Chapter 1

RESOURCE MENU_PANE r_hellogui_hello_menu
{
items =
}
{
MENU_ITEM
{
command = EHelloGuiCmd0;
txt = "Item 0";
},
MENU_ITEM
};
{
command = EEikCmdExit;
txt = "Close (debug)";
}
As you can see, each of the two menu items only specifies two of the nine elements – the
remaining seven take the default values that are specified in the declaration.
A hex dump of the resource file gives the following result:
The highlighted bytes represent the data for the menu pane resource. The most obviously
recognizable parts of this resource are the strings, "Item 0" and "Close (Debug)".
However, on reflection, you might be slightly puzzled: I have said that Symbian OS
applications use a Unicode build, whereas these strings appear to be plain ASCII text.
Furthermore, if you count through the resource, identifying items on the way, you will find
that there is an occasional extra byte here and there – for example, each of the strings
appears to be preceded by two identical count bytes, instead of the expected single byte.
The answer to these puzzles is that the compiled resource is compressed in order to save
space in Unicode string data. The content of the resource is divided into a sequence of runs,
alternating between compressed data and uncompressed data. Each run is preceded by a
count of the characters in that run, with the count being held in a single byte, provided that