/*
* 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 "SkPDFGradientShader.h"
#include "SkOpts.h"
#include "SkPDFDocument.h"
#include "SkPDFFormXObject.h"
#include "SkPDFResourceDict.h"
#include "SkPDFUtils.h"
static uint32_t hash(const SkShader::GradientInfo& v) {
uint32_t buffer[] = {
(uint32_t)v.fColorCount,
SkOpts::hash(v.fColors, v.fColorCount * sizeof(SkColor)),
SkOpts::hash(v.fColorOffsets, v.fColorCount * sizeof(SkScalar)),
SkOpts::hash(v.fPoint, 2 * sizeof(SkPoint)),
SkOpts::hash(v.fRadius, 2 * sizeof(SkScalar)),
(uint32_t)v.fTileMode,
v.fGradientFlags,
};
return SkOpts::hash(buffer, sizeof(buffer));
}
static uint32_t hash(const SkPDFGradientShader::Key& k) {
uint32_t buffer[] = {
(uint32_t)k.fType,
hash(k.fInfo),
SkOpts::hash(&k.fCanvasTransform, sizeof(SkMatrix)),
SkOpts::hash(&k.fShaderTransform, sizeof(SkMatrix)),
SkOpts::hash(&k.fBBox, sizeof(SkIRect))
};
return SkOpts::hash(buffer, sizeof(buffer));
}
static void unit_to_points_matrix(const SkPoint pts[2], SkMatrix* matrix) {
SkVector vec = pts[1] - pts[0];
SkScalar mag = vec.length();
SkScalar inv = mag ? SkScalarInvert(mag) : 0;
vec.scale(inv);
matrix->setSinCos(vec.fY, vec.fX);
matrix->preScale(mag, mag);
matrix->postTranslate(pts[0].fX, pts[0].fY);
}
static const int kColorComponents = 3;
typedef uint8_t ColorTuple[kColorComponents];
/* Assumes t + startOffset is on the stack and does a linear interpolation on t
between startOffset and endOffset from prevColor to curColor (for each color
component), leaving the result in component order on the stack. It assumes
there are always 3 components per color.
@param range endOffset - startOffset
@param curColor[components] The current color components.
@param prevColor[components] The previous color components.
@param result The result ps function.
*/
static void interpolate_color_code(SkScalar range, const ColorTuple& curColor,
const ColorTuple& prevColor,
SkDynamicMemoryWStream* result) {
SkASSERT(range != SkIntToScalar(0));
// Figure out how to scale each color component.
SkScalar multiplier[kColorComponents];
for (int i = 0; i < kColorComponents; i++) {
static const SkScalar kColorScale = SkScalarInvert(255);
multiplier[i] = kColorScale * (curColor[i] - prevColor[i]) / range;
}
// Calculate when we no longer need to keep a copy of the input parameter t.
// If the last component to use t is i, then dupInput[0..i - 1] = true
// and dupInput[i .. components] = false.
bool dupInput[kColorComponents];
dupInput[kColorComponents - 1] = false;
for (int i = kColorComponents - 2; i >= 0; i--) {
dupInput[i] = dupInput[i + 1] || multiplier[i + 1] != 0;
}
if (!dupInput[0] && multiplier[0] == 0) {
result->writeText("pop ");
}
for (int i = 0; i < kColorComponents; i++) {
// If the next components needs t and this component will consume a
// copy, make another copy.
if (dupInput[i] && multiplier[i] != 0) {
result->writeText("dup ");
}
if (multiplier[i] == 0) {
SkPDFUtils::AppendColorComponent(prevColor[i], result);
result->writeText(" ");
} else {
if (multiplier[i] != 1) {
SkPDFUtils::AppendScalar(multiplier[i], result);
result->writeText(" mul ");
}
if (prevColor[i] != 0) {
SkPDFUtils::AppendColorComponent(prevColor[i], result);
result->writeText(" add ");
}
}
if (dupInput[i]) {
result->writeText("exch\n");
}
}
}
/* Generate Type 4 function code to map t=[0,1) to the passed gradient,
clamping at the edges of the range. The generated code will be of the form:
if (t < 0) {
return colorData[0][r,g,b];
} else {
if (t < info.fColorOffsets[1]) {
return linearinterpolation(colorData[0][r,g,b],
colorData[1][r,g,b]);
} else {
if (t < info.fColorOffsets[2]) {
return linearinterpolation(colorData[1][r,g,b],
colorData[2][r,g,b]);
} else {
... } else {
return colorData[info.fColorCount - 1][r,g,b];
}
...
