保存图像文件在SD卡中的Firefox操作系统

Question

我想保存在SD卡中的图像。我正在关注this文档。

$('.btnSave').on('click', function() { 

     var imageRawData = canvas.toDataURL("image/png") ; 
     var sdcard = navigator.getDeviceStorage("sdcard"); 
     var file = new Blob([imageRawData], { type: "image/png" }); 
     var request = sdcard.addNamed(file, "FilertedImage.png"); 

       request.onsuccess = function() { 
       var name = this.result; 
       console.log('File "' + name + '" successfully wrote on the sdcard storage area'); 

       } 
       request.onerror = function (e) { 
       console.log('Unable to write the file: ' + e.target.error.name); 

       } 
    }); 

在本文档中我发现，“的照片只接受斑点具有有效image mime type”。那么如何使用javascript将imageRawData转换为有效的图像MIME类型。

Answer 1

我已经做了类似如下 - 保存，然后股份：

function saveAndSend(blob) { 
    var sdcard = navigator.getDeviceStorage("sdcard"); 
    var request = sdcard.addNamed(blob, "test/mycanvas.png"); 

    //could just share the blob instead of saving 
    request.onsuccess = function() { 
     var sharingImage = new MozActivity({ 
      name: "share", 
      data: { 
       type: "image/*", 
       number: 1, 
       blobs: [blob], 
       filenames: ["mycanvas.png"], 
       filepaths: ["test/mycanvas.png"] 
      } 
     }); 
    } 

    // An error could occur if a file with the same name already exist 
    request.onerror = function() { 
     alert('Unable to write the file: ' + this.error.name); 
    } 

} 


var cnv = document.getElementById('myCanvas'); 
cnv.toBlob(function (blob) { 

    //var sdcard = navigator.getDeviceStorage("pictures"); 
    var sdcard = navigator.getDeviceStorage("sdcard"); 
    var request = sdcard.delete("test/mycanvas.png"); 
    //try to delete in case it exists 
    request.onsuccess = function() { 
     saveAndSend(blob); 
    } 

    request.onerror = function() { 
     saveAndSend(blob); 
    } 


}); 

Answer 2

你的应用程序还需要确保它有适当的设备存储的权限。

例如：https://github.com/mozilla-b2g/gaia/blob/master/dev_apps/ds-test/manifest.webapp#L13。 ds-test是我为测试设备存储中的东西而编写的测试应用程序。