Keywords: greg

Next: GreG Manual Up: GreG CookBook Previous: Raster Devices Contents Index

## Internal Zooming

GREG has the possibility of zooming a plot being created. Use command `ZOOM` to do it. `ZOOM X1 X2 Y1 Y2` will compute scale factors to match the designed area (in Physical Coordinates) to the screen, preserving the aspect ratio. `ZOOM OFF` restores the full screen, `ZOOM REFRESH` redraws the plot with the current zooming factor. Without arguments `ZOOM` calls the cursor, and several keys can be used to control the zooming factor :

- ``0'' turns off zooming and displays the full plot page. The previous zooming factor is not destroyed, so that typing a space (see below) will restore a Viewing Window of same size as the last one centered on the cursor position. The cursor position is not modified by the command itself.
- `` '' (space) executes the standing zooming operations. With ``0'', it is the only effective command. The zoomed area is centered around the cursor position and can be delimited using command B.
- ``Z'' increases the zooming factor by 1.414 and draws the corresponding box around the zoomed area. The zooming is deferred until `` '' has been struck, allowing zooming factors to be changed by any power of square root of 2. The box drawn around the zoomed area is not a part of the current plot, and will not be visible in a Hardcopy for example.
- ``-'' decreases the zooming factor by 1.414, and draws the corresponding box if visible.
- ``B'' draws a box delimiting the area to be zoomed.
- ``A'' to erase the alphanumeric screen
- ``E'' to exit...

Any other gives you the cursor position. Zooming can be used for example to enlarge part of a complex drawing to make precise annotations. Note that the zooming has no effect on the hardcopy.

On X-Window systems, the zoomed area normally appears in another window. The mouse can be used instead of the keyboard for some actions:

- left button: as spacebar, execute the zoom
- middle button: increase zooming factor by 1.414
- right button: exit

Next: GreG Manual Up: GreG CookBook Previous: Raster Devices Contents Index