Box touch sensing for use on a GLCD menu

[Steve Scott]

I have looked at the demo programs and have success with a ILI9341 with printing to the screen and have looked at CreateButton but would like to understand how you can actually select a box by a touch input.
Do you just scan for a box that is close? Is there a better way?
A table has been suggested but 1st I need to know some of the philosophy of how you sense a graphic by getting a touch input.
It will eventually be learning how to change an empty box to a filled one if 'selected' by touch.
Any pointers?
Appreciation in advance.

[Kato]

The philosophy. Read the XY position from the XPT. Then, compare to range in the table.

Something like.. this is psuedo code.. it will need fixing.

#define ELEMENTSINTABLEROW 5

//I cannot remember the returned variable from reading the XPT, call it...
returnedXPOS = xptreturnedvalue()
returnedYPOS = xptreturnedvalue() 

// read the number of table elements and divide to get the number of rows of data.
readtable TableData,0, maxthingstocheck/ELEMENTSINTABLEROW

For thingstocheck = 1 to maxthingstocheck
    readtable TableData, ( thingstocheck * ELEMENTSINTABLEROW), MINXPOSRANGE
    readtable TableData, ( thingstocheck * ELEMENTSINTABLEROW)+1, MAXXPOSRANGE
    readtable TableData, ( thingstocheck * ELEMENTSINTABLEROW)+2, MINYPOSRANGE
    readtable TableData, ( thingstocheck * ELEMENTSINTABLEROW)+3, MAXXPOSRANGE
    readtable TableData, ( thingstocheck * ELEMENTSINTABLEROW)+4, VALUEOFTHING

      valueofitem = 0
    if XPOS > MINXPOSRANGE and XPOS < MAXXPOSRANGE and YPOS > MINYPOSRANGE and YPOS < MAXXPOSRANGE Then 
        valueofitem=VALUEOFTHING 
       endif
    next

// table is a grid of 10x10 pixels
table TableData
    0,0,10,10,1
    10,10,10,10,2
    20,20,10,10,3
    etc


end table

Good luck

[Kato]

Here is something that compiles.

So, this is meant to return a value when you select within the described logical boxes. What is displayed on the GLCD is purely a picture... the XPT is doing all the hard work.

Notes: maxthingstocheck return value may need to be adapted. See the code below.

#chip 18f67k40
#option Explicit
// Something like.. this is psuedo code.. it will need fixing.
#define ELEMENTSINTABLEROW 5


dim maxthingstocheck, thingstocheck, minxposrange, minyposrange, maxxposrange, maxyposrange, valueofthing, valueofitem
//I cannot remember the returned variable from reading the XPT, call it...
dim returnedXPOS, returnedYPOS
returnedXPOS = 5 //! xptreturnedvalue()
returnedYPOS = 5 //! xptreturnedvalue() 

// read the number of table elements and divide to get the number of rows of data.
readtable TableData,0, maxthingstocheck

//! need to check what maxthingstocheck returns, this may required to be
// maxthingstocheck = ( maxthingstocheck - 1 ) / ELEMENTSINTABLEROW 
maxthingstocheck = maxthingstocheck / ELEMENTSINTABLEROW

For thingstocheck = 1 to maxthingstocheck
    readtable TableData, ( thingstocheck * ELEMENTSINTABLEROW), minxposrange
    readtable TableData, ( thingstocheck * ELEMENTSINTABLEROW)+1, maxxposrange
    readtable TableData, ( thingstocheck * ELEMENTSINTABLEROW)+2, minyposrange
    readtable TableData, ( thingstocheck * ELEMENTSINTABLEROW)+3, maxxposrange
    readtable TableData, ( thingstocheck * ELEMENTSINTABLEROW)+4, valueofthing

      valueofitem = 0
    if returnedXPOS > minxposrange and returnedXPOS < maxxposrange and returnedYPOS > returnedYPOS and returnedYPOS < maxxposrange Then 
        valueofitem=valueofthing 
       end if
    next

// table is a grid of 10x10 pixels
table TableData
    0,0,10,10,1
    10,10,10,10,2
    20,20,10,10,3
end table

[Steve Scott]

Kato-
Thanks for the philosophy lesson - makes a bit more sense to me now.
I will try this and once it works will start to change things to get a better understanding of this.
I appreciate the assist!