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Radial shading
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Jakub Melka
parent
d7ba96ac5b
commit
8ddbcc0f4d
@ -1702,6 +1702,229 @@ PDFMesh PDFRadialShading::createMesh(const PDFMeshQualitySettings& settings, con
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return mesh;
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}
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class PDFRadialShadingSampler : public PDFShadingSampler
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{
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public:
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PDFRadialShadingSampler(const PDFRadialShading* radialShadingPattern, QMatrix userSpaceToDeviceSpaceMatrix) :
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PDFShadingSampler(radialShadingPattern),
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m_radialShadingPattern(radialShadingPattern),
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m_xStart(0.0),
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m_xEnd(0.0),
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m_tAtStart(0.0),
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m_tAtEnd(0.0),
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m_tMin(0.0),
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m_tMax(0.0),
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m_r0(0.0),
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m_r1(0.0)
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{
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QMatrix patternSpaceToDeviceSpace = radialShadingPattern->getMatrix() * userSpaceToDeviceSpaceMatrix;
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QPointF p1 = patternSpaceToDeviceSpace.map(radialShadingPattern->getStartPoint());
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QPointF p2 = patternSpaceToDeviceSpace.map(radialShadingPattern->getEndPoint());
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// Strategy: for simplification, we rotate the line clockwise so we will
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// get the shading axis equal to the x-axis.
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QLineF line(p1, p2);
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const double angle = line.angleTo(QLineF(0, 0, 1, 0));
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// Matrix p1p2LCS is local coordinate system of line p1-p2. It transforms
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// points on the line to the global coordinate system. So, point (0, 0) will
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// map onto p1 and point (length(p1-p2), 0) will map onto p2.
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QMatrix p1p2LCS;
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p1p2LCS.translate(p1.x(), p1.y());
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p1p2LCS.rotate(angle);
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QMatrix p1p2GCS = p1p2LCS.inverted();
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QPointF p1m = p1p2GCS.map(p1);
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QPointF p2m = p1p2GCS.map(p2);
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Q_ASSERT(isZero(p1m.y()));
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Q_ASSERT(isZero(p2m.y()));
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Q_ASSERT(p1m.x() <= p2m.x());
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m_xStart = p1m.x();
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m_xEnd = p2m.x();
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m_tAtStart = radialShadingPattern->getDomainStart();
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m_tAtEnd = radialShadingPattern->getDomainEnd();
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m_tMin = qMin(m_tAtStart, m_tAtEnd);
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m_tMax = qMax(m_tAtStart, m_tAtEnd);
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m_r0 = radialShadingPattern->getR0();
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m_r1 = radialShadingPattern->getR1();
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m_p1p2GCS = p1p2GCS;
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}
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virtual bool sample(const QPointF& devicePoint, PDFColorBuffer outputBuffer, int limit) const override
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{
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Q_UNUSED(limit);
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if (!m_pattern->getColorSpace() || m_pattern->getColorSpace()->getColorComponentCount() != outputBuffer.size())
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{
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// Invalid color space, or invalid color buffer
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return false;
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}
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QPointF mappedPoint = m_p1p2GCS.map(devicePoint);
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// Well, how to proceed with sampling? We would like to find parameter s for point (x_p, y_p),
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// where (x_p, y_p) is mappedPoint. According to the formulas in the PDF 2.0 specification, we want
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// to find variable s:
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//
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// x_c = x_0 + s * (x_1 - x_0)
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// y_c = y_0 + s * (y_1 - y_0)
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// r = r_0 + s * (r_1 - r_0)
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//
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// Where (x_c, y_c) is center of the circle. We assume this simplification: we translate the pattern
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// to horizontal axis, this implies y_0 = y_1 = 0, so y_c will be always zero. This will allow us to use
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// simplification.
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//
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// This is general equation, which we want to solve:
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//
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// (x_p - x_c)^2 + (y_p - y_c)^2 = r^2,
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// where (x_p, y_p) is sample point, (x_c, y_c) is coordinate of the circle center and r is radius.
