LiveCode LessonsLiveCode LessonsHow To - Step-By-Step Guides To Tasks In LiveCode LiveCode ArraysHow do I store an array in a text file and then retrieve it again?

How do I store an array in a text file and then retrieve it again?

LiveCode enables you to convert an array into a format that can be stored in a file or sent to a URL using arrayEncode. Conversely, you can use arrayDecode to to convert data back into a LiveCode array.

This lesson will show you an example of how to use arrayEncode/arrayDecode with the fillGradient property of a graphic.

You can download the stack for this lesson here: https://tinyurl.com/y9vv2u97

The Example Stack

The Example Stack

In LiveCode the fillgradient property of a graphic is an array containing all of the gradient information. The example stack demonstrates how to store the fillgradient array of the graphic in a file as well as load the fillgradient array from a file and assign it to the graphic.

Storing an Array in a File

This code snippet from the example stack demonstrates how to convert the fillGradient property (an array) of a graphic into a binary representation of the array using arrayEncode. This binary representation is stored in the variable theEncodedArray.

 if theFile is not empty then
      put arrayEncode(the fillgradient of graphic 1) into theEncodedArray
      put theEncodedArray into URL ("binfile:" & theFile)
   end if

When storing the array in a file it is important that you write the data to the file in binary format otherwise the encoded array data will be corrupted. That is why the binfile: prefix is used.

Loading an Array From a File

To load the binary representation of the array from a file you just reverse the steps. Begin by reading the data from the file in binary format using the binfile: prefix. In this snippet the binary data is stored in the variable theEncodedArray.

You can then pass the binary data to arrayDecode which transforms the binary data back into a LiveCode array variable, theFillGradientA in this case. At this point the array can be assigned to the fillgradient property of a graphic.

 if theFile is not empty then
      put URL ("binfile:" & theFile) into theEncodedArray
      put arrayDecode(theEncodedArray) into theFillGradientA
      set the fillgradient of graphic 1 to theFillGradientA
   end if

The Stack Script

This is the full stack script from the sample:

local theFile, theEncodedArray, theFillGradientA

command uiSaveGradientToFile
   ## Store the fillGradient array for the graphic object in a file
   ask file "Save fillGradient array to file:"
   put it into theFile
   
   if theFile is not empty then
      put arrayEncode(the fillgradient of graphic 1) into theEncodedArray
      put theEncodedArray into URL ("binfile:" & theFile)
   end if
end uiSaveGradientToFile
 
command uiLoadGradientFromFile
   ## Load fillGradient array from file
   answer file "Select file containing fillGradient array:"
   put it into theFile
   
   if theFile is not empty then
      put URL ("binfile:" & theFile) into theEncodedArray
      put arrayDecode(theEncodedArray) into theFillGradientA
      set the fillgradient of graphic 1 to theFillGradientA
end uiLoadGradientFromFile

The Button Scripts

This is the script from the "Save Array to File" button:

on mouseUp pBtnNum
   if pBtnNum is 1 then
      uiSaveGradientToFile
   end if   
end mouseUp

This is the script from the "Load Array from File" button:
on mouseUp pBtnNum
   if pBtnNum is 1 then
      uiLoadGradientFromFile
   end if
end mouseUp

2 Comments

anonymous

Nice. But to save as a TEXT file, you must base64Encode the encoded BINARY data. To load it, just base64Decode.

To save as text:
if theFile is not empty then
put arrayEncode(the fillgradient of graphic 1) into theEncodedArray
put base64Encode(theEncodedArray) into URL ("file:" & theFile)
end if

To load the text and convert back to the gradient array:
if theFile is not empty then
put URL ("file:" & theFile) into theBase64Array
put base64Decode(theBase64Array) into theEncodedArray
put arrayDecode(theEncodedArray) into theFillGradientA
set the fillgradient of graphic 1 to theFillGradientA
end if

Björnke von Gierke

Note that the example given uses "binfile". That takes care of binary just fine. Altho your solution works as well as the example, yours will generate much bigger files.

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