Camera face detection coords to screen coords

问题

i've recently started playing with Android's camera api. And i'm using face detection and it's callback setFaceDetectionListener. I'm having trouble trying to understand how to convert the faces[0].rect.centerX(); and faces[0].rect.centerY() to something i can use on screen like move a image around the face centered on that point.

can anyone help me understand how to convert from the coord system given by the camera to something i can use to set elements on my activity.

回答1:

From docs

(-1000, -1000) represents the top-left of the camera field of view, and (1000, 1000) represents the bottom-right of the field of view.

So to put in to screen coords (pseudocode):

screenX = (coord.x +1000) * screen.width / 2000
screenY = (coord.y +1000) * screen.height / 2000

回答2:

Use this code (assuming you have a width and a height integer variable):

LayoutParams params = new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
params.setMargins(faces[0].rect.centerX()-width/2,faces[0].rect.centerY()-height/2, 0,0);

...and to get the width and height:

public void onWindowFocusChanged(boolean hasFocus){
    width=image.getWidth();
    height=image.getHeight();
}

来源：https://stackoverflow.com/questions/22102503/camera-face-detection-coords-to-screen-coords