如何使用 Android CameraX 显示相机焦点矩形

Question

I use android camerax in my app.

The focus-on-tap is implemented as in this answer: https://stackoverflow.com/a/60095886/978067

            cameraPreview.setOnTouchListener((view, event)  -> {
                switch (event.getAction()) {
                    case MotionEvent.ACTION_DOWN:
                        return true;
                    case MotionEvent.ACTION_UP:
                        MeteringPoint point = cameraPreview.getMeteringPointFactory().createPoint(event.getX(), event.getY());
                        FocusMeteringAction action = new FocusMeteringAction.Builder(point).build();
                        camera.getCameraControl().startFocusAndMetering(action);

                        // HOW TO SHOW RECTANGLE SIGHT HERE? Thanx!

                        return true;
                    default:
                        return false;
                }
            });

But I need to show rectangle sight around focus point (as in standard camera app)

Have any ideas how to do it?

Answer 1

Using CameraX the tap to focus is done using the touch point - x, y coordinates. You can set the focus rectangle x and y as the motion event x and y. The focus rectangle should be a custom view that you can create.

/** Represents the x coordinate of the tap event */
val x = motionEvent.x
/** Represents the y coordinate of the tap event */
val y = motionEvent.y
// Setting the focus rectangle view x coordinate as the motion event x coordinate
focusRectangleView.x = x
// Setting the focus rectangle view y coordinate as the motion event y coordinate
focusRectangleView.y = y

This is how you can show the focus rectangle view where the tap occurred, and also simply change the view visibility whenever you want to show it or hide it.