Every time you create a new display object (image, rect, circle, etc.) in Corona SDK a “reference point” is attached to that object behind the scenes. That point determines exactly how the object is positioned on the screen.
Here’s a videos showing what that’s all about and then there’s a bunch of variables afterwards you can use in your code if you like.
This video will be available here for one week and then can be found at MasteringCoronaSDK.com for Gold members only.
display.tl = display.TopLeftReferencePoint
display.tc = display.TopCenterReferencePoint
display.tr = display.TopRightReferencePoint
display.cl = display.CenterLeftReferencePoint
display.c = display.CenterReferencePoint
display.cr = display.CenterRightReferencePoint
display.bl = display.BottomLeftReferencePoint
display.bc = display.BottomCenterReferencePoint
display.br = display.BottomRightReferencePoint
Daniel from http://thatssopanda.com asked me whether this affects the rotation point of an object. Yep, wherever you set the reference point, that’s where the image will rotate around. Makes it really handy to create some cool looking effects, simply by changing the reference point and then doing a rotation.