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1030 lines (891 loc) · 33.6 KB
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/* -*- mode: c++; c-basic-offset: 4 -*- */
#ifndef MPL_PATH_CONVERTERS_H
#define MPL_PATH_CONVERTERS_H
#include <cmath>
#include <stdint.h>
#include "agg_path_storage.h"
#include "agg_clip_liang_barsky.h"
#include "mplutils.h"
#include "agg_conv_segmentator.h"
/*
This file contains a number of vertex converters that modify
paths. They all work as iterators, where the output is generated
on-the-fly, and don't require a copy of the full data.
Each class represents a discrete step in a "path-cleansing" pipeline.
They are currently applied in the following order in the Agg backend:
1. Affine transformation (implemented in Agg, not here)
2. PathNanRemover: skips over segments containing non-finite numbers
by inserting MOVETO commands
3. PathClipper: Clips line segments to a given rectangle. This is
helpful for data reduction, and also to avoid a limitation in
Agg where coordinates can not be larger than 24-bit signed
integers.
4. PathSnapper: Rounds the path to the nearest center-pixels.
This makes rectilinear curves look much better.
5. PathSimplifier: Removes line segments from highly dense paths
that would not have an impact on their appearance. Speeds up
rendering and reduces file sizes.
6. curve-to-line-segment conversion (implemented in Agg, not here)
7. stroking (implemented in Agg, not here)
*/
/************************************************************
This is a base class for vertex converters that need to queue their
output. It is designed to be as fast as possible vs. the STL's queue
which is more flexible.
*/
template <int QueueSize>
class EmbeddedQueue
{
protected:
EmbeddedQueue() : m_queue_read(0), m_queue_write(0)
{
// empty
}
struct item
{
item()
{
}
inline void set(const unsigned cmd_, const double x_, const double y_)
{
cmd = cmd_;
x = x_;
y = y_;
}
unsigned cmd;
double x;
double y;
};
int m_queue_read;
int m_queue_write;
item m_queue[QueueSize];
inline void queue_push(const unsigned cmd, const double x, const double y)
{
m_queue[m_queue_write++].set(cmd, x, y);
}
inline bool queue_nonempty()
{
return m_queue_read < m_queue_write;
}
inline bool queue_pop(unsigned *cmd, double *x, double *y)
{
if (queue_nonempty()) {
const item &front = m_queue[m_queue_read++];
*cmd = front.cmd;
*x = front.x;
*y = front.y;
return true;
}
m_queue_read = 0;
m_queue_write = 0;
return false;
}
inline void queue_clear()
{
m_queue_read = 0;
m_queue_write = 0;
}
};
/* Defines when path segment types have more than one vertex */
static const size_t num_extra_points_map[] =
{0, 0, 0, 1,
2, 0, 0, 0,
0, 0, 0, 0,
0, 0, 0, 0
};
/* An implementation of a simple linear congruential random number
generator. This is a "classic" and fast RNG which works fine for
our purposes of sketching lines, but should not be used for things
that matter, like crypto. We are implementing this ourselves
rather than using the C stdlib so that the seed state is not shared
with other third-party code. There are recent C++ options, but we
still require nothing later than C++98 for compatibility
reasons. */
class RandomNumberGenerator
{
private:
/* These are the same constants from MS Visual C++, which
has the nice property that the modulus is 2^32, thus
saving an explicit modulo operation
*/
static const uint32_t a = 214013;
static const uint32_t c = 2531011;
uint32_t m_seed;
public:
RandomNumberGenerator() : m_seed(0) {}
RandomNumberGenerator(int seed) : m_seed(seed) {}
void seed(int seed)
{
m_seed = seed;
}
double get_double()
{
m_seed = (a * m_seed + c);
return (double)m_seed / (double)(1LL << 32);
}
};
/*
PathNanRemover is a vertex converter that removes non-finite values
from the vertices list, and inserts MOVETO commands as necessary to
skip over them. If a curve segment contains at least one non-finite
value, the entire curve segment will be skipped.
