eBookReaderSwitch/mupdf/source/fitz/path.c

#include "mupdf/fitz.h"
#include "fitz-imp.h"

#include <string.h>
#include <assert.h>

// Thoughts for further optimisations:
// All paths start with MoveTo. We could probably avoid most cases where
// we store that. The next thing after a close must be a move.
// Commands are MOVE, LINE, HORIZ, VERT, DEGEN, CURVE, CURVEV, CURVEY, QUAD, RECT.
// We'd need to drop 2 to get us down to 3 bits.
// Commands can be followed by CLOSE. Use 1 bit for close.
// PDF 'RECT' implies close according to the spec, but I suspect
// we can ignore this as filling closes implicitly.
// We use a single bit in the path header to tell us whether we have
// a trailing move. Trailing moves can always be stripped when path
// construction completes.

typedef enum fz_path_command_e
{
	FZ_MOVETO = 'M',
	FZ_LINETO = 'L',
	FZ_DEGENLINETO = 'D',
	FZ_CURVETO = 'C',
	FZ_CURVETOV = 'V',
	FZ_CURVETOY = 'Y',
	FZ_HORIZTO = 'H',
	FZ_VERTTO = 'I',
	FZ_QUADTO = 'Q',
	FZ_RECTTO = 'R',
	FZ_MOVETOCLOSE = 'm',
	FZ_LINETOCLOSE = 'l',
	FZ_DEGENLINETOCLOSE = 'd',
	FZ_CURVETOCLOSE = 'c',
	FZ_CURVETOVCLOSE = 'v',
	FZ_CURVETOYCLOSE = 'y',
	FZ_HORIZTOCLOSE = 'h',
	FZ_VERTTOCLOSE = 'i',
	FZ_QUADTOCLOSE = 'q',
} fz_path_item_kind;

struct fz_path_s
{
	int8_t refs;
	uint8_t packed;
	int cmd_len, cmd_cap;
	unsigned char *cmds;
	int coord_len, coord_cap;
	float *coords;
	fz_point current;
	fz_point begin;
};

typedef struct fz_packed_path_s
{
	int8_t refs;
	uint8_t packed;
	uint8_t coord_len;
	uint8_t cmd_len;
} fz_packed_path;

enum
{
	FZ_PATH_UNPACKED = 0,
	FZ_PATH_PACKED_FLAT = 1,
	FZ_PATH_PACKED_OPEN = 2
};

#define LAST_CMD(path) ((path)->cmd_len > 0 ? (path)->cmds[(path)->cmd_len-1] : 0)

fz_path *
fz_new_path(fz_context *ctx)
{
	fz_path *path;

	path = fz_malloc_struct(ctx, fz_path);
	path->refs = 1;
	path->packed = FZ_PATH_UNPACKED;
	path->current.x = 0;
	path->current.y = 0;
	path->begin.x = 0;
	path->begin.y = 0;

	return path;
}

/*
	Take an additional reference to
	a path.

	No modifications should be carried out on a path
	to which more than one reference is held, as
	this can cause race conditions.
*/
fz_path *
fz_keep_path(fz_context *ctx, const fz_path *pathc)
{
	fz_path *path = (fz_path *)pathc; /* Explicit cast away of const */

	if (path == NULL)
		return NULL;
	if (path->refs == 1 && path->packed == FZ_PATH_UNPACKED)
		fz_trim_path(ctx, path);
	return fz_keep_imp8(ctx, path, &path->refs);
}

void
fz_drop_path(fz_context *ctx, const fz_path *pathc)
{
	fz_path *path = (fz_path *)pathc; /* Explicit cast away of const */

	if (fz_drop_imp8(ctx, path, &path->refs))
	{
		if (path->packed != FZ_PATH_PACKED_FLAT)
		{
			fz_free(ctx, path->cmds);
			fz_free(ctx, path->coords);
		}
		if (path->packed == FZ_PATH_UNPACKED)
			fz_free(ctx, path);
	}
}

/*
	Return the number of
	bytes required to pack a path.
*/
int fz_packed_path_size(const fz_path *path)
{
	switch (path->packed)
	{
	case FZ_PATH_UNPACKED:
		if (path->cmd_len > 255 || path->coord_len > 255)
			return sizeof(fz_path);
		return sizeof(fz_packed_path) + sizeof(float) * path->coord_len + sizeof(uint8_t) * path->cmd_len;
	case FZ_PATH_PACKED_OPEN:
		return sizeof(fz_path);
	case FZ_PATH_PACKED_FLAT:
	{
		fz_packed_path *pack = (fz_packed_path *)path;
		return sizeof(fz_packed_path) + sizeof(float) * pack->coord_len + sizeof(uint8_t) * pack->cmd_len;
	}
	default:
		assert("This never happens" == NULL);
		return 0;
	}
}

/*
	Pack a path into the given block.
	To minimise the size of paths, this function allows them to be
	packed into a buffer with other information. Paths can be used
	interchangeably regardless of how they are packed.

	pack: Pointer to a block of data to pack the path into. Should
	be aligned by the caller to the same alignment as required for
	a fz_path pointer.

	max: The number of bytes available in the block.
	If max < sizeof(fz_path) then an exception will
	be thrown. If max >= the value returned by
	fz_packed_path_size, then this call will never
	fail, except in low memory situations with large
	paths.

	path: The path to pack.

	Returns the number of bytes within the block used. Callers can
	access the packed path data by casting the value of pack on
	entry to be a fz_path *.

	Throws exceptions on failure to allocate, or if
	max < sizeof(fz_path).

	Implementation details: Paths can be 'unpacked', 'flat', or
	'open'. Standard paths, as created are 'unpacked'. Paths that
	will pack into less than max bytes will be packed as 'flat',
	unless they are too large (where large indicates that they
	exceed some private implementation defined limits, currently
	including having more than 256 coordinates or commands).

	Large paths are 'open' packed as a header into the given block,
	plus pointers to other data blocks.

