Hi, I have cooked up these patches for implementing the display of a drag'n'drop surface. I think there are a lot of issues with them (see below) and getting some feedback now would be good.
This is implemented by adding data_device.set_surface request that creates a surface that follows the cursor when it moves, keeping the distance of the top-left corner of the surface to the cursor hotspot unchanged. The name set_surface is misleading, and I don't know what name the similar request for cursor surfaces will have. But I guess we should be consistent here. This request receives two parameters, x and y, that defines the initial distance between the surface and the cursor hotspot. One thing that is not clear is what is the behavior if a client calls this request twice for the same grab. What happens if attach is alternated between the two returned surfaces? I was also wondering if we should add a drag icon surface type to shell. The use case I'm thinking is in a touch screen scenario, where we might want to display the icon above the user's finger. So maybe we should define (x,y) as a hotspot instead of a delta from the cursor hotspot and have the shell define what it means. This would also solve the problem of mapping the drag surface under the shell panels. Since data_device is implemented in libwayland-server, moving the icon surface to the right position was a little tricky. When set_surface is called, it stores the delta on the wl_input_device. On the compositor side, whenever the surface's position needs to be udpated, this delta will be checked and used if necessary. The problem is that when the drag starts, the first attach will happen before any mouse movement, so it was necessary to check it also in output_repaint(). libwayland-server will also force an attach with a null buffer when the drag ends. This may causes flicker in the dnd demo. Wayland changes: Ander Conselvan de Oliveira (1): data_device: use a regular surface for drag icons protocol/wayland.xml | 18 +++++-- src/data-device.c | 142 +++++++++++++++++++++++++++++++++++++++++++++++--- src/wayland-server.h | 5 ++ 3 files changed, 152 insertions(+), 13 deletions(-) Weston changes: Ander Conselvan de Oliveira (4): shell: don't crash on get_shell_surface with non-client surfaces compositor: fix two crashs on surface_attach() with null buffer compositor: implement new data_device.set_surface protocol clients/dnd: use new data_device.set_surface protocol clients/dnd.c | 15 ++++++++++-- src/compositor.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ src/compositor.h | 1 + src/shell.c | 3 ++ 4 files changed, 80 insertions(+), 3 deletions(-) -- 1.7.4.1 _______________________________________________ wayland-devel mailing list wayland-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/wayland-devel