*/
template <class VertexSource>
class PathNanRemover : protected EmbeddedQueue<4>
{
VertexSource *m_source;
bool m_remove_nans;
bool m_has_curves;
bool valid_segment_exists;
public:
/* has_curves should be true if the path contains bezier curve
segments, as this requires a slower algorithm to remove the
NaNs. When in doubt, set to true.
*/
PathNanRemover(VertexSource &source, bool remove_nans, bool has_curves)
: m_source(&source), m_remove_nans(remove_nans), m_has_curves(has_curves)
{
// ignore all close/end_poly commands until after the first valid
// (nan-free) command is encountered
valid_segment_exists = false;
}
inline void rewind(unsigned path_id)
{
queue_clear();
m_source->rewind(path_id);
}
inline unsigned vertex(double *x, double *y)
{
unsigned code;
if (!m_remove_nans) {
return m_source->vertex(x, y);
}
if (m_has_curves) {
/* This is the slow method for when there might be curves. */
if (queue_pop(&code, x, y)) {
return code;
}
bool needs_move_to = false;
while (true) {
/* The approach here is to push each full curve
segment into the queue. If any non-finite values
are found along the way, the queue is emptied, and
the next curve segment is handled. */
code = m_source->vertex(x, y);
/* The vertices attached to STOP and CLOSEPOLY left are never
used, so we leave them as-is even if NaN. However, CLOSEPOLY
only makes sense if a valid MOVETO command has already been
emitted. */
if (code == agg::path_cmd_stop ||
(code == (agg::path_cmd_end_poly | agg::path_flags_close) &&
valid_segment_exists)) {
return code;
}
if (needs_move_to) {
queue_push(agg::path_cmd_move_to, *x, *y);
}
size_t num_extra_points = num_extra_points_map[code & 0xF];
bool has_nan = (!(std::isfinite(*x) && std::isfinite(*y)));
queue_push(code, *x, *y);
/* Note: this test can not be short-circuited, since we need to
advance through the entire curve no matter what */
for (size_t i = 0; i < num_extra_points; ++i) {
m_source->vertex(x, y);
has_nan = has_nan || !(std::isfinite(*x) && std::isfinite(*y));
queue_push(code, *x, *y);
}
if (!has_nan) {
valid_segment_exists = true;
break;
}
queue_clear();
/* If the last point is finite, we use that for the
moveto, otherwise, we'll use the first vertex of
the next curve. */
if (std::isfinite(*x) && std::isfinite(*y)) {
queue_push(agg::path_cmd_move_to, *x, *y);
needs_move_to = false;
} else {
needs_move_to = true;
}
}
if (queue_pop(&code, x, y)) {
return code;
} else {
return agg::path_cmd_stop;
}
} else // !m_has_curves
{
/* This is the fast path for when we know we have no curves */
code = m_source->vertex(x, y);
if (code == agg::path_cmd_stop ||
(code == (agg::path_cmd_end_poly | agg::path_flags_close) &&
valid_segment_exists)) {
return code;
}
if (!(std::isfinite(*x) && std::isfinite(*y))) {
do {
code = m_source->vertex(x, y);
if (code == agg::path_cmd_stop ||
(code == (agg::path_cmd_end_poly | agg::path_flags_close) &&
valid_segment_exists)) {
return code;
}
} while (!(std::isfinite(*x) && std::isfinite(*y)));
return agg::path_cmd_move_to;
}
valid_segment_exists = true;
return code;
}
}
};
/************************************************************
PathClipper uses the Liang-Barsky line clipping algorithm (as
implemented in Agg) to clip the path to a given rectangle. Lines
will never extend outside of the rectangle. Curve segments are not
clipped, but are always included in their entirety.
