struct or class

[nikki via Digitalmars-d-learn]

I come from languages that don't offer structs, I have this json 
load function that has to keep some data and intuitively I've 
written a struct, I've read about the differences, heap vs stack, 
value vs reference, but know I think i am overthinking it.

Is this decent:
	bool loadFromFile (string path)
	{
		auto data = readText(path);
	        JSONValue parsed = parseJSON(data);
		
		struct AtlasSpriteData
		{
			SDL_Rect clipRectangle;
			int xOffset;
			int yOffset;
		}
		AtlasSpriteData[string] dict;

	        foreach( string name, value; parsed["frames"] ){
			SDL_Rect clipRectangle;
                         auto spriteSourceSize = 
value["spriteSourceSize"];
			clipRectangle.x = to!int(frame["x"].toString());
			clipRectangle.y = to!int(frame["y"].toString());
			clipRectangle.w = to!int(frame["w"].toString());
			clipRectangle.h = to!int(frame["h"].toString());
			int xOffset = to!int(spriteSourceSize["x"].toString());
			int yOffset = to!int(spriteSourceSize["y"].toString());
			auto data = AtlasSpriteData(clipRectangle, xOffset, yOffset);
			dict[name] = data;
		}

Or should I use a class for that AtlasSpriteData?
reading about it I get the impression everytime I'll look up data 
from that dictionary data will get copied ?