ShaderNodes: Use PreviewValues instead of QImage

src/ShaderNode/Previews/PreviewValues.cpp

@@ -0,0 +1,95 @@
+#include <ShaderNode/Previews/PreviewValues.hpp>
+#include <QtGui/QImage>
+
+PreviewValues::PreviewValues() :
+PreviewValues(0, 0)
+{
+}
+
+PreviewValues::PreviewValues(std::size_t width, std::size_t height) :
+m_height(height),
+m_width(width)
+{
+	m_values.resize(m_width * m_height); //< RGBA
+}
+
+void PreviewValues::Fill(const Nz::Vector4f& value)
+{
+	std::fill(m_values.begin(), m_values.end(), value);
+}
+
+QImage PreviewValues::GenerateImage() const
+{
+	QImage preview(int(m_width), int(m_height), QImage::Format_RGBA8888);
+
+	Nz::UInt8* ptr = preview.bits();
+
+	const Nz::Vector4f* src = m_values.data();
+	for (std::size_t i = 0; i < m_values.size(); ++i)
+	{
+		for (std::size_t y = 0; y < 4; ++y)
+			*ptr++ = static_cast<Nz::UInt8>(std::clamp((*src)[y] * 0xFF, 0.f, 255.f));
+
+		*src++;
+	}
+
+	return preview;
+}
+
+PreviewValues PreviewValues::Resized(std::size_t newWidth, std::size_t newHeight) const
+{
+	PreviewValues resizedPreview(newWidth, newHeight);
+
+	float xStep = 1.f / newWidth;
+	float yStep = 1.f / newHeight;
+
+	for (std::size_t y = 0; y < newHeight; ++y)
+	{
+		for (std::size_t x = 0; x < newWidth; ++x)
+			resizedPreview(x, y) = Sample(x * xStep, y * yStep);
+	}
+
+	return resizedPreview;
+}
+
+Nz::Vector4f PreviewValues::Sample(float u, float v) const
+{
+	// Bilinear filtering
+	float x = std::clamp(u * m_width, 0.f, m_width - 1.f);
+	float y = std::clamp(v * m_height, 0.f, m_height - 1.f);
+
+	std::size_t iX = static_cast<std::size_t>(x);
+	std::size_t iY = static_cast<std::size_t>(y);
+
+	float dX = x - iX;
+	float dY = y - iY;
+
+	auto ColorAt = [&](std::size_t x, std::size_t y) -> Nz::Vector4f
+	{
+		x = std::min(x, m_width - 1);
+		y = std::min(y, m_height - 1);
+
+		return m_values[y * m_width + x];
+	};
+
+	Nz::Vector4f d00 = ColorAt(iX, iY);
+	Nz::Vector4f d10 = ColorAt(iX + 1, iY);
+	Nz::Vector4f d01 = ColorAt(iX, iY + 1);
+	Nz::Vector4f d11 = ColorAt(iX + 1, iY + 1);
+
+	return Nz::Lerp(Nz::Lerp(d00, d10, dX), Nz::Lerp(d01, d11, dX), dY);
+}
+
+Nz::Vector4f& PreviewValues::operator()(std::size_t x, std::size_t y)
+{
+	assert(x < m_width);
+	assert(y < m_height);
+	return m_values[y * m_width + x];
+}
+
+Nz::Vector4f PreviewValues::operator()(std::size_t x, std::size_t y) const
+{
+	assert(x < m_width);
+	assert(y < m_height);
+	return m_values[y * m_width + x];
+}