*/
template <class VertexSource>
class PathClipper : public EmbeddedQueue<3>
{
VertexSource *m_source;
bool m_do_clipping;
agg::rect_base<double> m_cliprect;
double m_lastX;
double m_lastY;
bool m_moveto;
double m_initX;
double m_initY;
bool m_has_init;
public:
PathClipper(VertexSource &source, bool do_clipping, double width, double height)
: m_source(&source),
m_do_clipping(do_clipping),
m_cliprect(-1.0, -1.0, width + 1.0, height + 1.0),
m_lastX(nan("")),
m_lastY(nan("")),
m_moveto(true),
m_initX(nan("")),
m_initY(nan("")),
m_has_init(false)
{
// empty
}
PathClipper(VertexSource &source, bool do_clipping, const agg::rect_base<double> &rect)
: m_source(&source),
m_do_clipping(do_clipping),
m_cliprect(rect),
m_lastX(nan("")),
m_lastY(nan("")),
m_moveto(true),
m_initX(nan("")),
m_initY(nan("")),
m_has_init(false)
{
m_cliprect.x1 -= 1.0;
m_cliprect.y1 -= 1.0;
m_cliprect.x2 += 1.0;
m_cliprect.y2 += 1.0;
}
inline void rewind(unsigned path_id)
{
m_has_init = false;
m_moveto = true;
m_source->rewind(path_id);
}
int draw_clipped_line(double x0, double y0, double x1, double y1)
{
unsigned moved = agg::clip_line_segment(&x0, &y0, &x1, &y1, m_cliprect);
// moved >= 4 - Fully clipped
// moved & 1 != 0 - First point has been moved
// moved & 2 != 0 - Second point has been moved
if (moved < 4) {
if (moved & 1 || m_moveto) {
queue_push(agg::path_cmd_move_to, x0, y0);
}
queue_push(agg::path_cmd_line_to, x1, y1);
m_moveto = false;
return 1;
}
return 0;
}
unsigned vertex(double *x, double *y)
{
unsigned code;
bool emit_moveto = false;
if (m_do_clipping) {
/* This is the slow path where we actually do clipping */
if (queue_pop(&code, x, y)) {
return code;
}
while ((code = m_source->vertex(x, y)) != agg::path_cmd_stop) {
emit_moveto = false;
switch (code) {
case (agg::path_cmd_end_poly | agg::path_flags_close):
if (m_has_init) {
draw_clipped_line(m_lastX, m_lastY, m_initX, m_initY);
}
queue_push(
agg::path_cmd_end_poly | agg::path_flags_close,
m_lastX, m_lastY);
goto exit_loop;
case agg::path_cmd_move_to:
// was the last command a moveto (and we have
// seen at least one command ?
// if so, shove it in the queue if in clip box
if (m_moveto && m_has_init &&
m_lastX >= m_cliprect.x1 &&
m_lastX <= m_cliprect.x2 &&
m_lastY >= m_cliprect.y1 &&
m_lastY <= m_cliprect.y2) {
// push the last moveto onto the queue
queue_push(agg::path_cmd_move_to, m_lastX, m_lastY);
// flag that we need to emit it
emit_moveto = true;
}
// update the internal state for this moveto
m_initX = m_lastX = *x;
m_initY = m_lastY = *y;
m_has_init = true;
m_moveto = true;
// if the last command was moveto exit the loop to emit the code
if (emit_moveto) {
goto exit_loop;
}
// else, break and get the next point
break;
case agg::path_cmd_line_to:
if (draw_clipped_line(m_lastX, m_lastY, *x, *y)) {
m_lastX = *x;
m_lastY = *y;
goto exit_loop;
}
m_lastX = *x;
m_lastY = *y;
break;
default:
if (m_moveto) {
queue_push(agg::path_cmd_move_to, m_lastX, m_lastY);
m_moveto = false;
}
queue_push(code, *x, *y);
m_lastX = *x;
m_lastY = *y;
goto exit_loop;
}
}
exit_loop:
if (queue_pop(&code, x, y)) {
return code;
}
if (m_moveto && m_has_init &&
m_lastX >= m_cliprect.x1 &&
m_lastX <= m_cliprect.x2 &&
m_lastY >= m_cliprect.y1 &&
m_lastY <= m_cliprect.y2) {
*x = m_lastX;
*y = m_lastY;
m_moveto = false;
return agg::path_cmd_move_to;
}
return agg::path_cmd_stop;
} else {
// If not doing any clipping, just pass along the vertices
// verbatim
return m_source->vertex(x, y);
}
}
};
/************************************************************
PathSnapper rounds vertices to their nearest center-pixels. This
makes rectilinear paths (rectangles, horizontal and vertical lines
etc.) look much cleaner.
