evdev-touchpad: Set some options using weston.ini

This patch adds 3 new options to weston.ini to allow
the user to change default constant_accel_factor,
min_accel_factor and max_accel_factor. If no options
are set, it falls back using defaults as it did before.

v2: create weston_config_section_get_double and use it
instead of manualy converting string to double.

v3: add default values in weston_config_get_double
instead of using conditionals.

v4: don't pass diagonal as pointer.

shared/config-parser.c

@@ -335,6 +335,32 @@ weston_config_section_get_uint(struct weston_config_section *section,
 	return 0;
 }
 
+WL_EXPORT
+int
+weston_config_section_get_double(struct weston_config_section *section,
+				 const char *key,
+				 double *value, double default_value)
+{
+	struct weston_config_entry *entry;
+	char *end;
+
+	entry = config_section_get_entry(section, key);
+	if (entry == NULL) {
+		*value = default_value;
+		errno = ENOENT;
+		return -1;
+	}
+
+	*value = strtod(entry->value, &end);
+	if (*end != '\0') {
+		*value = default_value;
+		errno = EINVAL;
+		return -1;
+	}
+
+	return 0;
+}
+
 WL_EXPORT
 int
 weston_config_section_get_string(struct weston_config_section *section,

shared/config-parser.h

@@ -88,6 +88,10 @@ weston_config_section_get_uint(struct weston_config_section *section,
 			       const char *key,
 			       uint32_t *value, uint32_t default_value);
 int
+weston_config_section_get_double(struct weston_config_section *section,
+				 const char *key,
+				 double *value, double default_value);
+int
 weston_config_section_get_string(struct weston_config_section *section,
 				 const char *key,
 				 char **value,

src/evdev-touchpad.c

@@ -26,10 +26,12 @@
 #include <math.h>
 #include <string.h>
 #include <stdbool.h>
+#include <unistd.h>
 #include <linux/input.h>
 
 #include "filter.h"
 #include "evdev.h"
+#include "../shared/config-parser.h"
 
 /* Default values */
 #define DEFAULT_CONSTANT_ACCEL_NUMERATOR 50
@@ -670,6 +672,38 @@ struct evdev_dispatch_interface touchpad_interface = {
 	touchpad_destroy
 };
 
+static void
+touchpad_parse_config(struct touchpad_dispatch *touchpad, double diagonal)
+{
+	struct weston_config *config;
+	struct weston_config_section *s;
+	int config_fd;
+
+	double constant_accel_factor;
+	double min_accel_factor;
+	double max_accel_factor;
+
+	config_fd = open_config_file("weston.ini");
+	config = weston_config_parse(config_fd);
+	close(config_fd);
+
+	s = weston_config_get_section(config, "touchpad", NULL, NULL);
+	weston_config_section_get_double(s, "constant_accel_factor",
+					 &constant_accel_factor,
+					 DEFAULT_CONSTANT_ACCEL_NUMERATOR);
+	weston_config_section_get_double(s, "min_accel_factor",
+					 &min_accel_factor,
+					 DEFAULT_MIN_ACCEL_FACTOR);
+	weston_config_section_get_double(s, "max_accel_factor",
+					 &max_accel_factor,
+					 DEFAULT_MAX_ACCEL_FACTOR);
+
+	touchpad->constant_accel_factor =
+		constant_accel_factor / diagonal;
+	touchpad->min_accel_factor = min_accel_factor;
+	touchpad->max_accel_factor = max_accel_factor;
+}
+
 static int
 touchpad_init(struct touchpad_dispatch *touchpad,
 	      struct evdev_device *device)
@@ -710,11 +744,7 @@ touchpad_init(struct touchpad_dispatch *touchpad,
 	height = abs(device->abs.max_y - device->abs.min_y);
 	diagonal = sqrt(width*width + height*height);
 
-	touchpad->constant_accel_factor =
+	touchpad_parse_config(touchpad, diagonal);
-		DEFAULT_CONSTANT_ACCEL_NUMERATOR / diagonal;
-
-	touchpad->min_accel_factor = DEFAULT_MIN_ACCEL_FACTOR;
-	touchpad->max_accel_factor = DEFAULT_MAX_ACCEL_FACTOR;
 
 	touchpad->hysteresis.margin_x =
 		diagonal / DEFAULT_HYSTERESIS_MARGIN_DENOMINATOR;

weston.ini

@@ -57,3 +57,8 @@ path=/usr/libexec/weston-keyboard
 #name=X1
 #mode=1024x768
 #transform=flipped-270
+
+#[touchpad]
+#constant_accel_factor = 50
+#min_accel_factor = 0.16
+#max_accel_factor = 1.0