From 1a4c280aaf00f23aa6a61867494e85f9b888d27f Mon Sep 17 00:00:00 2001
From: Sam Anthony <sam@samanthony.xyz>
Date: Fri, 28 Feb 2025 14:43:29 -0500
Subject: set displacement

---
 main.c |  2 +-
 ui.c   | 21 +++++++++++++++++++++
 ui.h   |  1 +
 3 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/main.c b/main.c
index 7d593f1..fd31910 100644
--- a/main.c
+++ b/main.c
@@ -149,7 +149,7 @@ displacement_row(mu_Context *ctx, UI *ui) {
 	mu_layout_row(ctx, nelem(widths), widths, 0);
 	mu_label(ctx, "Displacement:");
 	if (w_field(ctx, &ui->displacement) & MU_RES_CHANGE) {
-		/* TODO */
+		set_displacement(ui);
 	}
 	w_select(ctx, &ui->displacement_unit);
 }
diff --git a/ui.c b/ui.c
index 5dc9021..f3e5c4a 100644
--- a/ui.c
+++ b/ui.c
@@ -1,3 +1,4 @@
+#include <assert.h>
 #include <string.h>
 
 #include "microui.h"
@@ -11,6 +12,10 @@
 
 
 static const char *const displacement_units[] = {"cc", "l", "ci"};
+static Volume (*displacement_converters[nelem(displacement_units)])(double) = {
+	cubic_centimetre, litre, cubic_inch,
+};
+
 static const char *const map_units[] = {"mbar", "kPa", "bar", "psi"};
 
 
@@ -31,6 +36,22 @@ init_ui(UI *ui) {
 	init_engine(&ui->points[0]);
 }
 
+void
+set_displacement(UI *ui) {
+	int idx, i;
+	Volume (*convert)(double), disp;
+
+	idx = ui->displacement_unit.idx;
+	assert(idx >= 0 && (long unsigned int) idx < nelem(displacement_units));
+
+	convert = displacement_converters[idx];
+	disp = convert(ui->displacement.value);
+
+	for (i = 0; i < ui->npoints; i++) {
+		ui->points[i].displacement = disp;
+	}
+}
+
 void
 insert_point(UI *ui, int idx) {
 	int i;
diff --git a/ui.h b/ui.h
index ac8b047..4d0a63a 100644
--- a/ui.h
+++ b/ui.h
@@ -17,5 +17,6 @@ typedef struct {
 } UI;
 
 void init_ui(UI *ui);
+void set_displacement(UI *ui);
 void insert_point(UI *ui, int idx);
 void remove_point(UI *ui, int idx);
-- 
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