}
}
*/
static void gradient_function_code(const SkShader::GradientInfo& info,
SkDynamicMemoryWStream* result) {
/* We want to linearly interpolate from the previous color to the next.
Scale the colors from 0..255 to 0..1 and determine the multipliers
for interpolation.
C{r,g,b}(t, section) = t - offset_(section-1) + t * Multiplier{r,g,b}.
*/
SkAutoSTMalloc<4, ColorTuple> colorDataAlloc(info.fColorCount);
ColorTuple *colorData = colorDataAlloc.get();
for (int i = 0; i < info.fColorCount; i++) {
colorData[i][0] = SkColorGetR(info.fColors[i]);
colorData[i][1] = SkColorGetG(info.fColors[i]);
colorData[i][2] = SkColorGetB(info.fColors[i]);
}
// Clamp the initial color.
result->writeText("dup 0 le {pop ");
SkPDFUtils::AppendColorComponent(colorData[0][0], result);
result->writeText(" ");
SkPDFUtils::AppendColorComponent(colorData[0][1], result);
result->writeText(" ");
SkPDFUtils::AppendColorComponent(colorData[0][2], result);
result->writeText(" }\n");
// The gradient colors.
int gradients = 0;
for (int i = 1 ; i < info.fColorCount; i++) {
if (info.fColorOffsets[i] == info.fColorOffsets[i - 1]) {
continue;
}
gradients++;
result->writeText("{dup ");
SkPDFUtils::AppendScalar(info.fColorOffsets[i], result);
result->writeText(" le {");
if (info.fColorOffsets[i - 1] != 0) {
SkPDFUtils::AppendScalar(info.fColorOffsets[i - 1], result);
result->writeText(" sub\n");
}
interpolate_color_code(info.fColorOffsets[i] - info.fColorOffsets[i - 1],
colorData[i], colorData[i - 1], result);
result->writeText("}\n");
}
// Clamp the final color.
result->writeText("{pop ");
SkPDFUtils::AppendColorComponent(colorData[info.fColorCount - 1][0], result);
result->writeText(" ");
SkPDFUtils::AppendColorComponent(colorData[info.fColorCount - 1][1], result);
result->writeText(" ");
SkPDFUtils::AppendColorComponent(colorData[info.fColorCount - 1][2], result);
for (int i = 0 ; i < gradients + 1; i++) {
result->writeText("} ifelse\n");
}
}
static sk_sp<SkPDFDict> createInterpolationFunction(const ColorTuple& color1,
const ColorTuple& color2) {
auto retval = sk_make_sp<SkPDFDict>();
auto c0 = sk_make_sp<SkPDFArray>();
c0->appendColorComponent(color1[0]);
c0->appendColorComponent(color1[1]);
c0->appendColorComponent(color1[2]);
retval->insertObject("C0", std::move(c0));
auto c1 = sk_make_sp<SkPDFArray>();
c1->appendColorComponent(color2[0]);
c1->appendColorComponent(color2[1]);
c1->appendColorComponent(color2[2]);
retval->insertObject("C1", std::move(c1));
auto domain = sk_make_sp<SkPDFArray>();
domain->appendScalar(0);
domain->appendScalar(1.0f);
retval->insertObject("Domain", std::move(domain));
retval->insertInt("FunctionType", 2);
retval->insertScalar("N", 1.0f);
return retval;
}
static sk_sp<SkPDFDict> gradientStitchCode(const SkShader::GradientInfo& info) {
auto retval = sk_make_sp<SkPDFDict>();
// normalize color stops
int colorCount = info.fColorCount;
SkTDArray<SkColor> colors(info.fColors, colorCount);
SkTDArray<SkScalar> colorOffsets(info.fColorOffsets, colorCount);
int i = 1;
while (i < colorCount - 1) {
// ensure stops are in order
if (colorOffsets[i - 1] > colorOffsets[i]) {
colorOffsets[i] = colorOffsets[i - 1];
}
// remove points that are between 2 coincident points
if ((colorOffsets[i - 1] == colorOffsets[i]) && (colorOffsets[i] == colorOffsets[i + 1])) {
colorCount -= 1;
colors.remove(i);
colorOffsets.remove(i);
} else {
i++;
}
}
// find coincident points and slightly move them over
for (i = 1; i < colorCount - 1; i++) {
if (colorOffsets[i - 1] == colorOffsets[i]) {
colorOffsets[i] += 0.00001f;
}
}
// check if last 2 stops coincide
if (colorOffsets[i - 1] == colorOffsets[i]) {
colorOffsets[i - 1] -= 0.00001f;
}
SkAutoSTMalloc<4, ColorTuple> colorDataAlloc(colorCount);
ColorTuple *colorData = colorDataAlloc.get();
for (int i = 0; i < colorCount; i++) {
colorData[i][0] = SkColorGetR(colors[i]);
colorData[i][1] = SkColorGetG(colors[i]);
colorData[i][2] = SkColorGetB(colors[i]);
}
// no need for a stitch function if there are only 2 stops.
