plugins: add a crop filter module

This should simply drop input events for x/y values ouside of the
framebuffer (and thus ts_uinput) Min/Max values.

Author: merge

Android.mk

@@ -178,6 +178,24 @@ LOCAL_MODULE_TAGS := optional
 include $(BUILD_SHARED_LIBRARY)
 
 
+# plugin: crop
+include $(CLEAR_VARS)
+
+LOCAL_PRELINK_MODULE := false
+
+LOCAL_SRC_FILES := plugins/crop.c
+
+LOCAL_C_INCLUDES += $(LOCAL_PATH)/src/
+
+LOCAL_SHARED_LIBRARIES := libdl \
+                        libts
+
+LOCAL_MODULE := ts/plugins/crop
+LOCAL_MODULE_TAGS := optional
+
+include $(BUILD_SHARED_LIBRARY)
+
+
 # plugin: evthres
 include $(CLEAR_VARS)
 

README.md

@@ -61,8 +61,8 @@ through the library:
                module       module      module       module
 
 ### calibrate the touch screen
-Calibration is done by the `linear` plugin, which uses its own config file
-`/etc/pointercal`. Don't edit this file manually. It is created by the
+Calibration is applied by the `linear` plugin, which uses its own config file
+`TSLIB_CALIBFILE`. Don't edit this file manually. It is created by the
 [`ts_calibrate`](https://manpages.debian.org/unstable/libts0/ts_calibrate.1.en.html) program:
 
     # ts_calibrate
@@ -197,8 +197,7 @@ for example (yet).
 ### module: linear
   Linear scaling - calibration - module, primerily used for conversion of touch
   screen co-ordinates to screen co-ordinates. It applies the corrections as
-  recorded and saved by the [`ts_calibrate`](https://manpages.debian.org/unstable/libts0/ts_calibrate.1.en.html) tool. It's the only module that reads
-  a configuration file.
+  recorded and saved by the [`ts_calibrate`](https://manpages.debian.org/unstable/libts0/ts_calibrate.1.en.html) tool.
 
 Parameters (usually not needed):
 * `rot`
@@ -382,6 +381,20 @@ Parameters:
 Example: `module evthres N=5`
 
 
+### module: crop
+  The goal of this filter is to drop input touch events that lie outside
+  of the Min/Max values for the x/y event codes, i.e. touch points that
+  might (due to applied filters) lie ouside of the visible framebuffer.
+
+  It sends "pen/finger up" for a given slot when said values are outside of
+  the framebuffer.
+
+  It read the framebuffer dimensions from `TSLIB_CALIBFILE` which is
+  generated and saved by the [`ts_calibrate`](https://manpages.debian.org/unstable/libts0/ts_calibrate.1.en.html) tool.
+
+Example: `module crop`
+
+
 ### module:	variance
   Variance filter. Tries to do its best in order to filter out random noise
   coming from touchscreen ADC's. This is achieved by limiting the sample
@@ -649,7 +662,7 @@ For testing purposes there are tools like [ts_test_mt](#test-the-filtered-input-
 too.
 
 #### shipped as part of tslib
-* [ts_calibrate](#filter-modules) - graphical calibration tool. Configures the `linear` filter module.
+* [ts_calibrate](#filter-modules) - graphical calibration tool. Configures the `linear` and `crop` filter modules.
 * [ts_uinput](#use-the-filtered-result-in-your-system-ts_uinput-method) - userspace **evdev** driver for the tslib-filtered samples.
 
 #### third party applications

configure.ac

@@ -106,6 +106,7 @@ TSLIB_CHECK_MODULE([skip], [yes], [Enable building of skip filter])
 TSLIB_CHECK_MODULE([lowpass], [yes], [Enable building of lowpass filter])
 TSLIB_CHECK_MODULE([invert], [yes], [Enable building of invert filter])
 TSLIB_CHECK_MODULE([variance], [yes], [Enable building of variance filter])
+TSLIB_CHECK_MODULE([crop], [yes], [Enable building of crop filter])
 
 # hardware access modules
 #########################

doc/ts.conf.5

@@ -227,6 +227,7 @@ numerator of the smoothing fraction. Default: 0.
 \fBD\fR
 .sp
 denominator of the smoothing fraction. Default: 1.
+
 .RE
 .RE
 .PP
@@ -259,6 +260,15 @@ Minimum pressure value for a sample to be valid. Default: 1.
 .sp
 Maximum pressure value for a sample to be valid. Default: INT_MAX.
 
