From 17b32097fe6fb20025794e89ad6c4435f751c6ff Mon Sep 17 00:00:00 2001
From: Bob Polis <bob.polis@gmail.com>
Date: Sat, 27 Jan 2024 16:25:23 +0100
Subject: [PATCH] If no truecolor support, degrade to 216-colors

---
 src/pixels.cpp | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/src/pixels.cpp b/src/pixels.cpp
index a5ad44e..715cc6b 100644
--- a/src/pixels.cpp
+++ b/src/pixels.cpp
@@ -3,7 +3,15 @@
 #include <netpbm/pam.h>
 #include "pixels.hpp"
 
+// truecolor to palette color (216-color)
+static inline int t2p(int val) {
+    return .5 + 5 * val / 255.0;
+}
+
 void write_image(std::ostream& os, const std::string& path) {
+    char* tc = getenv("TRUECOLOR");
+    std::string truecolor {tc ? tc : ""};
+    bool has_truecolor = truecolor.size() > 0;
     std::unique_ptr<FILE, void(*)(FILE*)> infile {pm_openr(path.c_str()), pm_close};
     struct pam info;
     pnm_readpaminit(infile.get(), &info, PAM_STRUCT_SIZE(tuple_type));
@@ -15,9 +23,17 @@ void write_image(std::ostream& os, const std::string& path) {
         for (int x = 0; x < info.width; ++x) {
             if (info.depth == 3) { // assume RGB, 1 byte per sample
                 tuple* t1 {row1.get()};
-                os << sc::io::truecolorb(t1[x][0], t1[x][1], t1[x][2]);
+                if (has_truecolor) {
+                    os << sc::io::truecolorb(t1[x][0], t1[x][1], t1[x][2]);
+                } else {
+                    os << sc::io::rgbb(t2p(t1[x][0]), t2p(t1[x][1]), t2p(t1[x][2]));
+                }
                 tuple* t2 {row2.get()};
-                os << sc::io::truecolorf(t2[x][0], t2[x][1], t2[x][2]);
+                if (has_truecolor) {
+                    os << sc::io::truecolorf(t2[x][0], t2[x][1], t2[x][2]);
+                } else {
+                    os << sc::io::rgbf(t2p(t2[x][0]), t2p(t2[x][1]), t2p(t2[x][2]));
+                }
                 os << u8"\u2584"; // unicode lower half block
             }
         }