// 撮影ボタンを押した時の処理
$('#btnCamera').on('click', function(){
  navigator.camera.getPicture(function cameraSuccess(imageUri) {
      postToApi(imageUri);
  }, function cameraError(error) {
      console.debug("Unable to obtain picture: " + error, "app");
  }, {
      quality: 90,
      destinationType: Camera.DestinationType.DATA_URL,
      targetWidth: 1200,
      targetHeight: 1200
  });
});

// Cloud Visionに画像をPOST
var postToApi = function (dataUrl) {
    var params = {
        requests: [
            {
                image: {
                    content: dataUrl
                },
                features: [{
                        type: 'LABEL_DETECTION',
                        maxResults: 1
                }]
            }
        ]
    };
    var req = JSON.stringify(params);
    $.ajax({
        url: 'https://vision.googleapis.com/v1/images:annotate?key=' + API_KEY,
        type: 'POST',
        data: req,
        dataType: 'json',
        contentType: 'application/json'
    }).done(function (data) {
        …
    });
}