+.RE
+.RE
+.PP
+\fBcrop\fR
+.RS 4
+Ignore touch points outside of the framebuffer.
+.sp
+.RS 4
+
 .RE
 .RE
 .PP

etc/ts.conf

@@ -39,3 +39,6 @@ module dejitter delta=100
 
 # Uncomment to use ts_calibrate's settings
 module linear
+
+# Uncomment to drop events outside of the framebuffer
+# module crop

plugins/Makefile.am

@@ -72,6 +72,12 @@ else
 IIR_MODULE =
 endif
 
+if ENABLE_CROP_MODULE
+CROP_MODULE = crop.la
+else
+CROP_MODULE =
+endif
+
 if ENABLE_EVTHRES_MODULE
 EVTHRES_MODULE = evthres.la
 else
@@ -197,6 +203,7 @@ pluginexec_LTLIBRARIES = \
 	$(SKIP_MODULE) \
 	$(INVERT_MODULE) \
 	$(IIR_MODULE) \
+	$(CROP_MODULE) \
 	$(EVTHRES_MODULE) \
 	$(LOWPASS_MODULE) \
 	$(UCB1X00_MODULE) \
@@ -287,6 +294,13 @@ iir_la_LDFLAGS		+= -no-undefined
 endif
 iir_la_LIBADD		= $(top_builddir)/src/libts.la
 
+crop_la_SOURCES		= crop.c
+crop_la_LDFLAGS		= -module $(LTVSN)
+if WINDOWS
+crop_la_LDFLAGS		+= -no-undefined
+endif
+crop_la_LIBADD		= $(top_builddir)/src/libts.la
+
 evthres_la_SOURCES	= evthres.c
 evthres_la_LDFLAGS	= -module $(LTVSN)
 if WINDOWS

