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/* libs/graphics/effects/SkCullPoints.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 "SkCullPoints.h"
#include "Sk64.h"
static bool cross_product_is_neg(const SkIPoint& v, int dx, int dy)
{
#if 0
return v.fX * dy - v.fY * dx < 0;
#else
Sk64 tmp0, tmp1;
tmp0.setMul(v.fX, dy);
tmp1.setMul(dx, v.fY);
tmp0.sub(tmp1);
return tmp0.isNeg();
#endif
}
bool SkCullPoints::sect_test(int x0, int y0, int x1, int y1) const
{
const SkIRect& r = fR;
if (x0 < r.fLeft && x1 < r.fLeft ||
x0 > r.fRight && x1 > r.fRight ||
y0 < r.fTop && y1 < r.fTop ||
y0 > r.fBottom && y1 > r.fBottom)
return false;
// since the crossprod test is a little expensive, check for easy-in cases first
if (r.contains(x0, y0) || r.contains(x1, y1))
return true;
// At this point we're not sure, so we do a crossprod test
SkIPoint vec;
const SkIPoint* rAsQuad = fAsQuad;
vec.set(x1 - x0, y1 - y0);
bool isNeg = cross_product_is_neg(vec, x0 - rAsQuad[0].fX, y0 - rAsQuad[0].fY);
for (int i = 1; i < 4; i++) {
if (cross_product_is_neg(vec, x0 - rAsQuad[i].fX, y0 - rAsQuad[i].fY) != isNeg)
{
return true;
}
}
return false; // we didn't intersect
}
static void toQuad(const SkIRect& r, SkIPoint quad[4])
{
SkASSERT(quad);
quad[0].set(r.fLeft, r.fTop);
quad[1].set(r.fRight, r.fTop);
quad[2].set(r.fRight, r.fBottom);
quad[3].set(r.fLeft, r.fBottom);
}
SkCullPoints::SkCullPoints()
{
SkIRect r;
r.setEmpty();
this->reset(r);
}
SkCullPoints::SkCullPoints(const SkIRect& r)
{
this->reset(r);
}
void SkCullPoints::reset(const SkIRect& r)
{
fR = r;
toQuad(fR, fAsQuad);
fPrevPt.set(0, 0);
fPrevResult = kNo_Result;
}
void SkCullPoints::moveTo(int x, int y)
{
fPrevPt.set(x, y);
fPrevResult = kNo_Result; // so we trigger a movetolineto later
}
SkCullPoints::LineToResult SkCullPoints::lineTo(int x, int y, SkIPoint line[])
{
SkASSERT(line != NULL);
LineToResult result = kNo_Result;
int x0 = fPrevPt.fX;
int y0 = fPrevPt.fY;
// need to upgrade sect_test to chop the result
// and to correctly return kLineTo_Result when the result is connected
// to the previous call-out
if (this->sect_test(x0, y0, x, y))
{
line[0].set(x0, y0);
line[1].set(x, y);
if (fPrevResult != kNo_Result && fPrevPt.equals(x0, y0))
result = kLineTo_Result;
else
result = kMoveToLineTo_Result;
}
fPrevPt.set(x, y);
fPrevResult = result;
return result;
}
/////////////////////////////////////////////////////////////////////////////////////////////////
#include "SkPath.h"
SkCullPointsPath::SkCullPointsPath()
: fCP(), fPath(NULL)
{
}
SkCullPointsPath::SkCullPointsPath(const SkIRect& r, SkPath* dst)
: fCP(r), fPath(dst)
{
}
void SkCullPointsPath::reset(const SkIRect& r, SkPath* dst)
{
fCP.reset(r);
fPath = dst;
}
void SkCullPointsPath::moveTo(int x, int y)
{
fCP.moveTo(x, y);
}
void SkCullPointsPath::lineTo(int x, int y)
{
SkIPoint pts[2];
switch (fCP.lineTo(x, y, pts)) {
case SkCullPoints::kMoveToLineTo_Result:
fPath->moveTo(SkIntToScalar(pts[0].fX), SkIntToScalar(pts[0].fY));
// fall through to the lineto case
case SkCullPoints::kLineTo_Result:
fPath->lineTo(SkIntToScalar(pts[1].fX), SkIntToScalar(pts[1].fY));
break;
default:
break;
}
}
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