Chapter 16 // Exercise 8
Provide a currency converter. Read the conversion rates from a file on startup. Enter an amount in an input window and provide a way of selecting currencies to convert to and from (e.g., a pair of menus).
Github: https://github.com/l-paz91/principles-practice/tree/master/Chapter%2016/Exercise%208
I'm not sure how but I did it. It took me a good hour of staring at the documentation and this very helpful post from 2007:
http://www.murga-projects.com/forum/showthread.php?tid=122
My excitement though is not because I created a currency converter but, I enabled the Window class to use a jpg image as a background for the window.
In all of the previous exercises, you may have noticed that images always draw on top of widgets, no matter what order you draw in. There is a hack however, and that is to create an Fl_Box, give the box an image and then attach the box to your window. Sounds good. The problem though is that we are using Bjarne's helper classes which do not have any functionality to support this so I had to add it.
I basically made a new Widget called FakeBkg that holds an Fl_Image. attach() needs to be overridden as it's pure virtual. In here I assigned a new Fl_Box to the Fl_Widget stored in Widget, gave the widget the image stored in FakeBkg and then assigned the window with my window...I think I might do a separate post on this one.
Anyway, I added a new function to In_box to handle getting floats out of a text box and used a fixed size text file which kind of feels like cheating. I know exactly what line the conversion rates are on and how many characters in so my switch statement is extremely hard coded but efficient. Instead of reading in the text file at the beginning and storing all the different formats (which may or may not get used), it gets the rate from the file when needed.
http://www.murga-projects.com/forum/showthread.php?tid=122
My excitement though is not because I created a currency converter but, I enabled the Window class to use a jpg image as a background for the window.
In all of the previous exercises, you may have noticed that images always draw on top of widgets, no matter what order you draw in. There is a hack however, and that is to create an Fl_Box, give the box an image and then attach the box to your window. Sounds good. The problem though is that we are using Bjarne's helper classes which do not have any functionality to support this so I had to add it.
I basically made a new Widget called FakeBkg that holds an Fl_Image. attach() needs to be overridden as it's pure virtual. In here I assigned a new Fl_Box to the Fl_Widget stored in Widget, gave the widget the image stored in FakeBkg and then assigned the window with my window...I think I might do a separate post on this one.
Anyway, I added a new function to In_box to handle getting floats out of a text box and used a fixed size text file which kind of feels like cheating. I know exactly what line the conversion rates are on and how many characters in so my switch statement is extremely hard coded but efficient. Instead of reading in the text file at the beginning and storing all the different formats (which may or may not get used), it gets the rate from the file when needed.
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