*/
enum e_snap_mode {
SNAP_AUTO,
SNAP_FALSE,
SNAP_TRUE
};
template <class VertexSource>
class PathSnapper
{
private:
VertexSource *m_source;
bool m_snap;
double m_snap_value;
static bool should_snap(VertexSource &path, e_snap_mode snap_mode, unsigned total_vertices)
{
// If this contains only straight horizontal or vertical lines, it should be
// snapped to the nearest pixels
double x0 = 0, y0 = 0, x1 = 0, y1 = 0;
unsigned code;
switch (snap_mode) {
case SNAP_AUTO:
if (total_vertices > 1024) {
return false;
}
code = path.vertex(&x0, &y0);
if (code == agg::path_cmd_stop) {
return false;
}
while ((code = path.vertex(&x1, &y1)) != agg::path_cmd_stop) {
switch (code) {
case agg::path_cmd_curve3:
case agg::path_cmd_curve4:
return false;
case agg::path_cmd_line_to:
if (fabs(x0 - x1) >= 1e-4 && fabs(y0 - y1) >= 1e-4) {
return false;
}
}
x0 = x1;
y0 = y1;
}
return true;
case SNAP_FALSE:
return false;
case SNAP_TRUE:
return true;
}
return false;
}
public:
/*
snap_mode should be one of:
- SNAP_AUTO: Examine the path to determine if it should be snapped
- SNAP_TRUE: Force snapping
- SNAP_FALSE: No snapping
*/
PathSnapper(VertexSource &source,
e_snap_mode snap_mode,
unsigned total_vertices = 15,
double stroke_width = 0.0)
: m_source(&source)
{
m_snap = should_snap(source, snap_mode, total_vertices);
if (m_snap) {
int is_odd = (int)mpl_round(stroke_width) % 2;
m_snap_value = (is_odd) ? 0.5 : 0.0;
}
source.rewind(0);
}
inline void rewind(unsigned path_id)
{
m_source->rewind(path_id);
}
inline unsigned vertex(double *x, double *y)
{
unsigned code;
code = m_source->vertex(x, y);
if (m_snap && agg::is_vertex(code)) {
*x = floor(*x + 0.5) + m_snap_value;
*y = floor(*y + 0.5) + m_snap_value;
}
return code;
}
inline bool is_snapping()
{
return m_snap;
}
};
/************************************************************
PathSimplifier reduces the number of vertices in a dense path without
changing its appearance.
*/
template <class VertexSource>
class PathSimplifier : protected EmbeddedQueue<9>
{
public:
/* Set simplify to true to perform simplification */
PathSimplifier(VertexSource &source, bool do_simplify, double simplify_threshold)
: m_source(&source),
m_simplify(do_simplify),
/* we square simplify_threshold so that we can compute
norms without doing the square root every step. */
m_simplify_threshold(simplify_threshold * simplify_threshold),
m_moveto(true),
m_after_moveto(false),
m_clipped(false),
// the x, y values from last iteration
m_lastx(0.0),
m_lasty(0.0),
// the dx, dy comprising the original vector, used in conjunction
// with m_currVecStart* to define the original vector.
m_origdx(0.0),
m_origdy(0.0),
// the squared norm of the original vector
m_origdNorm2(0.0),
// maximum squared norm of vector in forward (parallel) direction
m_dnorm2ForwardMax(0.0),
// maximum squared norm of vector in backward (anti-parallel) direction
m_dnorm2BackwardMax(0.0),
// was the last point the furthest from lastWritten in the
// forward (parallel) direction?