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// If we use y_c = 0, then we get following equation:
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//
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// (x_p - x_c)^2 + y_p^2 = r^2,
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//
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// If we substitute x_c and r with formulas above, we get:
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//
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// (x_p - x_0 - s * (x_1 - x_0))^2 + y_p^2 = (r_0 + s * (r_1 - r_0))^2,
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//
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// We also have x_0 = 0, because we have origin at (0, 0), so we get following final equation:
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//
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// (x_p - s * x_1)^2 + y_p^2 = (r_0 + s * (r_1 - r_0))^2,
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//
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// which is easily solvable quadratic equation in variable s. Using wxMaxima, we get following formula
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// for our variable s:
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//
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// a.s^2 + b.s + c = 0,
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//
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// where:
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//
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// a = x_1 * x_1 - r_1 * r_1 + 2.0 * r_0 * r_1 - r_0 * r_0 = (x_1 - r_1 + r_0) * (x_1 + r_1 - r_0)
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// b = 2.0 * (-x_1 * x_p - r_0 * r_1 + r_0 * r_0)
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// c = y_p * y_p + x_p * x_p - r_0 * r_0
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//
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Q_ASSERT(qIsNull(m_xStart));
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const PDFReal x_p = mappedPoint.x();
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const PDFReal y_p = mappedPoint.y();
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const PDFReal x_1 = m_xEnd;
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const PDFReal r_0 = m_r0;
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const PDFReal r_1 = m_r1;
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const PDFReal a = (x_1 - r_1 + r_0) * (x_1 + r_1 - r_0);
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const PDFReal b = 2.0 * (-x_1 * x_p - r_0 * r_1 + r_0 * r_0);
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const PDFReal c = y_p * y_p + x_p * x_p - r_0 * r_0;
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const PDFReal Dsqr = b * b - 4.0 * a * c;
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if (Dsqr < 0.0)
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{
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return false;
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}
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const PDFReal D = std::sqrt(Dsqr);
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PDFReal s1 = (-b - D) / (2.0 * a);
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PDFReal s2 = (-b + D) / (2.0 * a);
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PDFReal s = 0.0;
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if (s1 < 0.0 && m_radialShadingPattern->isExtendStart())
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{
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s1 = 0.0;
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}
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if (s2 > 1.0 && m_radialShadingPattern->isExtendEnd())
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{
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s2 = 1.0;
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}
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const bool s1Valid = s1 >= 0.0 && s1 <= 0.0;
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const bool s2Valid = s2 >= 0.0 && s2 <= 0.0;
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if (s2Valid)
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{
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s = s2;
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}
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else if (s1Valid)
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{
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s = s1;
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}
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else
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{
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return false;
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}
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PDFReal t = interpolate(s, m_xStart, m_xEnd, m_tAtStart, m_tAtEnd);
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t = qBound(m_tMin, t, m_tMax);
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const auto& functions = m_radialShadingPattern->getFunctions();
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std::array<PDFReal, PDF_MAX_COLOR_COMPONENTS> colorBuffer = { };
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if (colorBuffer.size() < outputBuffer.size())
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{
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// Jakub Melka: Too much colors - we cant process it
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return false;
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}
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if (functions.size() == 1)
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{
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Q_ASSERT(outputBuffer.size() <= colorBuffer.size());
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PDFFunction::FunctionResult result = functions.front()->apply(&t, &t + 1, colorBuffer.data(), colorBuffer.data() + outputBuffer.size());
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if (!result)
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{
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// Function call failed
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return false;
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}
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}
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else
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{
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if (functions.size() != outputBuffer.size())
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{
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// Invalid number of functions
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return false;
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}
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Q_ASSERT(outputBuffer.size() <= colorBuffer.size());
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for (size_t i = 0, count = outputBuffer.size(); i < count; ++i)
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{
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PDFFunction::FunctionResult result = functions[i]->apply(&t, &t + 1, colorBuffer.data() + i, colorBuffer.data() + i + 1);
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if (!result)
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{
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// Function call failed
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return false;
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}
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}
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}
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for (size_t i = 0, count = outputBuffer.size(); i < count; ++i)
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{
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outputBuffer[i] = colorBuffer[i];
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}
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return true;
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}
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private:
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const PDFRadialShading* m_radialShadingPattern;
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QMatrix m_p1p2GCS;
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PDFReal m_xStart;
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PDFReal m_xEnd;
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PDFReal m_tAtStart;
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PDFReal m_tAtEnd;
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PDFReal m_tMin;
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PDFReal m_tMax;
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PDFReal m_r0;
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PDFReal m_r1;
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};
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PDFShadingSampler* PDFRadialShading::createSampler(QMatrix userSpaceToDeviceSpaceMatrix) const
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{
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return new PDFRadialShadingSampler(this, userSpaceToDeviceSpaceMatrix);
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}
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ShadingType PDFFreeFormGouradTriangleShading::getShadingType() const
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{
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return ShadingType::FreeFormGouradTriangle;
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@ -417,6 +417,10 @@ public:
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virtual ShadingType getShadingType() const override;
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virtual PDFMesh createMesh(const PDFMeshQualitySettings& settings, const PDFCMS* cms, RenderingIntent intent, PDFRenderErrorReporter* reporter) const override;
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virtual PDFShadingSampler* createSampler(QMatrix userSpaceToDeviceSpaceMatrix) const override;
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PDFReal getR0() const { return m_r0; }
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PDFReal getR1() const { return m_r1; }
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private:
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friend class PDFPattern;
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