Center maya camera 2D pan/zoom on object using python api 2.0

2d_center_on_object_api_1.0.py

from maya import OpenMaya

# create selection
sel = OpenMaya.MSelectionList()
sel.add("locator1")
sel.add("camera1")

# get dag paths
loc_dag = OpenMaya.MDagPath()
sel.getDagPath(0, loc_dag)
cam_dag = OpenMaya.MDagPath()
sel.getDagPath(1, cam_dag)

# camera object
cam = OpenMaya.MFnCamera(cam_dag)
# camera transform
cam_trans = OpenMaya.MFnTransform(cam_dag)
# camera world position
cam_pos = cam_trans.translation(OpenMaya.MSpace.kWorld)
# camera rotation matrix
rot_mat = cam_dag.inclusiveMatrix()

# locator bounding box
loc_dag_node = OpenMaya.MFnDagNode(loc_dag)
loc_bb = loc_dag_node.boundingBox()
# locator position in world space
loc_pos = loc_bb.center()

# get locator position in camera space
# multiply the locator to camera vector by the camera rotation matrix
loc_vec = OpenMaya.MVector(loc_pos - cam_pos)
# api 1.0 doesn't allow matrix * vector, but does allow vector * matrix
# transpose the matrix to account for this
loc_cam_pos = loc_vec * rot_mat.transpose()

focal_len = cam.focalLength()
# get the x and y position on the imaginary plane at the focal length
# distance away from the camera
# f -> distance away from camera
# X,Y,Z -> object's camera space coordinates 
# x' = f(X/Z)    y' = f(Y/Z)
# refer to http://www.cse.psu.edu/~rtc12/CSE486/lecture12.pdf
# negate because maya camera looks in -z direction 
# convert to inches because 2d pan operates in inches
x = -(focal_len*(loc_cam_pos.x/loc_cam_pos.z))/25.4 
y = -(focal_len*(loc_cam_pos.y/loc_cam_pos.z))/25.4 

# set the camera's x and y pan. Account for camera scale and offsets
cam.setHorizontalPan((x/cam.cameraScale()) - cam.horizontalFilmOffset())
cam.setVerticalPan((y/cam.cameraScale()) - cam.verticalFilmOffset())

2d_center_on_object_api_2.0.py

from maya.api import OpenMaya

# create selection
sel = OpenMaya.MSelectionList()
sel.add("locator1")
sel.add("camera1")

# get dag paths
loc_dag = sel.getDagPath(0)
cam_dag = sel.getDagPath(1)

# camera object
cam = OpenMaya.MFnCamera(cam_dag)
# camera transform
cam_trans = OpenMaya.MFnTransform(cam_dag)
# camera world position
cam_pos = cam_trans.translation(OpenMaya.MSpace.kWorld)
# camera rotation matrix
rot_mat = cam_dag.inclusiveMatrix()

# locator bounding box
loc_dag_node = OpenMaya.MFnDagNode(loc_dag)
loc_bb = loc_dag_node.boundingBox
# locator position in world space
loc_pos = loc_bb.center

# get locator position in camera space
# multiply the locator to camera vector by the camera rotation matrix
loc_cam_pos = rot_mat * (loc_pos - cam_pos)

focal_len = cam.focalLength
# get the x and y position on the imaginary plane at the focal length
# distance away from the camera
# f -> distance away from camera
# X,Y,Z -> object's camera space coordinates 
# x' = f(X/Z)    y' = f(Y/Z)
# refer to http://www.cse.psu.edu/~rtc12/CSE486/lecture12.pdf
# negate because maya camera looks in -z direction 
# convert to inches because 2d pan operates in inches
x = -(focal_len*(loc_cam_pos.x/loc_cam_pos.z))/25.4 
y = -(focal_len*(loc_cam_pos.y/loc_cam_pos.z))/25.4 

# set the camera's x and y pan. Account for camera scale and offsets
cam.horizontalPan = (x/cam.cameraScale) - cam.horizontalFilmOffset
cam.verticalPan = (y/cam.cameraScale) - cam.verticalFilmOffset

Greetings.

for api2 line 19: rot_mat = cam_dag.inclusiveMatrix() instead of rot_mat = cam_trans.inclusiveMatrix()

Thanks @orgazmaat