m_lastForwardMax(false),
// was the last point the furthest from lastWritten in the
// backward (anti-parallel) direction?
m_lastBackwardMax(false),
// added to queue when _push is called
m_nextX(0.0),
m_nextY(0.0),
// added to queue when _push is called if any backwards
// (anti-parallel) vectors were observed
m_nextBackwardX(0.0),
m_nextBackwardY(0.0),
// start of the current vector that is being simplified
m_currVecStartX(0.0),
m_currVecStartY(0.0)
{
// empty
}
inline void rewind(unsigned path_id)
{
queue_clear();
m_moveto = true;
m_source->rewind(path_id);
}
unsigned vertex(double *x, double *y)
{
unsigned cmd;
/* The simplification algorithm doesn't support curves or compound paths
so we just don't do it at all in that case... */
if (!m_simplify) {
return m_source->vertex(x, y);
}
/* idea: we can skip drawing many lines: we can combine
sequential parallel lines into a
single line instead of redrawing lines over the same
points. The loop below works a bit like a state machine,
where what it does depends on what it did in the last
looping. To test whether sequential lines are close to
parallel, I calculate the distance moved perpendicular to
the last line. Once it gets too big, the lines cannot be
combined. */
/* This code was originally written by Allan Haldane and I
have modified to work in-place -- meaning not creating an
entirely new path list each time. In order to do that
without too much additional code complexity, it keeps a
small queue around so that multiple points can be emitted
in a single call, and those points will be popped from the
queue in subsequent calls. The following block will empty
the queue before proceeding to the main loop below.
-- Michael Droettboom */
/* This code was originally written by Allan Haldane and
updated by Michael Droettboom. I have modified it to
handle anti-parallel vectors. This is done essentially
the same way as parallel vectors, but requires a little
additional book-keeping to track whether or not we have
observed an anti-parallel vector during the current run.
-- Kevin Rose */
if (queue_pop(&cmd, x, y)) {
return cmd;
}
/* The main simplification loop. The point is to consume only
as many points as necessary until something has been added
to the outbound queue, not to run through the entire path
in one go. This eliminates the need to allocate and fill
an entire additional path array on each draw. */
while ((cmd = m_source->vertex(x, y)) != agg::path_cmd_stop) {
/* if we are starting a new path segment, move to the first point
+ init */
if (m_moveto || cmd == agg::path_cmd_move_to) {
/* m_moveto check is not generally needed because
m_source generates an initial moveto; but it is
retained for safety in case circumstances arise
where this is not true. */
if (m_origdNorm2 != 0.0 && !m_after_moveto) {
/* m_origdNorm2 is nonzero only if we have a
vector; the m_after_moveto check ensures we
push this vector to the queue only once. */
_push(x, y);
}
m_after_moveto = true;
m_lastx = *x;
m_lasty = *y;
m_moveto = false;
m_origdNorm2 = 0.0;
m_dnorm2BackwardMax = 0.0;
m_clipped = true;
if (queue_nonempty()) {
/* If we did a push, empty the queue now. */
break;
}
continue;
}
m_after_moveto = false;
/* NOTE: We used to skip this very short segments, but if
you have a lot of them cumulatively, you can miss
maxima or minima in the data. */
/* Don't render line segments less than one pixel long */
/* if (fabs(*x - m_lastx) < 1.0 && fabs(*y - m_lasty) < 1.0) */
/* { */
/* continue; */
/* } */
/* if we have no orig vector, set it to this vector and
continue. this orig vector is the reference vector we
