Function DrawScreen

deps/SDL2/test/testgesture.c:127–169

}

static void
DrawScreen(SDL_Window *window)
{
    SDL_Surface *screen = SDL_GetWindowSurface(window);
    int i;

    if (!screen) {
        return;
    }

    SDL_FillRect(screen, NULL, SDL_MapRGB(screen->format, 75, 75, 75));

    /* draw Touch History */
    for (i = eventWrite; i < eventWrite + EVENT_BUF_SIZE; ++i) {
        const SDL_Event *event = &events[i & (EVENT_BUF_SIZE - 1)];
        const float age = (float)(i - eventWrite) / EVENT_BUF_SIZE;
        float x, y;
        unsigned int c, col;

        if ( (event->type == SDL_FINGERMOTION) ||
             (event->type == SDL_FINGERDOWN) ||
             (event->type == SDL_FINGERUP) ) {
            x = event->tfinger.x;
            y = event->tfinger.y;

            /* draw the touch: */
            c = colors[event->tfinger.fingerId % 7];
            col = ((unsigned int) (c * (0.1f + 0.85f))) | (unsigned int) (0xFF * age) << 24;

            if (event->type == SDL_FINGERMOTION) {
                drawCircle(screen, x * screen->w, y * screen->h, 5, col);
            } else if (event->type == SDL_FINGERDOWN) {
                drawCircle(screen, x * screen->w, y * screen->h, -10, col);
            }
        }
    }

    if (knob.p.x > 0) {
        drawKnob(screen, &knob);
    }

    SDL_UpdateWindowSurface(window);
}

static void
loop(void)