#include "SuperImposedFrame.hh"

#include "LineScalers.hh"

#include "inplace_buffer.hh"

#include <algorithm>

#include <cstdint>

namespace openmsx {

using Pixel = uint32_t;

void SuperImposedFrame::init(

	const FrameSource* top_, const FrameSource* bottom_)

{

	top = top_;

	bottom = bottom_;

	setHeight(std::max(top->getHeight(), bottom->getHeight()));

}

unsigned SuperImposedFrame::getLineWidth(unsigned line) const

{

	unsigned tNum = (getHeight() == top   ->getHeight()) ? line : line / 2;

	unsigned bNum = (getHeight() == bottom->getHeight()) ? line : line / 2;

	unsigned tWidth = top   ->getLineWidth(tNum);

	unsigned bWidth = bottom->getLineWidth(bNum);

	return std::max(tWidth, bWidth);

}

std::span<const FrameSource::Pixel> SuperImposedFrame::getUnscaledLine(

	unsigned line, std::span<Pixel> helpBuf) const

{

	unsigned tNum = (getHeight() == top   ->getHeight()) ? line : line / 2;

	unsigned bNum = (getHeight() == bottom->getHeight()) ? line : line / 2;

	unsigned tWidth = top   ->getLineWidth(tNum);

	unsigned bWidth = bottom->getLineWidth(bNum);

	auto width = std::min(std::max<size_t>(tWidth, bWidth), // as wide as the widest source

	                      helpBuf.size()); // but no wider than the output buffer

	auto tBuf = helpBuf.subspan(0, width);

	inplace_buffer<Pixel, 1280> bBuf(uninitialized_tag{}, width);

	auto tLine = top   ->getLine(narrow<int>(tNum), tBuf);

	auto bLine = bottom->getLine(narrow<int>(bNum), bBuf);

	alphaBlendLines(tLine, bLine, tBuf); // possibly tLine == tBuf

	return tBuf;

}

} // namespace openmsx