A Deep Look Into Camera API of Rhomobile

In this post, we will go through the available methods for Camera API in details using Rhodes. This post will just explain the methods and uses of the Camera API from ruby excluding the rho-element javascript API.

Camera Permission:

In order to use the device camera, we need to get the permission by defining the capabilities in build.yml file.

    capabilities: 
       - camera

This denotes the Rhomobile build stage to add respective access permissions to the application keeping the platform and required settings on focus.

Available APIs:

Rhomobile provides the listed APIs to interact with the Device Camera.

1. get_camera_info
2. save_image_to_device_gallery
3. take_picture
4. choose_picture

Camera Options:

The APIs (take_picture & choose_picture) takes a hash as options for extra configurations, if we need to set.

 camera_option = {
  camera_type  =>  “main”,
  desired_width  => “640”,
  desired_height => “480”,
  color_model => “RGB”,
  format => “png”,
  enable_editing => false,
  flash_mode => “auto”,
  save_to_shared_gallery => true
 }

Lets go through each options in details,

         1. camera_type :

            Possible values are “main” or “front”.

            Default is “main”.

2. desired_width :
The value to be in px.
Default is the maximum possible camera width.
3. desired_height :
        The value to be in px.
        Default is the maximum possible camera height.

4. color_model :
        Possible values are “RGB” or “Grayscale”.
        Default is “RGB”.

5. format :
        Possible values are “png” or “jpg”.
        Default is “jpg”.

6. flash_mode :
        Possible values are “on” | “off” | “auto” | “red-eye” 

        | “torch”.
        Default is “auto”. This option is for Android only.

7. enable_editing :
        Posible value Boolean true / false.
        Default is true. This option is for iPhone only.

9. save_to_shared_gallery :
Possible values are Boolean true | false.
Default is false. This option is for iOs only.

How to use APIs:

1. get_camera_info 

This method takes parameter ( camera_type ) and returns the
hash value with width and height as numeric value and returns NIL if camera_type is not supported.
   

         camera_info = Camera::get_camera_info(camera_type)
   

    
    camera_info will be something like 
          { width => 640, height => 480 } | NIL

2. choose_picture


   This method is used to select the image file from the gallery or sdcard. This method takes two parameters callback_method and camera_option.
   
   

         Camera::choose_picture(callback_method,camera_option)
   

    The callback_method (“/app/camera/callback_method”) will be 
    called after the operation completes, with parameter as hash 
    described in callback_params.

3. take_picture

     This method is used to open the camera view and snap a photo.
     This method takes two parameters callback_method and 
     camera_option as like above one.

•       Camera::take_picture(callback_method,camera_option)
  

     The callback_method will be called after the operation
     completes, with parameter as hash described in callback_params.

4. save_image_to_device_gallery
   This method is used to store the generated or created image file to device gallery. This method takes parameter as the image path.

•      
       image_path = Rho::RhoApplication::get_blob_path(image_uri)
       Camera::save_image_to_device_gallery(image_path)
  

    The image_uri will be the uri of the image in the 
    callback_params.

Camera Callback Parameters:

The callback method with be called by POST method, and the passed parameters are:

•      
  
      {
       status => “ok”,
       image_uri => “some uri”,
       message => “”,
       image_format => “jpg”,
       image_width => 640,
       image_height => 480
      }
  
  

Lets go through each parameters in details,

         1. status :

             Possible values are “ok” or “cancel” or “error”.

2. message :
Some error message as string if the status is “error”.
3. image_uri :

The uri of the taken or choosen image.
4. image_format :

Possible values are “png” or “jpg”.
5. image_width :

Width of the image in numeric value.
6. image_height :

Height of the image in numeric value.

Thats all. We can now explore device camera with the above APIs.