plugins/crop.c

@@ -0,0 +1,202 @@
+/*
+ *  tslib/plugins/crop.c
+ *
+ *  Copyright (C) 2024 Martin Kepplinger-Novaković
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * SPDX-License-Identifier: LGPL-2.1
+ */
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include <limits.h>
+#include <sys/stat.h>
+#include <stdint.h>
+#include <stdio.h>
+
+#include "config.h"
+#include "tslib-private.h"
+
+struct tslib_crop {
+	struct tslib_module_info module;
+	int32_t *last_tid;
+	uint32_t last_pressure;
+	int	a[7];
+	/* fb res from calibration-time */
+	uint32_t cal_res_x;
+	uint32_t cal_res_y;
+	uint32_t rot;
+};
+
+static int crop_read(struct tslib_module_info *info, struct ts_sample *samp,
+		     int nr)
+{
+	struct tslib_crop *crop = (struct tslib_crop *)info;
+	int ret;
+	int nread = 0;
+
+	while (nread < nr) {
+		struct ts_sample cur;
+
+		ret = info->next->ops->read(info->next, &cur, 1);
+		if (ret < 0)
+			return ret;
+
+		if (cur.x >= crop->cal_res_x ||
+		    cur.x < 0 ||
+		    cur.y >= crop->cal_res_y ||
+		    cur.y < 0) {
+			if (cur.pressure == 0) {
+				if (crop->last_pressure == 0)
+					continue;
+			} else {
+				continue;
+			}
+		}
+
+		samp[nread++] = cur;
+		crop->last_pressure = cur.pressure;
+	}
+
+	return nread;
+}
+
+static int crop_read_mt(struct tslib_module_info *info,
+		       struct ts_sample_mt **samp, int max_slots, int nr)
+{
+	struct tslib_crop *crop = (struct tslib_crop *)info;
+	int32_t ret;
+	int32_t i, j;
+
+	if (!info->next->ops->read_mt)
+		return -ENOSYS;
+
+	ret = info->next->ops->read_mt(info->next, samp, max_slots, nr);
+	if (ret < 0)
+		return ret;
+
+	if (!crop->last_tid) {
+		free(crop->last_tid);
+
+		crop->last_tid = calloc(max_slots, sizeof(int32_t));
+		if (!crop->last_tid)
+			return -ENOMEM;
+	}
+
+	for (i = 0; i < ret; i++) {
+		for (j = 0; j < max_slots; j++) {
+			if (!(samp[i][j].valid & TSLIB_MT_VALID))
+				continue;
+
+			/* assume the input device uses 0..(fb-1) value. */
+
+			if (samp[i][j].x >= crop->cal_res_x ||
+			    samp[i][j].x < 0 ||
+			    samp[i][j].y >= crop->cal_res_y ||
+			    samp[i][j].y < 0) {
+				if (samp[i][j].tracking_id == -1) {
+					/*
+					 * don't drop except last seen tid also -1
+					 * otherwise, tid would get filtered
+					 * out and new x/y would reach the app
+					 */
+					if (crop->last_tid[j] == -1) {
+						samp[i][j].valid &= ~TSLIB_MT_VALID;
+					}
+				} else {
+					/* drop */
+					samp[i][j].valid &= ~TSLIB_MT_VALID;
+				}
+			}
+
+			/* save the last not-dropped tid value */
+			if (samp[i][j].valid & TSLIB_MT_VALID)
+				crop->last_tid[j] = samp[i][j].tracking_id;
+		}
+	}
+
+	return ret;
+}
+
+static int crop_fini(struct tslib_module_info *info)
+{
+	struct tslib_crop *crop = (struct tslib_crop *)info;
+
+	free(crop->last_tid);
+	free(info);
+
+	return 0;
+}
+
+static const struct tslib_ops crop_ops = {
+	.read		= crop_read,
+	.read_mt	= crop_read_mt,
+	.fini		= crop_fini,
+};
+
+TSAPI struct tslib_module_info *crop_mod_init(__attribute__ ((unused)) struct tsdev *dev,
+					     const char *params)
+{
+	struct tslib_crop *crop;
+	struct stat sbuf;
+	FILE *pcal_fd;
+	int index;
+	char *calfile;
+
+	crop = malloc(sizeof(struct tslib_crop));
+	if (crop == NULL)
+		return NULL;
+
+	memset(crop, 0, sizeof(struct tslib_crop));
+	crop->module.ops = &crop_ops;
+
+	crop->last_tid = NULL;
+
+	/*
+	 * Get resolution from calibration file
+	 */
+	if ((calfile = getenv("TSLIB_CALIBFILE")) == NULL)
+		calfile = TS_POINTERCAL;
+
+	if (stat(calfile, &sbuf) == 0) {
+		pcal_fd = fopen(calfile, "r");
+		if (!pcal_fd) {
+			free(crop);
+			perror("fopen");
+			return NULL;
+		}
+
+		for (index = 0; index < 7; index++)
+			if (fscanf(pcal_fd, "%d", &crop->a[index]) != 1)
+				break;
+
+		if (!fscanf(pcal_fd, "%d %d",
+			    &crop->cal_res_x, &crop->cal_res_y)) {
+			fprintf(stderr,
+				"CROP: Couldn't read resolution values\n");
+		}
+
+		if (!fscanf(pcal_fd, "%d", &crop->rot)) {
+			fprintf(stderr, "CROP: Couldn't read rotation value\n");
+		}
+
+		fclose(pcal_fd);
+	}
+	return &crop->module;
+}
+
+#ifndef TSLIB_STATIC_CROP_MODULE
+	TSLIB_MODULE_INIT(crop_mod_init);
+#endif

plugins/plugins.h

@@ -16,6 +16,7 @@ TSLIB_DECLARE_MODULE(invert);
 TSLIB_DECLARE_MODULE(iir);
 TSLIB_DECLARE_MODULE(evthres);
 TSLIB_DECLARE_MODULE(lowpass);
+TSLIB_DECLARE_MODULE(crop);
 
 TSLIB_DECLARE_MODULE(arctic2);
 TSLIB_DECLARE_MODULE(collie);

src/Makefile.am

@@ -50,6 +50,10 @@ if ENABLE_STATIC_IIR_MODULE
 libts_la_SOURCES += $(top_srcdir)/plugins/iir.c
 endif
 
+if ENABLE_STATIC_CROP_MODULE
+libts_la_SOURCES += $(top_srcdir)/plugins/crop.c
+endif
+
 if ENABLE_STATIC_LINEAR_MODULE
 libts_la_SOURCES += $(top_srcdir)/plugins/linear.c
 endif

src/ts_load_module.c

@@ -45,6 +45,9 @@ static const struct tslib_module_desc tslib_modules[] = {
 #ifdef TSLIB_STATIC_CORGI_MODULE
 	{ "corgi", corgi_mod_init },
 #endif
+#ifdef TSLIB_STATIC_CROP_MODULE
+	{ "crop", crop_mod_init },
+#endif
 #ifdef TSLIB_STATIC_CY8MRLN_PALMPRE_MODULE
 	{ "cy8mrln_palmpre", cy8mrln_palmpre_mod_init },
 #endif