是否可以使用BlackBerry OS5 API聚焦相机？

Question

I am developing an app which takes a preview of the device's camera and analyses that feed. I can create the camera preview, but cannot get the camera to adjust its focus automatically.

I know that the underlying hardware is possible of performing an auto focus because the native BlackBerry camera app responds to the 'take photo' media key by auto focussing the image prior to taking the photo.

However, I'm not trying to take a photo, I'm trying to continuously scan the input feed for a barcode.

Here's my code:

Player _player = Manager.createPlayer("capture://video");
_player.realize();
_player.start();
_vc = (VideoControl) _player.getControl("VideoControl");

//this is added to the screen
_viewFinder = (Field) _vc.initDisplayMode(
    VideoControl.USE_GUI_PRIMITIVE, "net.rim.device.api.ui.Field");

FocusControl focusControl = (FocusControl) _player.getControl("javax.microedition.amms.control.camera.FocusControl");

//this has no effect
focusControl.setFocus(FocusControl.AUTO);

I have tested on BlackBerry Storm 9500 and Bold 9700 both running OS5.

Answer 1

Try this

this.player = Manager.createPlayer("capture://video");
this.player.realize();
this.videoControl = ((VideoControl)this.player.getControl("VideoControl"));
this.field = ((Field)this.videoControl.initDisplayMode(0, "net.rim.device.api.ui.Field"));
this.videoControl.setVisible(true); 
this.player.start();
try {
        //get focuscontrol
      FocusControl focusControl = (FocusControl)getCurrentObject().player.getControl("javax.microedition.amms.control.camera.FocusControl");
      if (focusControl == null) {
          //no focus control
        Log.Debug("Focus control not available.");
      } else {
        if (focusControl.isMacroSupported()) {
            //setting macro
          Log.Debug("Setting macro mode.");
          focusControl.setMacro(true);
        } else {
            //no macro
          Log.Debug("Macro mode not supported.");
        }
        if (focusControl.isAutoFocusSupported()) {
            //setting autofocus
          Log.Debug("Using autofocus.");
          focusControl.setFocus(-1000);
        } else {
            //no autofocus
          Log.Debug("Autofocus not supported.");
        }
      }

It works for me !!!

Answer 2

The only way to focus the camera in OS5 is to use VideoControl.getSnapshot(). There is no other way.