	Users should not have to care about whether paths are 'open'
	or 'flat' packed. Simply pack a path (if required), and then
	forget about the details.
*/
int
fz_pack_path(fz_context *ctx, uint8_t *pack_, size_t max, const fz_path *path)
{
	uint8_t *ptr;
	size_t size;

	if (path->packed)
		fz_throw(ctx, FZ_ERROR_GENERIC, "Can't repack a packed path");

	size = sizeof(fz_packed_path) + sizeof(float) * path->coord_len + sizeof(uint8_t) * path->cmd_len;

	/* If the path can't be packed flat, then pack it open */
	if (path->cmd_len > 255 || path->coord_len > 255 || size > max)
	{
		fz_path *pack = (fz_path *)pack_;

		if (sizeof(fz_path) > max)
			fz_throw(ctx, FZ_ERROR_GENERIC, "Can't pack a path that small!");

		if (pack != NULL)
		{
			pack->refs = 1;
			pack->packed = FZ_PATH_PACKED_OPEN;
			pack->current.x = 0;
			pack->current.y = 0;
			pack->begin.x = 0;
			pack->begin.y = 0;
			pack->coord_cap = path->coord_len;
			pack->coord_len = path->coord_len;
			pack->cmd_cap = path->cmd_len;
			pack->cmd_len = path->cmd_len;
			pack->coords = fz_malloc_array(ctx, path->coord_len, float);
			fz_try(ctx)
			{
				pack->cmds = fz_malloc_array(ctx, path->cmd_len, uint8_t);
			}
			fz_catch(ctx)
			{
				fz_free(ctx, pack->coords);
				fz_rethrow(ctx);
			}
			memcpy(pack->coords, path->coords, sizeof(float) * path->coord_len);
			memcpy(pack->cmds, path->cmds, sizeof(uint8_t) * path->cmd_len);
		}
		return sizeof(fz_path);
	}
	else
	{
		fz_packed_path *pack = (fz_packed_path *)pack_;

		if (pack != NULL)
		{
			pack->refs = 1;
			pack->packed = FZ_PATH_PACKED_FLAT;
			pack->cmd_len = path->cmd_len;
			pack->coord_len = path->coord_len;
			ptr = (uint8_t *)&pack[1];
			memcpy(ptr, path->coords, sizeof(float) * path->coord_len);
			ptr += sizeof(float) * path->coord_len;
			memcpy(ptr, path->cmds, sizeof(uint8_t) * path->cmd_len);
		}

		return size;
	}
}

static void
push_cmd(fz_context *ctx, fz_path *path, int cmd)
{
	if (path->refs != 1)
		fz_throw(ctx, FZ_ERROR_GENERIC, "cannot modify shared paths");

	if (path->cmd_len + 1 >= path->cmd_cap)
	{
		int new_cmd_cap = fz_maxi(16, path->cmd_cap * 2);
		path->cmds = fz_realloc_array(ctx, path->cmds, new_cmd_cap, unsigned char);
		path->cmd_cap = new_cmd_cap;
	}

	path->cmds[path->cmd_len++] = cmd;
}

static void
push_coord(fz_context *ctx, fz_path *path, float x, float y)
{
	if (path->coord_len + 2 >= path->coord_cap)
	{
		int new_coord_cap = fz_maxi(32, path->coord_cap * 2);
		path->coords = fz_realloc_array(ctx, path->coords, new_coord_cap, float);
		path->coord_cap = new_coord_cap;
	}

	path->coords[path->coord_len++] = x;
	path->coords[path->coord_len++] = y;

	path->current.x = x;
	path->current.y = y;
}

static void
push_ord(fz_context *ctx, fz_path *path, float xy, int isx)
{
	if (path->coord_len + 1 >= path->coord_cap)
	{
		int new_coord_cap = fz_maxi(32, path->coord_cap * 2);
		path->coords = fz_realloc_array(ctx, path->coords, new_coord_cap, float);
		path->coord_cap = new_coord_cap;
	}

	path->coords[path->coord_len++] = xy;

	if (isx)
		path->current.x = xy;
	else
		path->current.y = xy;
}

/*
	Return the current point that a path has
	reached or (0,0) if empty.

	path: path to return the current point of.
*/
fz_point
fz_currentpoint(fz_context *ctx, fz_path *path)
{
	return path->current;
}

/*
	Append a 'moveto' command to a path.
	This 'opens' a path.

	path: The path to modify.

	x, y: The coordinate to move to.

	Throws exceptions on failure to allocate.
*/
void
fz_moveto(fz_context *ctx, fz_path *path, float x, float y)
{
	if (path->packed)
		fz_throw(ctx, FZ_ERROR_GENERIC, "Cannot modify a packed path");

	if (path->cmd_len > 0 && LAST_CMD(path) == FZ_MOVETO)
	{
		/* Collapse moveto followed by moveto. */
		path->coords[path->coord_len-2] = x;
		path->coords[path->coord_len-1] = y;
		path->current.x = x;
		path->current.y = y;
		path->begin = path->current;
		return;
	}

	push_cmd(ctx, path, FZ_MOVETO);
	push_coord(ctx, path, x, y);

	path->begin = path->current;
}

/*
	Append a 'lineto' command to an open path.

	path: The path to modify.

	x, y: The coordinate to line to.

	Throws exceptions on failure to allocate.
*/
void
fz_lineto(fz_context *ctx, fz_path *path, float x, float y)
{
	float x0, y0;

	if (path->packed)
		fz_throw(ctx, FZ_ERROR_GENERIC, "Cannot modify a packed path");

	x0 = path->current.x;
	y0 = path->current.y;

	if (path->cmd_len == 0)
	{
		fz_warn(ctx, "lineto with no current point");
		return;
	}

	/* (Anything other than MoveTo) followed by (LineTo the same place) is a nop */
	if (LAST_CMD(path) != FZ_MOVETO && x0 == x && y0 == y)
		return;

	if (x0 == x)
	{
		if (y0 == y)
		{
			if (LAST_CMD(path) != FZ_MOVETO)
				return;
			push_cmd(ctx, path, FZ_DEGENLINETO);
		}
		else
		{
			push_cmd(ctx, path, FZ_VERTTO);
			push_ord(ctx, path, y, 0);
		}
	}
	else if (y0 == y)
	{
		push_cmd(ctx, path, FZ_HORIZTO);
		push_ord(ctx, path, x, 1);
	}
	else
	{
		push_cmd(ctx, path, FZ_LINETO);
		push_coord(ctx, path, x, y);
	}
}

/*
	Append a 'curveto' command to an open path. (For a
	cubic bezier).

	path: The path to modify.

	x0, y0: The coordinates of the first control point for the
	curve.

	x1, y1: The coordinates of the second control point for the
	curve.

	x2, y2: The end coordinates for the curve.

	Throws exceptions on failure to allocate.
*/
void
fz_curveto(fz_context *ctx, fz_path *path,
	float x1, float y1,
	float x2, float y2,
	float x3, float y3)
{
	float x0, y0;

	if (path->packed)
		fz_throw(ctx, FZ_ERROR_GENERIC, "Cannot modify a packed path");

	x0 = path->current.x;
	y0 = path->current.y;

	if (path->cmd_len == 0)
	{
		fz_warn(ctx, "curveto with no current point");
		return;
	}

	/* Check for degenerate cases: */
	if (x0 == x1 && y0 == y1)
	{
		if (x2 == x3 && y2 == y3)
		{
			/* If (x1,y1)==(x2,y2) and prev wasn't a moveto, then skip */
			if (x1 == x2 && y1 == y2 && LAST_CMD(path) != FZ_MOVETO)
				return;
			/* Otherwise a line will suffice */
			fz_lineto(ctx, path, x3, y3);
		}
		else if (x1 == x2 && y1 == y2)
		{
			/* A line will suffice */
			fz_lineto(ctx, path, x3, y3);
		}
		else
			fz_curvetov(ctx, path, x2, y2, x3, y3);
		return;
	}
	else if (x2 == x3 && y2 == y3)
	{
		if (x1 == x2 && y1 == y2)
		{
			/* A line will suffice */
			fz_lineto(ctx, path, x3, y3);
		}
		else
			fz_curvetoy(ctx, path, x1, y1, x3, y3);
		return;
	}

	push_cmd(ctx, path, FZ_CURVETO);
	push_coord(ctx, path, x1, y1);
	push_coord(ctx, path, x2, y2);
	push_coord(ctx, path, x3, y3);
}

/*
	Append a 'quadto' command to an open path. (For a
	quadratic bezier).

	path: The path to modify.

	x0, y0: The control coordinates for the quadratic curve.

	x1, y1: The end coordinates for the quadratic curve.

