point C++

Hi, as I am new to C++, I am stuck on a problem which I do not understand how to go about doing it. I have this class renderedpoint to render a point(Obviously). But I am stuck on what to add inside the class renderedpoint and due to this, I am receiving a compilation error in my Object* Factory::createPoint member function. Anyone able to help me out on this? Much appreciated. I cut out some parts of the file as I do not want to pour everything here as it is a lot unless really needed.

Compilation error:
invalid new-expression of abstract class type ‘RenderedPoint’
return new RenderedPoint(//Unsure about what to write here..);

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Header file:
class Factory;

class IRenderingInformation
{
public:
	virtual Factory& getFactory() const = 0;
	virtual unsigned int getColor() const = 0;
	virtual ~IRenderingInformation() = default;
};
class Factory final
{
private:
	Factory() = delete;
	Factory(const Factory&) = delete;
	Factory(Factory&&) = delete;
	Factory& operator=(const Factory&) = delete;
	Factory& operator=(Factory&&) = delete;

public:
	typedef Object::VectorType VectorType;
	typedef Object::PointType PointType;
	typedef IRenderingInformation RenderingInformation;
	typedef uint8_t Byte;

	Factory(unsigned int width, unsigned int height, const VectorType& extents);
	~Factory();

	Object* createPoint(const PointType& center,
		unsigned color, float depth = 1);
	 
	void writeToBitmap(const char* name);

	static char* readFromBitmap(unsigned int& width, unsigned int& height,
		const char* name);

	static unsigned getColor(Byte r, Byte g, Byte b);

	POINT toDevice(const VectorType& v) const;
	HDC getContext() const;

private:
	HBITMAP _bitmap;
	HDC _context;
	unsigned int _width;
	unsigned int _height;
	void* _bitmapData;
	float _xFactor;
	float _yFactor;
};

cpp file:

namespace
{
	const unsigned char BYTES_PER_PIXEL = 3;
}

class RenderedPoint : public Point, public IRenderingInformation
{
public:
	void render() const override;
	
	// What do I need to do here?
};

 
Factory::Factory(
	unsigned int width,
	unsigned int height,
	const VectorType& extents
) :
	_width{width},
	_height{height},
	_xFactor{static_cast<float>(width) / extents.x()},
	_yFactor{static_cast<float>(height) / extents.y()}
{
	_context = CreateCompatibleDC(0);
	BITMAPINFO bitmapInfo;
	ZeroMemory(&bitmapInfo, sizeof(bitmapInfo));
	bitmapInfo.bmiHeader.biSize = sizeof(bitmapInfo);
	bitmapInfo.bmiHeader.biWidth = width;
	bitmapInfo.bmiHeader.biHeight = height;
	bitmapInfo.bmiHeader.biPlanes = 1;
	bitmapInfo.bmiHeader.biBitCount = 24;
	bitmapInfo.bmiHeader.biCompression = BI_RGB;
	_bitmap = CreateDIBSection(_context, &bitmapInfo, DIB_RGB_COLORS,
		&_bitmapData, 0, 0
	);
	SelectObject(_context, _bitmap);
}

Factory::~Factory()
{
	HGDIOBJ old = SelectObject(_context, GetStockObject(NULL_BRUSH));
	DeleteObject(old);
	DeleteDC(_context);
	DeleteObject(_bitmap);
}

HDC Factory::getContext() const
{
	return _context;
}

unsigned Factory::getColor(Byte r, Byte g, Byte b)
{
	return RGB(r, g, b);
}

void Factory::writeToBitmap(const char* name)
{
	const unsigned int rowData = BYTES_PER_PIXEL * _width;
	const unsigned int rowPadding = (rowData % 4 != 0)
		? (4 - rowData % 4)
		: 0;
	const unsigned int stride = rowData + rowPadding;
	std::fstream out{name, std::ios_base::binary | std::ios_base::out};
	if (out)
	{
		BITMAPFILEHEADER bmfh;
		BITMAPINFOHEADER bmih;

		ZeroMemory(&bmfh, sizeof(bmfh));
		bmfh.bfType = 'B' + ('M' << 8);
		bmfh.bfSize = static_cast<unsigned int>(
			sizeof(bmfh) +
			sizeof(bmih) +
			stride * _height
		);
		bmfh.bfOffBits = sizeof(bmfh) + sizeof(bmih);
		out.write(reinterpret_cast<char*>(&bmfh), sizeof(bmfh));

		ZeroMemory(&bmih, sizeof(bmih));
		bmih.biSize = sizeof(bmih);
		bmih.biWidth = _width;
		bmih.biHeight = _height;
		bmih.biPlanes = 1;
		bmih.biBitCount = 8 * BYTES_PER_PIXEL;
		bmih.biCompression = BI_RGB;
		out.write(reinterpret_cast<char*>(&bmih), sizeof(bmih));

		for (unsigned int h = 0; h < _height; ++h)
		{
			out.write(
				reinterpret_cast<char*>(_bitmapData) + h * stride,
				rowData
			);
			if (stride > rowData)
			{
				out.write("000", stride - rowData);
			}
		}
	}
}

char* Factory::readFromBitmap(unsigned int& width, unsigned int& height,
	const char* name
)
{
	std::fstream in{name, std::ios_base::in | std::ios_base::binary};
	if (in)
	{
		char header[54];
		in.read(header, 54);
		width = *reinterpret_cast<unsigned int*>(header + 18);
		const int signedHeight = *reinterpret_cast<int*>(header + 22);
		height = static_cast<unsigned int>(std::abs(signedHeight));
		const unsigned int size = *reinterpret_cast<unsigned int*>(header + 34);
		const unsigned int stride = size / height;
		const unsigned int rowData = BYTES_PER_PIXEL * width;
		char* const data = new char[rowData * height];
		for (unsigned int i = 0; i < height; ++i)
		{
			in.read(data + rowData * i, rowData);
			if (stride > rowData)
			{
				char buffer[4];
				in.read(buffer, stride - rowData);
			}
		}
		return data;
	}
	else
	{
		return nullptr;
	}
}

Object* Factory::createPoint(const PointType& center, unsigned color,
	float depth
)
{
	return new RenderedPoint(//Unsure about what to write here..);
}

void RenderedPoint::render() const
{
	POINT p = getFactory().toDevice(center());
	SetPixel(getFactory().getContext(), p.x, p.y, getColor());
}
Last edited on
Your RenderedPoint class is unfinished. Not fully defined. Missing pieces.

You can't create an object with missing pieces. There is at least one function that your RenderedPoint needs to implement. A function that you didn't write the code for. I suspect a function that is virtual in IRenderingInformation

Identify the function(s) you haven't written in the RenderedPoint class, and write them.
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