commit 0206e263dc1954fd44167ed8ce326dc8669bd64c
author Mike Frysinger <vapier@chromium.org> Thu Jun 13 10:18:19 2019 -0400
committer Mike Frysinger <vapier@chromium.org> Sun Jul 07 08:50:21 2019 +0000
tree 271adeacea9e331841a047cef0b92601c59f8f85
parent 60a156d09d5c6a58fcc25cd6fa47a107d69e4060

hterm: terminal: speed up realize helpers slightly

Sometimes these functions get called with the same sizes as the
terminal is already using.  To avoid needless reprocessing, add
some checks to return early when the state is already in sync.

Change-Id: I81ea7bfc1cbc3892b9b238cd7694356c6090e9e7
Reviewed-on: https://chromium-review.googlesource.com/c/apps/libapps/+/1657573
Reviewed-by: Vitaliy Shipitsyn <vsh@google.com>
Tested-by: Mike Frysinger <vapier@chromium.org>

hterm/js/hterm_terminal.js

diff --git a/hterm/js/hterm_terminal.js b/hterm/js/hterm_terminal.js
index d3decb7..c2d6505 100644
--- a/hterm/js/hterm_terminal.js
+++ b/hterm/js/hterm_terminal.js
@@ -1065,14 +1065,22 @@
  * @param {number} rowCount The number of rows.
  */
 hterm.Terminal.prototype.realizeSize_ = function(columnCount, rowCount) {
-  if (columnCount != this.screenSize.width)
-    this.realizeWidth_(columnCount);
+  let notify = false;
 
-  if (rowCount != this.screenSize.height)
+  if (columnCount != this.screenSize.width) {
+    notify = true;
+    this.realizeWidth_(columnCount);
+  }
+
+  if (rowCount != this.screenSize.height) {
+    notify = true;
     this.realizeHeight_(rowCount);
+  }
 
   // Send new terminal size to plugin.
-  this.io.onTerminalResize_(columnCount, rowCount);
+  if (notify) {
+    this.io.onTerminalResize_(columnCount, rowCount);
+  }
 };
 
 /**
@@ -1093,6 +1101,10 @@
     throw new Error('Attempt to realize bad width: ' + columnCount);
 
   var deltaColumns = columnCount - this.screen_.getWidth();
+  if (deltaColumns == 0) {
+    // No change, so don't bother recalculating things.
+    return;
+  }
 
   this.screenSize.width = columnCount;
   this.screen_.setColumnCount(columnCount);
@@ -1130,6 +1142,10 @@
     throw new Error('Attempt to realize bad height: ' + rowCount);
 
   var deltaRows = rowCount - this.screen_.getHeight();
+  if (deltaRows == 0) {
+    // No change, so don't bother recalculating things.
+    return;
+  }
 
   this.screenSize.height = rowCount;