	Throws exceptions on failure to allocate.
*/
void
fz_quadto(fz_context *ctx, fz_path *path,
	float x1, float y1,
	float x2, float y2)
{
	float x0, y0;

	if (path->packed)
		fz_throw(ctx, FZ_ERROR_GENERIC, "Cannot modify a packed path");

	x0 = path->current.x;
	y0 = path->current.y;

	if (path->cmd_len == 0)
	{
		fz_warn(ctx, "quadto with no current point");
		return;
	}

	/* Check for degenerate cases: */
	if ((x0 == x1 && y0 == y1) || (x1 == x2 && y1 == y2))
	{
		if (x0 == x2 && y0 == y2 && LAST_CMD(path) != FZ_MOVETO)
			return;
		/* A line will suffice */
		fz_lineto(ctx, path, x2, y2);
		return;
	}

	push_cmd(ctx, path, FZ_QUADTO);
	push_coord(ctx, path, x1, y1);
	push_coord(ctx, path, x2, y2);
}

/*
	Append a 'curvetov' command to an open path. (For a
	cubic bezier with the first control coordinate equal to
	the start point).

	path: The path to modify.

	x1, y1: The coordinates of the second control point for the
	curve.

	x2, y2: The end coordinates for the curve.

	Throws exceptions on failure to allocate.
*/
void
fz_curvetov(fz_context *ctx, fz_path *path, float x2, float y2, float x3, float y3)
{
	float x0, y0;

	if (path->packed)
		fz_throw(ctx, FZ_ERROR_GENERIC, "Cannot modify a packed path");

	x0 = path->current.x;
	y0 = path->current.y;

	if (path->cmd_len == 0)
	{
		fz_warn(ctx, "curveto with no current point");
		return;
	}

	/* Check for degenerate cases: */
	if (x2 == x3 && y2 == y3)
	{
		/* If (x0,y0)==(x2,y2) and prev wasn't a moveto, then skip */
		if (x0 == x2 && y0 == y2 && LAST_CMD(path) != FZ_MOVETO)
			return;
		/* Otherwise a line will suffice */
		fz_lineto(ctx, path, x3, y3);
	}
	else if (x0 == x2 && y0 == y2)
	{
		/* A line will suffice */
		fz_lineto(ctx, path, x3, y3);
	}

	push_cmd(ctx, path, FZ_CURVETOV);
	push_coord(ctx, path, x2, y2);
	push_coord(ctx, path, x3, y3);
}

/*
	Append a 'curvetoy' command to an open path. (For a
	cubic bezier with the second control coordinate equal to
	the end point).

	path: The path to modify.

	x0, y0: The coordinates of the first control point for the
	curve.

	x2, y2: The end coordinates for the curve (and the second
	control coordinate).

	Throws exceptions on failure to allocate.
*/
void
fz_curvetoy(fz_context *ctx, fz_path *path, float x1, float y1, float x3, float y3)
{
	float x0, y0;

	if (path->packed)
		fz_throw(ctx, FZ_ERROR_GENERIC, "Cannot modify a packed path");

	x0 = path->current.x;
	y0 = path->current.y;

	if (path->cmd_len == 0)
	{
		fz_warn(ctx, "curveto with no current point");
		return;
	}

	/* Check for degenerate cases: */
	if (x1 == x3 && y1 == y3)
	{
		/* If (x0,y0)==(x1,y1) and prev wasn't a moveto, then skip */
		if (x0 == x1 && y0 == y1 && LAST_CMD(path) != FZ_MOVETO)
			return;
		/* Otherwise a line will suffice */
		fz_lineto(ctx, path, x3, y3);
	}

	push_cmd(ctx, path, FZ_CURVETOY);
	push_coord(ctx, path, x1, y1);
	push_coord(ctx, path, x3, y3);
}

/*
	Close the current subpath.

	path: The path to modify.

	Throws exceptions on failure to allocate, and illegal
	path closes (i.e. closing a non open path).
*/
void
fz_closepath(fz_context *ctx, fz_path *path)
{
	uint8_t rep;

	if (path->packed)
		fz_throw(ctx, FZ_ERROR_GENERIC, "Cannot modify a packed path");

	if (path->cmd_len == 0)
	{
		fz_warn(ctx, "closepath with no current point");
		return;
	}

	switch(LAST_CMD(path))
	{
	case FZ_MOVETO:
		rep = FZ_MOVETOCLOSE;
		break;
	case FZ_LINETO:
		rep = FZ_LINETOCLOSE;
		break;
	case FZ_DEGENLINETO:
		rep = FZ_DEGENLINETOCLOSE;
		break;
	case FZ_CURVETO:
		rep = FZ_CURVETOCLOSE;
		break;
	case FZ_CURVETOV:
		rep = FZ_CURVETOVCLOSE;
		break;
	case FZ_CURVETOY:
		rep = FZ_CURVETOYCLOSE;
		break;
	case FZ_HORIZTO:
		rep = FZ_HORIZTOCLOSE;
		break;
	case FZ_VERTTO:
		rep = FZ_VERTTOCLOSE;
		break;
	case FZ_QUADTO:
		rep = FZ_QUADTOCLOSE;
		break;
	case FZ_RECTTO:
		/* RectTo implies close */
		return;
	case FZ_MOVETOCLOSE:
	case FZ_LINETOCLOSE:
	case FZ_DEGENLINETOCLOSE:
	case FZ_CURVETOCLOSE:
	case FZ_CURVETOVCLOSE:
	case FZ_CURVETOYCLOSE:
	case FZ_HORIZTOCLOSE:
	case FZ_VERTTOCLOSE:
	case FZ_QUADTOCLOSE:
		/* CLOSE following a CLOSE is a NOP */
		return;
	default: /* default never happens */
	case 0:
		/* Closing an empty path is a NOP */
		return;
	}

	path->cmds[path->cmd_len-1] = rep;

	path->current = path->begin;
}

/*
	Append a 'rectto' command to an open path.

