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/*
* Copyright 2012 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "GrPath.h"
namespace {
// Verb count limit for generating path key from content of a volatile path.
// The value should accomodate at least simple rects and rrects.
static const int kSimpleVolatilePathVerbLimit = 10;
inline static bool compute_key_for_line_path(const SkPath& path, const GrStrokeInfo& stroke,
GrUniqueKey* key) {
SkPoint pts[2];
if (!path.isLine(pts)) {
return false;
}
static_assert((sizeof(pts) % sizeof(uint32_t)) == 0 && sizeof(pts) > sizeof(uint32_t),
"pts_needs_padding");
const int kBaseData32Cnt = 1 + sizeof(pts) / sizeof(uint32_t);
int strokeDataCnt = stroke.computeUniqueKeyFragmentData32Cnt();
static const GrUniqueKey::Domain kOvalPathDomain = GrUniqueKey::GenerateDomain();
GrUniqueKey::Builder builder(key, kOvalPathDomain, kBaseData32Cnt + strokeDataCnt);
builder[0] = path.getFillType();
memcpy(&builder[1], &pts, sizeof(pts));
if (strokeDataCnt > 0) {
stroke.asUniqueKeyFragment(&builder[kBaseData32Cnt]);
}
return true;
}
inline static bool compute_key_for_oval_path(const SkPath& path, const GrStrokeInfo& stroke,
GrUniqueKey* key) {
SkRect rect;
// Point order is significant when dashing, so we cannot devolve to a rect key.
if (stroke.isDashed() || !path.isOval(&rect)) {
return false;
}
static_assert((sizeof(rect) % sizeof(uint32_t)) == 0 && sizeof(rect) > sizeof(uint32_t),
"rect_needs_padding");
const int kBaseData32Cnt = 1 + sizeof(rect) / sizeof(uint32_t);
int strokeDataCnt = stroke.computeUniqueKeyFragmentData32Cnt();
static const GrUniqueKey::Domain kOvalPathDomain = GrUniqueKey::GenerateDomain();
GrUniqueKey::Builder builder(key, kOvalPathDomain, kBaseData32Cnt + strokeDataCnt);
builder[0] = path.getFillType();
memcpy(&builder[1], &rect, sizeof(rect));
if (strokeDataCnt > 0) {
stroke.asUniqueKeyFragment(&builder[kBaseData32Cnt]);
}
return true;
}
// Encodes the full path data to the unique key for very small, volatile paths. This is typically
// hit when clipping stencils the clip stack. Intention is that this handles rects too, since
// SkPath::isRect seems to do non-trivial amount of work.
inline static bool compute_key_for_simple_path(const SkPath& path, const GrStrokeInfo& stroke,
GrUniqueKey* key) {
if (!path.isVolatile()) {
return false;
}
// The check below should take care of negative values casted positive.
const int verbCnt = path.countVerbs();
if (verbCnt > kSimpleVolatilePathVerbLimit) {
return false;
}
// If somebody goes wild with the constant, it might cause an overflow.
static_assert(kSimpleVolatilePathVerbLimit <= 100,
"big_simple_volatile_path_verb_limit_may_cause_overflow");
const int pointCnt = path.countPoints();
if (pointCnt < 0) {
SkASSERT(false);
return false;
}
// Construct counts that align as uint32_t counts.
#define ARRAY_DATA32_COUNT(array_type, count) \
static_cast<int>((((count) * sizeof(array_type) + sizeof(uint32_t) - 1) / sizeof(uint32_t)))
const int verbData32Cnt = ARRAY_DATA32_COUNT(uint8_t, verbCnt);
const int pointData32Cnt = ARRAY_DATA32_COUNT(SkPoint, pointCnt);
#undef ARRAY_DATA32_COUNT
// The unique key data is a "message" with following fragments:
// 0) domain, key length, uint32_t for fill type and uint32_t for verbCnt
// (fragment 0, fixed size)
// 1) verb and point data (varying size)
// 2) stroke data (varying size)
const int baseData32Cnt = 2 + verbData32Cnt + pointData32Cnt;
const int strokeDataCnt = stroke.computeUniqueKeyFragmentData32Cnt();
static const GrUniqueKey::Domain kSimpleVolatilePathDomain = GrUniqueKey::GenerateDomain();
GrUniqueKey::Builder builder(key, kSimpleVolatilePathDomain, baseData32Cnt + strokeDataCnt);
int i = 0;
builder[i++] = path.getFillType();
// Serialize the verbCnt to make the whole message unambiguous.
