file access

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Objectif

• Understand why we wrap interface on file system

Limitation

Application generation is really simple, but package management can create some problems...
For example :

• Android does not permit access on the file system, but we need data that is named assets, thes data in contained in a zip file.
• Linux set his own application data in a special path : /usr/shared/applName/
• MacOs create a bundle (*.app) that is a folder with all application data.
• ...

For all tese reason we need to wrap standard application interface. (you can acces directly but it could be tricky and depend on the target)

Generic Properties

By default we dertermine some basics for files.
Then we need to determine file in the tree with :

• "DATA:XXX" Application internal data
• "USERDATA:XXX" User save data (like game save)
• "HOME:XXX" User home folder
• "/XXX" Direct acces on a file in the fileSystem
• ...

When you will call a file, you need to just call it with the starting name.
For example if I want to acces at an application data I will call the file : "DATA:myImage.png"

Integrate a file in a package

In your lutin_xxx.py file add:

	# to copy a single file:
	myModule.copy_file("relative/path/file.svg","destination/folder/file.svg")
	# to copy an entire patern path
	myModule.copy_folder("relative/path/start*.png","destination/folder/")

And now you can acces on these file with : "DATA:destination/folder/file.svg"

Read a file

	#include <etk/os/FSNode.h>
	
	...
	
	etk::FSNode file("DATA:destination/folder/file.svg");
	if (file.exist() == false) {
		APPL_ERROR("Can not read the file (Does not exist)");
		return;
	}
	APPL_INFO("open :" << file << " with size=" << file.fileSize());
	if (file.fileOpenRead() == false) {
		APPL_ERROR("Can not open in read mode the file: " << file);
		return;
	}
	// get a char
	APPL_INFO("read in: " << file << " the first char='" << file.fileGet() << "'");
	// Get a line
	std::string output;
	file.fileGets(output);
	APPL_INFO("and the end of the line ='" << output << "'");
	// close the file (note : if you did not do it, it will be close automaticly with an error)
	file.fileClose();

Write a file

	#include <etk/os/FSNode.h>
	
	...
	
	etk::FSNode file("USERDATA:exmple.txt");
	APPL_INFO("open :" << file);
	if (file.fileOpenWrite() == false) {
		APPL_ERROR("Can not open in write mode the file: " << file);
		return;
	}
	// put a char
	file.filePut('A');
	// write a line
	file.filePuts(" other string to put in the file ... \n");
	// close the file (note : if you did not do it, it will be close automaticly with an error)
	file.fileClose();

'Theme' management

The theme management is a subset a file selected by a main key. For example The basic theme of an API can be manage with only 2 commands (set the theme, and request upate of GUI)
At the start of the program, you might specify the default path theme:

	etk::theme::setNameDefault("GUI_COLOR", "theme/black");
	etk::theme::setNameDefault("GUI_SHAPE", "theme/rounded");

And when you want to change the theme, just call:

	// change the theme :
	etk::theme::setName("GUI_COLOR", "theme/white");
	// force reload of all the resources :
	ewol::getContext().getResourcesManager().reLoadResources();
	ewol::getContext().forceRedrawAll();

Note:

This is not done automaticly, because reloading the resources can have a real cost of time.

You can acces on your theme with accessing the filename: "THEME:GUI_COLOR:your/sub/path/file.xx"
An important think is that the theme file is searching in many path in the order:

• USERDATA:GUI_COLOR:your/sub/path/file.xx
• DATA:GUI_COLOR:your/sub/path/file.xx
• USERDATA:GUI_COLOR(default):your/sub/path/file.xx
• DATA:GUI_COLOR(default):your/sub/path/file.xx

Like this a user can overload the application theme...