From 99a0db84dd16935f9357176248c824bcc372ee43 Mon Sep 17 00:00:00 2001
From: Benjamin Barenblat <bbaren@google.com>
Date: Wed, 13 May 2020 13:58:04 -0400
Subject: Support fractional values
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Treat values passed on the command line as floats instead of longs.
This allows you to specify fractional percentages (and fractional
absolute values, too, though they’ll just be rounded down, so they’re
not particularly useful).

Report the display brightness as a percentage with two decimal places
rather than zero. To ensure backward compatibility in machine-readable
mode, report the high-precision percentage in a new field rather than
replacing the existing field. This does cause some redundancy in the
output, but that’s better than breaking scripts that assume the 4th
field is an integer followed by “%”.

Closes: https://github.com/Hummer12007/brightnessctl/issues/50
---
 brightnessctl.c | 38 ++++++++++++++++++++++----------------
 1 file changed, 22 insertions(+), 16 deletions(-)

(limited to 'brightnessctl.c')

diff --git a/brightnessctl.c b/brightnessctl.c
index 1629a35..7fbd160 100644
--- a/brightnessctl.c
+++ b/brightnessctl.c
@@ -67,7 +67,7 @@ enum delta_type { DIRECT, DELTA };
 enum sign { PLUS, MINUS };
 
 struct value {
-	unsigned long val;
+	float val;
 	enum value_type v_type;
 	enum delta_type d_type;
 	enum sign sign;
@@ -276,7 +276,7 @@ int apply_operation(struct device *dev, enum operation operation, struct value *
 }
 
 bool parse_value(struct value *val, char *str) {
-	long n;
+	float n;
 	char c;
 	char *buf;
 	errno = 0;
@@ -290,10 +290,10 @@ bool parse_value(struct value *val, char *str) {
 		val->d_type = DELTA;
 		str++;
 	}
-	n = strtol(str, &buf, 10);
+	n = strtof(str, &buf);
 	if (errno || buf == str)
 		return false;
-	val->val = labs(n) % LONG_MAX;
+	val->val = fabsf(n);
 	while ((c = *(buf++))) switch(c) {
 	case '+':
 		val->sign = PLUS;
@@ -326,11 +326,10 @@ void list_devices(struct device **devs) {
 		print_device(dev);
 }
 
-float val_to_percent(float val, struct device *d, bool rnd) {
+float val_to_percent(float val, struct device *d) {
 	if (val < 0)
 		return 0;
-	float ret = powf(val / d->max_brightness, 1.0f / p.exponent) * 100;
-	return rnd ? roundf(ret) : ret;
+	return powf(val / d->max_brightness, 1.0f / p.exponent) * 100;
 }
 
 unsigned long percent_to_val(float percent, struct device *d) {
@@ -338,13 +337,20 @@ unsigned long percent_to_val(float percent, struct device *d) {
 }
 
 void print_device(struct device *dev) {
-	char *format = p.mach ? "%s,%s,%d,%d%%,%d\n" :
-		"Device '%s' of class '%s':\n\tCurrent brightness: %d (%d%%)\n\tMax brightness: %d\n\n";
-	fprintf(stdout, format,
-		dev->id, dev->class,
-		dev->curr_brightness,
-		(int) val_to_percent(dev->curr_brightness, dev, true),
-		dev->max_brightness);
+	float brightness = val_to_percent(dev->curr_brightness, dev);
+	if (p.mach)
+		fprintf(stdout, "%s,%s,%d,%d%%,%d,%f%%\n",
+			dev->id, dev->class,
+			dev->curr_brightness,
+			(int) roundf(brightness),
+			dev->max_brightness,
+			(double) brightness);
+	else
+		fprintf(stdout, "Device '%s' of class '%s':\n\tCurrent brightness: %d (%.02f%%)\n\tMax brightness: %d\n\n",
+			dev->id, dev->class,
+			dev->curr_brightness,
+			(double) brightness,
+			dev->max_brightness);
 }
 
 unsigned int calc_value(struct device *d, struct value *val) {
@@ -357,7 +363,7 @@ unsigned int calc_value(struct device *d, struct value *val) {
 	if (val->sign == MINUS)
 		mod *= -1;
 	if (val->v_type == RELATIVE) {
-		mod = percent_to_val(val_to_percent(d->curr_brightness, d, false) + mod, d) - d->curr_brightness;
+		mod = percent_to_val(val_to_percent(d->curr_brightness, d) + mod, d) - d->curr_brightness;
 		if (val->val != 0 && mod == 0)
 			mod = val->sign == PLUS ? 1 : -1;
 	}
@@ -670,7 +676,7 @@ Operations:\n\
 \n\
 Valid values:\n\
   specific value             \tExample: 500\n\
-  percentage value           \tExample: 50%%\n\
+  percentage value           \tExample: 50.75%%\n\
   specific delta             \tExample: 50- or +10\n\
   percentage delta           \tExample: 50%%- or +10%%\n\
 \n");
-- 
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