	The rectangle is equivalent to:
		moveto x0 y0
		lineto x1 y0
		lineto x1 y1
		lineto x0 y1
		closepath

	path: The path to modify.

	x0, y0: First corner of the rectangle.

	x1, y1: Second corner of the rectangle.

	Throws exceptions on failure to allocate.
*/
void
fz_rectto(fz_context *ctx, fz_path *path, float x1, float y1, float x2, float y2)
{
	if (path->packed)
		fz_throw(ctx, FZ_ERROR_GENERIC, "Cannot modify a packed path");

	if (path->cmd_len > 0 && LAST_CMD(path) == FZ_MOVETO)
	{
		/* Collapse moveto followed by rectto. */
		path->coord_len -= 2;
		path->cmd_len--;
	}

	push_cmd(ctx, path, FZ_RECTTO);
	push_coord(ctx, path, x1, y1);
	push_coord(ctx, path, x2, y2);

	path->current = path->begin;
}

static inline void bound_expand(fz_rect *r, fz_point p)
{
	if (p.x < r->x0) r->x0 = p.x;
	if (p.y < r->y0) r->y0 = p.y;
	if (p.x > r->x1) r->x1 = p.x;
	if (p.y > r->y1) r->y1 = p.y;
}

/*
	Walk the segments of a path, calling the
	appropriate callback function from a given set for each
	segment of the path.

	path: The path to walk.

	walker: The set of callback functions to use. The first
	4 callback pointers in the set must be non-NULL. The
	subsequent ones can either be supplied, or can be left
	as NULL, in which case the top 4 functions will be
	called as appropriate to simulate them.

	arg: An opaque argument passed in to each callback.

	Exceptions will only be thrown if the underlying callback
	functions throw them.
*/
void fz_walk_path(fz_context *ctx, const fz_path *path, const fz_path_walker *proc, void *arg)
{
	int i, k, cmd_len;
	float x, y, sx, sy;
	uint8_t *cmds;
	float *coords;

	switch (path->packed)
	{
	case FZ_PATH_UNPACKED:
	case FZ_PATH_PACKED_OPEN:
		cmd_len = path->cmd_len;
		coords = path->coords;
		cmds = path->cmds;
		break;
	case FZ_PATH_PACKED_FLAT:
		cmd_len = ((fz_packed_path *)path)->cmd_len;
		coords = (float *)&((fz_packed_path *)path)[1];
		cmds = (uint8_t *)&coords[((fz_packed_path *)path)->coord_len];
		break;
	default:
		assert("This never happens" == NULL);
		return;
	}

	if (cmd_len == 0)
		return;

	for (k=0, i = 0; i < cmd_len; i++)
	{
		uint8_t cmd = cmds[i];

		switch (cmd)
		{
		case FZ_CURVETO:
		case FZ_CURVETOCLOSE:
			proc->curveto(ctx, arg,
					coords[k],
					coords[k+1],
					coords[k+2],
					coords[k+3],
					x = coords[k+4],
					y = coords[k+5]);
			k += 6;
			if (cmd == FZ_CURVETOCLOSE)
			{
				if (proc->closepath)
					proc->closepath(ctx, arg);
				x = sx;
				y = sy;
			}
			break;
		case FZ_CURVETOV:
		case FZ_CURVETOVCLOSE:
			if (proc->curvetov)
				proc->curvetov(ctx, arg,
						coords[k],
						coords[k+1],
						x = coords[k+2],
						y = coords[k+3]);
			else
			{
				proc->curveto(ctx, arg,
						x,
						y,
						coords[k],
						coords[k+1],
						coords[k+2],
						coords[k+3]);
				x = coords[k+2];
				y = coords[k+3];
			}
			k += 4;
			if (cmd == FZ_CURVETOVCLOSE)
			{
				if (proc->closepath)
					proc->closepath(ctx, arg);
				x = sx;
				y = sy;
			}
			break;
		case FZ_CURVETOY:
		case FZ_CURVETOYCLOSE:
			if (proc->curvetoy)
				proc->curvetoy(ctx, arg,
						coords[k],
						coords[k+1],
						x = coords[k+2],
						y = coords[k+3]);
			else
				proc->curveto(ctx, arg,
						coords[k],
						coords[k+1],
						coords[k+2],
						coords[k+3],
						x = coords[k+2],
						y = coords[k+3]);
			k += 4;
			if (cmd == FZ_CURVETOYCLOSE)
			{
				if (proc->closepath)
					proc->closepath(ctx, arg);
				x = sx;
				y = sy;
			}
			break;
		case FZ_QUADTO:
		case FZ_QUADTOCLOSE:
			if (proc->quadto)
				proc->quadto(ctx, arg,
					coords[k],
					coords[k+1],
					x = coords[k+2],
					y = coords[k+3]);
			else
			{
				float c2x = coords[k] * 2;
				float c2y = coords[k+1] * 2;
				float c1x = (x + c2x) / 3;
				float c1y = (y + c2y) / 3;
				x = coords[k+2];
				y = coords[k+3];
				c2x = (c2x + x) / 3;
				c2y = (c2y + y) / 3;

				proc->curveto(ctx, arg,
					c1x,
					c1y,
					c2x,
					c2y,
					x,
					y);
			}
			k += 4;
			if (cmd == FZ_QUADTOCLOSE)
			{
				if (proc->closepath)
					proc->closepath(ctx, arg);
				x = sx;
				y = sy;
			}
			break;
		case FZ_MOVETO:
		case FZ_MOVETOCLOSE:
			proc->moveto(ctx, arg,
				x = coords[k],
				y = coords[k+1]);
			k += 2;
			sx = x;
			sy = y;
			if (cmd == FZ_MOVETOCLOSE)
			{
				if (proc->closepath)
					proc->closepath(ctx, arg);
				x = sx;
				y = sy;
			}
			break;
		case FZ_LINETO:
		case FZ_LINETOCLOSE:
			proc->lineto(ctx, arg,
				x = coords[k],
				y = coords[k+1]);
			k += 2;
			if (cmd == FZ_LINETOCLOSE)
			{
				if (proc->closepath)
					proc->closepath(ctx, arg);
				x = sx;
				y = sy;
			}
			break;
		case FZ_HORIZTO:
		case FZ_HORIZTOCLOSE:
			proc->lineto(ctx, arg,
				x = coords[k],
				y);
			k += 1;
			if (cmd == FZ_HORIZTOCLOSE)
			{
				if (proc->closepath)
					proc->closepath(ctx, arg);
				x = sx;
				y = sy;
			}
			break;
		case FZ_VERTTO:
		case FZ_VERTTOCLOSE:
			proc->lineto(ctx, arg,
				x,
				y = coords[k]);
			k += 1;
			if (cmd == FZ_VERTTOCLOSE)
			{
				if (proc->closepath)
					proc->closepath(ctx, arg);
				x = sx;
				y = sy;
			}
			break;
		case FZ_DEGENLINETO:
		case FZ_DEGENLINETOCLOSE:
			proc->lineto(ctx, arg,
				x,
				y);
			if (cmd == FZ_DEGENLINETOCLOSE)
			{
				if (proc->closepath)
					proc->closepath(ctx, arg);
				x = sx;
				y = sy;
			}
			break;
		case FZ_RECTTO:
			if (proc->rectto)
			{
				proc->rectto(ctx, arg,
						x = coords[k],
						y = coords[k+1],
						coords[k+2],
						coords[k+3]);
			}
			else
			{
				proc->moveto(ctx, arg,
					x = coords[k],
					y = coords[k+1]);
				proc->lineto(ctx, arg,
					coords[k+2],
					coords[k+1]);
				proc->lineto(ctx, arg,
					coords[k+2],
					coords[k+3]);
				proc->lineto(ctx, arg,
					coords[k],
					coords[k+3]);
				if (proc->closepath)
					proc->closepath(ctx, arg);
			}
			sx = x;
			sy = y;
			k += 4;
			break;
		}
	}
}

