Function DoZoomInOutWindow

src/main_gui.cpp:93–140

* Zooms a viewport in a window in or out. * @param how Zooming direction. * @param w Window owning the viewport. * @return Returns \c true if zooming step could be done, \c false if further zooming is not possible. * @note No button handling or what so ever is done. */

 * @note No button handling or what so ever is done.
 */
bool DoZoomInOutWindow(ZoomStateChange how, Window *w)
{
	assert(w != nullptr);

	switch (how) {
		case ZOOM_NONE:
			/* On initialisation of the viewport we don't do anything. */
			break;

		case ZOOM_IN: {
			ViewportData &vp = *w->viewport;
			if (vp.zoom <= _settings_client.gui.zoom_min) return false;
			--vp.zoom;
			vp.virtual_width >>= 1;
			vp.virtual_height >>= 1;

			vp.scrollpos_x += vp.virtual_width >> 1;
			vp.scrollpos_y += vp.virtual_height >> 1;
			vp.dest_scrollpos_x = vp.scrollpos_x;
			vp.dest_scrollpos_y = vp.scrollpos_y;
			break;
		}

		case ZOOM_OUT: {
			ViewportData &vp = *w->viewport;
			if (vp.zoom >= _settings_client.gui.zoom_max) return false;
			++vp.zoom;

			vp.scrollpos_x -= vp.virtual_width >> 1;
			vp.scrollpos_y -= vp.virtual_height >> 1;
			vp.dest_scrollpos_x = vp.scrollpos_x;
			vp.dest_scrollpos_y = vp.scrollpos_y;

			vp.virtual_width <<= 1;
			vp.virtual_height <<= 1;
			break;
		}
	}

	if (w->viewport != nullptr) { // the viewport can be null when how == ZOOM_NONE
		w->viewport->virtual_left = w->viewport->scrollpos_x;
		w->viewport->virtual_top = w->viewport->scrollpos_y;
	}

	/* Update the windows that have zoom-buttons to perhaps disable their buttons */
	w->InvalidateData();
	return true;
}

void ZoomInOrOutToCursorWindow(bool in, Window *w)
{