if (colorCount == 2)
return createInterpolationFunction(colorData[0], colorData[1]);
auto encode = sk_make_sp<SkPDFArray>();
auto bounds = sk_make_sp<SkPDFArray>();
auto functions = sk_make_sp<SkPDFArray>();
auto domain = sk_make_sp<SkPDFArray>();
domain->appendScalar(0);
domain->appendScalar(1.0f);
retval->insertObject("Domain", std::move(domain));
retval->insertInt("FunctionType", 3);
for (int i = 1; i < colorCount; i++) {
if (i > 1) {
bounds->appendScalar(colorOffsets[i-1]);
}
encode->appendScalar(0);
encode->appendScalar(1.0f);
functions->appendObject(createInterpolationFunction(colorData[i-1], colorData[i]));
}
retval->insertObject("Encode", std::move(encode));
retval->insertObject("Bounds", std::move(bounds));
retval->insertObject("Functions", std::move(functions));
return retval;
}
/* Map a value of t on the stack into [0, 1) for Repeat or Mirror tile mode. */
static void tileModeCode(SkShader::TileMode mode,
SkDynamicMemoryWStream* result) {
if (mode == SkShader::kRepeat_TileMode) {
result->writeText("dup truncate sub\n"); // Get the fractional part.
result->writeText("dup 0 le {1 add} if\n"); // Map (-1,0) => (0,1)
return;
}
if (mode == SkShader::kMirror_TileMode) {
// Map t mod 2 into [0, 1, 1, 0].
// Code Stack
result->writeText("abs " // Map negative to positive.
"dup " // t.s t.s
"truncate " // t.s t
"dup " // t.s t t
"cvi " // t.s t T
"2 mod " // t.s t (i mod 2)
"1 eq " // t.s t true|false
"3 1 roll " // true|false t.s t
"sub " // true|false 0.s
"exch " // 0.s true|false
"{1 exch sub} if\n"); // 1 - 0.s|0.s
}
}
/**
* Returns PS function code that applies inverse perspective
* to a x, y point.
* The function assumes that the stack has at least two elements,
* and that the top 2 elements are numeric values.
* After executing this code on a PS stack, the last 2 elements are updated
* while the rest of the stack is preserved intact.
* inversePerspectiveMatrix is the inverse perspective matrix.
*/
static void apply_perspective_to_coordinates(const SkMatrix& inversePerspectiveMatrix,
SkDynamicMemoryWStream* code) {
if (!inversePerspectiveMatrix.hasPerspective()) {
return;
}
// Perspective matrix should be:
// 1 0 0
// 0 1 0
// p0 p1 p2
const SkScalar p0 = inversePerspectiveMatrix[SkMatrix::kMPersp0];
const SkScalar p1 = inversePerspectiveMatrix[SkMatrix::kMPersp1];
const SkScalar p2 = inversePerspectiveMatrix[SkMatrix::kMPersp2];
// y = y / (p2 + p0 x + p1 y)
// x = x / (p2 + p0 x + p1 y)
// Input on stack: x y
code->writeText(" dup "); // x y y
SkPDFUtils::AppendScalar(p1, code); // x y y p1
code->writeText(" mul " // x y y*p1
" 2 index "); // x y y*p1 x
SkPDFUtils::AppendScalar(p0, code); // x y y p1 x p0
code->writeText(" mul "); // x y y*p1 x*p0
SkPDFUtils::AppendScalar(p2, code); // x y y p1 x*p0 p2
code->writeText(" add " // x y y*p1 x*p0+p2
"add " // x y y*p1+x*p0+p2
"3 1 roll " // y*p1+x*p0+p2 x y
"2 index " // z x y y*p1+x*p0+p2
"div " // y*p1+x*p0+p2 x y/(y*p1+x*p0+p2)
"3 1 roll " // y/(y*p1+x*p0+p2) y*p1+x*p0+p2 x
"exch " // y/(y*p1+x*p0+p2) x y*p1+x*p0+p2
"div " // y/(y*p1+x*p0+p2) x/(y*p1+x*p0+p2)
"exch\n"); // x/(y*p1+x*p0+p2) y/(y*p1+x*p0+p2)
}
static void linearCode(const SkShader::GradientInfo& info,
const SkMatrix& perspectiveRemover,
SkDynamicMemoryWStream* function) {
function->writeText("{");
apply_perspective_to_coordinates(perspectiveRemover, function);
function->writeText("pop\n"); // Just ditch the y value.
