Method managedPageRange

YACReader/continuous_page_widget.cpp:408–427

}

void ContinuousPageWidget::managedPageRange(int &minPageIndex, int &maxPageIndex) const
{
    minPageIndex = 0;
    maxPageIndex = -1;

    if (!continuousViewModel || continuousViewModel->numPages() <= 0) {
        return;
    }

    const int numPages = continuousViewModel->numPages();
    const int viewportHeight = continuousViewModel->viewportHeight() > 0 ? continuousViewModel->viewportHeight() : height();
    const int visibleTop = continuousViewModel->scrollY();
    const int visibleBottom = visibleTop + std::max(0, viewportHeight - 1);

    const int firstVisiblePage = qBound(0, continuousViewModel->pageAtY(visibleTop), numPages - 1);
    const int lastVisiblePage = qBound(0, continuousViewModel->pageAtY(visibleBottom), numPages - 1);

    minPageIndex = std::max(0, firstVisiblePage - kPrefetchBehind);
    maxPageIndex = std::min(numPages - 1, lastVisiblePage + kPrefetchAhead);
}