ultimatepp/tutorial/Image06/main.cpp

#include <CtrlLib/CtrlLib.h>

using namespace Upp;

Image CreateBall(int r, Color color)
{
	int rr = 2 * r;
	int r2 = r * r;
	ImageBuffer b(rr, rr);
	for(int y = 0; y < rr; y++)
		for(int x = 0; x < rr; x++) {
			RGBA& a = b[y][x];
			a.r = color.GetR();
			a.g = color.GetG();
			a.b = color.GetB();
			int q = ((x - r) * (x - r) + (y - r) * (y - r)) * 256 / r2;
			a.a = q <= 255 ? q : 0;
		}
	return Image(b);
}

struct BallMaker : ImageMaker {
	Color color;
	int   r;

	String Key() const override {
		char h[sizeof(int) + 3];
		*(int *)h = r;
		h[sizeof(int)] = color.GetR();
		h[sizeof(int) + 1] = color.GetG();
		h[sizeof(int) + 2] = color.GetB();
		return String(h, sizeof(int) + 3);
	}
	
	Image Make() const override {
		return CreateBall(r, color);
	}
};

Image CreateBallCached(int r, Color color)
{
	BallMaker m;
	m.r = r;
	m.color = color;
	return MakeImage(m);
}

struct MyApp : public TopWindow {
	bool cached;

	void Paint(Draw& w) override {
		w.DrawRect(GetSize(), White);
		for(int y = 0; y < 300; y += 30)
			for(int i = 10; i < 500; i += i / 3) {
				Color c = Color((200 * i) & 255, (150 * i) & 255, (300 * i) & 255);
				w.DrawImage(i, y + i / 5, (cached ? CreateBallCached : CreateBall)(i / 2, c));
			}
	}

	void LeftDown(Point, dword) override {
		cached = true;
		Title("Now cached - try to resize the window to see the speed");
	}

	MyApp() {
		cached = false;
		Title("Not cached - try to resize the window to see the speed, click to activate the cache");
		Sizeable().Zoomable();
	}
};

GUI_APP_MAIN
{
	MyApp().Run();
}