tileModeCode(info.fTileMode, function);
gradient_function_code(info, function);
function->writeText("}");
}
static void radialCode(const SkShader::GradientInfo& info,
const SkMatrix& perspectiveRemover,
SkDynamicMemoryWStream* function) {
function->writeText("{");
apply_perspective_to_coordinates(perspectiveRemover, function);
// Find the distance from the origin.
function->writeText("dup " // x y y
"mul " // x y^2
"exch " // y^2 x
"dup " // y^2 x x
"mul " // y^2 x^2
"add " // y^2+x^2
"sqrt\n"); // sqrt(y^2+x^2)
tileModeCode(info.fTileMode, function);
gradient_function_code(info, function);
function->writeText("}");
}
/* Conical gradient shader, based on the Canvas spec for radial gradients
See: http://www.w3.org/TR/2dcontext/#dom-context-2d-createradialgradient
*/
static void twoPointConicalCode(const SkShader::GradientInfo& info,
const SkMatrix& perspectiveRemover,
SkDynamicMemoryWStream* function) {
SkScalar dx = info.fPoint[1].fX - info.fPoint[0].fX;
SkScalar dy = info.fPoint[1].fY - info.fPoint[0].fY;
SkScalar r0 = info.fRadius[0];
SkScalar dr = info.fRadius[1] - info.fRadius[0];
SkScalar a = dx * dx + dy * dy - dr * dr;
// First compute t, if the pixel falls outside the cone, then we'll end
// with 'false' on the stack, otherwise we'll push 'true' with t below it
// We start with a stack of (x y), copy it and then consume one copy in
// order to calculate b and the other to calculate c.
function->writeText("{");
apply_perspective_to_coordinates(perspectiveRemover, function);
function->writeText("2 copy ");
// Calculate b and b^2; b = -2 * (y * dy + x * dx + r0 * dr).
SkPDFUtils::AppendScalar(dy, function);
function->writeText(" mul exch ");
SkPDFUtils::AppendScalar(dx, function);
function->writeText(" mul add ");
SkPDFUtils::AppendScalar(r0 * dr, function);
function->writeText(" add -2 mul dup dup mul\n");
// c = x^2 + y^2 + radius0^2
function->writeText("4 2 roll dup mul exch dup mul add ");
SkPDFUtils::AppendScalar(r0 * r0, function);
function->writeText(" sub dup 4 1 roll\n");
// Contents of the stack at this point: c, b, b^2, c
// if a = 0, then we collapse to a simpler linear case
if (a == 0) {
// t = -c/b
function->writeText("pop pop div neg dup ");
// compute radius(t)
SkPDFUtils::AppendScalar(dr, function);
function->writeText(" mul ");
SkPDFUtils::AppendScalar(r0, function);
function->writeText(" add\n");
// if r(t) < 0, then it's outside the cone
function->writeText("0 lt {pop false} {true} ifelse\n");
} else {
// quadratic case: the Canvas spec wants the largest
// root t for which radius(t) > 0
// compute the discriminant (b^2 - 4ac)
SkPDFUtils::AppendScalar(a * 4, function);
function->writeText(" mul sub dup\n");
// if d >= 0, proceed
function->writeText("0 ge {\n");
// an intermediate value we'll use to compute the roots:
// q = -0.5 * (b +/- sqrt(d))
function->writeText("sqrt exch dup 0 lt {exch -1 mul} if");
function->writeText(" add -0.5 mul dup\n");
// first root = q / a
SkPDFUtils::AppendScalar(a, function);
function->writeText(" div\n");
// second root = c / q
function->writeText("3 1 roll div\n");
// put the larger root on top of the stack
function->writeText("2 copy gt {exch} if\n");
// compute radius(t) for larger root
function->writeText("dup ");
SkPDFUtils::AppendScalar(dr, function);
function->writeText(" mul ");
SkPDFUtils::AppendScalar(r0, function);
function->writeText(" add\n");
// if r(t) > 0, we have our t, pop off the smaller root and we're done
function->writeText(" 0 gt {exch pop true}\n");
// otherwise, throw out the larger one and try the smaller root
function->writeText("{pop dup\n");
SkPDFUtils::AppendScalar(dr, function);
function->writeText(" mul ");
SkPDFUtils::AppendScalar(r0, function);
function->writeText(" add\n");
