skia2/experimental/skottie/SkottieValue.cpp
Florin Malita c353ee211f [skottie] Power-reduce paths (cubicTo -> lineTo)
For straight lines, Lottie exports control points conincident with the
vertices.  We can detect this case and emit more efficient lineTo's.

One wrinkle: we can only apply this power-reduction post-interpolation
(otherwise the path verbs and point count would not be guaranteed to
match).  Hence we store explicit shape data and defer the SkPath
conversion.

TBR=

Change-Id: I7818be464eabee6096d2078440843243a55c6e98
Reviewed-on: https://skia-review.googlesource.com/124800
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Florin Malita <fmalita@chromium.org>
2018-05-01 02:27:34 +00:00

162 lines
4.4 KiB
C++

/*
* Copyright 2017 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "SkottieValue.h"
#include "SkColor.h"
#include "SkNx.h"
#include "SkPoint.h"
#include "SkSize.h"
namespace skottie {
template <>
size_t ValueTraits<ScalarValue>::Cardinality(const ScalarValue&) {
return 1;
}
template <>
ScalarValue ValueTraits<ScalarValue>::Lerp(const ScalarValue& v0, const ScalarValue& v1, float t) {
SkASSERT(t >= 0 && t <= 1);
return v0 + (v1 - v0) * t;
}
template <>
template <>
SkScalar ValueTraits<ScalarValue>::As<SkScalar>(const ScalarValue& v) {
return v;
}
template <>
size_t ValueTraits<VectorValue>::Cardinality(const VectorValue& vec) {
return vec.size();
}
template <>
VectorValue ValueTraits<VectorValue>::Lerp(const VectorValue& v0, const VectorValue& v1, float t) {
SkASSERT(v0.size() == v1.size());
VectorValue v;
v.reserve(v0.size());
for (size_t i = 0; i < v0.size(); ++i) {
v.push_back(ValueTraits<ScalarValue>::Lerp(v0[i], v1[i], t));
}
return v;
}
template <>
template <>
SkColor ValueTraits<VectorValue>::As<SkColor>(const VectorValue& v) {
// best effort to turn this into a color
const auto r = v.size() > 0 ? v[0] : 0,
g = v.size() > 1 ? v[1] : 0,
b = v.size() > 2 ? v[2] : 0,
a = v.size() > 3 ? v[3] : 1;
return SkColorSetARGB(SkTPin<SkScalar>(a, 0, 1) * 255,
SkTPin<SkScalar>(r, 0, 1) * 255,
SkTPin<SkScalar>(g, 0, 1) * 255,
SkTPin<SkScalar>(b, 0, 1) * 255);
}
template <>
template <>
SkPoint ValueTraits<VectorValue>::As<SkPoint>(const VectorValue& vec) {
// best effort to turn this into a point
const auto x = vec.size() > 0 ? vec[0] : 0,
y = vec.size() > 1 ? vec[1] : 0;
return SkPoint::Make(x, y);
}
template <>
template <>
SkSize ValueTraits<VectorValue>::As<SkSize>(const VectorValue& vec) {
const auto pt = ValueTraits::As<SkPoint>(vec);
return SkSize::Make(pt.x(), pt.y());
}
template <>
size_t ValueTraits<ShapeValue>::Cardinality(const ShapeValue& shape) {
return shape.fVertices.size();
}
static SkPoint lerp_point(const SkPoint& v0, const SkPoint& v1, const Sk2f& t) {
const auto v2f0 = Sk2f::Load(&v0),
v2f1 = Sk2f::Load(&v1);
SkPoint v;
(v2f0 + (v2f1 - v2f0) * t).store(&v);
return v;
}
template <>
ShapeValue ValueTraits<ShapeValue>::Lerp(const ShapeValue& v0, const ShapeValue& v1, float t) {
SkASSERT(t >= 0 && t <= 1);
SkASSERT(v0.fVertices.size() == v1.fVertices.size());
SkASSERT(v0.fClosed == v1.fClosed);
ShapeValue v;
v.fClosed = v0.fClosed;
v.fVolatile = true; // interpolated values are volatile
const auto t2f = Sk2f(t);
v.fVertices.reserve(v0.fVertices.size());
for (size_t i = 0; i < v0.fVertices.size(); ++i) {
v.fVertices.emplace_back(BezierVertex({
lerp_point(v0.fVertices[i].fInPoint , v1.fVertices[i].fInPoint , t2f),
lerp_point(v0.fVertices[i].fOutPoint, v1.fVertices[i].fOutPoint, t2f),
lerp_point(v0.fVertices[i].fVertex , v1.fVertices[i].fVertex , t2f)
}));
}
return v;
}
template <>
template <>
SkPath ValueTraits<ShapeValue>::As<SkPath>(const ShapeValue& shape) {
SkPath path;
if (!shape.fVertices.empty()) {
path.moveTo(shape.fVertices.front().fVertex);
}
const auto& addCubic = [&](size_t from, size_t to) {
const auto c0 = shape.fVertices[from].fVertex + shape.fVertices[from].fOutPoint,
c1 = shape.fVertices[to].fVertex + shape.fVertices[to].fInPoint;
if (c0 == shape.fVertices[from].fVertex &&
c1 == shape.fVertices[to].fVertex) {
// If the control points are coincident, we can power-reduce to a straight line.
// TODO: we could also do that when the controls are on the same line as the
// vertices, but it's unclear how common that case is.
path.lineTo(shape.fVertices[to].fVertex);
} else {
path.cubicTo(c0, c1, shape.fVertices[to].fVertex);
}
};
for (size_t i = 1; i < shape.fVertices.size(); ++i) {
addCubic(i - 1, i);
}
if (!shape.fVertices.empty() && shape.fClosed) {
addCubic(shape.fVertices.size() - 1, 0);
path.close();
}
path.setIsVolatile(shape.fVolatile);
return path;
}
} // namespace skottie