typedef struct
{
	fz_matrix ctm;
	fz_rect rect;
	fz_point move;
	int trailing_move;
	int first;
} bound_path_arg;

static void
bound_moveto(fz_context *ctx, void *arg_, float x, float y)
{
	bound_path_arg *arg = (bound_path_arg *)arg_;
	arg->move = fz_transform_point_xy(x, y, arg->ctm);
	arg->trailing_move = 1;
}

static void
bound_lineto(fz_context *ctx, void *arg_, float x, float y)
{
	bound_path_arg *arg = (bound_path_arg *)arg_;
	fz_point p = fz_transform_point_xy(x, y, arg->ctm);
	if (arg->first)
	{
		arg->rect.x0 = arg->rect.x1 = p.x;
		arg->rect.y0 = arg->rect.y1 = p.y;
		arg->first = 0;
	}
	else
		bound_expand(&arg->rect, p);
	if (arg->trailing_move)
	{
		arg->trailing_move = 0;
		bound_expand(&arg->rect, arg->move);
	}
}

static void
bound_curveto(fz_context *ctx, void *arg_, float x1, float y1, float x2, float y2, float x3, float y3)
{
	bound_path_arg *arg = (bound_path_arg *)arg_;
	fz_point p = fz_transform_point_xy(x1, y1, arg->ctm);
	if (arg->first)
	{
		arg->rect.x0 = arg->rect.x1 = p.x;
		arg->rect.y0 = arg->rect.y1 = p.y;
		arg->first = 0;
	}
	else
		bound_expand(&arg->rect, p);
	bound_expand(&arg->rect, fz_transform_point_xy(x2, y2, arg->ctm));
	bound_expand(&arg->rect, fz_transform_point_xy(x3, y3, arg->ctm));
	if (arg->trailing_move)
	{
		arg->trailing_move = 0;
		bound_expand(&arg->rect, arg->move);
	}
}

static const fz_path_walker bound_path_walker =
{
	bound_moveto,
	bound_lineto,
	bound_curveto,
	NULL
};

/*
	Return a bounding rectangle for a path.

	path: The path to bound.

	stroke: If NULL, the bounding rectangle given is for
	the filled path. If non-NULL the bounding rectangle
	given is for the path stroked with the given attributes.

	ctm: The matrix to apply to the path during stroking.

	r: Pointer to a fz_rect which will be used to hold
	the result.

	Returns r, updated to contain the bounding rectangle.
*/
fz_rect
fz_bound_path(fz_context *ctx, const fz_path *path, const fz_stroke_state *stroke, fz_matrix ctm)
{
	bound_path_arg arg;

	arg.ctm = ctm;
	arg.rect = fz_empty_rect;
	arg.trailing_move = 0;
	arg.first = 1;

	fz_walk_path(ctx, path, &bound_path_walker, &arg);

	if (!arg.first && stroke)
	{
		arg.rect = fz_adjust_rect_for_stroke(ctx, arg.rect, stroke, ctm);
	}

	return arg.rect;
}

fz_rect
fz_adjust_rect_for_stroke(fz_context *ctx, fz_rect r, const fz_stroke_state *stroke, fz_matrix ctm)
{
	float expand;

	if (!stroke)
		return r;

	expand = stroke->linewidth;
	if (expand == 0)
		expand = 1.0f;
	expand *= fz_matrix_max_expansion(ctm);
	if ((stroke->linejoin == FZ_LINEJOIN_MITER || stroke->linejoin == FZ_LINEJOIN_MITER_XPS) && stroke->miterlimit > 1)
		expand *= stroke->miterlimit;

	r.x0 -= expand;
	r.y0 -= expand;
	r.x1 += expand;
	r.y1 += expand;
	return r;
}

/*
	Transform a path by a given
	matrix.

	path: The path to modify (must not be a packed path).

	transform: The transform to apply.

	Throws exceptions if the path is packed, or on failure
	to allocate.
*/
void
fz_transform_path(fz_context *ctx, fz_path *path, fz_matrix ctm)
{
	int i, k, n;
	fz_point p, p1, p2, p3, q, s;

	if (path->packed)
		fz_throw(ctx, FZ_ERROR_GENERIC, "Cannot transform a packed path");

	if (ctm.b == 0 && ctm.c == 0)
	{
		/* Simple, in place transform */
		i = 0;
		k = 0;
		while (i < path->cmd_len)
		{
			uint8_t cmd = path->cmds[i];

			switch (cmd)
			{
			case FZ_MOVETO:
			case FZ_LINETO:
			case FZ_MOVETOCLOSE:
			case FZ_LINETOCLOSE:
				n = 1;
				break;
			case FZ_DEGENLINETO:
			case FZ_DEGENLINETOCLOSE:
				n = 0;
				break;
			case FZ_CURVETO:
			case FZ_CURVETOCLOSE:
				n = 3;
				break;
			case FZ_RECTTO:
				s.x = path->coords[k];
				s.y = path->coords[k+1];
				n = 2;
				break;
			case FZ_CURVETOV:
			case FZ_CURVETOY:
			case FZ_QUADTO:
			case FZ_CURVETOVCLOSE:
			case FZ_CURVETOYCLOSE:
			case FZ_QUADTOCLOSE:
				n = 2;
				break;
			case FZ_HORIZTO:
			case FZ_HORIZTOCLOSE:
				q.x = path->coords[k];
				p = fz_transform_point(q, ctm);
				path->coords[k++] = p.x;
				n = 0;
				break;
			case FZ_VERTTO:
			case FZ_VERTTOCLOSE:
				q.y = path->coords[k];
				p = fz_transform_point(q, ctm);
				path->coords[k++] = p.y;
				n = 0;
				break;
			default:
				assert("Unknown path cmd" == NULL);
			}
			while (n > 0)
			{
				q.x = path->coords[k];
				q.y = path->coords[k+1];
				p = fz_transform_point(q, ctm);
				path->coords[k++] = p.x;
				path->coords[k++] = p.y;
				n--;
			}
			switch (cmd)
			{
			case FZ_MOVETO:
			case FZ_MOVETOCLOSE:
				s = q;
				break;
			case FZ_LINETOCLOSE:
			case FZ_DEGENLINETOCLOSE:
			case FZ_CURVETOCLOSE:
			case FZ_CURVETOVCLOSE:
			case FZ_CURVETOYCLOSE:
			case FZ_QUADTOCLOSE:
			case FZ_HORIZTOCLOSE:
			case FZ_VERTTOCLOSE:
			case FZ_RECTTO:
				q = s;
				break;
			}
			i++;
		}
	}
	else if (ctm.a == 0 && ctm.d == 0)
	{
		/* In place transform with command rewriting */
		i = 0;
		k = 0;
		while (i < path->cmd_len)
		{
			uint8_t cmd = path->cmds[i];