// if r(t) < 0, push false, otherwise the smaller root is our t
function->writeText("0 le {pop false} {true} ifelse\n");
function->writeText("} ifelse\n");
// d < 0, clear the stack and push false
function->writeText("} {pop pop pop false} ifelse\n");
}
// if the pixel is in the cone, proceed to compute a color
function->writeText("{");
tileModeCode(info.fTileMode, function);
gradient_function_code(info, function);
// otherwise, just write black
function->writeText("} {0 0 0} ifelse }");
}
static void sweepCode(const SkShader::GradientInfo& info,
const SkMatrix& perspectiveRemover,
SkDynamicMemoryWStream* function) {
function->writeText("{exch atan 360 div\n");
tileModeCode(info.fTileMode, function);
gradient_function_code(info, function);
function->writeText("}");
}
// catch cases where the inner just touches the outer circle
// and make the inner circle just inside the outer one to match raster
static void FixUpRadius(const SkPoint& p1, SkScalar& r1, const SkPoint& p2, SkScalar& r2) {
// detect touching circles
SkScalar distance = SkPoint::Distance(p1, p2);
SkScalar subtractRadii = fabs(r1 - r2);
if (fabs(distance - subtractRadii) < 0.002f) {
if (r1 > r2) {
r1 += 0.002f;
} else {
r2 += 0.002f;
}
}
}
// Finds affine and persp such that in = affine * persp.
// but it returns the inverse of perspective matrix.
static bool split_perspective(const SkMatrix in, SkMatrix* affine,
SkMatrix* perspectiveInverse) {
const SkScalar p2 = in[SkMatrix::kMPersp2];
if (SkScalarNearlyZero(p2)) {
return false;
}
const SkScalar zero = SkIntToScalar(0);
const SkScalar one = SkIntToScalar(1);
const SkScalar sx = in[SkMatrix::kMScaleX];
const SkScalar kx = in[SkMatrix::kMSkewX];
const SkScalar tx = in[SkMatrix::kMTransX];
const SkScalar ky = in[SkMatrix::kMSkewY];
const SkScalar sy = in[SkMatrix::kMScaleY];
const SkScalar ty = in[SkMatrix::kMTransY];
const SkScalar p0 = in[SkMatrix::kMPersp0];
const SkScalar p1 = in[SkMatrix::kMPersp1];
// Perspective matrix would be:
// 1 0 0
// 0 1 0
// p0 p1 p2
// But we need the inverse of persp.
perspectiveInverse->setAll(one, zero, zero,
zero, one, zero,
-p0/p2, -p1/p2, 1/p2);
affine->setAll(sx - p0 * tx / p2, kx - p1 * tx / p2, tx / p2,
ky - p0 * ty / p2, sy - p1 * ty / p2, ty / p2,
zero, zero, one);
return true;
}
static sk_sp<SkPDFArray> make_range_object() {
auto range = sk_make_sp<SkPDFArray>();
range->reserve(6);
range->appendInt(0);
range->appendInt(1);
range->appendInt(0);
range->appendInt(1);
range->appendInt(0);
range->appendInt(1);
return range;
}
static sk_sp<SkPDFStream> make_ps_function(
std::unique_ptr<SkStreamAsset> psCode,
sk_sp<SkPDFArray> domain,
sk_sp<SkPDFObject> range) {
auto result = sk_make_sp<SkPDFStream>(std::move(psCode));
result->dict()->insertInt("FunctionType", 4);
result->dict()->insertObject("Domain", std::move(domain));
result->dict()->insertObject("Range", std::move(range));
return result;
}
static sk_sp<SkPDFDict> make_function_shader(SkPDFCanon* canon,
const SkPDFGradientShader::Key& state) {
SkPoint transformPoints[2];
const SkShader::GradientInfo& info = state.fInfo;
SkMatrix finalMatrix = state.fCanvasTransform;
finalMatrix.preConcat(state.fShaderTransform);
bool doStitchFunctions = (state.fType == SkShader::kLinear_GradientType ||
state.fType == SkShader::kRadial_GradientType ||
state.fType == SkShader::kConical_GradientType) &&
info.fTileMode == SkShader::kClamp_TileMode &&
!finalMatrix.hasPerspective();
auto domain = sk_make_sp<SkPDFArray>();
int32_t shadingType = 1;
auto pdfShader = sk_make_sp<SkPDFDict>();
// The two point radial gradient further references
// state.fInfo
// in translating from x, y coordinates to the t parameter. So, we have
// to transform the points and radii according to the calculated matrix.
