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gecko-dev/dom/svg/SVGPathSegUtils.h

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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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/. */
#ifndef MOZILLA_SVGPATHSEGUTILS_H__
#define MOZILLA_SVGPATHSEGUTILS_H__
#include "mozilla/ArrayUtils.h"
#include "mozilla/gfx/Point.h"
#include "nsDebug.h"
namespace mozilla {
// Path Segment Types
static const unsigned short PATHSEG_UNKNOWN = 0;
static const unsigned short PATHSEG_CLOSEPATH = 1;
static const unsigned short PATHSEG_MOVETO_ABS = 2;
static const unsigned short PATHSEG_MOVETO_REL = 3;
static const unsigned short PATHSEG_LINETO_ABS = 4;
static const unsigned short PATHSEG_LINETO_REL = 5;
static const unsigned short PATHSEG_CURVETO_CUBIC_ABS = 6;
static const unsigned short PATHSEG_CURVETO_CUBIC_REL = 7;
static const unsigned short PATHSEG_CURVETO_QUADRATIC_ABS = 8;
static const unsigned short PATHSEG_CURVETO_QUADRATIC_REL = 9;
static const unsigned short PATHSEG_ARC_ABS = 10;
static const unsigned short PATHSEG_ARC_REL = 11;
static const unsigned short PATHSEG_LINETO_HORIZONTAL_ABS = 12;
static const unsigned short PATHSEG_LINETO_HORIZONTAL_REL = 13;
static const unsigned short PATHSEG_LINETO_VERTICAL_ABS = 14;
static const unsigned short PATHSEG_LINETO_VERTICAL_REL = 15;
static const unsigned short PATHSEG_CURVETO_CUBIC_SMOOTH_ABS = 16;
static const unsigned short PATHSEG_CURVETO_CUBIC_SMOOTH_REL = 17;
static const unsigned short PATHSEG_CURVETO_QUADRATIC_SMOOTH_ABS = 18;
static const unsigned short PATHSEG_CURVETO_QUADRATIC_SMOOTH_REL = 19;
#define NS_SVG_PATH_SEG_MAX_ARGS 7
#define NS_SVG_PATH_SEG_FIRST_VALID_TYPE mozilla::PATHSEG_CLOSEPATH
#define NS_SVG_PATH_SEG_LAST_VALID_TYPE mozilla::PATHSEG_CURVETO_QUADRATIC_SMOOTH_REL
#define NS_SVG_PATH_SEG_TYPE_COUNT (NS_SVG_PATH_SEG_LAST_VALID_TYPE + 1)
/**
* Code that works with path segments can use an instance of this class to
* store/provide information about the start of the current subpath and the
* last path segment (if any).
*/
struct SVGPathTraversalState
{
typedef gfx::Point Point;
enum TraversalMode {
eUpdateAll,
eUpdateOnlyStartAndCurrentPos
};
SVGPathTraversalState()
: start(0.0, 0.0)
, pos(0.0, 0.0)
, cp1(0.0, 0.0)
, cp2(0.0, 0.0)
, length(0.0)
, mode(eUpdateAll)
{}
bool ShouldUpdateLengthAndControlPoints() { return mode == eUpdateAll; }
Point start; // start point of current sub path (reset each moveto)
Point pos; // current position (end point of previous segment)
Point cp1; // quadratic control point - if the previous segment was a
// quadratic bezier curve then this is set to the absolute
// position of its control point, otherwise its set to pos
Point cp2; // cubic control point - if the previous segment was a cubic
// bezier curve then this is set to the absolute position of
// its second control point, otherwise it's set to pos
float length; // accumulated path length
TraversalMode mode; // indicates what to track while traversing a path
};
/**
* This class is just a collection of static methods - it doesn't have any data
* members, and it's not possible to create instances of this class. This class
* exists purely as a convenient place to gather together a bunch of methods
* related to manipulating and answering questions about path segments.
* Internally we represent path segments purely as an array of floats. See the
* comment documenting SVGPathData for more info on that.
*
* The DOM wrapper classes for encoded path segments (data contained in
* instances of SVGPathData) is DOMSVGPathSeg and its sub-classes. Note that
* there are multiple different DOM classes for path segs - one for each of the
* 19 SVG 1.1 segment types.