			switch (cmd)
			{
			case FZ_MOVETO:
			case FZ_LINETO:
			case FZ_MOVETOCLOSE:
			case FZ_LINETOCLOSE:
				n = 1;
				break;
			case FZ_DEGENLINETO:
			case FZ_DEGENLINETOCLOSE:
				n = 0;
				break;
			case FZ_CURVETO:
			case FZ_CURVETOCLOSE:
				n = 3;
				break;
			case FZ_RECTTO:
				s.x = path->coords[k];
				s.y = path->coords[k+1];
				n = 2;
				break;
			case FZ_CURVETOV:
			case FZ_CURVETOY:
			case FZ_QUADTO:
			case FZ_CURVETOVCLOSE:
			case FZ_CURVETOYCLOSE:
			case FZ_QUADTOCLOSE:
				n = 2;
				break;
			case FZ_HORIZTO:
				q.x = path->coords[k];
				p = fz_transform_point(q, ctm);
				path->coords[k++] = p.y;
				path->cmds[i] = FZ_VERTTO;
				n = 0;
				break;
			case FZ_HORIZTOCLOSE:
				q.x = path->coords[k];
				p = fz_transform_point(q, ctm);
				path->coords[k++] = p.y;
				path->cmds[i] = FZ_VERTTOCLOSE;
				n = 0;
				break;
			case FZ_VERTTO:
				q.y = path->coords[k];
				p = fz_transform_point(q, ctm);
				path->coords[k++] = p.x;
				path->cmds[i] = FZ_HORIZTO;
				n = 0;
				break;
			case FZ_VERTTOCLOSE:
				q.y = path->coords[k];
				p = fz_transform_point(q, ctm);
				path->coords[k++] = p.x;
				path->cmds[i] = FZ_HORIZTOCLOSE;
				n = 0;
				break;
			default:
				assert("Unknown path cmd" == NULL);
			}
			while (n > 0)
			{
				q.x = path->coords[k];
				q.y = path->coords[k+1];
				p = fz_transform_point(q, ctm);
				path->coords[k++] = p.x;
				path->coords[k++] = p.y;
				n--;
			}
			switch (cmd)
			{
			case FZ_MOVETO:
			case FZ_MOVETOCLOSE:
				s = q;
				break;
			case FZ_LINETOCLOSE:
			case FZ_DEGENLINETOCLOSE:
			case FZ_CURVETOCLOSE:
			case FZ_CURVETOVCLOSE:
			case FZ_CURVETOYCLOSE:
			case FZ_QUADTOCLOSE:
			case FZ_HORIZTOCLOSE:
			case FZ_VERTTOCLOSE:
			case FZ_RECTTO:
				q = s;
				break;
			}
			i++;
		}
	}
	else
	{
		int extra_coord = 0;
		int extra_cmd = 0;
		int coord_read, coord_write, cmd_read, cmd_write;

		/* General case. Have to allow for rects/horiz/verts
		 * becoming non-rects/horiz/verts. */
		for (i = 0; i < path->cmd_len; i++)
		{
			uint8_t cmd = path->cmds[i];
			switch (cmd)
			{
			case FZ_HORIZTO:
			case FZ_VERTTO:
			case FZ_HORIZTOCLOSE:
			case FZ_VERTTOCLOSE:
				extra_coord += 1;
				break;
			case FZ_RECTTO:
				extra_coord += 2;
				extra_cmd += 3;
				break;
			default:
				/* Do nothing */
				break;
			}
		}
		if (path->cmd_len + extra_cmd < path->cmd_cap)
		{
			path->cmds = fz_realloc_array(ctx, path->cmds, path->cmd_len + extra_cmd, unsigned char);
			path->cmd_cap = path->cmd_len + extra_cmd;
		}
		if (path->coord_len + extra_coord < path->coord_cap)
		{
			path->coords = fz_realloc_array(ctx, path->coords, path->coord_len + extra_coord, float);
			path->coord_cap = path->coord_len + extra_coord;
		}
		memmove(path->cmds + extra_cmd, path->cmds, path->cmd_len * sizeof(unsigned char));
		path->cmd_len += extra_cmd;
		memmove(path->coords + extra_coord, path->coords, path->coord_len * sizeof(float));
		path->coord_len += extra_coord;

		for (cmd_write = 0, cmd_read = extra_cmd, coord_write = 0, coord_read = extra_coord; cmd_read < path->cmd_len; i += 2)
		{
			uint8_t cmd = path->cmds[cmd_write++] = path->cmds[cmd_read++];