if (doStitchFunctions) {
pdfShader->insertObject("Function", gradientStitchCode(info));
shadingType = (state.fType == SkShader::kLinear_GradientType) ? 2 : 3;
auto extend = sk_make_sp<SkPDFArray>();
extend->reserve(2);
extend->appendBool(true);
extend->appendBool(true);
pdfShader->insertObject("Extend", std::move(extend));
auto coords = sk_make_sp<SkPDFArray>();
if (state.fType == SkShader::kConical_GradientType) {
coords->reserve(6);
SkScalar r1 = info.fRadius[0];
SkScalar r2 = info.fRadius[1];
SkPoint pt1 = info.fPoint[0];
SkPoint pt2 = info.fPoint[1];
FixUpRadius(pt1, r1, pt2, r2);
coords->appendScalar(pt1.fX);
coords->appendScalar(pt1.fY);
coords->appendScalar(r1);
coords->appendScalar(pt2.fX);
coords->appendScalar(pt2.fY);
coords->appendScalar(r2);
} else if (state.fType == SkShader::kRadial_GradientType) {
coords->reserve(6);
const SkPoint& pt1 = info.fPoint[0];
coords->appendScalar(pt1.fX);
coords->appendScalar(pt1.fY);
coords->appendScalar(0);
coords->appendScalar(pt1.fX);
coords->appendScalar(pt1.fY);
coords->appendScalar(info.fRadius[0]);
} else {
coords->reserve(4);
const SkPoint& pt1 = info.fPoint[0];
const SkPoint& pt2 = info.fPoint[1];
coords->appendScalar(pt1.fX);
coords->appendScalar(pt1.fY);
coords->appendScalar(pt2.fX);
coords->appendScalar(pt2.fY);
}
pdfShader->insertObject("Coords", std::move(coords));
} else {
// Depending on the type of the gradient, we want to transform the
// coordinate space in different ways.
transformPoints[0] = info.fPoint[0];
transformPoints[1] = info.fPoint[1];
switch (state.fType) {
case SkShader::kLinear_GradientType:
break;
case SkShader::kRadial_GradientType:
transformPoints[1] = transformPoints[0];
transformPoints[1].fX += info.fRadius[0];
break;
case SkShader::kConical_GradientType: {
transformPoints[1] = transformPoints[0];
transformPoints[1].fX += SK_Scalar1;
break;
}
case SkShader::kSweep_GradientType:
transformPoints[1] = transformPoints[0];
transformPoints[1].fX += SK_Scalar1;
break;
case SkShader::kColor_GradientType:
case SkShader::kNone_GradientType:
default:
return nullptr;
}
// Move any scaling (assuming a unit gradient) or translation
// (and rotation for linear gradient), of the final gradient from
// info.fPoints to the matrix (updating bbox appropriately). Now
// the gradient can be drawn on on the unit segment.
SkMatrix mapperMatrix;
unit_to_points_matrix(transformPoints, &mapperMatrix);
finalMatrix.preConcat(mapperMatrix);
// Preserves as much as posible in the final matrix, and only removes
// the perspective. The inverse of the perspective is stored in
// perspectiveInverseOnly matrix and has 3 useful numbers
// (p0, p1, p2), while everything else is either 0 or 1.
// In this way the shader will handle it eficiently, with minimal code.
