gout

commit c4080dcdb82c89b83170f36df9ada4d604f19407
parent 32a587d492299ddf147a7a70e130cbebe6f20659
Author: Chris Bracken <chris@bracken.jp>
Date:   Thu, 19 Feb 2026 13:35:09 +0900

delta: fix diffstat graph max width

Diffstat:
M
BUILD.gn
 | 
1
+
M
src/git/delta.c
 | 
5
++++-
A
src/git/delta_tests.c
 | 
36
++++++++++++++++++++++++++++++++++++

3 files changed, 41 insertions(+), 1 deletion(-)
diff --git a/BUILD.gn b/BUILD.gn
@@ -68,6 +68,7 @@ executable("gout_tests") {
 
   sources = [
     "src/format_tests.c",
+    "src/git/delta_tests.c",
     "src/gout_tests.c",
     "src/gout_tests_main.c",
     "src/utils_tests.c",
diff --git a/src/git/delta.c b/src/git/delta.c
@@ -184,7 +184,10 @@ char* gitdelta_graph(const GitDelta* delta,
                      size_t max_width) {
   size_t changed = delta->addcount + delta->delcount;
   if (changed > max_width && length > 0) {
-    length = ((float)max_width / changed * length) + 1;
+    length = (length * max_width) / changed;
+    if (length == 0) {
+      length = 1;
+    }
   }
   char* graph = ecalloc(length + 1, sizeof(char));
   memset(graph, c, length);
diff --git a/src/git/delta_tests.c b/src/git/delta_tests.c
@@ -0,0 +1,36 @@
+#include <stdlib.h>
+#include <string.h>
+#include "git/delta.h"
+#include "utest.h"
+
+// Ensure graph is scaled to the maximum width when linecount exceeds max_width.
+UTEST(delta, GraphScalingDoesNotExceedMaxWidth) {
+  GitDelta delta = {
+      .addcount = 50,
+      .delcount = 50,
+  };
+  size_t max_width = 10;
+  char* added = gitdelta_added_graph(&delta, max_width);
+  char* deleted = gitdelta_deleted_graph(&delta, max_width);
+  size_t total_len = strlen(added) + strlen(deleted);
+  EXPECT_LE(total_len, max_width);
+
+  free(added);
+  free(deleted);
+}
+
+// For small changes where sum < max_width, we expect exact line counts.
+UTEST(delta, GraphScalingSmallChanges) {
+  GitDelta delta = {
+      .addcount = 1,
+      .delcount = 1,
+  };
+  size_t max_width = 80;
+  char* added = gitdelta_added_graph(&delta, max_width);
+  char* deleted = gitdelta_deleted_graph(&delta, max_width);
+  EXPECT_EQ((size_t)1, strlen(added));
+  EXPECT_EQ((size_t)1, strlen(deleted));
+
+  free(added);
+  free(deleted);
+}