			switch (cmd)
			{
			case FZ_MOVETO:
			case FZ_LINETO:
			case FZ_MOVETOCLOSE:
			case FZ_LINETOCLOSE:
				n = 1;
				break;
			case FZ_DEGENLINETO:
			case FZ_DEGENLINETOCLOSE:
				n = 0;
				break;
			case FZ_CURVETO:
			case FZ_CURVETOCLOSE:
				n = 3;
				break;
			case FZ_CURVETOV:
			case FZ_CURVETOY:
			case FZ_QUADTO:
			case FZ_CURVETOVCLOSE:
			case FZ_CURVETOYCLOSE:
			case FZ_QUADTOCLOSE:
				n = 2;
				break;
			case FZ_RECTTO:
				p.x = path->coords[coord_read++];
				p.y = path->coords[coord_read++];
				p2.x = path->coords[coord_read++];
				p2.y = path->coords[coord_read++];
				p1.x = p2.x;
				p1.y = p.y;
				p3.x = p.x;
				p3.y = p2.y;
				s = p;
				p = fz_transform_point(p, ctm);
				p1 = fz_transform_point(p1, ctm);
				p2 = fz_transform_point(p2, ctm);
				p3 = fz_transform_point(p3, ctm);
				path->coords[coord_write++] = p.x;
				path->coords[coord_write++] = p.y;
				path->coords[coord_write++] = p1.x;
				path->coords[coord_write++] = p1.y;
				path->coords[coord_write++] = p2.x;
				path->coords[coord_write++] = p2.y;
				path->coords[coord_write++] = p3.x;
				path->coords[coord_write++] = p3.y;
				path->cmds[cmd_write-1] = FZ_MOVETO;
				path->cmds[cmd_write++] = FZ_LINETO;
				path->cmds[cmd_write++] = FZ_LINETO;
				path->cmds[cmd_write++] = FZ_LINETOCLOSE;
				n = 0;
				break;
			case FZ_HORIZTO:
				q.x = path->coords[coord_read++];
				p = fz_transform_point(q, ctm);
				path->coords[coord_write++] = p.x;
				path->coords[coord_write++] = p.y;
				path->cmds[cmd_write-1] = FZ_LINETO;
				n = 0;
				break;
			case FZ_HORIZTOCLOSE:
				p.x = path->coords[coord_read++];
				p.y = q.y;
				p = fz_transform_point(p, ctm);
				path->coords[coord_write++] = p.x;
				path->coords[coord_write++] = p.y;
				path->cmds[cmd_write-1] = FZ_LINETOCLOSE;
				q = s;
				n = 0;
				break;
			case FZ_VERTTO:
				q.y = path->coords[coord_read++];
				p = fz_transform_point(q, ctm);
				path->coords[coord_write++] = p.x;
				path->coords[coord_write++] = p.y;
				path->cmds[cmd_write-1] = FZ_LINETO;
				n = 0;
				break;
			case FZ_VERTTOCLOSE:
				p.x = q.x;
				p.y = path->coords[coord_read++];
				p = fz_transform_point(p, ctm);
				path->coords[coord_write++] = p.x;
				path->coords[coord_write++] = p.y;
				path->cmds[cmd_write-1] = FZ_LINETOCLOSE;
				q = s;
				n = 0;
				break;
			default:
				assert("Unknown path cmd" == NULL);
			}
			while (n > 0)
			{
				q.x = path->coords[coord_read++];
				q.y = path->coords[coord_read++];
				p = fz_transform_point(q, ctm);
				path->coords[coord_write++] = p.x;
				path->coords[coord_write++] = p.y;
				n--;
			}
			switch (cmd)
			{
			case FZ_MOVETO:
			case FZ_MOVETOCLOSE:
				s = q;
				break;
			case FZ_LINETOCLOSE:
			case FZ_DEGENLINETOCLOSE:
			case FZ_CURVETOCLOSE:
			case FZ_CURVETOYCLOSE:
			case FZ_CURVETOVCLOSE:
			case FZ_QUADTOCLOSE:
			case FZ_HORIZTOCLOSE:
			case FZ_VERTTOCLOSE:
			case FZ_RECTTO:
				q = s;
				break;
			}
		}
	}
}

/*
	Minimise the internal storage
	used by a path.

	As paths are constructed, the internal buffers
	grow. To avoid repeated reallocations they
	grow with some spare space. Once a path has
	been fully constructed, this call allows the
	excess space to be trimmed.
*/
void fz_trim_path(fz_context *ctx, fz_path *path)
{
	if (path->packed)
		fz_throw(ctx, FZ_ERROR_GENERIC, "Can't trim a packed path");
	if (path->cmd_cap > path->cmd_len)
	{
		path->cmds = fz_realloc_array(ctx, path->cmds, path->cmd_len, unsigned char);
		path->cmd_cap = path->cmd_len;
	}
	if (path->coord_cap > path->coord_len)
	{
		path->coords = fz_realloc_array(ctx, path->coords, path->coord_len, float);
		path->coord_cap = path->coord_len;
	}
}

const fz_stroke_state fz_default_stroke_state = {
	-2, /* -2 is the magic number we use when we have stroke states stored on the stack */
	FZ_LINECAP_BUTT, FZ_LINECAP_BUTT, FZ_LINECAP_BUTT,
	FZ_LINEJOIN_MITER,
	1, 10,
	0, 0, { 0 }
};

/*
	Take an additional reference to
	a stroke state structure.

	No modifications should be carried out on a stroke
	state to which more than one reference is held, as
	this can cause race conditions.
*/
fz_stroke_state *
fz_keep_stroke_state(fz_context *ctx, const fz_stroke_state *strokec)
{
	fz_stroke_state *stroke = (fz_stroke_state *)strokec; /* Explicit cast away of const */

	if (!stroke)
		return NULL;

	/* -2 is the magic number we use when we have stroke states stored on the stack */
	if (stroke->refs == -2)
		return fz_clone_stroke_state(ctx, stroke);

	return fz_keep_imp(ctx, stroke, &stroke->refs);
}

/*
	Drop a reference to a stroke
	state structure, destroying the structure if it is
	the last reference.
*/
void
fz_drop_stroke_state(fz_context *ctx, const fz_stroke_state *strokec)
{
	fz_stroke_state *stroke = (fz_stroke_state *)strokec; /* Explicit cast away of const */

	if (fz_drop_imp(ctx, stroke, &stroke->refs))
		fz_free(ctx, stroke);
}

/*
	Create a new (empty)
	stroke state structure, with room for dash data of the
	given length, and return a reference to it.

	len: The number of dash elements to allow room for.

	Throws exception on failure to allocate.
*/
fz_stroke_state *
fz_new_stroke_state_with_dash_len(fz_context *ctx, int len)
{
	fz_stroke_state *state;

	len -= nelem(state->dash_list);
	if (len < 0)
		len = 0;

	state = Memento_label(fz_malloc(ctx, sizeof(*state) + sizeof(state->dash_list[0]) * len), "fz_stroke_state");
	state->refs = 1;
	state->start_cap = FZ_LINECAP_BUTT;
	state->dash_cap = FZ_LINECAP_BUTT;
	state->end_cap = FZ_LINECAP_BUTT;
	state->linejoin = FZ_LINEJOIN_MITER;
	state->linewidth = 1;
	state->miterlimit = 10;
	state->dash_phase = 0;
	state->dash_len = 0;
	memset(state->dash_list, 0, sizeof(state->dash_list[0]) * (len + nelem(state->dash_list)));

	return state;
}

/*
	Create a new (empty) stroke state
	structure (with no dash data) and return a reference to it.

	Throws exception on failure to allocate.
*/
fz_stroke_state *
fz_new_stroke_state(fz_context *ctx)
{
	return fz_new_stroke_state_with_dash_len(ctx, 0);
}

/*
	Create an identical stroke_state
	structure and return a reference to it.

	stroke: The stroke state reference to clone.

