The ABS_RECT_* codes allow for partial multitouch support for devices
that do not provide accurate touch coordinate pairings. For example, a
device may emit two touches at points (X1, Y1) and (X2, Y2); however,
the real touch coordinates may be (X1, Y2) and (X2, Y1). Providing a
bounding rectangle allows for panning and pinching multitouch support.
Signed-off-by: Chase Douglas <chase.douglas@xxxxxxxxxxxxx>
---
Documentation/input/evdev-codes.txt | 10 ++++++++++
include/linux/input.h | 5 +++++
2 files changed, 15 insertions(+), 0 deletions(-)
diff --git a/Documentation/input/evdev-codes.txt b/Documentation/input/evdev-codes.txt
index 69c810f..65db20e 100644
--- a/Documentation/input/evdev-codes.txt
+++ b/Documentation/input/evdev-codes.txt
@@ -116,6 +116,16 @@ A few EV_ABS codes have special meanings:
should only be used while the tool is in close proximity of the device. If
the input device may be used freely in three dimensions, consider ABS_Z
instead.
+* ABS_RECT_MIN_X, ABS_RECT_MIN_Y, ABS_RECT_MAX_X, ABS_RECT_MAX_Y:
+ - Used to convey partial multitouch support. Some legacy device multitouch
+ coordinates are not accurate enough to be relied on directly. For example,
+ the device may give coordinates (X1, Y1) and (X2, Y2) for two touch points,
+ but in reality the touches are at (X1, Y2) and (X2, Y1). The maximum and
+ minimum axis values are accurate, so they may be used to provide a rectangle
+ bounding box for the touches.
+ The values for these codes are undefined unless two or more touches are
+ active, designated by BTN_TOOL_DOUBLETAP or higher order code being set to
+ 1.
* ABS_MT_<name>:
- Used to describe multitouch input events. Please see
multi-touch-protocol.txt for details.
diff --git a/include/linux/input.h b/include/linux/input.h
index cd0618c..5acdc60 100644
--- a/include/linux/input.h
+++ b/include/linux/input.h
@@ -719,6 +719,11 @@ struct input_keymap_entry {
#define ABS_VOLUME 0x20
+#define ABS_RECT_MIN_X 0x21
+#define ABS_RECT_MIN_Y 0x22
+#define ABS_RECT_MAX_X 0x23
+#define ABS_RECT_MAX_Y 0x24
+
#define ABS_MISC 0x28
#define ABS_MT_SLOT 0x2f /* MT slot being modified */
--
1.7.1
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