will build up the line to */
if (m_origdNorm2 == 0.0) {
if (m_clipped) {
queue_push(agg::path_cmd_move_to, m_lastx, m_lasty);
m_clipped = false;
}
m_origdx = *x - m_lastx;
m_origdy = *y - m_lasty;
m_origdNorm2 = m_origdx * m_origdx + m_origdy * m_origdy;
// set all the variables to reflect this new orig vector
m_dnorm2ForwardMax = m_origdNorm2;
m_dnorm2BackwardMax = 0.0;
m_lastForwardMax = true;
m_lastBackwardMax = false;
m_currVecStartX = m_lastx;
m_currVecStartY = m_lasty;
m_nextX = m_lastx = *x;
m_nextY = m_lasty = *y;
continue;
}
/* If got to here, then we have an orig vector and we just got
a vector in the sequence. */
/* Check that the perpendicular distance we have moved
from the last written point compared to the line we are
building is not too much. If o is the orig vector (we
are building on), and v is the vector from the last
written point to the current point, then the
perpendicular vector is p = v - (o.v)o/(o.o)
(here, a.b indicates the dot product of a and b). */
/* get the v vector */
double totdx = *x - m_currVecStartX;
double totdy = *y - m_currVecStartY;
/* get the dot product o.v */
double totdot = m_origdx * totdx + m_origdy * totdy;
/* get the para vector ( = (o.v)o/(o.o)) */
double paradx = totdot * m_origdx / m_origdNorm2;
double parady = totdot * m_origdy / m_origdNorm2;
/* get the perp vector ( = v - para) */
double perpdx = totdx - paradx;
double perpdy = totdy - parady;
/* get the squared norm of perp vector ( = p.p) */
double perpdNorm2 = perpdx * perpdx + perpdy * perpdy;
/* If the perpendicular vector is less than
m_simplify_threshold pixels in size, then merge
current x,y with the current vector */
if (perpdNorm2 < m_simplify_threshold) {
/* check if the current vector is parallel or
anti-parallel to the orig vector. In either case,
test if it is the longest of the vectors
we are merging in that direction. If it is, then
update the current vector in that direction. */
double paradNorm2 = paradx * paradx + parady * parady;
m_lastForwardMax = false;
m_lastBackwardMax = false;
if (totdot > 0.0) {
if (paradNorm2 > m_dnorm2ForwardMax) {
m_lastForwardMax = true;
m_dnorm2ForwardMax = paradNorm2;
m_nextX = *x;
m_nextY = *y;
}
} else {
if (paradNorm2 > m_dnorm2BackwardMax) {
m_lastBackwardMax = true;
m_dnorm2BackwardMax = paradNorm2;
m_nextBackwardX = *x;
m_nextBackwardY = *y;
}
}
m_lastx = *x;
m_lasty = *y;
continue;
}
/* If we get here, then this vector was not similar enough to the
line we are building, so we need to draw that line and start the
next one. */
/* If the line needs to extend in the opposite direction from the
direction we are drawing in, move back to we start drawing from
back there. */
_push(x, y);
break;
}
/* Fill the queue with the remaining vertices if we've finished the
path in the above loop. */
if (cmd == agg::path_cmd_stop) {
if (m_origdNorm2 != 0.0) {
queue_push((m_moveto || m_after_moveto) ? agg::path_cmd_move_to
: agg::path_cmd_line_to,
m_nextX,
m_nextY);
if (m_dnorm2BackwardMax > 0.0) {
queue_push((m_moveto || m_after_moveto) ? agg::path_cmd_move_to
: agg::path_cmd_line_to,
m_nextBackwardX,
m_nextBackwardY);
}
m_moveto = false;
}
queue_push((m_moveto || m_after_moveto) ? agg::path_cmd_move_to : agg::path_cmd_line_to,
m_lastx,
m_lasty);
m_moveto = false;
queue_push(agg::path_cmd_stop, 0.0, 0.0);
}
/* Return the first item in the queue, if any, otherwise
indicate that we're done. */
if (queue_pop(&cmd, x, y)) {
return cmd;
} else {
return agg::path_cmd_stop;
}
}
private:
VertexSource *m_source;
bool m_simplify;
double m_simplify_threshold;
bool m_moveto;
bool m_after_moveto;
bool m_clipped;
