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/* libs/graphics/animator/SkSVGPath.cpp
**
** Copyright 2006, The Android Open Source Project
**
** Licensed under the Apache License, Version 2.0 (the "License");
** you may not use this file except in compliance with the License.
** You may obtain a copy of the License at
**
** http://www.apache.org/licenses/LICENSE-2.0
**
** Unless required by applicable law or agreed to in writing, software
** distributed under the License is distributed on an "AS IS" BASIS,
** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
** See the License for the specific language governing permissions and
** limitations under the License.
*/
#include <ctype.h>
#include "SkDrawPath.h"
#include "SkParse.h"
#include "SkPoint.h"
#include "SkUtils.h"
#define QUADRATIC_APPROXIMATION 1
#if QUADRATIC_APPROXIMATION
////////////////////////////////////////////////////////////////////////////////////
//functions to approximate a cubic using two quadratics
// midPt sets the first argument to be the midpoint of the other two
// it is used by quadApprox
static inline void midPt(SkPoint& dest,const SkPoint& a,const SkPoint& b)
{
dest.set(SkScalarAve(a.fX, b.fX),SkScalarAve(a.fY, b.fY));
}
// quadApprox - makes an approximation, which we hope is faster
static void quadApprox(SkPath &fPath, const SkPoint &p0, const SkPoint &p1, const SkPoint &p2)
{
//divide the cubic up into two cubics, then convert them into quadratics
//define our points
SkPoint c,j,k,l,m,n,o,p,q, mid;
fPath.getLastPt(&c);
midPt(j, p0, c);
midPt(k, p0, p1);
midPt(l, p1, p2);
midPt(o, j, k);
midPt(p, k, l);
midPt(q, o, p);
//compute the first half
m.set(SkScalarHalf(3*j.fX - c.fX), SkScalarHalf(3*j.fY - c.fY));
n.set(SkScalarHalf(3*o.fX -q.fX), SkScalarHalf(3*o.fY - q.fY));
midPt(mid,m,n);
fPath.quadTo(mid,q);
c = q;
//compute the second half
m.set(SkScalarHalf(3*p.fX - c.fX), SkScalarHalf(3*p.fY - c.fY));
n.set(SkScalarHalf(3*l.fX -p2.fX),SkScalarHalf(3*l.fY -p2.fY));
midPt(mid,m,n);
fPath.quadTo(mid,p2);
}
#endif
static inline bool is_between(int c, int min, int max)
{
return (unsigned)(c - min) <= (unsigned)(max - min);
}
static inline bool is_ws(int c)
{
return is_between(c, 1, 32);
}
static inline bool is_digit(int c)
{
return is_between(c, '0', '9');
}
static inline bool is_sep(int c)
{
return is_ws(c) || c == ',';
}
static const char* skip_ws(const char str[])
{
SkASSERT(str);
while (is_ws(*str))
str++;
return str;
}
static const char* skip_sep(const char str[])
{
SkASSERT(str);
while (is_sep(*str))
str++;
return str;
}
static const char* find_points(const char str[], SkPoint value[], int count,
bool isRelative, SkPoint* relative)
{
str = SkParse::FindScalars(str, &value[0].fX, count * 2);
if (isRelative) {
for (int index = 0; index < count; index++) {
value[index].fX += relative->fX;
value[index].fY += relative->fY;
}
}
return str;
}
static const char* find_scalar(const char str[], SkScalar* value,
bool isRelative, SkScalar relative)
{
str = SkParse::FindScalar(str, value);
if (isRelative)
*value += relative;
return str;
}
void SkDrawPath::parseSVG() {
fPath.reset();
const char* data = d.c_str();
SkPoint f = {0, 0};
SkPoint c = {0, 0};
SkPoint lastc = {0, 0};
SkPoint points[3];
char op = '\0';
char previousOp = '\0';
bool relative = false;
do {
data = skip_ws(data);
if (data[0] == '\0')
break;
char ch = data[0];
if (is_digit(ch) || ch == '-' || ch == '+') {
if (op == '\0')
return;
}
else {
op = ch;
relative = false;
if (islower(op)) {
op = (char) toupper(op);
relative = true;
}
data++;
data = skip_sep(data);
}
switch (op) {
case 'M':
data = find_points(data, points, 1, relative, &c);
fPath.moveTo(points[0]);
op = 'L';
c = points[0];
break;
case 'L':
data = find_points(data, points, 1, relative, &c);
fPath.lineTo(points[0]);
c = points[0];
break;
case 'H': {
SkScalar x;
data = find_scalar(data, &x, relative, c.fX);
fPath.lineTo(x, c.fY);
c.fX = x;
}
break;
case 'V': {
SkScalar y;
data = find_scalar(data, &y, relative, c.fY);
fPath.lineTo(c.fX, y);
c.fY = y;
}
break;
case 'C':
data = find_points(data, points, 3, relative, &c);
goto cubicCommon;
case 'S':
data = find_points(data, &points[1], 2, relative, &c);
points[0] = c;
if (previousOp == 'C' || previousOp == 'S') {
points[0].fX -= lastc.fX - c.fX;
points[0].fY -= lastc.fY - c.fY;
}
cubicCommon:
// if (data[0] == '\0')
// return;
#if QUADRATIC_APPROXIMATION
quadApprox(fPath, points[0], points[1], points[2]);
#else //this way just does a boring, slow old cubic
fPath.cubicTo(points[0], points[1], points[2]);
#endif
//if we are using the quadApprox, lastc is what it would have been if we had used
//cubicTo
lastc = points[1];
c = points[2];
break;
case 'Q': // Quadratic Bezier Curve
data = find_points(data, points, 2, relative, &c);
goto quadraticCommon;
case 'T':
data = find_points(data, &points[1], 1, relative, &c);
points[0] = points[1];
if (previousOp == 'Q' || previousOp == 'T') {
points[0].fX = c.fX * 2 - lastc.fX;
points[0].fY = c.fY * 2 - lastc.fY;
}
quadraticCommon:
fPath.quadTo(points[0], points[1]);
lastc = points[0];
c = points[1];
break;
case 'Z':
fPath.close();
#if 0 // !!! still a bug?
if (fPath.isEmpty() && (f.fX != 0 || f.fY != 0)) {
c.fX -= SkScalar.Epsilon; // !!! enough?
fPath.moveTo(c);
fPath.lineTo(f);
fPath.close();
}
#endif
c = f;
op = '\0';
break;
case '~': {
SkPoint args[2];
data = find_points(data, args, 2, false, NULL);
fPath.moveTo(args[0].fX, args[0].fY);
fPath.lineTo(args[1].fX, args[1].fY);
}
break;
default:
SkASSERT(0);
return;
}
if (previousOp == 0)
f = c;
previousOp = op;
} while (data[0] > 0);
}
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