MenuCursor.cpp

Go to the documentation of this file.

#include "Menu/MenuCursor.hpp"
 
#include <algorithm>
#include <cstddef>
 
namespace VoltMod
{
 
static bool IsSelectable(const CursorRows& rows, int index)
{
    if (index < 0 || index >= rows.Count)
    {
        return false;
    }
 
    return !rows.Selectable || rows.Selectable(index);
}
 
int MenuCursor::Step(const CursorRows& rows, int index, int step)
{
    if (rows.Count <= 0)
    {
        return index;
    }
 
    // Bound the search so an all-disabled menu cannot loop forever.
    int attempts = rows.Count;
    do
    {
        index = WrapIndex(index + step, rows.Count);
    }
    while (!IsSelectable(rows, index) && --attempts > 0);
 
    return index;
}
 
int MenuCursor::First(const CursorRows& rows)
{
    if (rows.Count <= 0 || IsSelectable(rows, 0))
    {
        return 0;
    }
 
    return Step(rows, 0, +1);
}
 
int MenuCursor::JumpPage(const CursorRows& rows, int index, int rowsPerPage, int delta)
{
    if (rows.Count <= 0 || rowsPerPage <= 0)
    {
        return index;
    }
 
    const int pages = PageCount(rows.Count, rowsPerPage);
    const int page = WrapIndex(index / rowsPerPage + delta, pages);
    const int start = page * rowsPerPage;
    const int end = std::min(rows.Count, start + rowsPerPage);
 
    // Preserve the page offset, then skip rows that cannot be selected.
    int landed = std::min(start + index % rowsPerPage, end - 1);
    for (int attempts = end - start; attempts > 0; --attempts)
    {
        if (IsSelectable(rows, landed))
        {
            break;
        }
        landed = (landed + 1 < end) ? landed + 1 : start;
    }
 
    return landed;
}
 
}  // namespace VoltMod