gdamore · dejlek · Nov 30, 2025
diff --git a/demos/screen_write_strings.d b/demos/screen_write_strings.d
@@ -0,0 +1,114 @@
+/+ dub.sdl:
+    name "screen_write_strings"
+    description "Demo showcasing Screen string/style write helpers"
+    dependency "dcell" path=".."
+    targetType "executable"
+ +/
+
+// SPDX-License-Identifier: BSL-1.0
+
+/**
+ * Demo: Screen string and style writing helpers.
+ *
+ * This tiny demo showcases the convenience helpers added to `Screen`:
+ *  - Single-cell string assignment via index operators: `screen[x, y] = "A"` and `screen[Coord(x,y)] = "Z"`.
+ *  - Style assignment via index operators: `screen[x, y] = someStyle;` (preserves existing text).
+ *  - Multi-cell string write with truncation: `screen.write(x, y, s);`
+ *  - Multi-cell string write with wrapping: `screen.writeWrap(x, y, s);`
+ *  - Styled variants that apply a uniform style across written cells.
+ *
+ * Press ESC (or F1) to exit. Resizing the terminal will redraw the content.
+ */
+module screen_write_strings;
+
+import std.concurrency : thisTid, receive;
+import dcell; // public imports provide Screen, Style, Color, Key, Event, etc.
+
+private void draw(Screen s)
+{
+    auto sz = s.size();
+
+    // Set a pleasant default background for readability.
+    Style def; def.bg = Color.silver; def.fg = Color.black;
+    s.setStyle(def);
+    s.clear();
+
+    // Title centered using opDollar ($) and Coord overloads later below.
+    Style title; title.fg = Color.white; title.bg = Color.darkBlue; title.attr = Attr.bold;
+    string titleText = "Screen.write* demo";
+    // Use truncate write for the title (it will naturally truncate if terminal is very small).
+    int titleX = (sz.x - cast(int) titleText.length) / 2;
+    if (titleX < 0) titleX = 0;
+    s.write(cast(size_t) titleX, 0, titleText, title);
+
+    // 1) Single-cell string assignment via index operators.
+    s[2, 2] = "A";                 // string write (preserves style)
+    s[3, 2] = "角";                // non-ASCII example
+    s[4, 2] = "\n";               // control normalized to space
+    s[Coord(5, 2)] = "Z";          // Coord overload
+
+    s.write(1, 4, "Дејан Лекић"); // Serbian cyrillic
+    s.write(1, 5, "Dejan Lekić"); // Serbian latin
+
+    // 2) Style assignment via index operators, preserving text.
+    // Seed a cell's text then apply style only.
+    s[8, 2] = "S";
+    Style emph; emph.fg = Color.yellow; emph.bg = Color.maroon; emph.attr = Attr.bold | Attr.underline;
+    s[8, 2] = emph;                 // apply style, text stays "S"
+
+    // 3) Multi-cell string write (truncate at end of row).
+    string truncMsg = "This will truncate at row end";
+    size_t tx = cast(size_t) (sz.x > 24 ? sz.x - 24 : 0);
+    s.write(tx, 4, truncMsg);       // preserves existing styles
+
+    // 4) Multi-cell string write with wrapping.
+    string wrapMsg = "Wrapping across rows using writeWrap(...)";
+    size_t wx = (sz.x > 6) ? cast(size_t) (sz.x - 6) : 0; // start near the right edge
+    s.writeWrap(wx, 6, wrapMsg);
+
+    // 5) Styled variants: apply a uniform style while writing.
+    Style banner; banner.fg = Color.black; banner.bg = Color.papayaWhip; banner.attr = Attr.reverse;
+    s.write(2, 8, "Styled truncate", banner);
+    s.writeWrap(2, 10, "Styled wrapping continues to next line if needed", banner);
+
+    // 6) Coord overloads for write helpers and use of $ for center marker.
+    s.write(Coord(2, 12), "Coord overload works →" );
+    s[$/2, $/2] = "+";            // center marker
+
+    s.show();
+}
+
+private void handleEvent(Screen s, Event ev)
+{
+    import core.stdc.stdlib : exit;
+    switch (ev.type)
+    {
+    case EventType.key:
+        if (ev.key.key == Key.esc || ev.key.key == Key.f1)
+        {
+            s.stop();
+            exit(0);
+        }
+        break;
+    case EventType.resize:
+        s.resize();
+        draw(s);
+        s.sync();
+        break;
+    default:
+        break;
+    }
+}
+
+void main()
+{
+    auto screen = newScreen();
+    assert(screen !is null);
+
+    screen.start(thisTid());
+    draw(screen);
+    for (;;)
+    {
+        receive((Event ev) { handleEvent(screen, ev); });
+    }
+}