Zooming and panning-graphs in action
Well ... We are now going to explain something kewl!!
Our program plots the graph of a function defined in my_func(x) and then you can
use these keys:
|+||Zoom out the Y-Axis|
|-||Zoom in the Y-Axis|
|[||Zoom out the X-Axis|
|]||Zoom in the X-Axis|
|/||Default (initial) view|
This all can be achieved through changing the scale of plotting and then replotting the curve. For example, to pan left, the leftmost X-coordinate of the viewable area is decreased together with the rightmost X-coordinate. This forces the plotted function to shift right, and thus it appears to be panned left...
For example, if the viewable range of the X-axis for your chosen scaling is -50 to 150, and then you press ], this forces the X-axis to zoom in.
What happens is that the viewable range of the X-axis will be changed into 0 to 100, thus the zooming-in effect is achieved.
Want the code? here it is!
Or you can download the source from here. A compiled version for DOS
is also available from here. You need the file "egavga.bgi" (which comes with Borland/Turbo C) in the same directory as the program to run properly.