*/
class SVGPathSegUtils
{
private:
SVGPathSegUtils(){} // private to prevent instances
public:
static void GetValueAsString(const float *aSeg, nsAString& aValue);
/**
* Encode a segment type enum to a float.
*
* At some point in the future we will likely want to encode other
* information into the float, such as whether the command was explicit or
* not. For now all this method does is save on int to float runtime
* conversion by requiring uint32_t and float to be of the same size so we
* can simply do a bitwise uint32_t<->float copy.
*/
static float EncodeType(uint32_t aType) {
static_assert(sizeof(uint32_t) == sizeof(float), "sizeof uint32_t and float must be the same");
MOZ_ASSERT(IsValidType(aType), "Seg type not recognized");
return *(reinterpret_cast<float*>(&aType));
}
static uint32_t DecodeType(float aType) {
static_assert(sizeof(uint32_t) == sizeof(float), "sizeof uint32_t and float must be the same");
uint32_t type = *(reinterpret_cast<uint32_t*>(&aType));
MOZ_ASSERT(IsValidType(type), "Seg type not recognized");
return type;
}
static char16_t GetPathSegTypeAsLetter(uint32_t aType) {
MOZ_ASSERT(IsValidType(aType), "Seg type not recognized");
static const char16_t table[] = {
char16_t('x'), // 0 == PATHSEG_UNKNOWN
char16_t('z'), // 1 == PATHSEG_CLOSEPATH
char16_t('M'), // 2 == PATHSEG_MOVETO_ABS
char16_t('m'), // 3 == PATHSEG_MOVETO_REL
char16_t('L'), // 4 == PATHSEG_LINETO_ABS
char16_t('l'), // 5 == PATHSEG_LINETO_REL
char16_t('C'), // 6 == PATHSEG_CURVETO_CUBIC_ABS
char16_t('c'), // 7 == PATHSEG_CURVETO_CUBIC_REL
char16_t('Q'), // 8 == PATHSEG_CURVETO_QUADRATIC_ABS
char16_t('q'), // 9 == PATHSEG_CURVETO_QUADRATIC_REL
char16_t('A'), // 10 == PATHSEG_ARC_ABS
char16_t('a'), // 11 == PATHSEG_ARC_REL
char16_t('H'), // 12 == PATHSEG_LINETO_HORIZONTAL_ABS
char16_t('h'), // 13 == PATHSEG_LINETO_HORIZONTAL_REL
char16_t('V'), // 14 == PATHSEG_LINETO_VERTICAL_ABS
char16_t('v'), // 15 == PATHSEG_LINETO_VERTICAL_REL
char16_t('S'), // 16 == PATHSEG_CURVETO_CUBIC_SMOOTH_ABS
char16_t('s'), // 17 == PATHSEG_CURVETO_CUBIC_SMOOTH_REL
char16_t('T'), // 18 == PATHSEG_CURVETO_QUADRATIC_SMOOTH_ABS
char16_t('t') // 19 == PATHSEG_CURVETO_QUADRATIC_SMOOTH_REL
};
static_assert(MOZ_ARRAY_LENGTH(table) == NS_SVG_PATH_SEG_TYPE_COUNT, "Unexpected table size");
return table[aType];
}
static uint32_t ArgCountForType(uint32_t aType) {
MOZ_ASSERT(IsValidType(aType), "Seg type not recognized");
static const uint8_t table[] = {
0, // 0 == PATHSEG_UNKNOWN
0, // 1 == PATHSEG_CLOSEPATH
2, // 2 == PATHSEG_MOVETO_ABS
2, // 3 == PATHSEG_MOVETO_REL
2, // 4 == PATHSEG_LINETO_ABS
2, // 5 == PATHSEG_LINETO_REL
6, // 6 == PATHSEG_CURVETO_CUBIC_ABS
6, // 7 == PATHSEG_CURVETO_CUBIC_REL
4, // 8 == PATHSEG_CURVETO_QUADRATIC_ABS
4, // 9 == PATHSEG_CURVETO_QUADRATIC_REL
7, // 10 == PATHSEG_ARC_ABS
7, // 11 == PATHSEG_ARC_REL
1, // 12 == PATHSEG_LINETO_HORIZONTAL_ABS
1, // 13 == PATHSEG_LINETO_HORIZONTAL_REL
1, // 14 == PATHSEG_LINETO_VERTICAL_ABS
1, // 15 == PATHSEG_LINETO_VERTICAL_REL
4, // 16 == PATHSEG_CURVETO_CUBIC_SMOOTH_ABS
4, // 17 == PATHSEG_CURVETO_CUBIC_SMOOTH_REL
2, // 18 == PATHSEG_CURVETO_QUADRATIC_SMOOTH_ABS
2 // 19 == PATHSEG_CURVETO_QUADRATIC_SMOOTH_REL
};
static_assert(MOZ_ARRAY_LENGTH(table) == NS_SVG_PATH_SEG_TYPE_COUNT, "Unexpected table size");
return table[aType];
}
/**
* Convenience so that callers can pass a float containing an encoded type
* and have it decoded implicitly.
