PrintPreview: Added code to identify the printer default duplex value.

chrome/browser/resources/print_preview/copies_settings.js

Index: chrome/browser/resources/print_preview/copies_settings.js
diff --git a/chrome/browser/resources/print_preview/copies_settings.js b/chrome/browser/resources/print_preview/copies_settings.js
index 3c48e45e271cd50787056e8a05a498e00e9954e9..c3144fa3d1663936db40679884c62ab902465167 100644
--- a/chrome/browser/resources/print_preview/copies_settings.js
+++ b/chrome/browser/resources/print_preview/copies_settings.js
@@ -22,6 +22,13 @@ cr.define('print_preview', function() {
     this.collateCheckbox_ = $('collate');
     this.hint_ = $('copies-hint');
     this.twoSidedCheckbox_ = $('two-sided');
+    this.twoSidedOption_ = $('two-sided-div');
+
+    // Constant values matches printing::DuplexMode enum. Not using const
+    // keyword because it is not allowed by JS strict mode.
+    this.SIMPLEX = 0;
+    this.LONG_EDGE = 1;
+    this.UNKNOWN_DUPLEX_MODE = -1;
   }
 
   cr.addSingletonGetter(CopiesSettings);
@@ -56,15 +63,16 @@ cr.define('print_preview', function() {
     },
 
     /**
-     * Gets the duplex mode for printing.
+     * Gets the duplex mode information for printing.
      * @return {number} duplex mode.
      */
-     get duplexMode() {
-      // Constant values matches printing::DuplexMode enum. Not using const
-      // keyword because it is not allowed by JS strict mode.
-      var SIMPLEX = 0;
-      var LONG_EDGE = 1;
-      return !this.twoSidedCheckbox_.checked ? SIMPLEX : LONG_EDGE;
+    get duplexMode() {
+      if (this.twoSidedOption_.hidden)
+        return this.UNKNOWN_DUPLEX_MODE;
+      else if (this.twoSidedCheckbox_.checked)
+        return this.LONG_EDGE;
+      else
+        return this.SIMPLEX;

[dpapad, 2011/09/08 15:52:06]

Nit: you could compress this if statement to
if (this.twoSidedOption_.hidden)
  return this.UNKNOWN_DUPLEX_MODE;
else
  return this.twoSidedCheckbox_.checked ? LONG_EDGE : SIMPLEX;

[kmadhusu, 2011/09/08 17:13:10]

I prefer if..elseif.. structure here.

     },
 
     /**
@@ -158,7 +166,8 @@ cr.define('print_preview', function() {
         fadeInElement(this.copiesOption_);
         $('hr-before-copies').classList.add('invisible');
       }
-      this.twoSidedCheckbox_.checked = e.printerCapabilities.setDuplexAsDefault;
+      this.updateTwoSidedOption_(
+          e.printerCapabilities.printerDefaultDuplexValue);
     },
 
     /**
@@ -190,6 +199,25 @@ cr.define('print_preview', function() {
                                        this.collateOption_.hidden);
     },
 
+    /*
+     * Takes care of showing/hiding the two sided option and also updates the
+     * default state of the checkbox.
+     * @param {boolean} defaultDuplexValue Specifies the default duplex value.
+     * @private
+     */
+     updateTwoSidedOption_: function(defaultDuplexValue) {
+      // On Windows, some printers don't specify their duplex values in the
+      // printer schema. If the printer duplex value is UNKNOWN_DUPLEX_MODE,
+      // hide the two sided option in preview tab UI.
+      // Ref bug: http://crbug.com/89204
+      this.twoSidedOption_.hidden =
+          (defaultDuplexValue == this.UNKNOWN_DUPLEX_MODE);

[dpapad, 2011/09/08 15:52:06]

Is |defaultDuplexValue| a boolean? It is compared with a non boolean here. If it
is not, update the @param comment otherwise use !!this.UNKNOWN_DUPLEX_MODE.

[kmadhusu, 2011/09/08 17:13:10]

It is not a boolean. Updated the @param comment.

+      this.twoSidedOption_.setAttribute('aria-hidden',
+                                        this.twoSidedOption_.hidden);
+      if (!this.twoSidedOption_.hidden)
+        this.twoSidedCheckbox_.checked = defaultDuplexValue;

[dpapad, 2011/09/08 15:52:06]

Same here, if |defaultDuplexValue| is not a boolean use !!defaultDuplexValue.

[kmadhusu, 2011/09/08 17:13:10]

Done.

+     },
+
     /**
      * Updates the state of the increment/decrement buttons based on the current
      * |textfield_| value.