Designed by Mark Little
The development of this program requires an understanding of plotting software to display the sensor readings as an image. A series of graphical libraries were investigated, including the gd library and the plplot library. While the gd library is relative easy to use, it did nto seem to have the high level functions that plplot can provide.
plplot, on the other hand, has the high level functions that allow for high quality graphics, however, the interface was unfamiliar and appears to have some rather odd "features" that made the use of some functions inconvenient.
The initial prototyping is aimed at gaining an understanding of plplot and making a convenient interface for the functions required by this program. One of the "unusual" issues with plplot is that to put text on an angle, it requires that a dx and a dy value is provided so that the routine can figure out which way the text will slope. An interface was made that allows the programmer to provide an angle that sets the slope of the text.
The objective of the display software is to produce an image that can be used in a webpage to represent the sensor readings stored in the WeatherStation Database. This method is used because it reduces the risk that the database name, table names and Username/Password can be accessed from the Internet. All that is passed to the program is the start and end date and the sensor type.
Weather Station Extension Display Software