protected virtual PageOnScreen GetInitialPage(ref PositionInBook position, Size screenSize)
{
// Find physical page at position
PageOnScreen curPage = NewPage(position.PageNum, screenSize);
curPage.TopOnScreen = position.GetTopOnScreen(curPage.Layout.Bounds.Height);
return curPage;
}
/// <summary>
/// Assemble screen -- return a list of pages for the screen with TopOnScreen set
/// </summary>
/// <param name="position"></param>
/// <param name="screenSize"></param>
/// <returns></returns>
public List<PageOnScreen> AssembleScreen(ref PositionInBook position, Size screenSize)
{
ArgCheck.NotNull(position, "newPosition");
if (!CanApply(position, screenSize)) { throw new InvalidOperationException("Cannot apply at: " + position); }
// Get the initial page.
// Does not necessarily return page at position -- in case of next, will advance it by one page.
PageOnScreen curPage = GetInitialPage(ref position, screenSize);
// Stack the pages
List<PageOnScreen> pageContents = new List<PageOnScreen>();
while (true)
{
pageContents.Add(curPage);
if (ScreenFull(curPage, screenSize)) { break; }
AdvancePage(ref curPage, screenSize);
}
// Update position based on the topmost page (with lowest page num)
int minPageNum = pageContents.Min(x => x.PageNum);
PageOnScreen topPage = pageContents.Find(x => x.PageNum == minPageNum);
position = PositionInBook.FromPhysicalPage(topPage.PageNum, PageCount,
topPage.TopOnScreen, topPage.Layout.Bounds.Height);
return pageContents;
}
/// <summary> /// True if algorithm can be applied in the given state. /// (e.g. if moving back, it would apply to all positions except the start). /// </summary> /// <param name="position"></param> /// <param name="screenSize"></param> /// <returns></returns> public abstract bool CanApply(PositionInBook position, Size screenSize);
protected override PageOnScreen GetInitialPage(ref PositionInBook position, Size screenSize)
{
PageOnScreen curPage = base.GetInitialPage(ref position, screenSize);
curPage.TopOnScreen += screenSize.Height;
// Edge case: if page is exactly below the screen, take the next one
if (curPage.TopOnScreen == screenSize.Height)
{
AdvancePage(ref curPage, screenSize);
}
// Adjust position
position = PositionInBook.FromPhysicalPage(curPage.PageNum, PageCount,
curPage.TopOnScreen, curPage.Layout.Bounds.Height);
return curPage;
}
public override bool CanApply(PositionInBook position, Size screenSize)
{
PageOnScreen firstPage = base.GetInitialPage(ref position, screenSize);
return firstPage.PageNum > 1 ||
// If first page in book, it must overflow above current screen
firstPage.TopOnScreen < 0;
}
protected override PageOnScreen GetInitialPage(ref PositionInBook position, Size screenSize)
{
// Assemble current screen
PageOnScreen curPage = _assembleCurrent.AssembleScreen(ref position, screenSize).Last();
// Move the last page of current screen up by one screen
curPage.TopOnScreen -= screenSize.Height;
// Edge case: if page is exactly above the screen, take the next one
if (curPage.TopOnScreen == -curPage.Layout.Bounds.Height)
{
AdvancePage(ref curPage, screenSize);
}
return curPage;
}
public override bool CanApply(PositionInBook position, Size screenSize)
{
// Get last page of current screen
// Current screen render won't mess up position
var pages = _assembleCurrent.AssembleScreen(ref position, screenSize);
PageOnScreen lastPage = pages.Last();
return lastPage.PageNum < PageCount ||
// If last page in book, it must overflow the screen
lastPage.BottomOnScreen > screenSize.Height;
}
public override bool CanApply(PositionInBook position, Size screenSize)
{
// Re-rendering current screen always possible
// Position bounds are guarented already
return true;
}
