Besides simply building your 2d engine on top of a multi-platform library as @ddriver is suggesting, you can allocate a large buffer for pixel colors and write code to render all your primitives (individual pixels, lines, boxes, circles, ellipses, arcs, textures/bitmaps/images, text characters) into it. Once you've completed rendering of a frame in this buffer you can then call whatever library is there to display this buffer as an image on the screen or in a window. Or, if your code is running on bare hardware w/o any support libraries, you can simply copy this buffer into the video buffer of the graphics card.
Your API could look something like this:
typedef struct
{
unsigned BitsPerPixel; // 8,16,32
unsigned ColorScheme; // something that tells the order of the R, G and B components and how many bits are in each or if there's a palette used instead of RGB
unsigned Width; // in pixels
unsigned Height; // in pixels
size_t Size; // buffer size in bytes
void* Buf; // pointer to the beginning of the buffer itself
// extra info
} tBuffer;
int BufferInit(tBuffer* Buf, unsigned BitsPerPixel, unsigned ColorScheme, unsigned Width, unsigned Height)
{
Buf->BitsPerPixel = BitsPerPixel;
Buf->ColorScheme = ColorScheme;
Buf->Width = Width;
Buf->Height = Height;
Buf->Size = Buf->Width * Buf->Height * Buf->BitsPerPixel / 8;
Buf->Buf = malloc(Buf->Size);
if (Buf->Buf != NULL)
{
memset(Buf->Buf, 0, Buf->Size);
return 1;
}
return 0;
}
void BufferDone(tBuffer* Buf)
{
free(Buf->Buf);
Buf->Buf = NULL;
}
unsigned FindClosest8BitPaletteIndex(unsigned R, unsigned G, unsigned B)
{
// find the palette element that's closest to the given R, G and B
// and return its index
}
unsigned BufferRgbToColor(tBuffer* Buf, unsigned R, unsigned G, unsigned B)
{
switch (Buf->BitsPerPixel)
{
case 8:
return FindClosest8BitPaletteIndex(R, G, B);
case 16:
return ((R & 0x1F) << 11) | ((G & 0x3F) << 6) | (B & 0x1F); // 5-6-5
case 32:
return ((R & 0xFF) << 16) | ((G & 0xFF) << 8) | (B & 0xFF); // (8)-8-8-8
default:
return 0; // error
}
}
void BufferSetPixel(tBuffer* Buf, unsigned X, unsigned Y, unsigned Color)
{
switch (Buf->BitsPerPixel)
{
case 8:
*((unsigned char*)Buf->Buf + Buf->Width * Y + X) = Color;
break;
case 16:
*((unsigned short*)Buf->Buf + Buf->Width * Y + X) = Color;
break;
case 32:
*((unsigned*)Buf->Buf + Buf->Width * Y + X) = Color;
break;
}
}
And then you could use it like this:
tBuffer buf;
if (BufferInit(&buf, 32, 0, 1024, 768))
{
BufferSetPixel(&buf, 512, 384, BufferRgbToColor(&buf, 0xFF, 0xFF, 0xFF));
// make the contents of buf.Buf visible in some way
BufferDone(&buf);
}
This should give you some ideas.
