optimize updateCursor with CUU, CUD, CUF, and CUB.

lib/program.js

@@ -49,6 +49,14 @@ function Program(options) {
 
   this.listen();
 
+  if (options.zero) {
+    this.ti = 0;
+    this.ni = 1;
+  } else {
+    this.ti = -1;
+    this.ni = 0;
+  }
+
   //if (!Program.global) {
   //  Program._write = process.stdout.write;
   //  process.stdout.write = function() {};
@@ -750,10 +758,13 @@ Program.prototype.repeat = function(ch, i) {
  * Normal
  */
 
+//Program.prototype.pad =
 Program.prototype.nul = function() {
+  //if (this.tput) return this.put.nul();
   return this.write('\0');
 };
 
+Program.prototype.bel =
 Program.prototype.bell = function() {
   if (this.tput) return this.put.bel();
   return this.write('\x07');
@@ -768,11 +779,14 @@ Program.prototype.form = function() {
   return this.write('\x0c');
 };
 
+Program.prototype.kbs =
 Program.prototype.backspace = function() {
   this.x--;
+  if (this.tput) return this.put.kbs();
   return this.write('\x08');
 };
 
+Program.prototype.ht =
 Program.prototype.tab = function() {
   this.x += 8;
   if (this.tput) return this.put.ht(); // or `tab`
@@ -794,9 +808,12 @@ Program.prototype.return = function() {
   return this.write('\r');
 };
 
+Program.prototype.nel =
+Program.prototype.newline =
 Program.prototype.feed = function() {
   this.x = 1;
   this.y++;
+  if (this.tput) return this.put.nel();
   return this.write('\n');
 };
 
@@ -809,6 +826,7 @@ Program.prototype.esc = function(code) {
 };
 
 // ESC D Index (IND is 0x84).
+Program.prototype.ind =
 Program.prototype.index = function() {
   this.y++;
   if (this.tput) return this.put.ind();
@@ -816,6 +834,7 @@ Program.prototype.index = function() {
 };
 
 // ESC M Reverse Index (RI is 0x8d).
+Program.prototype.ri =
 Program.prototype.reverse =
 Program.prototype.reverseIndex = function() {
   this.y--;

lib/widget.js

@@ -2503,6 +2503,9 @@ function Textarea(options) {
 
   this.value = options.value || '';
 
+  this.cx = -1;
+  this.cy = -1;
+
   this.__updateCursor = this.updateCursor.bind(this);
   this.on('resize', this.__updateCursor);
   this.on('move', this.__updateCursor);
@@ -2512,12 +2515,16 @@ Textarea.prototype.__proto__ = ScrollableText.prototype;
 
 Textarea.prototype.type = 'textarea';
 
-// TODO: Optimize this. Remember cursor coords.
-// Optimize to use CUU, CUD, CUB, CUF.
 Textarea.prototype.updateCursor = function() {
-  if (this.screen.focused !== this) return;
+  if (this.screen.focused !== this) {
+    return;
+  }
 
-  var last = this._clines[this._clines.length-1];
+  var last = this._clines[this._clines.length-1]
+    , program = this.screen.program
+    , line
+    , cx
+    , cy;
 
   // Stop a situation where the textarea begins scrolling
   // and the last cline appears to always be empty from the
@@ -2526,13 +2533,43 @@ Textarea.prototype.updateCursor = function() {
     last = this._clines[this._clines.length-2] || '';
   }
 
-  var line = Math.min(
+  line = Math.min(
     this._clines.length - 1 - this.childBase,
     this.height - (this.border ? 2 : 0) - 1);
 
-  this.screen.program.cup(
-    this.top + 1 + (this.border ? 1 : 0) + line,
-    this.left + 1 + (this.border ? 1 : 0) + last.length);
+  cy = this.top + 1 + (this.border ? 1 : 0) + line;
+  cx = this.left + 1 + (this.border ? 1 : 0) + last.length;
+
+  if (cy === this.cy && cx === this.cx) {
+    return;
+  }
+
+  if (cy === this.cy) {
+    if (cx > this.cx) {
+      program.cuf(cx - this.cx);
+    } else if (cx < this.cx) {
+      program.cub(this.cx - cx);
+    }
+  } else if (cx === this.cx) {
+    if (cy > this.cy) {
+      if (cy - this.cy === 1) {
+        program.ind();
+      } else {
+        program.cud(cy - this.cy);
+      }
+    } else if (cy < this.cy) {
+      if (this.cy - cy === 1) {
+        program.ri();
+      } else {
+        program.cuu(this.cy - cy);
+      }
+    }
+  } else {
+    program.cup(cy, cx);
+  }
+
+  this.cx = cx;
+  this.cy = cy;
 };
 
 Textarea.prototype.input =
@@ -2548,6 +2585,9 @@ Textarea.prototype.setInput = function(callback) {
 
   this.screen.grabKeys = true;
 
+  this.cx = -1;
+  this.cy = -1;
+
   this.updateCursor();
   this.screen.program.showCursor();
   this.screen.program.sgr('normal');