From c259d8d258494dbdd61595548936fcfcf62ae7aa Mon Sep 17 00:00:00 2001
From: Guillaume Nodet <gnodet@gmail.com>
Date: Mon, 29 Jan 2018 10:33:55 +0100
Subject: [PATCH] Focus tracking support, fixes #222

---
 .../main/java/org/jline/reader/LineReader.java  |  2 ++
 .../org/jline/reader/impl/LineReaderImpl.java   | 15 +++++++++++++++
 .../main/java/org/jline/terminal/Terminal.java  | 17 +++++++++++++++++
 .../jline/terminal/impl/AbstractTerminal.java   | 16 ++++++++++++++++
 4 files changed, 50 insertions(+)

diff --git a/reader/src/main/java/org/jline/reader/LineReader.java b/reader/src/main/java/org/jline/reader/LineReader.java
index 94f2dd98e..86421672f 100644
--- a/reader/src/main/java/org/jline/reader/LineReader.java
+++ b/reader/src/main/java/org/jline/reader/LineReader.java
@@ -247,6 +247,8 @@ public interface LineReader {
     String YANK = "yank";
     String YANK_POP = "yank-pop";
     String MOUSE = "mouse";
+    String FOCUS_IN = "terminal-focus-in";
+    String FOCUS_OUT = "terminal-focus-out";
 
     String BEGIN_PASTE = "begin-paste";
 
diff --git a/reader/src/main/java/org/jline/reader/impl/LineReaderImpl.java b/reader/src/main/java/org/jline/reader/impl/LineReaderImpl.java
index 94e09dd2c..fee9de870 100644
--- a/reader/src/main/java/org/jline/reader/impl/LineReaderImpl.java
+++ b/reader/src/main/java/org/jline/reader/impl/LineReaderImpl.java
@@ -100,6 +100,9 @@ public class LineReaderImpl implements LineReader, Flushable
     public static final String BRACKETED_PASTE_BEGIN = "\033[200~";
     public static final String BRACKETED_PASTE_END = "\033[201~";
 
+    public static final String FOCUS_IN_SEQ = "\033[I";
+    public static final String FOCUS_OUT_SEQ = "\033[O";
+
     /**
      * Possible states in which the current readline operation may be in.
      */
@@ -3338,6 +3341,8 @@ protected Map<String, Widget> builtinWidgets() {
         widgets.put(YANK_POP, this::yankPop);
         widgets.put(MOUSE, this::mouse);
         widgets.put(BEGIN_PASTE, this::beginPaste);
+        widgets.put(FOCUS_IN, this::focusIn);
+        widgets.put(FOCUS_OUT, this::focusOut);
         return widgets;
     }
 
@@ -4995,6 +5000,14 @@ public boolean beginPaste() {
         return true;
     }
 
+    public boolean focusIn() {
+        return false;
+    }
+
+    public boolean focusOut() {
+        return false;
+    }
+
     /**
      * Clean the used display
      */
@@ -5426,6 +5439,8 @@ private void bindArrowKeys(KeyMap<Binding> map) {
         bind(map, OVERWRITE_MODE,       key(Capability.key_ic));
         bind(map, MOUSE,                key(Capability.key_mouse));
         bind(map, BEGIN_PASTE,          BRACKETED_PASTE_BEGIN);
+        bind(map, FOCUS_IN,             FOCUS_IN_SEQ);
+        bind(map, FOCUS_OUT,            FOCUS_OUT_SEQ);
     }
 
     /**
diff --git a/terminal/src/main/java/org/jline/terminal/Terminal.java b/terminal/src/main/java/org/jline/terminal/Terminal.java
index 76ec1a381..95ac3bed4 100644
--- a/terminal/src/main/java/org/jline/terminal/Terminal.java
+++ b/terminal/src/main/java/org/jline/terminal/Terminal.java
@@ -247,4 +247,21 @@ enum MouseTracking {
      */
     MouseEvent readMouseEvent(IntSupplier reader);
 
+    /**
+     * Returns <code>true</code> if the terminal has support for focus tracking.
+     * @return whether focus tracking is supported by the terminal
+     * @see #trackFocus(boolean)
+     */
+    boolean hasFocusSupport();
+
+    /**
+     * Enable or disable focus tracking mode.
+     * When focus tracking has been activated, each time the terminal grabs the focus,
+     * the string "\33[I" will be sent to the input stream and each time the focus is lost,
+     * the string "\33[O" will be sent to the input stream.
+     *
+     * @param tracking whether the focus tracking mode should be enabled or not
+     * @return <code>true</code> if focus tracking is supported
+     */
+    boolean trackFocus(boolean tracking);
 }
diff --git a/terminal/src/main/java/org/jline/terminal/impl/AbstractTerminal.java b/terminal/src/main/java/org/jline/terminal/impl/AbstractTerminal.java
index c88406998..7f899d601 100644
--- a/terminal/src/main/java/org/jline/terminal/impl/AbstractTerminal.java
+++ b/terminal/src/main/java/org/jline/terminal/impl/AbstractTerminal.java
@@ -206,6 +206,22 @@ public MouseEvent readMouseEvent(IntSupplier reader) {
         return lastMouseEvent = MouseSupport.readMouse(reader, lastMouseEvent);
     }
 
+    @Override
+    public boolean hasFocusSupport() {
+        return type != null && type.startsWith("xterm");
+    }
+
+    @Override
+    public boolean trackFocus(boolean tracking) {
+        if (hasFocusSupport()) {
+            writer().write(tracking ? "\033[?1004h" : "\033[?1004l");
+            writer().flush();
+            return true;
+        } else {
+            return false;
+        }
+    }
+
     protected void checkInterrupted() throws InterruptedIOException {
         if (Thread.interrupted()) {
             throw new InterruptedIOException();