[PATCH xf86-input-libinput 2/2] Implement stylus pressure curve support
Peter Hutterer
peter.hutterer at who-t.net
Mon Oct 31 05:26:33 UTC 2016
Takes a 4-point cubic bezier curve as input and maps the pressure coordinates
to the values outlined by this curve. This is an extension of the current
implementation in the xf86-input-wacom driver which only allows the two center
control points to be modified.
Over the years a few users have noted that the wacom driver's pressure curve
makes it impossible to cap the pressure at a given value. Given our bezier
implementation here, it's effectively a freebie to add configurability of the
first and last control points. We do require all control points' x coordinates
to be in ascending order.
Signed-off-by: Peter Hutterer <peter.hutterer at who-t.net>
---
include/libinput-properties.h | 7 ++
man/libinput.man | 31 +++++++
src/Makefile.am | 2 +-
src/bezier.c | 7 ++
src/bezier.h | 2 +
src/xf86libinput.c | 184 +++++++++++++++++++++++++++++++++++++++++-
6 files changed, 230 insertions(+), 3 deletions(-)
diff --git a/include/libinput-properties.h b/include/libinput-properties.h
index 8c6942d..f76500f 100644
--- a/include/libinput-properties.h
+++ b/include/libinput-properties.h
@@ -183,4 +183,11 @@
/* Device rotation: FLOAT, 1 value, 32 bit, read-only */
#define LIBINPUT_PROP_ROTATION_ANGLE_DEFAULT "libinput Rotation Angle Default"
+/* Tablet tool pressure curve: float, 8 values, 32 bit
+ * Value range is [0.0, 1.0], the values specify the x/y of the four
+ * control points for a cubic bezier curve.
+ * Default value: 0.0 0.0 0.0 0.0 1.0 1.0 1.0 1.0
+ */
+#define LIBINPUT_PROP_TABLET_TOOL_PRESSURECURVE "libinput Tablet Tool Pressurecurve"
+
#endif /* _LIBINPUT_PROPERTIES_H_ */
diff --git a/man/libinput.man b/man/libinput.man
index 36775e6..c1655a7 100644
--- a/man/libinput.man
+++ b/man/libinput.man
@@ -155,6 +155,12 @@ default scroll option for this device is used.
Sets the send events mode to disabled, enabled, or "disable when an external
mouse is connected".
.TP 7
+.BI "Option \*qTabletToolPressureCurve\*q \*q" "x0/y0 x1/y1 x2/y2 x3/y3" \*q
+Set the pressure curve for a tablet stylus to the bezier formed by the four
+points. The respective x/y coordinate must be in the [0.0, 1.0] range. For
+more information see section
+.B TABLET STYLUS PRESSURE CURVE.
+.TP 7
.BI "Option \*qTapping\*q \*q" bool \*q
Enables or disables tap-to-click behavior.
.TP 7
@@ -252,6 +258,11 @@ on this device.
"disabled-on-external-mouse". Indicates which send-event modes is currently
enabled on this device.
.TP 7
+.BI "libinput Tablet Tool Pressurecurve"
+4 32-bit float values [0.0 to 1.0]. See section
+.B TABLET TOOL PRESSURE CURVE
+for more information.
+.TP 7
.BI "libinput Tapping Enabled"
1 boolean value (8 bit, 0 or 1). 1 enables tapping
.TP 7
@@ -313,6 +324,26 @@ and only the target button events are sent.
.TP
This feature is provided by this driver, not by libinput.
+.SH TABLET TOOL PRESSURECURVE
+The pressure curve affects how stylus pressure is reported. By default, the
+hardware pressure is reported as-is and (usually). By setting a pressure curve,
+the feel of the stylus can be adjusted to be more like e.g. a pencil or a
+brush.
+.PP
+The pressure curve is a cubic Bezier curve, drawn within a normalized range
+of 0.0 to 1.0 between the four points provided. This normalized range is
+applied to the tablet's pressure input so that the highest pressure maps to
+1.0. The points must have increasing x coordinates, if x0 is larger than 0.0
+all pressure values lower than x0 are equivalent to y0. If x3 is less than
+1.0, all pressure values higher than x3 are equivalent to y3.