// We serialize two variable length fragments to the message:
// * verb and point data (fragment 1)
// * stroke data (fragment 2)
// "Proof:"
// Verb count establishes unambiguous verb data.
// Unambiguous verb data establishes unambiguous point data, making fragment 1 unambiguous.
// Unambiguous fragment 1 establishes unambiguous fragment 2, since the length of the message
// has been established.
builder[i++] = SkToU32(verbCnt); // The path limit is compile-asserted above, so the cast is ok.
// Fill the last uint32_t with 0 first, since the last uint8_ts of the uint32_t may be
// uninitialized. This does not produce ambiguous verb data, since we have serialized the exact
// verb count.
if (verbData32Cnt != static_cast<int>((verbCnt * sizeof(uint8_t) / sizeof(uint32_t)))) {
builder[i + verbData32Cnt - 1] = 0;
}
path.getVerbs(reinterpret_cast<uint8_t*>(&builder[i]), verbCnt);
i += verbData32Cnt;
static_assert(((sizeof(SkPoint) % sizeof(uint32_t)) == 0) && sizeof(SkPoint) > sizeof(uint32_t),
"skpoint_array_needs_padding");
// Here we assume getPoints does a memcpy, so that we do not need to worry about the alignment.
path.getPoints(reinterpret_cast<SkPoint*>(&builder[i]), pointCnt);
SkDEBUGCODE(i += pointData32Cnt);
SkASSERT(i == baseData32Cnt);
if (strokeDataCnt > 0) {
stroke.asUniqueKeyFragment(&builder[baseData32Cnt]);
}
return true;
}
inline static void compute_key_for_general_path(const SkPath& path, const GrStrokeInfo& stroke,
GrUniqueKey* key) {
const int kBaseData32Cnt = 2;
int strokeDataCnt = stroke.computeUniqueKeyFragmentData32Cnt();
static const GrUniqueKey::Domain kGeneralPathDomain = GrUniqueKey::GenerateDomain();
GrUniqueKey::Builder builder(key, kGeneralPathDomain, kBaseData32Cnt + strokeDataCnt);
builder[0] = path.getGenerationID();
builder[1] = path.getFillType();
if (strokeDataCnt > 0) {
stroke.asUniqueKeyFragment(&builder[kBaseData32Cnt]);
}
}
}
void GrPath::ComputeKey(const SkPath& path, const GrStrokeInfo& stroke, GrUniqueKey* key,
bool* outIsVolatile) {
if (compute_key_for_line_path(path, stroke, key)) {
*outIsVolatile = false;
return;
}
if (compute_key_for_oval_path(path, stroke, key)) {
*outIsVolatile = false;
return;
}
if (compute_key_for_simple_path(path, stroke, key)) {
*outIsVolatile = false;
return;
}
compute_key_for_general_path(path, stroke, key);
*outIsVolatile = path.isVolatile();
}
#ifdef SK_DEBUG
bool GrPath::isEqualTo(const SkPath& path, const GrStrokeInfo& stroke) const {
if (!fStroke.hasEqualEffect(stroke)) {
return false;
}
// We treat same-rect ovals as identical - but only when not dashing.
SkRect ovalBounds;
if (!fStroke.isDashed() && fSkPath.isOval(&ovalBounds)) {
SkRect otherOvalBounds;
return path.isOval(&otherOvalBounds) && ovalBounds == otherOvalBounds;
}
return fSkPath == path;
}
#endif
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