feat: added isFocusIn() and isFocusOut() methods

Author: quintesse

examples/PrintFocus.java

@@ -0,0 +1,36 @@
+//DEPS org.codejive.miniterm:ansiparser:0.1.3
+//DEPS org.codejive.miniterm:termcap:0.1.4-SNAPSHOT
+
+package examples;
+
+import java.io.IOException;
+import org.codejive.miniterm.Terminal;
+import org.codejive.miniterm.ansiparser.AnsiReader;
+import org.codejive.miniterm.termcap.TermCaps;
+
+public class PrintFocus {
+    public static void main(String[] args) {
+        try (Terminal terminal = Terminal.create()) {
+            terminal.enableRawMode();
+            TermCaps.enableFocusTracking(terminal);
+            try {
+                System.out.println("Focus the terminal window (Ctrl+C to exit):");
+                AnsiReader reader = new AnsiReader(() -> terminal.read(-1));
+                String token;
+                while ((token = reader.read()) != null) {
+                    if (token.isEmpty()) continue;
+                    if (!token.startsWith("\033") && token.charAt(0) == 3) break; // Ctrl+C
+                    if (TermCaps.isFocusIn(token)) {
+                        System.out.println("Focus IN");
+                    } else if (TermCaps.isFocusOut(token)) {
+                        System.out.println("Focus OUT");
+                    }
+                }
+            } finally {
+                TermCaps.disableFocusTracking(terminal);
+            }
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+}

termcap/src/main/java/org/codejive/miniterm/termcap/TermCaps.java

@@ -280,6 +280,26 @@ public static void disableFocusTracking(Appendable out) throws java.io.IOExcepti
         out.append(CSI).append("?1004l");
     }
 
+    /**
+     * Returns {@code true} if {@code sequence} is the focus-in event ({@code ESC[I}).
+     *
+     * @param sequence input sequence to test
+     * @return {@code true} when the sequence signals the terminal window has gained focus
+     */
+    public static boolean isFocusIn(String sequence) {
+        return (CSI + "I").equals(sequence);
+    }
+
+    /**
+     * Returns {@code true} if {@code sequence} is the focus-out event ({@code ESC[O}).
+     *
+     * @param sequence input sequence to test
+     * @return {@code true} when the sequence signals the terminal window has lost focus
+     */
+    public static boolean isFocusOut(String sequence) {
+        return (CSI + "O").equals(sequence);
+    }
+
     /**
      * Begins a synchronized-output frame (DEC private mode 2026).
      *