improve Log element.

README.md

@@ -1027,15 +1027,21 @@ A log permanently scrolled to the bottom.
 ##### Options:
 
 - inherits all from ScrollableText.
+- __scrollback__ - amount of scrollback allowed. default: Infinity.
+- __scrollOnInput__ - scroll to bottom on input even if the user has scrolled
+  up. default: false.
 
 ##### Properties:
 
 - inherits all from ScrollableText.
+- __scrollback__ - amount of scrollback allowed. default: Infinity.
+- __scrollOnInput__ - scroll to bottom on input even if the user has scrolled
+  up. default: false.
 
 ##### Events:
 
 - inherits all from ScrollableText.
-- __line__ - emitted on a log line. passes in line.
+- __log__ - emitted on a log line. passes in line.
 
 ##### Methods:
 

lib/widget.js

@@ -11,6 +11,7 @@
 var EventEmitter = require('./events').EventEmitter
   , assert = require('assert')
   , path = require('path')
+  , util = require('util')
   , fs = require('fs');
 
 var colors = require('./colors')
@@ -4003,6 +4004,7 @@ Element.prototype.shiftLine = function(n) {
 };
 
 Element.prototype.pushLine = function(line) {
+  if (!this.content) return this.setLine(0, line);
   return this.insertLine(this._clines.fake.length, line);
 };
 
@@ -4423,12 +4425,11 @@ function ScrollableText(options) {
     return new ScrollableText(options);
   }
   options = options || {};
-  options.scrollable = true;
   options.alwaysScroll = true;
-  Box.call(this, options);
+  ScrollableBox.call(this, options);
 }
 
-ScrollableText.prototype.__proto__ = Box.prototype;
+ScrollableText.prototype.__proto__ = ScrollableBox.prototype;
 
 ScrollableText.prototype.type = 'scrollable-text';
 
@@ -6779,11 +6780,19 @@ function Log(options) {
 
   ScrollableText.call(this, options);
 
+  this.scrollback = options.scrollback != null
+    ? options.scrollback
+    : Infinity;
+  this.scrollOnInput = options.scrollOnInput;
+
   this.on('set content', function() {
-    nextTick(function() {
-      self.setScrollPerc(100);
-      self.screen.render();
-    });
+    if (!self._userScrolled || self.scrollOnInput) {
+      nextTick(function() {
+        self.setScrollPerc(100);
+        self._userScrolled = false;
+        self.screen.render();
+      });
+    }
   });
 }
 
@@ -6792,9 +6801,29 @@ Log.prototype.__proto__ = ScrollableText.prototype;
 Log.prototype.type = 'log';
 
 Log.prototype.log =
-Log.prototype.add = function(text) {
-  this.emit('line', text);
-  return this.pushLine(text);
+Log.prototype.add = function() {
+  var args = Array.prototype.slice.call(arguments);
+  if (typeof args[0] === 'object') {
+    args[0] = util.inspect(args[0], true, 20, true);
+  }
+  var text = util.format.apply(util, args);
+  this.emit('log', text);
+  var ret = this.pushLine(text);
+  if (this._clines.fake.length > this.scrollback) {
+    this.shiftLine(0, (this.scrollback / 3) | 0);
+  }
+  return ret;
+};
+
+Log.prototype._scroll = Log.prototype.scroll;
+Log.prototype.scroll = function(offset, always) {
+  if (offset === 0) return this._scroll(offset, always);
+  this._userScrolled = true;
+  var ret = this._scroll(offset, always);
+  if (this.getScrollPerc() === 100) {
+    this._userScrolled = false;
+  }
+  return ret;
 };
 
 /**

test/widget-log.js

@@ -0,0 +1,47 @@
+var blessed = require('../')
+  , screen;
+
+screen = blessed.screen({
+  dump: __dirname + '/logs/logger.log',
+  smartCSR: true,
+  autoPadding: false
+});
+
+var logger = blessed.log({
+  parent: screen,
+  top: 'center',
+  left: 'center',
+  width: '50%',
+  height: '50%',
+  border: 'line',
+  tags: true,
+  keys: true,
+  vi: true,
+  mouse: true,
+  scrollback: 100,
+  scrollbar: {
+    ch: ' ',
+    track: {
+      bg: 'yellow'
+    },
+    style: {
+      inverse: true
+    }
+  }
+});
+
+logger.focus();
+
+setInterval(function() {
+  logger.log('Hello {green-fg}world{/}: {bold}%s{/bold}.', Date.now().toString(36));
+  if (Math.random() < 0.30) {
+    logger.log({foo:{bar:{baz:true}}});
+  }
+  screen.render();
+}, 1000).unref();
+
+screen.key('q', function() {
+  return process.exit(0);
+});
+
+screen.render();