5f30d87fd0
This is necessary to allow calculation of correct intersection of visible canvas area and items for the new Item::prepare_for_render() API. samples_per_pixel must be set first to calculate the new horizontal canvas position in Editor::set_horizontal_position and then WaveView::set_samples_per_pixel will eventually call WaveView::prepare_for_render for those items that are visible on the new canvas position at the new position. Or if there is not a change to zoom state then call Canvas::prepare_for_render explicitly. Also changes so that each method is only called once during Editor::visual_changer
Please see the Ardour web site at http://ardour.org/ for all documentation..
For information on building ardour:
http://ardour.org/development.html