Improve label adaptation performance

Author: pandamicro

cocos2d/core/labelttf/CCLabelTTF.js

@@ -133,7 +133,9 @@ cc.LabelTTF = cc.Sprite.extend(/** @lends cc.LabelTTF# */{
         this._renderCmd._setFontStyle(this._fontName, fontSize, this._fontStyle, this._fontWeight);
         this.string = strInfo;
         this._renderCmd._setColorsString();
-        this._renderCmd._updateTexture();
+        if (this._string) {
+            this._renderCmd._updateTexture();
+        }
         this._setUpdateTextureDirty();
 
         // Needed for high dpi text.

cocos2d/core/labelttf/CCLabelTTFCanvasRenderCmd.js

@@ -430,7 +430,11 @@ cc.LabelTTF._firsrEnglish = /^[a-zA-Z0-9ÄÖÜäöüßéèçàùêâîôû]/;
     };
 
     proto._measure = function (text) {
-        return this._labelContext.measureText(text).width;
+        if (text) {
+            return this._labelContext.measureText(text).width;
+        } else {
+            return 0;
+        }
     };
 
 })();
@@ -462,9 +466,13 @@ cc.LabelTTF._firsrEnglish = /^[a-zA-Z0-9ÄÖÜäöüßéèçàùêâîôû]/;
     };
 
     proto._measure = function (text) {
-        var context = cc._renderContext.getContext();
-        context.font = this._fontStyleStr;
-        return context.measureText(text).width;
+        if(text) {
+            var context = cc._renderContext.getContext();
+            context.font = this._fontStyleStr;
+            return context.measureText(text).width;
+        } else {
+            return 0;
+        }
     };
 
     proto._updateTexture = function () {

cocos2d/labels/CCLabelBMFont.js

@@ -128,7 +128,9 @@ cc.LabelBMFont = cc.SpriteBatchNode.extend(/** @lends cc.LabelBMFont# */{
             }
         }
         if (this._textureLoaded) {
-            this.createFontChars();
+            if(this._string && this._string.length > 0) {
+                this.createFontChars();
+            }
             if (needUpdateLabel)
                 this.updateLabel();
         }
@@ -273,6 +275,9 @@ cc.LabelBMFont = cc.SpriteBatchNode.extend(/** @lends cc.LabelBMFont# */{
      * updates the font chars based on the string to render
      */
     createFontChars: function () {
+        var locStr = this._string;
+        var stringLen = locStr ? locStr.length : 0;
+
         var self = this;
         var cmd = this._renderCmd;
         var locTexture = cmd._texture || this._texture;
@@ -285,11 +290,6 @@ cc.LabelBMFont = cc.SpriteBatchNode.extend(/** @lends cc.LabelBMFont# */{
 
         var quantityOfLines = 1;
 
-        var locStr = self._string;
-        var stringLen = locStr ? locStr.length : 0;
-
-        if (stringLen === 0)
-            return;
 
         var i, locCfg = self._config, locKerningDict = locCfg.kerningDict,
             locCommonH = locCfg.commonHeight, locFontDict = locCfg.fontDefDictionary;
@@ -383,13 +383,17 @@ cc.LabelBMFont = cc.SpriteBatchNode.extend(/** @lends cc.LabelBMFont# */{
         var self = this;
         var locChildren = self._children;
         if (locChildren) {
-            for (var i = 0, li = locChildren.length; i < li; i++) {
+            var length = locChildren.length;
+            for (var i = 0, li = length; i < li; i++) {
                 var node = locChildren[i];
                 if (node) node.visible = false;
             }
         }
-        if (self._config)
-            self.createFontChars();
+        if (self._config) {
+            if(self._string && self._string.length > 0) {
+                self.createFontChars();
+            }
+        }
 
         if (!fromUpdate)
             self.updateLabel();
@@ -715,15 +719,20 @@ cc.LabelBMFont = cc.SpriteBatchNode.extend(/** @lends cc.LabelBMFont# */{
                     var self1 = this;
                     self1._textureLoaded = true;
                     self1.setTexture(sender);
-                    self1.createFontChars();
+                    if(self1._string && self1._string.length > 0) {
+                        self1.createFontChars();
+                    }
+
                     self1._changeTextureColor();
                     self1.updateLabel();
 
                     self1.dispatchEvent("load");
                 }, self);
             } else {
                 self.setTexture(texture);
-                self.createFontChars();
+                if(self._string && self._string.length > 0) {
+                    self.createFontChars();
+                }
             }
         }
     },