+
+The input for a linear curve (default) is "0.0/0.0 0.0/0.0 1.0/1.0 1.0/1.0";
+a slightly
+depressed curve (firmer) might be "0.0/0.0 0.05/0.0 1.0/0.95 1.0/1.0"; a slightly raised
+curve (softer) might be "0.0/0.0 0.0/0.05 0.95/1.0 1.0/1.0".
+.TP
+This feature is provided by this driver, not by libinput.
+
.SH AUTHORS
Peter Hutterer
.SH "SEE ALSO"
diff --git a/src/Makefile.am b/src/Makefile.am
index 8634b69..5dcb55e 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -30,7 +30,7 @@ AM_CPPFLAGS =-I$(top_srcdir)/include $(LIBINPUT_CFLAGS)
@DRIVER_NAME at _drv_la_LTLIBRARIES = @DRIVER_NAME at _drv.la
@DRIVER_NAME at _drv_la_LDFLAGS = -module -avoid-version
- at DRIVER_NAME@_drv_la_LIBADD = $(LIBINPUT_LIBS) libdraglock.la -lm
+ at DRIVER_NAME@_drv_la_LIBADD = $(LIBINPUT_LIBS) libdraglock.la libbezier.la -lm
@DRIVER_NAME at _drv_ladir = @inputdir@
@DRIVER_NAME at _drv_la_SOURCES = xf86libinput.c
diff --git a/src/bezier.c b/src/bezier.c
index e571a3c..95af16a 100644
--- a/src/bezier.c
+++ b/src/bezier.c
@@ -31,6 +31,13 @@
#include "bezier.h"
+const struct bezier_control_point bezier_defaults[4] = {
+ { 0.0, 0.0 },
+ { 0.0, 0.0 },
+ { 1.0, 1.0 },
+ { 1.0, 1.0 },
+};
+
struct point {
int x, y;
};
diff --git a/src/bezier.h b/src/bezier.h
index c7f3b27..7406565 100644
--- a/src/bezier.h
+++ b/src/bezier.h
@@ -35,6 +35,8 @@ struct bezier_control_point {
double x, y;
};
+extern const struct bezier_control_point bezier_defaults[4];
+
/**
* Given four control points in the range [(0.0/0.0), (1.0/1.0)]
* construct a Bézier curve.
diff --git a/src/xf86libinput.c b/src/xf86libinput.c
index 07b4d4e..470b1ff 100644
--- a/src/xf86libinput.c
+++ b/src/xf86libinput.c
@@ -42,6 +42,7 @@
#include <X11/Xatom.h>
+#include "bezier.h"
#include "draglock.h"
#include "libinput-properties.h"
@@ -162,6 +163,7 @@ struct xf86libinput {
BOOL horiz_scrolling_enabled;
float rotation_angle;
+ struct bezier_control_point pressurecurve[4];
} options;
struct draglock draglock;
@@ -172,6 +174,13 @@ struct xf86libinput {
struct libinput_tablet_tool *tablet_tool;
bool allow_mode_group_updates;
+
+ /* Pre-calculated pressure curve.
