expensive calculations require to prove it is.)
        if self.forward:
            self.opaque = False
            return False
        
        rv = False
        vc = [ ]
        
        for i in self.children:
            child, xo, yo, focus, main = i

            if xo <= 0 and yo <= 0:
                cw, ch = child.get_size()
                if cw + xo < self.width or ch + yo < self.height:
                    if child.is_opaque():
                        vc = [ ]
                        rv = True
              
            vc.append(i)

        self.visible_children = vc
        self.opaque = rv
        return rv

    
    def is_pixel_opaque(self, x, y):
        """
        Determine if the pixel at x and y is opaque or not.
        """

        if x < 0 or y < 0 or x >= self.width or y >= self.height:
            return False

        if self.is_opaque():
            return True

        return renpy.display.draw.is_pixel_opaque(self, x, y)

    
    def fill(self, color):
        """
        Fills this Render with the given color.
        """

        color = renpy.easy.color(color)
        solid = renpy.display.imagelike.Solid(color)
        surf = render(solid, self.width, self.height, 0, 0)
        self.blit(surf, (0, 0), focus=False, main=False)

        
    def canvas(self):
        """
        Returns a canvas object that draws to this Render.
        """

        surf = renpy.display.pgrender.surface((self.width, self.height), True)

        mutated_surface(surf)

        self.blit(surf, (0, 0))

        return Canvas(surf)

        
class Canvas(object):

    def __init__(self, surf): #@DuplicatedSignature
        self.surf = surf
        
    def rect(self, color, rect, width=0):

        try:
            blit_lock.acquire()
            pygame.draw.rect(self.surf,
                             renpy.easy.color(color),
                             rect,
                             width)
        finally:
            blit_lock.release()

    def polygon(self, color, pointlist, width=0):
        try:
            blit_lock.acquire()
            pygame.draw.polygon(self.surf,
                                renpy.easy.color(color),
                                pointlist,
                                width)
        finally:
            blit_lock.release()

    def circle(self, color, pos, radius, width=0):

        try:
            blit_lock.acquire()
            pygame.draw.circle(self.surf,
                               renpy.easy.color(color),
                               pos,
                               radius,
                               width)

        finally:
            blit_lock.release()

    def ellipse(self, color, rect, width=0):
        try:
            blit_lock.acquire()
            pygame.draw.ellipse(self.surf,
                                renpy.easy.color(color),
                                rect,
                                width)
        finally:
            blit_lock.release()


    def arc(self, color, rect, start_angle, stop_angle, width=1):
        try:
            blit_lock.acquire()
            pygame.draw.arc(self.surf,
                            renpy.easy.color(color),
                            rect,
                            start_angle,
                            stop_angle,
                            width)
        finally:
            blit_lock.release()


    def line(self, color, start_pos, end_pos, width=1):
        try:
            blit_lock.acquire()
            pygame.draw.line(self.surf,
                             renpy.easy.color(color),
                             start_pos,
                             end_pos,
                             width)
        finally:
            blit_lock.release()

    def lines(self, color, closed, pointlist, width=1):
        try:
            blit_lock.acquire()
            pygame.draw.lines(self.surf,
                              renpy.easy.color(color),
                              closed,
                              pointlist,
                              width)
        finally:
            blit_lock.release()
    
    def aaline(self, color, startpos, endpos, blend=1):
        try:
            blit_lock.acquire()
            pygame.draw.aaline(self.surf,
                               renpy.easy.color(color),
                               startpos,
                               endpos,
                               blend)
        finally:
            blit_lock.release()

    def aalines(self, color, closed, pointlist, blend=1):
        try:
            blit_lock.acquire()
            pygame.draw.aalines(self.surf,
                                renpy.easy.color(color),
                                closed,
                                pointlist,
                                blend)
        finally:
            blit_lock.release()