	Exceptions may be thrown in the event of a failure to
	allocate.
*/
fz_stroke_state *
fz_clone_stroke_state(fz_context *ctx, fz_stroke_state *stroke)
{
	fz_stroke_state *clone = fz_new_stroke_state_with_dash_len(ctx, stroke->dash_len);
	int extra = stroke->dash_len - nelem(stroke->dash_list);
	int size = sizeof(*stroke) + sizeof(stroke->dash_list[0]) * extra;
	memcpy(clone, stroke, size);
	clone->refs = 1;
	return clone;
}

/*
	Given a reference to a
	(possibly) shared stroke_state structure, return a reference
	to a stroke_state structure (with room for a given amount of
	dash data) that is guaranteed to be unshared (i.e. one that
	can safely be modified).

	shared: The reference to a (possibly) shared structure
	to unshare. Ownership of this reference is passed in
	to this function, even in the case of exceptions being
	thrown.

	Exceptions may be thrown in the event of failure to
	allocate if required.
*/
fz_stroke_state *
fz_unshare_stroke_state_with_dash_len(fz_context *ctx, fz_stroke_state *shared, int len)
{
	int single, unsize, shsize, shlen;
	fz_stroke_state *unshared;

	fz_lock(ctx, FZ_LOCK_ALLOC);
	single = (shared->refs == 1);
	fz_unlock(ctx, FZ_LOCK_ALLOC);

	shlen = shared->dash_len - nelem(shared->dash_list);
	if (shlen < 0)
		shlen = 0;
	shsize = sizeof(*shared) + sizeof(shared->dash_list[0]) * shlen;
	len -= nelem(shared->dash_list);
	if (len < 0)
		len = 0;
	if (single && shlen >= len)
		return shared;

	unsize = sizeof(*unshared) + sizeof(unshared->dash_list[0]) * len;
	unshared = Memento_label(fz_malloc(ctx, unsize), "fz_stroke_state");
	memcpy(unshared, shared, (shsize > unsize ? unsize : shsize));
	unshared->refs = 1;

	if (fz_drop_imp(ctx, shared, &shared->refs))
		fz_free(ctx, shared);
	return unshared;
}

/*
	Given a reference to a
	(possibly) shared stroke_state structure, return
	a reference to an equivalent stroke_state structure
	that is guaranteed to be unshared (i.e. one that can
	safely be modified).

	shared: The reference to a (possibly) shared structure
	to unshare. Ownership of this reference is passed in
	to this function, even in the case of exceptions being
	thrown.

	Exceptions may be thrown in the event of failure to
	allocate if required.
*/
fz_stroke_state *
fz_unshare_stroke_state(fz_context *ctx, fz_stroke_state *shared)
{
	return fz_unshare_stroke_state_with_dash_len(ctx, shared, shared->dash_len);
}

static void *
clone_block(fz_context *ctx, void *block, size_t len)
{
	void *target;

	if (len == 0 || block == NULL)
		return NULL;

	target = fz_malloc(ctx, len);
	memcpy(target, block, len);
	return target;
}

/*
	Clone the data for a path.

	This is used in preference to fz_keep_path when a whole
	new copy of a path is required, rather than just a shared
	pointer. This probably indicates that the path is about to
	be modified.

	path: path to clone.

	Throws exceptions on failure to allocate.
*/
fz_path *
fz_clone_path(fz_context *ctx, fz_path *path)
{
	fz_path *new_path;

	assert(ctx != NULL);

	if (path == NULL)
		return NULL;

	new_path = fz_malloc_struct(ctx, fz_path);
	new_path->refs = 1;
	new_path->packed = FZ_PATH_UNPACKED;
	fz_try(ctx)
	{
		switch(path->packed)
		{
		case FZ_PATH_UNPACKED:
		case FZ_PATH_PACKED_OPEN:
			new_path->cmd_len = path->cmd_len;
			new_path->cmd_cap = path->cmd_cap;
			new_path->cmds = Memento_label(clone_block(ctx, path->cmds, path->cmd_cap), "path_cmds");
			new_path->coord_len = path->coord_len;
			new_path->coord_cap = path->coord_cap;
			new_path->coords = Memento_label(clone_block(ctx, path->coords, sizeof(float)*path->coord_cap), "path_coords");
			new_path->current = path->current;
			new_path->begin = path->begin;
			break;
		case FZ_PATH_PACKED_FLAT:
			{
				uint8_t *data;
				float *xy;
				int i;
				fz_packed_path *ppath = (fz_packed_path *)path;

				new_path->cmd_len = ppath->cmd_len;
				new_path->cmd_cap = ppath->cmd_len;
				new_path->coord_len = ppath->coord_len;
				new_path->coord_cap = ppath->coord_len;
				data = (uint8_t *)&ppath[1];
				new_path->coords = Memento_label(clone_block(ctx, data, sizeof(float)*path->coord_cap), "path_coords");
				data += sizeof(float) * path->coord_cap;
				new_path->cmds = Memento_label(clone_block(ctx, data, path->cmd_cap), "path_cmds");
				xy = new_path->coords;
				for (i = 0; i < new_path->cmd_len; i++)
				{
					switch (new_path->cmds[i])
					{
					case FZ_MOVETOCLOSE:
					case FZ_MOVETO:
						new_path->current.x = *xy++;
						new_path->current.y = *xy++;
						new_path->begin.x = new_path->current.x;
						new_path->begin.y = new_path->current.y;
						break;
					case FZ_CURVETO:
						xy += 2;
						/* fallthrough */
					case FZ_CURVETOV:
					case FZ_CURVETOY:
					case FZ_QUADTO:
						/* fallthrough */
						xy += 2;
					case FZ_LINETO:
						new_path->current.x = *xy++;
						new_path->current.y = *xy++;
						break;
					case FZ_DEGENLINETO:
						break;
					case FZ_HORIZTO:
						new_path->current.x = *xy++;
						break;
					case FZ_VERTTO:
						new_path->current.y = *xy++;
						break;
					case FZ_RECTTO:
						xy += 2;
						break;
					case FZ_CURVETOCLOSE:
						xy += 2;
						/* fallthrough */
					case FZ_CURVETOVCLOSE:
					case FZ_CURVETOYCLOSE:
					case FZ_QUADTOCLOSE:
					case FZ_LINETOCLOSE:
						xy++;
						/* fallthrough */
					case FZ_HORIZTOCLOSE:
					case FZ_VERTTOCLOSE:
						xy++;
						/* fallthrough */
					case FZ_DEGENLINETOCLOSE:
						new_path->current.x = new_path->begin.x;
						new_path->current.y = new_path->begin.y;
						break;
					}
				}
			}
		default:
			fz_throw(ctx, FZ_ERROR_GENERIC, "Unknown packing method found in path");
		}
	}
	fz_catch(ctx)
	{
		fz_free(ctx, new_path->coords);
		fz_free(ctx, new_path->cmds);
		fz_free(ctx, new_path);
		fz_rethrow(ctx);
	}
	return new_path;
}