使用WinRT编辑图片文件的基本和高级属性

这里所谓的基本属性是指：tags (keywords), rating。高级属性是指：geographic information (including latitude and longitude) 。

     Step1: 打开File Picker选择图片文件：

               var picker = new Windows.Storage.Pickers.FileOpenPick();

               picker.viewMode = Windows.Storage.Pickers.PickerViewMode.thumbnail;

               picker.pickSingleFileAsync().then(function (file) {... ...});

 

     Step2: 使用得到的file object得到image properties object:

               file.properties.getImagePropertiesAsync().then(function (imageProperties) {... ...});

 

     Step3: 使用得到的image properites object获取图片文件的基本属性：

               imageProperites.title = tileValue;

               imageProperties.rating = userRating;       // rating的范围是0~99

               imageProperites.keywords.append(keyword);   // keywords可以添加多个，系统会自动用“;"分割，无需用户添加

 

     Step4: 获取图片文件高级属性对象advProperites, 并使用它访问geographic information:

               imageProperites.retrievePropertiesAsync(

                     ["System.GPS.LatitudeNumerator",

                      "System.GPS.LatitudeDenominator",

                      "System.GPS.LongitudeNumerator",

                      "System.GPS.LongitudeDenominator"]

               ).then(function(advProperties) {

                     advProperties.insert("System.GPS.LatitudeNumerator", latNum);  

                     advProperties.insert("System.GPS.LatitudeDenominator", latDen); 

                     advProperties.insert("System.GPS.LongitudeNumerator", longNum); 

                     advProperties.insert("System.GPS.LongitudeDenominator", longDen); 

              });

 

  特别注意，rating这个属性必须要大于0，否则keywords以及geographic information均无法修改和访问。