Fix iText space width justification (#2971)

src/shapes/itext.class.js

@@ -934,7 +934,7 @@
      * @param {CanvasRenderingContext2D} ctx Context to render on
      */
     _getWidthOfChar: function(ctx, _char, lineIndex, charIndex) {
-      if (this.textAlign === 'justify' && this._reSpacesAndTabs.test(_char)) {
+      if (!this._isMeasuring && this.textAlign === 'justify' && this._reSpacesAndTabs.test(_char)) {
         return this._getWidthOfSpace(ctx, lineIndex);
       }
 
@@ -965,6 +965,8 @@
     /**
      * @private
      * @param {CanvasRenderingContext2D} ctx Context to render on
+     * @param {Number} lineIndex
+     * @param {Number} charIndex
      */
     _getWidthOfCharsAt: function(ctx, lineIndex, charIndex) {
       var width = 0, i, _char;
@@ -978,13 +980,14 @@
     /**
      * @private
      * @param {CanvasRenderingContext2D} ctx Context to render on
+     * @param {Number} lineIndex line number
+     * @return {Number} Line width
      */
-    _getLineWidth: function(ctx, lineIndex) {
-      if (this.__lineWidths[lineIndex]) {
-        return this.__lineWidths[lineIndex];
-      }
-      this.__lineWidths[lineIndex] = this._getWidthOfCharsAt(ctx, lineIndex, this._textLines[lineIndex].length);
-      return this.__lineWidths[lineIndex];
+    _measureLine: function(ctx, lineIndex) {
+      this._isMeasuring = true;
+      var width = this._getWidthOfCharsAt(ctx, lineIndex, this._textLines[lineIndex].length);
+      this._isMeasuring = false;
+      return width;
     },
 
     /**
@@ -1000,7 +1003,7 @@
           wordsWidth = this._getWidthOfWords(ctx, line, lineIndex, 0),
           widthDiff = this.width - wordsWidth,
           numSpaces = line.length - line.replace(this._reSpacesAndTabs, '').length,
-          width = widthDiff / numSpaces;
+          width = Math.max(widthDiff / numSpaces, ctx.measureText(' ').width);
       this.__widthOfSpace[lineIndex] = width;
       return width;
     },

src/shapes/text.class.js

@@ -352,11 +352,7 @@
       }
       this._textLines = this._splitTextIntoLines();
       this._clearCache();
-      //if textAlign is 'justify' i have to disable caching
-      //when calculating width of text and widths of line.
-      this._cacheLinesWidth = (this.textAlign !== 'justify');
       this.width = this._getTextWidth(ctx);
-      this._cacheLinesWidth = true;
       this.height = this._getTextHeight(ctx);
     },
 
@@ -664,8 +660,8 @@
       ctx.fillStyle = this.textBackgroundColor;
       for (var i = 0, len = this._textLines.length; i < len; i++) {
         heightOfLine = this._getHeightOfLine(ctx, i);
-        if (this._textLines[i] !== '') {
-          lineWidth = this.textAlign === 'justify' ? this.width : this._getLineWidth(ctx, i);
+        lineWidth = this._getLineWidth(ctx, i);
+        if (lineWidth > 0) {
           lineLeftOffset = this._getLineLeftOffset(lineWidth);
           ctx.fillRect(
             this._getLeftOffset() + lineLeftOffset,
@@ -730,29 +726,38 @@
      */
     _getLineWidth: function(ctx, lineIndex) {
       if (this.__lineWidths[lineIndex]) {
-        return this.__lineWidths[lineIndex];
+        return this.__lineWidths[lineIndex] === -1 ? this.width : this.__lineWidths[lineIndex];
       }
+
       var width, wordCount, line = this._textLines[lineIndex];
+
       if (line === '') {
         width = 0;
       }
-      else if (this.textAlign === 'justify' && this._cacheLinesWidth) {
-        wordCount = line.split(/\s+/);
-        //consider not justify last line, not for now.
-        if (wordCount.length > 1) {
-          width = this.width;
-        }
-        else {
-          width = ctx.measureText(line).width;
-        }
-      }
       else {
-        width = ctx.measureText(line).width;
+        width = this._measureLine(ctx, lineIndex);
+      }
+      this.__lineWidths[lineIndex] = width;
+
+      if (width && this.textAlign === 'justify') {
+        wordCount = line.split(/\s+/);
+        if (wordCount.length > 1) {
+          this.__lineWidths[lineIndex] = -1;
+        }
       }
-      this._cacheLinesWidth && (this.__lineWidths[lineIndex] = width);
       return width;
     },
 
+    /**
+     * @private
+     * @param {CanvasRenderingContext2D} ctx Context to render on
+     * @param {Number} lineIndex line number
+     * @return {Number} Line width
+     */
+    _measureLine: function(ctx, lineIndex) {
+      return ctx.measureText(this._textLines[lineIndex]).width;
+    },
+
     /**
      * @private
      * @param {CanvasRenderingContext2D} ctx Context to render on