Graphic surface

Fortunate, the disko provides its own surface which can be work with the cairo. This can be seen in its flash support. The createSurface can be used to create a directfb surface.

this->window->getLayer()->createSurface(&(this->flash_temp_surface), this->width, this->height, MMSFB_PF_ARGB, 0);

Then, we can use lock to acquire the framebuffer from the directfb.

this->flash_temp_surface->lock(MMSFB_LOCK_WRITE, &ptr, &pitch);
this->flash_temp_surface->unlock();

Then we can use cairo_image_surface_create_for_data to create a cairo surface from this buffer.

this->cairosurface = cairo_image_surface_create_for_data((unsigned char*)ptr, CAIRO_FORMAT_ARGB32,
                                                            this->width, this->height, pitch);

Finally, a cairo instance is created with this cairo surface

this->cairo = cairo_create((cairo_surface_t *)cairosurface);

In this way, we create a cairo surface on top of the directfb framebuffer. All remaining cairo operation is applied against this surface. By this way, we can not enjoy the acceleration provided by a direct DFB integration. However, it's good enough for non-accelerated platform.

The madbutterfly can be implemented in the same way. If the acceleration is required, we should create a cairo surface directly from the cairo directfb backend. In this way, we can create a cairo directfb surface and use the window cliping to limit its drawing area to be within the window.