SkMatrix perspectiveInverseOnly = SkMatrix::I();
if (finalMatrix.hasPerspective()) {
if (!split_perspective(finalMatrix,
&finalMatrix, &perspectiveInverseOnly)) {
return nullptr;
}
}
SkRect bbox;
bbox.set(state.fBBox);
if (!SkPDFUtils::InverseTransformBBox(finalMatrix, &bbox)) {
return nullptr;
}
domain->reserve(4);
domain->appendScalar(bbox.fLeft);
domain->appendScalar(bbox.fRight);
domain->appendScalar(bbox.fTop);
domain->appendScalar(bbox.fBottom);
SkDynamicMemoryWStream functionCode;
SkShader::GradientInfo infoCopy = info;
if (state.fType == SkShader::kConical_GradientType) {
SkMatrix inverseMapperMatrix;
if (!mapperMatrix.invert(&inverseMapperMatrix)) {
return nullptr;
}
inverseMapperMatrix.mapPoints(infoCopy.fPoint, 2);
infoCopy.fRadius[0] = inverseMapperMatrix.mapRadius(info.fRadius[0]);
infoCopy.fRadius[1] = inverseMapperMatrix.mapRadius(info.fRadius[1]);
}
switch (state.fType) {
case SkShader::kLinear_GradientType:
linearCode(infoCopy, perspectiveInverseOnly, &functionCode);
break;
case SkShader::kRadial_GradientType:
radialCode(infoCopy, perspectiveInverseOnly, &functionCode);
break;
case SkShader::kConical_GradientType:
twoPointConicalCode(infoCopy, perspectiveInverseOnly, &functionCode);
break;
case SkShader::kSweep_GradientType:
sweepCode(infoCopy, perspectiveInverseOnly, &functionCode);
break;
default:
SkASSERT(false);
}
pdfShader->insertObject("Domain", domain);
sk_sp<SkPDFArray>& rangeObject = canon->fRangeObject;
if (!rangeObject) {
rangeObject = make_range_object();
}
pdfShader->insertObjRef("Function",
make_ps_function(functionCode.detachAsStream(), std::move(domain),
rangeObject));
}
pdfShader->insertInt("ShadingType", shadingType);
pdfShader->insertName("ColorSpace", "DeviceRGB");
auto pdfFunctionShader = sk_make_sp<SkPDFDict>("Pattern");
pdfFunctionShader->insertInt("PatternType", 2);
pdfFunctionShader->insertObject("Matrix", SkPDFUtils::MatrixToArray(finalMatrix));
pdfFunctionShader->insertObject("Shading", std::move(pdfShader));
return pdfFunctionShader;
}
static sk_sp<SkPDFObject> find_pdf_shader(SkPDFDocument* doc,
SkPDFGradientShader::Key key,
bool keyHasAlpha);
static sk_sp<SkPDFDict> get_gradient_resource_dict(SkPDFObject* functionShader,
SkPDFObject* gState) {
SkTDArray<SkPDFObject*> patterns;
if (functionShader) {
patterns.push(functionShader);
}
SkTDArray<SkPDFObject*> graphicStates;
if (gState) {
graphicStates.push(gState);
}
return SkPDFResourceDict::Make(&graphicStates, &patterns, nullptr, nullptr);
}
// Creates a content stream which fills the pattern P0 across bounds.
// @param gsIndex A graphics state resource index to apply, or <0 if no
// graphics state to apply.
static std::unique_ptr<SkStreamAsset> create_pattern_fill_content(int gsIndex, SkRect& bounds) {
SkDynamicMemoryWStream content;
if (gsIndex >= 0) {
SkPDFUtils::ApplyGraphicState(gsIndex, &content);
}
SkPDFUtils::ApplyPattern(0, &content);
SkPDFUtils::AppendRectangle(bounds, &content);
SkPDFUtils::PaintPath(SkPaint::kFill_Style, SkPath::kEvenOdd_FillType, &content);
return content.detachAsStream();
}
static bool gradient_has_alpha(const SkPDFGradientShader::Key& key) {
SkASSERT(key.fType != SkShader::kNone_GradientType);
for (int i = 0; i < key.fInfo.fColorCount; i++) {
if ((SkAlpha)SkColorGetA(key.fInfo.fColors[i]) != SK_AlphaOPAQUE) {
return true;
}
}
return false;
}
// warning: does not set fHash on new key. (Both callers need to change fields.)
static SkPDFGradientShader::Key clone_key(const SkPDFGradientShader::Key& k) {
SkPDFGradientShader::Key clone = {
k.fType,
k.fInfo, // change pointers later.
