Implement AS2's TextFormat#getTextExtent

Another fix for the ad from mozilla#471
tschneidereit · Oct 31, 2013 · 23c12e4 · 23c12e4
1 parent fcec5e9
commit 23c12e4
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Showing 3 changed files with 62 additions and 22 deletions.
diff --git a/src/flash/avm1lib/AS2Globals.js b/src/flash/avm1lib/AS2Globals.js
@@ -15,18 +15,25 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-/*global AS2Context, Multiname, Stubs */
+/*global AS2Context, Multiname, Stubs, TextFormatDefinition */
 var AS2GlobalsDefinition = (function () {
   var def = {
     __class__: 'avm1lib.AS2Globals',
 
     initialize: function () {
+      // The AS2 version of TextFormat has an additional method "getTextExtent".
+      // We install that here so we don't need to have a full AS2 version of
+      // TextFormat and take care to return that everywhere when in AS2 mode.
+      flash.text.TextFormat.prototype.asDefinePublicProperty('getTextExtent', {
+        value: TextFormatDefinition.as2GetTextExtent,
+        writable: false,
+        enumerable: false,
+        configurable: false
+      });
     },
 
   };
 
-  var desc = Object.getOwnPropertyDescriptor;
-
   def.__glue__ = {
     native: {
       instance: {
@@ -69,4 +76,4 @@ var AS2GlobalsDefinition = (function () {
   };
 
   return def;
-}).call(this);
+}).call(this);
diff --git a/src/flash/text/TextField.js b/src/flash/text/TextField.js
@@ -808,6 +808,26 @@ var TextFieldDefinition = (function () {
       }
       this._bbox.yMax = value;
       this._invalidate();
+    },
+    getLineMetrics: function(lineIndex) {
+      this.ensureDimensions();
+      if (lineIndex < 0 || lineIndex >= this._lines.length) {
+        throwError('RangeError', Errors.ParamRangeError);
+      }
+      var line = this._lines[lineIndex];
+      var format = line.largestFormat;
+      var metrics = format.font._metrics;
+      var size = format.size;
+      // Rounding for metrics seems to be screwy. A descent of 3.5 gets
+      // rounded to 3, but an ascent of 12.8338 gets rounded to 13.
+      // For now, round up for things slightly above .5.
+      var ascent = metrics.ascent * size + 0.49999 | 0;
+      var descent = metrics.descent * size + 0.49999 | 0;
+      var leading = metrics.leading * size + 0.49999 + line.leading | 0;
+      // TODO: check if metrics values can be floats for embedded fonts
+      return new flash.text.TextLineMetrics(line.x + 2, line.width,
+                                            line.height,
+                                            ascent, descent, leading);
     }
   };
 
@@ -904,24 +924,7 @@ var TextFieldDefinition = (function () {
           }
         },
         getLineMetrics: function (lineIndex) { // (lineIndex:int) -> TextLineMetrics
-          this.ensureDimensions();
-          if (lineIndex < 0 || lineIndex >= this._lines.length) {
-            throwError('RangeError', Errors.ParamRangeError);
-          }
-          var line = this._lines[lineIndex];
-          var format = line.largestFormat;
-          var metrics = format.font._metrics;
-          var size = format.size;
-          // Rounding for metrics seems to be screwy. A descent of 3.5 gets
-          // rounded to 3, but an ascent of 12.8338 gets rounded to 13.
-          // For now, round up for things slightly above .5.
-          var ascent = metrics.ascent * size + 0.49999 | 0;
-          var descent = metrics.descent * size + 0.49999 | 0;
-          var leading = metrics.leading * size + 0.49999 + line.leading | 0;
-          // TODO: check if metrics values can be floats for embedded fonts
-          return new flash.text.TextLineMetrics(line.x + 2, line.width,
-                                                line.height,
-                                                ascent, descent, leading);
+          return this.getLineMetrics(lineIndex);
         },
         scrollV: {
           get: function scrollV() {

diff --git a/src/flash/text/TextFormatClass.js b/src/flash/text/TextFormatClass.js
@@ -17,6 +17,7 @@
  */
 
 var TextFormatDefinition = (function () {
+  var measureTextField;
   return {
     // (font:String = null, size:Object = null, color:Object = null, bold:Object = null,
     // italic:Object = null, underline:Object = null, url:String = null, target:String = null,
@@ -65,6 +66,35 @@ var TextFormatDefinition = (function () {
         leading: this._leading || 0
       };
     },
+    as2GetTextExtent: function(text, width /* optional */) {
+      if (!measureTextField) {
+        measureTextField = new flash.text.TextField();
+        measureTextField._multiline = true;
+      }
+      if (!isNaN(width) && width > 0) {
+        measureTextField.width = width + 4;
+        measureTextField._wordWrap = true;
+      } else {
+        measureTextField._wordWrap = false;
+      }
+      measureTextField.defaultTextFormat = this;
+      measureTextField.text = text;
+      measureTextField.ensureDimensions();
+      var result = {};
+      var textWidth = measureTextField._textWidth;
+      var textHeight = measureTextField._textHeight;
+      result.asSetPublicProperty('width', textWidth);
+      result.asSetPublicProperty('height', textHeight);
+      result.asSetPublicProperty('textFieldWidth', textWidth + 4);
+      result.asSetPublicProperty('textFieldHeight', textHeight + 4);
+      var metrics = measureTextField.getLineMetrics(0);
+      result.asSetPublicProperty('ascent',
+                                 metrics.asGetPublicProperty('ascent'));
+      result.asSetPublicProperty('descent',
+                                 metrics.asGetPublicProperty('descent'));
+      return result;
+    },
+
     __glue__: {
       native: {
         static: {