+ In the 0...TABLET_AXIS_MAX range */
+ struct {
+ int *values;
+ size_t sz;
+ } pressurecurve;
};
enum event_handling {
@@ -382,6 +391,30 @@ xf86libinput_shared_is_enabled(struct xf86libinput_device *shared_device)
return shared_device->enabled_count > 0;
}
+static inline bool
+xf86libinput_set_pressurecurve(struct xf86libinput *driver_data,
+ const struct bezier_control_point controls[4])
+{
+ if (memcmp(controls, bezier_defaults, sizeof(bezier_defaults)) == 0) {
+ free(driver_data->pressurecurve.values);
+ driver_data->pressurecurve.values = NULL;
+ return true;
+ }
+
+ if (!driver_data->pressurecurve.values) {
+ int *vals = calloc(TABLET_PRESSURE_AXIS_MAX + 1, sizeof(int));
+ if (!vals)
+ return false;
+
+ driver_data->pressurecurve.values = vals;
+ driver_data->pressurecurve.sz = TABLET_PRESSURE_AXIS_MAX + 1;
+ }
+
+ return cubic_bezier(controls,
+ driver_data->pressurecurve.values,
+ driver_data->pressurecurve.sz);
+}
+
static int
LibinputSetProperty(DeviceIntPtr dev, Atom atom, XIPropertyValuePtr val,
BOOL checkonly);
@@ -1626,8 +1659,9 @@ xf86libinput_handle_tablet_axis(InputInfoPtr pInfo,
tool = libinput_event_tablet_tool_get_tool(event);
if (libinput_tablet_tool_has_pressure(tool)) {
- value = libinput_event_tablet_tool_get_pressure(event);
- value *= TABLET_PRESSURE_AXIS_MAX;
+ value = TABLET_PRESSURE_AXIS_MAX * libinput_event_tablet_tool_get_pressure(event);
+ if (driver_data->pressurecurve.values)
+ value = driver_data->pressurecurve.values[(int)value];
valuator_mask_set_double(mask, 2, value);
}
@@ -2606,6 +2640,69 @@ xf86libinput_parse_rotation_angle_option(InputInfoPtr pInfo,
}
static void
+xf86libinput_parse_pressurecurve_option(InputInfoPtr pInfo,
+ struct xf86libinput *driver_data,
+ struct bezier_control_point pcurve[4])
+{
+ struct bezier_control_point controls[4] = {
+ { 0.0, 0.0 },
+ { 0.0, 0.0 },
+ { 1.0, 1.0 },
+ { 1.0, 1.0 },
+ };
+ float points[8];
+ char *str;
+ int rc = 0;
+ int test_bezier[64];
+ struct libinput_tablet_tool *tool = driver_data->tablet_tool;
+
+ if ((driver_data->capabilities & CAP_TABLET_TOOL) == 0)
+ return;
+
+ if (!tool || !libinput_tablet_tool_has_pressure(tool))
+ return;
+
+ str = xf86SetStrOption(pInfo->options,
+ "TabletToolPressureCurve",
+ NULL);
+ if (!str)
+ goto out;
+
+ rc = sscanf(str, "%f/%f %f/%f %f/%f %f/%f",
+ &points[0], &points[1], &points[2], &points[3],
+ &points[4], &points[5], &points[6], &points[7]);
+ if (rc != 8)
+ goto out;
+
+ for (int i = 0; i < 4; i++) {
+ if (points[i] < 0.0 || points[i] > 1.0)
+ goto out;
+ }
+
+ controls[0].x = points[0];
+ controls[0].y = points[1];
+ controls[1].x = points[2];
+ controls[1].y = points[3];
+ controls[2].x = points[4];
+ controls[2].y = points[5];
+ controls[3].x = points[6];
+ controls[3].y = points[7];
+
+ if (!cubic_bezier(controls, test_bezier, ARRAY_SIZE(test_bezier))) {
+ memcpy(controls, bezier_defaults, sizeof(controls));
+ goto out;
+ }
+
+ rc = 0;
+out:
+ if (rc != 0)
+ xf86IDrvMsg(pInfo, X_ERROR, "Invalid pressure curve: %s\n", str);
+ free(str);
+ memcpy(pcurve, controls, sizeof(controls));
+ xf86libinput_set_pressurecurve(driver_data, controls);
+}
+
+static void
xf86libinput_parse_options(InputInfoPtr pInfo,
struct xf86libinput *driver_data,
struct libinput_device *device)
@@ -2638,6 +2735,10 @@ xf86libinput_parse_options(InputInfoPtr pInfo,
