gecko-dev/gfx/thebes/gfxPath.cpp

112 строки
3.2 KiB
C++

/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "gfxPath.h"
#include "gfxPoint.h"
#include "cairo.h"
gfxPath::gfxPath(cairo_path_t* aPath) : mPath(aPath)
{
}
gfxPath::~gfxPath()
{
cairo_path_destroy(mPath);
}
gfxFlattenedPath::gfxFlattenedPath(cairo_path_t* aPath) : gfxPath(aPath)
{
}
gfxFlattenedPath::~gfxFlattenedPath()
{
}
static gfxFloat
CalcSubLengthAndAdvance(cairo_path_data_t *aData,
gfxPoint &aPathStart, gfxPoint &aCurrent)
{
float sublength = 0;
switch (aData->header.type) {
case CAIRO_PATH_MOVE_TO:
{
aCurrent = aPathStart = gfxPoint(aData[1].point.x,
aData[1].point.y);
break;
}
case CAIRO_PATH_LINE_TO:
{
gfxPoint diff =
gfxPoint(aData[1].point.x, aData[1].point.y) - aCurrent;
sublength = sqrt(diff.x * diff.x + diff.y * diff.y);
aCurrent = gfxPoint(aData[1].point.x, aData[1].point.y);
break;
}
case CAIRO_PATH_CURVE_TO:
/* should never happen with a flattened path */
NS_WARNING("curve_to in flattened path");
break;
case CAIRO_PATH_CLOSE_PATH:
{
gfxPoint diff = aPathStart - aCurrent;
sublength = sqrt(diff.x * diff.x + diff.y * diff.y);
aCurrent = aPathStart;
break;
}
}
return sublength;
}
gfxFloat
gfxFlattenedPath::GetLength()
{
gfxPoint start(0, 0); // start of current subpath
gfxPoint current(0, 0); // current point
gfxFloat length = 0; // current summed length
for (PRInt32 i = 0;
i < mPath->num_data;
i += mPath->data[i].header.length) {
length += CalcSubLengthAndAdvance(&mPath->data[i], start, current);
}
return length;
}
gfxPoint
gfxFlattenedPath::FindPoint(gfxPoint aOffset, gfxFloat *aAngle)
{
gfxPoint start(0, 0); // start of current subpath
gfxPoint current(0, 0); // current point
gfxFloat length = 0; // current summed length
for (PRInt32 i = 0;
i < mPath->num_data;
i += mPath->data[i].header.length) {
gfxPoint prev = current;
gfxFloat sublength = CalcSubLengthAndAdvance(&mPath->data[i],
start, current);
gfxPoint diff = current - prev;
if (aAngle)
*aAngle = atan2(diff.y, diff.x);
if (sublength != 0 && length + sublength >= aOffset.x) {
gfxFloat ratio = (aOffset.x - length) / sublength;
gfxFloat normalization =
1.0 / sqrt(diff.x * diff.x + diff.y * diff.y);
return prev * (1.0f - ratio) + current * ratio +
gfxPoint(-diff.y, diff.x) * aOffset.y * normalization;
}
length += sublength;
}
// requested offset is past the end of the path - return last point
return current;
}