On 12/10/2010 08:00 PM, Ping Cheng wrote: > On Fri, Dec 10, 2010 at 10:13 AM, Henrik Rydberg <rydberg@xxxxxxxxxxx> wrote: >> >>> Can we make MT_TOOL_ENVELOPE cover a bit more cases by: >>> >>> 1. Removing ", and is only used for legacy hardware"; >>> 2. Adding "Or the number of contacts inside the bounding rectangle is >>> reported if hardware provides the number but not the real contact >>> positions" to the end of the paragraph. >> >> You might disagree, but "old" is still somewhat apt in this situation. > > It's ok if we say the new type was inspired by legacy hardware. But > saying that it "is only used for legacy hardware" closes the door for > future development. That's not what we are trying to do, right? Well, in a sense we are. I would agree that data aiming to provide gestures as a 2D transformation matrix can be handled quite well with two tracked points and a finger count. However, a multitouch interface where users manipulate different objects on the screen simultaneously is a different story. > >> How would you suggest we report the number of fingers? > > I guess if we want to make it generic, we could have something like > ABS_MT_NUM_CONTACTS to go with MT_TOOL_ENVELOPE. Clients, such as > synaptics touchpads, that only care about the number of contacts > inside the envelope don't need to process the contact positions even > when they are reported. This also resolve the potential that > BTN_TOOL_QUADTAP is not enough to tell us how many contacts are on the > surface. I really would like to avoid adding a new way to solve an old problem, in particular given the statement above. Adding something like BTN_TOOL_QUINTAP would hurt a little bit, but not nearly as much. > > Maybe we should also tell the clients whether they are going to get > the contact positions or not. I may not understand what you mean here, but if you are referring to an up-front declaration of what MT_TOOL types are to be expected, we did discuss this before, without any conclusion. Perhaps it is relevant to outline why this would be important. Thanks, Henrik -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
