Mobile Device Features 1

In the next two segments, we will talk about some features that are unique to mobile devices and how to use them.

Camera

• May not be supported on older devices
• Done using a TextBox, with inputType set to 'file'.
• Once the user has taken or selected a picture, TxtBox_onchange is executed:

reader = new FileReader()

Function txtPhoto_onchange()
   reader.readAsDataURL(txtPhoto.files[0])
End Function

• Reading the picture in is asynchronous: pictures can be large and take time to load.
• Once the read is complete, reader_onload is called.

To display the picture, we need to put it into a PictureBox object. 

Function reader_onload(e)

 'Now, let's put it in our PictureBox
 pb = pbPhoto.getContext("2d")
 pb.addImage(e.target.result,0,0,0,0,0,0,pbPhoto.width,pbPhoto.height)

End Function

Emoji

• Emoji are extended characters that are built into mobile devices.
• There are hundreds of them: arrows, letters, roman numerals, pictures of food, building, transportation, flags, animals. And of course, happy faces, sad faces, crying faces.
• They are saved as standard characters: each has its own character code number.
• There is a complete list here: http://en.wikipedia.org/wiki/Emoji
• Support varies by browser
• Most mobile devices are OK
• Desktop Safari works
• Desktop Chrome needs an (but an extension to see these)
• The characters are in the format &#xxxxxx; where xxxxxx is the decimal value
• Cheeseburger is 🍔 (or &#x1F354 in hex)

Orientation

Mobile devices can be rotated. It's up to you to decide how you want your app to handle this.

• The two orientations are referred to as Portrait and Landscape.

• The layout of your form will be completely different between the two.

• If you don't want to support rotation, add the Orientation control to your app. Set its screenOrientation property to portrait or landscape. When the screen is rotated, this message will appear:

• If you do want to support orientation, you will want to take action when the screen is rotated

Function window_onorientationchange()
  'This function is called if the orientation of the device is changed.
  MsgBox "orientation changed to " & window.orientation
End Function

• You can now resize and reposition your controls, using code like this:

Function window_onorientationchange()
  If Abs(window.orientation)=90 Then 'Landscape
    btnSubmit.Left="100px"
    btnSubmit.Top="100px"
  Else                               'Portrait 
    btnSubmit.Left="20px"
    btnSubmit.Top="120px"
  End If
End Function

• You will have to do this to all controls which are affected.