double m_lastx, m_lasty;
double m_origdx;
double m_origdy;
double m_origdNorm2;
double m_dnorm2ForwardMax;
double m_dnorm2BackwardMax;
bool m_lastForwardMax;
bool m_lastBackwardMax;
double m_nextX;
double m_nextY;
double m_nextBackwardX;
double m_nextBackwardY;
double m_currVecStartX;
double m_currVecStartY;
inline void _push(double *x, double *y)
{
bool needToPushBack = (m_dnorm2BackwardMax > 0.0);
/* If we observed any backward (anti-parallel) vectors, then
we need to push both forward and backward vectors. */
if (needToPushBack) {
/* If the last vector seen was the maximum in the forward direction,
then we need to push the forward after the backward. Otherwise,
the last vector seen was the maximum in the backward direction,
or somewhere in between, either way we are safe pushing forward
before backward. */
if (m_lastForwardMax) {
queue_push(agg::path_cmd_line_to, m_nextBackwardX, m_nextBackwardY);
queue_push(agg::path_cmd_line_to, m_nextX, m_nextY);
} else {
queue_push(agg::path_cmd_line_to, m_nextX, m_nextY);
queue_push(agg::path_cmd_line_to, m_nextBackwardX, m_nextBackwardY);
}
} else {
/* If we did not observe any backwards vectors, just push forward. */
queue_push(agg::path_cmd_line_to, m_nextX, m_nextY);
}
/* If we clipped some segments between this line and the next line
we are starting, we also need to move to the last point. */
if (m_clipped) {
queue_push(agg::path_cmd_move_to, m_lastx, m_lasty);
} else if ((!m_lastForwardMax) && (!m_lastBackwardMax)) {
/* If the last line was not the longest line, then move
back to the end point of the last line in the
sequence. Only do this if not clipped, since in that
case lastx,lasty is not part of the line just drawn. */
/* Would be move_to if not for the artifacts */
queue_push(agg::path_cmd_line_to, m_lastx, m_lasty);
}
/* Now reset all the variables to get ready for the next line */
m_origdx = *x - m_lastx;
m_origdy = *y - m_lasty;
m_origdNorm2 = m_origdx * m_origdx + m_origdy * m_origdy;
m_dnorm2ForwardMax = m_origdNorm2;
m_lastForwardMax = true;
m_currVecStartX = m_queue[m_queue_write - 1].x;
m_currVecStartY = m_queue[m_queue_write - 1].y;
m_lastx = m_nextX = *x;
m_lasty = m_nextY = *y;
m_dnorm2BackwardMax = 0.0;
m_lastBackwardMax = false;
m_clipped = false;
}
};
template <class VertexSource>
class Sketch
{
public:
/*
scale: the scale of the wiggle perpendicular to the original
line (in pixels)
length: the base wavelength of the wiggle along the
original line (in pixels)
randomness: the factor that the sketch length will randomly
shrink and expand.
*/
Sketch(VertexSource &source, double scale, double length, double randomness)
: m_source(&source),
m_scale(scale),
m_length(length),
m_randomness(randomness),
m_segmented(source),
m_last_x(0.0),
m_last_y(0.0),
m_has_last(false),
m_p(0.0),
m_rand(0)
{
rewind(0);
}
unsigned vertex(double *x, double *y)
{
if (m_scale == 0.0) {
return m_source->vertex(x, y);
}
unsigned code = m_segmented.vertex(x, y);
if (code == agg::path_cmd_move_to) {
m_has_last = false;
m_p = 0.0;
}
if (m_has_last) {
// We want the "cursor" along the sine wave to move at a
// random rate.
double d_rand = m_rand.get_double();
double d_M_PI = 3.14159265358979323846;
m_p += pow(m_randomness, d_rand * 2.0 - 1.0);
double r = sin(m_p / (m_length / (d_M_PI * 2.0))) * m_scale;
double den = m_last_x - *x;
double num = m_last_y - *y;
double len = num * num + den * den;
m_last_x = *x;
m_last_y = *y;
if (len != 0) {
len = sqrt(len);
*x += r * num / len;
*y += r * -den / len;
}
} else {
m_last_x = *x;
m_last_y = *y;
}
m_has_last = true;
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