xf86libinput_parse_draglock_option(pInfo, driver_data);
options->horiz_scrolling_enabled = xf86libinput_parse_horiz_scroll_option(pInfo);
}
+
+ xf86libinput_parse_pressurecurve_option(pInfo,
+ driver_data,
+ options->pressurecurve);
}
static const char*
@@ -3086,6 +3187,7 @@ static Atom prop_rotation_angle_default;
/* driver properties */
static Atom prop_draglock;
static Atom prop_horiz_scroll;
+static Atom prop_pressurecurve;
/* general properties */
static Atom prop_float;
@@ -3815,6 +3917,52 @@ LibinputSetPropertyRotationAngle(DeviceIntPtr dev,
return Success;
}
+static inline int
+LibinputSetPropertyPressureCurve(DeviceIntPtr dev,
+ Atom atom,
+ XIPropertyValuePtr val,
+ BOOL checkonly)
+{
+ InputInfoPtr pInfo = dev->public.devicePrivate;
+ struct xf86libinput *driver_data = pInfo->private;
+ float *vals;
+ struct bezier_control_point controls[4];
+
+ if (val->format != 32 || val->size != 8 || val->type != prop_float)
+ return BadMatch;
+
+ vals = val->data;
+ controls[0].x = vals[0];
+ controls[0].y = vals[1];
+ controls[1].x = vals[2];
+ controls[1].y = vals[3];
+ controls[2].x = vals[4];
+ controls[2].y = vals[5];
+ controls[3].x = vals[6];
+ controls[3].y = vals[7];
+
+ if (checkonly) {
+ int test_bezier[64];
+
+ for (int i = 0; i < val->size; i++) {
+ if (vals[i] < 0.0 || vals[i] > 1.0)
+ return BadValue;
+ }
+
+ if (!xf86libinput_check_device (dev, atom))
+ return BadMatch;
+
+ if (!cubic_bezier(controls, test_bezier, ARRAY_SIZE(test_bezier)))
+ return BadValue;
+ } else {
+ xf86libinput_set_pressurecurve(driver_data, controls);
+ memcpy(driver_data->options.pressurecurve, controls,
+ sizeof(controls));
+ }
+
+ return Success;
+}
+
static int
LibinputSetProperty(DeviceIntPtr dev, Atom atom, XIPropertyValuePtr val,
BOOL checkonly)
@@ -3867,6 +4015,8 @@ LibinputSetProperty(DeviceIntPtr dev, Atom atom, XIPropertyValuePtr val,
}
else if (atom == prop_rotation_angle)
rc = LibinputSetPropertyRotationAngle(dev, atom, val, checkonly);
+ else if (atom == prop_pressurecurve)
+ rc = LibinputSetPropertyPressureCurve(dev, atom, val, checkonly);
else if (atom == prop_device || atom == prop_product_id ||
atom == prop_tap_default ||
atom == prop_tap_drag_default ||
@@ -4691,6 +4841,35 @@ LibinputInitRotationAngleProperty(DeviceIntPtr dev,
}
static void
+LibinputInitPressureCurveProperty(DeviceIntPtr dev,
+ struct xf86libinput *driver_data)
+{
+ const struct bezier_control_point *curve = driver_data->options.pressurecurve;
+ struct libinput_tablet_tool *tool = driver_data->tablet_tool;
+ float data[8];
+
+ if ((driver_data->capabilities & CAP_TABLET_TOOL) == 0)
+ return;
+
+ if (!tool || !libinput_tablet_tool_has_pressure(tool))
+ return;
+
+ data[0] = curve[0].x;
+ data[1] = curve[0].y;
+ data[2] = curve[1].x;
+ data[3] = curve[1].y;
+ data[4] = curve[2].x;
+ data[5] = curve[2].y;
+ data[6] = curve[3].x;
+ data[7] = curve[3].y;
+
+ prop_pressurecurve = LibinputMakeProperty(dev,
+ LIBINPUT_PROP_TABLET_TOOL_PRESSURECURVE,
+ prop_float, 32,
+ 8, data);
+}
+
+static void
LibinputInitProperty(DeviceIntPtr dev)
{
InputInfoPtr pInfo = dev->public.devicePrivate;
@@ -4746,4 +4925,5 @@ LibinputInitProperty(DeviceIntPtr dev)
LibinputInitDragLockProperty(dev, driver_data);
LibinputInitHorizScrollProperty(dev, driver_data);
+ LibinputInitPressureCurveProperty(dev, driver_data);
}
--
2.9.3
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