Fix issue with scrolling in item description #35766

[8street]

Summary

SUMMARY: Bugfixes "Issue with scrolling in item description #35766"

Purpose of change

It fully resolves an issue: Fixes #35766
When scrolling the item description of an item with PgUp and PgDown, the scrolling now not get stuck.

Describe the solution

Scroll position now passed to "draw_item_info()" function by reference.

Testing

Tested in crafting menu, picking menu, compare menu and shift+V menu.

[Qrox]

Perhaps it's better to pass selected as a reference to draw_item_info instead.

[8street]

This is the reference. But I understood what you mean. I tried. This does not work. The function "draw_item_info" is also called without the parameter "selected" and it should equal zero. If the reference is zero, an exception will be thrown. Thus, the structure must store both parameters - the value "selected" and a link to it "ptr_selected".

[Qrox]

You can add a new signature of draw_item_info without the parameter selected, and initialize a local variable with 0 and pass it to the actual draw_item_info function.

void draw_item_info( ... )
{
   int selected = 0;
   draw_item_info( ..., selected );
}

void draw_item_info( ..., int &selected )
{
  // the actual implementation of draw_item_info
}

And use it like this

item_info_data data( ... );
draw_item_info( win, data );
// or draw_item_info( win, data, selected );

[8street]

Then you need to change a lot of code in the files where the function "draw_item_info" is called.
Instead, I'd changed one function "draw_item_info". In my case, the function interface is fully compatible with existing calls.

[Qrox]

Well, having a struct contain a pointer to a value that is not managed by the struct itself could be dangerous. What if someone constructs item_info_data with a local selected variable and then uses
the item_info_data ouside the scope of selected? Then he gets a dangling pointer. If you pass selected as a reference directly to draw_item_info, there wouldn't be such problems.

[8street]

You're right. But I can not figure out how to make it easier without lot code to be modified. Can you change the files yourself?