For full use of FIT2D's display possibilities it is useful to understand the coordinate systems used for different user controllable items. Interactive control of the position and size of false colour images and contour plots is available as are the position of extra graphical items.
The positions of all graphical items are specified in X/Y coordinates, where the X-axis is horizontal and a larger X-value is further to the right, and the Y-axis is vertical and a larger Y-value is higher on the page.
There are two different types of coordinate system:
'Data coordinates' are the coordinate system of the data, and the range of displayed data coordinates is either automatically determined or is set by the user (REGION, PIXEL REGION). This region is the ROI, but is also referred to as the 'Data Display Region' (DDR) by the graphics system.
'Page Coordinates' are the coordinates of the 'page' and the position of all the graphical items may be altered by altering their page coordinate. The position of the graph on the page is referred to as the 'Graph Page Position' (GPP). This is the position of DDR on the page. There is a mapping, or transformation, between data coordinates and page coordinates.
The page coordinate system goes from 0.0 to 1.0 in the longest edge, and from 0.0 to the page aspect ratio in the the other direction. e.g. For A4 portrait, X may be between 0.0 and 0.7071, and Y may be between 0.0 and 1.0.
Almost all items whose layout position may be changed are in page coordinates. The exception is annotation labels and annotation arrows. These may be defined in either page coordinates or in data coordinates. This allows the possibility to link the position of annotation labels the arrows to parts of the graph.