Add "scale" node type

Makefile

@@ -12,7 +12,7 @@ CPPFLAGS += $(shell pkg-config --cflags $(DEPS))
 LDLIBS += $(shell pkg-config --libs $(DEPS))
 INTERP ?=
 MAIN = main
-OBJS = main.o events.o processing.o graph.o config.o event_code_names.o hash_table.o module_registry.o event_predicate.o nodes/getchar.o nodes/print.o nodes/evdev.o nodes/tee.o nodes/router.o nodes/modifiers.o nodes/modify_predicate.o nodes/uinput.o nodes/assign.o nodes/differentiate.o
+OBJS = main.o events.o processing.o graph.o config.o event_code_names.o hash_table.o module_registry.o event_predicate.o nodes/getchar.o nodes/print.o nodes/evdev.o nodes/tee.o nodes/router.o nodes/modifiers.o nodes/modify_predicate.o nodes/uinput.o nodes/assign.o nodes/differentiate.o nodes/scale.o
 
 all: $(MAIN)
 

nodes/scale.c

@@ -0,0 +1,111 @@
+#include "../graph.h"
+#include "../module_registry.h"
+
+typedef struct {
+	GraphNode as_GraphNode;
+	int64_t numerator;
+	int64_t denominator;
+	int64_t center;
+	int64_t defect;
+	bool amortize_rounding_error;
+} ScaleGraphNode;
+
+static bool
+handle_event(EventPositionBase * self, EventNode * event)
+{
+	ScaleGraphNode *node = DOWNCAST(ScaleGraphNode, GraphNode, DOWNCAST(GraphNode, EventPositionBase, self));
+	size_t count = node->as_GraphNode.outputs.length;
+	if (!count) {
+		event_destroy(event);
+		return true;
+	}
+
+	int64_t value = event->data.payload;
+	value -= node->center;
+	value *= node->numerator;
+	if (node->amortize_rounding_error) {
+		value += node->defect;
+	}
+	if (node->denominator) {
+		uint64_t undivided = value;
+		value /= node->denominator;
+		node->defect = undivided - value * node->denominator;
+	}
+	value += node->center;
+	event->data.payload = value;
+
+	if (count > 1) {
+		count = event_replicate(event, count - 1) + 1;
+	}
+	for (size_t i = 0; i < count; ++i) {
+		event->position = &node->as_GraphNode.outputs.elements[i]->as_EventPositionBase;
+		event = event->next;
+	}
+	return true;
+}
+
+static GraphNode *
+create(GraphNodeSpecification * spec, GraphNodeConfig * config, InitializationEnvironment * env)
+{
+	(void) config;
+	(void) env;
+	ScaleGraphNode * node = T_ALLOC(1, ScaleGraphNode);
+	if (!node) {
+		return NULL;
+	}
+
+	int64_t
+		numerator = 1,
+		denominator = 1,
+		center = 0;
+	bool amortize_rounding_error = false;
+	if (config->options) {
+		numerator = env_resolve_constant_or(env, config_setting_get_member(config->options, "numerator"), numerator);
+		denominator = env_resolve_constant_or(env, config_setting_get_member(config->options, "denominator"), denominator);
+		center = env_resolve_constant_or(env, config_setting_get_member(config->options, "center"), center);
+		amortize_rounding_error = env_resolve_constant(env, config_setting_get_member(config->options, "amortize_rounding_error")) != 0;
+	}
+
+	*node = (ScaleGraphNode) {
+		.as_GraphNode = {
+			.as_EventPositionBase = {
+				.handle_event = &handle_event,
+				.waiting_new_event = false,
+			},
+			.specification = spec,
+			.inputs = EMPTY_GRAPH_CHANNEL_LIST,
+			.outputs = EMPTY_GRAPH_CHANNEL_LIST,
+		},
+		.numerator = numerator,
+		.denominator = denominator,
+		.center = center,
+		.amortize_rounding_error = amortize_rounding_error,
+		.defect = 0,
+	};
+	return &node->as_GraphNode;
+}
+
+static void destroy
+(GraphNodeSpecification * self, GraphNode * target)
+{
+	(void) self;
+	free(target);
+}
+
+GraphNodeSpecification nodespec_scale = (GraphNodeSpecification) {
+	.create = &create,
+	.destroy = &destroy,
+	.register_io = NULL,
+	.name = "scale",
+	.documentation = "Multiplies event payload by a constant fraction\nAccepts events on any connector\nSends events on all connectors"
+	                 "\nOption 'numerator' (optional): an integer to multiply by"
+	                 "\nOption 'denominator' (optional): an integer to divide by"
+	                 "\nOption 'center' (optional): an integer to scale around"
+	                 "\nOption 'amortize_rounding_error' (optional): whether to adjust the new event value by the rounding error of the previous event value"
+	,
+};
+
+MODULE_CONSTRUCTOR(init)
+{
+	register_graph_node_specification(&nodespec_scale);
+}

quadtap-both-click.cfg

@@ -1,3 +1,8 @@
+constants = {
+	sensitivity_num = 2;
+	sensitivity_denom = 5;
+};
+
 enums = {
 	namespaces: ["clickpad"];
 };
@@ -195,6 +200,22 @@ nodes = {
 			predicates = ["quadtap_held"];
 		};
 	};
+	sensitivity_x = {
+		type = "scale";
+		options = {
+			numerator = "sensitivity_num";
+			denominator = "sensitivity_denom";
+			amortize_rounding_error = "true";
+		};
+	};
+	sensitivity_y = {
+		type = "scale";
+		options = {
+			numerator = "sensitivity_num";
+			denominator = "sensitivity_denom";
+			amortize_rounding_error = "true";
+		};
+	};
 };
 
 channels = ({
@@ -226,9 +247,15 @@ channels = ({
 	to: ("differentiate_y", 0);
 }, {
 	from: ("differentiate_x", 0);
-	to: ("while_quadtap_held", 0);
+	to: ("sensitivity_x", 0);
 }, {
 	from: ("differentiate_y", 0);
+	to: ("sensitivity_y", 0);
+}, {
+	from: ("sensitivity_x", 0);
+	to: ("while_quadtap_held", 0);
+}, {
+	from: ("sensitivity_y", 0);
 	to: ("while_quadtap_held", 1);
 }, {
 	from: ("while_quadtap_held", 0);