Gets the AST Plot associated with a graphics-database picture KPG1_GDGET
On exit, the PGPLOT viewport corresponds to the area encompassed by the specified picture. The world co-ordinate bounds within this viewport are set so that the PGPLOT world co-ordinate system is millimetres from the bottom-left corner of the view surface. This corresponds to the Base (GRAPHICS) Frame in the returned Plot.
The returned Plot will normally be obtained from the MORE structure in the graphics database (where it was stored by a previous AST-based application). The Base Frame will be a GRAPHICS Frame, giving millimetres from the bottom-left corner of the view surface.
If no Plot is available in the database, then an initial PLOT is created containing a Base Frame with Domain GRAPHICS (giving millimetres from the bottom-left corner of the view surface), and a Current Frame corresponding to AGI world co-ordinates. The Frame to represent AGI world co-ordinates in the Plot may be supplied by the calling application (for instance, an application may supply a PIXEL Frame on the assumption that AGI world co-ordinates are pixel co-ordinates). If no such Frame is supplied then a simple Frame is used, with Domain set to AGI_WORLD.
A third Frame may optionally be added to the Plot representing AGI DATA co-ordinates. This Frame
will have Domain AGI_DATA, and the Mapping from world to data co-ordinates will be given by
the TRANSFORM structure stored with the picture in the database. If present, it will be
the Current Frame in the Plot on exit. See "
Usage"
below for warnings about using this
option.
Finally, some other Frames are added to the Plot representing various normalised co-ordinates:
BASEPIC: The co-ordinates of the bottom-left corner of the BASE picture are (0,0). The shorter dimension of the BASE picture has length 1.0, and the other axis has a length greater than 1.0.
NDC: Normalized device co-ordinates. The bottom-left corner of the screen is (0,0) and the top-right corner is (1,1).
CURPIC: The co-ordinates of the bottom-left corner of the current picture are (0,0). The shorter dimension of the current picture has length 1.0, and the other axis has a length greater than 1.0.
CURNDC: The co-ordinates of the bottom-left corner of the current picture are (0,0), and the top-right corner is (1,1).
If the Plot read from the database already contains any of these Frames then they are retained and no new Frame is added.
The PGPLOT interface to the AGI library should be opened before calling this routine.