std::unique_ptr<SkColor[]>(new SkColor[k.fInfo.fColorCount]),
std::unique_ptr<SkScalar[]>(new SkScalar[k.fInfo.fColorCount]),
k.fCanvasTransform,
k.fShaderTransform,
k.fBBox, 0};
clone.fInfo.fColors = clone.fColors.get();
clone.fInfo.fColorOffsets = clone.fStops.get();
for (int i = 0; i < clone.fInfo.fColorCount; i++) {
clone.fInfo.fColorOffsets[i] = k.fInfo.fColorOffsets[i];
clone.fInfo.fColors[i] = k.fInfo.fColors[i];
}
return clone;
}
static sk_sp<SkPDFObject> create_smask_graphic_state(SkPDFDocument* doc,
const SkPDFGradientShader::Key& state) {
SkASSERT(state.fType != SkShader::kNone_GradientType);
SkPDFGradientShader::Key luminosityState = clone_key(state);
for (int i = 0; i < luminosityState.fInfo.fColorCount; i++) {
SkAlpha alpha = SkColorGetA(luminosityState.fInfo.fColors[i]);
luminosityState.fInfo.fColors[i] = SkColorSetARGB(255, alpha, alpha, alpha);
}
luminosityState.fHash = hash(luminosityState);
SkASSERT(!gradient_has_alpha(luminosityState));
sk_sp<SkPDFObject> luminosityShader = find_pdf_shader(doc, std::move(luminosityState), false);
sk_sp<SkPDFDict> resources = get_gradient_resource_dict(luminosityShader.get(), nullptr);
SkRect bbox = SkRect::Make(state.fBBox);
sk_sp<SkPDFObject> alphaMask = SkPDFMakeFormXObject(create_pattern_fill_content(-1, bbox),
SkPDFUtils::RectToArray(bbox),
std::move(resources),
SkMatrix::I(),
"DeviceRGB");
return SkPDFGraphicState::GetSMaskGraphicState(
std::move(alphaMask), false,
SkPDFGraphicState::kLuminosity_SMaskMode, doc->canon());
}
static sk_sp<SkPDFStream> make_alpha_function_shader(SkPDFDocument* doc,
const SkPDFGradientShader::Key& state) {
SkASSERT(state.fType != SkShader::kNone_GradientType);
SkPDFGradientShader::Key opaqueState = clone_key(state);
for (int i = 0; i < opaqueState.fInfo.fColorCount; i++) {
opaqueState.fInfo.fColors[i] = SkColorSetA(opaqueState.fInfo.fColors[i], SK_AlphaOPAQUE);
}
opaqueState.fHash = hash(opaqueState);
SkASSERT(!gradient_has_alpha(opaqueState));
SkRect bbox = SkRect::Make(state.fBBox);
sk_sp<SkPDFObject> colorShader = find_pdf_shader(doc, std::move(opaqueState), false);
if (!colorShader) {
return nullptr;
}
// Create resource dict with alpha graphics state as G0 and
// pattern shader as P0, then write content stream.
sk_sp<SkPDFObject> alphaGs = create_smask_graphic_state(doc, state);
sk_sp<SkPDFDict> resourceDict =
get_gradient_resource_dict(colorShader.get(), alphaGs.get());
std::unique_ptr<SkStreamAsset> colorStream(create_pattern_fill_content(0, bbox));
auto alphaFunctionShader = sk_make_sp<SkPDFStream>(std::move(colorStream));
SkPDFUtils::PopulateTilingPatternDict(alphaFunctionShader->dict(), bbox,
std::move(resourceDict), SkMatrix::I());
return alphaFunctionShader;
}
static SkPDFGradientShader::Key make_key(const SkShader* shader,
const SkMatrix& canvasTransform,
const SkIRect& bbox) {
SkPDFGradientShader::Key key = {
SkShader::kNone_GradientType,
{0, nullptr, nullptr, {{0, 0}, {0, 0}}, {0, 0}, SkShader::kClamp_TileMode, 0},
nullptr,
nullptr,
canvasTransform,
SkPDFUtils::GetShaderLocalMatrix(shader),
bbox, 0};
key.fType = shader->asAGradient(&key.fInfo);
SkASSERT(SkShader::kNone_GradientType != key.fType);
SkASSERT(key.fInfo.fColorCount > 0);
key.fColors.reset(new SkColor[key.fInfo.fColorCount]);
key.fStops.reset(new SkScalar[key.fInfo.fColorCount]);
key.fInfo.fColors = key.fColors.get();
key.fInfo.fColorOffsets = key.fStops.get();
(void)shader->asAGradient(&key.fInfo);
key.fHash = hash(key);
return key;
}
static sk_sp<SkPDFObject> find_pdf_shader(SkPDFDocument* doc,
SkPDFGradientShader::Key key,
bool keyHasAlpha) {
SkASSERT(gradient_has_alpha(key) == keyHasAlpha);
SkPDFCanon* canon = doc->canon();
if (sk_sp<SkPDFObject>* ptr = canon->fGradientPatternMap.find(key)) {
return *ptr;
}
sk_sp<SkPDFObject> pdfShader;
if (keyHasAlpha) {
pdfShader = make_alpha_function_shader(doc, key);
} else {
pdfShader = make_function_shader(canon, key);
}
canon->fGradientPatternMap.set(std::move(key), pdfShader);
return pdfShader;
}
sk_sp<SkPDFObject> SkPDFGradientShader::Make(SkPDFDocument* doc,
SkShader* shader,
const SkMatrix& canvasTransform,
const SkIRect& bbox) {
SkASSERT(shader);
SkASSERT(SkShader::kNone_GradientType != shader->asAGradient(nullptr));
SkPDFGradientShader::Key key = make_key(shader, canvasTransform, bbox);
bool alpha = gradient_has_alpha(key);
return find_pdf_shader(doc, std::move(key), alpha);
}