*/
static uint32_t ArgCountForType(float aType) {
return ArgCountForType(DecodeType(aType));
}
static bool IsValidType(uint32_t aType) {
return aType >= NS_SVG_PATH_SEG_FIRST_VALID_TYPE &&
aType <= NS_SVG_PATH_SEG_LAST_VALID_TYPE;
}
static bool IsCubicType(uint32_t aType) {
return aType == PATHSEG_CURVETO_CUBIC_REL ||
aType == PATHSEG_CURVETO_CUBIC_ABS ||
aType == PATHSEG_CURVETO_CUBIC_SMOOTH_REL ||
aType == PATHSEG_CURVETO_CUBIC_SMOOTH_ABS;
}
static bool IsQuadraticType(uint32_t aType) {
return aType == PATHSEG_CURVETO_QUADRATIC_REL ||
aType == PATHSEG_CURVETO_QUADRATIC_ABS ||
aType == PATHSEG_CURVETO_QUADRATIC_SMOOTH_REL ||
aType == PATHSEG_CURVETO_QUADRATIC_SMOOTH_ABS;
}
static bool IsArcType(uint32_t aType) {
return aType == PATHSEG_ARC_ABS ||
aType == PATHSEG_ARC_REL;
}
static bool IsRelativeOrAbsoluteType(uint32_t aType) {
MOZ_ASSERT(IsValidType(aType), "Seg type not recognized");
// When adding a new path segment type, ensure that the returned condition
// below is still correct.
static_assert(NS_SVG_PATH_SEG_LAST_VALID_TYPE == PATHSEG_CURVETO_QUADRATIC_SMOOTH_REL,
"Unexpected type");
return aType >= PATHSEG_MOVETO_ABS;
}
static bool IsRelativeType(uint32_t aType) {
MOZ_ASSERT
(IsRelativeOrAbsoluteType(aType),
"IsRelativeType called with segment type that does not come in relative and absolute forms");
// When adding a new path segment type, ensure that the returned condition
// below is still correct.
static_assert(NS_SVG_PATH_SEG_LAST_VALID_TYPE == PATHSEG_CURVETO_QUADRATIC_SMOOTH_REL,
"Unexpected type");
return aType & 1;
}
static uint32_t RelativeVersionOfType(uint32_t aType) {
MOZ_ASSERT
(IsRelativeOrAbsoluteType(aType),
"RelativeVersionOfType called with segment type that does not come in relative and absolute forms");
// When adding a new path segment type, ensure that the returned condition
// below is still correct.
static_assert(NS_SVG_PATH_SEG_LAST_VALID_TYPE == PATHSEG_CURVETO_QUADRATIC_SMOOTH_REL,
"Unexpected type");
return aType | 1;
}
static uint32_t SameTypeModuloRelativeness(uint32_t aType1, uint32_t aType2) {
if (!IsRelativeOrAbsoluteType(aType1)) {
return aType1 == aType2;
}
return RelativeVersionOfType(aType1) == RelativeVersionOfType(aType2);
}
/**
* Traverse the given path segment and update the SVGPathTraversalState
* object.
*/
static void TraversePathSegment(const float* aData,
SVGPathTraversalState& aState);
};
} // namespace mozilla
#endif // MOZILLA_SVGPATHSEGUTILS_H__
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