Add truecolor demo

progress.cpp

@@ -1,6 +1,5 @@
 #include <iostream>
 #include <ctime>
-#include <cmath>
 #include <libscterm.hpp>
 
 void show_rows_cols(const sc::term& t) {
@@ -36,7 +35,7 @@ void show_hue_bar(int top) {
     }
     r = 0;
     // green -> cyan
-    while (b < 6) {
+    while (b < top) {
         std::cerr << sc::io::rgbb(r, g, b++) << ' ';
     }
     b = top;
@@ -117,6 +116,53 @@ void show_words() {
     std::cout << std::endl;
 }
 
+void show_truecolor(const sc::term& t) {
+    const char* lhb = u8"\u2584"; // lower half block
+    int inc = 6.0 * t.cols() / 256.0;
+    if (inc == 0) inc = 1;
+    for (int s = 16; s < 224; s += 32) {
+        int r = s;
+        int g = 0;
+        int b = 0;
+        // red -> yellow
+        while (g <= s) {
+            std::cerr << sc::io::truecolorb(r, g, b) << sc::io::truecolorf(r, 16 + g, b) << lhb;
+            g += inc;
+        }
+        g = s;
+        // yellow -> green
+        while (r >= 0) {
+            std::cerr << sc::io::truecolorb(r, g, b) << sc::io::truecolorf(16 + r, g, b) << lhb;
+            r -= inc;
+        }
+        r = 0;
+        // green -> cyan
+        while (b < s) {
+            std::cerr << sc::io::truecolorb(r, g, b) << sc::io::truecolorf(r, g, 16 + b) << lhb;
+            b += inc;
+        }
+        b = s;
+        // cyan -> blue
+        while (g >= 0) {
+            std::cerr << sc::io::truecolorb(r, g, b) << sc::io::truecolorf(r, 16 + g, b) << lhb;
+            g -= inc;
+        }
+        g = 0;
+        // blue -> magenta
+        while (r <= s) {
+            std::cerr << sc::io::truecolorb(r, g, b) << sc::io::truecolorf(16 + r, g, b) << lhb;
+            r += inc;
+        }
+        r = s;
+        // magenta -> red
+        while (b >= 0) {
+            std::cerr << sc::io::truecolorb(r, g, b) << sc::io::truecolorf(r, g, 16 + b) << lhb;
+            b -= inc;
+        }
+        std::cerr << sc::io::reset << std::endl;
+    }
+}
+
 int main() {
     try {
         sc::term term {STDERR_FILENO};
@@ -124,6 +170,7 @@ int main() {
         show_grayscale_bar();
         show_hue_bars();
         show_words();
+        show_truecolor(term);
         show_progress(term);
     } catch (const std::exception& ex) {
         std::cerr << sc::io::reset << ex.what() << std::endl;