/// <summary>
/// Gets all pages to be drawn in specified region.
/// </summary>
/// <param name="pageOnCenter">The page on which is center of vertical direction of the viewport.</param>
/// <param name="topLine">Top line of viewport.</param>
/// <param name="bottomLine">Bottom line of viewport.</param>
/// <param name="pageMargin">Margin around the page.</param>
/// <param name="zoomFactor">Zoom factor to use for pages. Not for page margin.</param>
/// <returns>Pages to draw in required region.</returns>
protected virtual IList <IPDFPageRenderInfo> DeterminePagesToRenderVirtual(IPDFPageRenderInfo pageOnCenter, ref double topLine, ref double bottomLine, double pageMargin, double zoomFactor)
{
// Base check.
if (pageOnCenter == null ||
!pageOnCenter.IsOnCenter ||
pageOnCenter.Page == null ||
pageOnCenter.Page.PageIndex >= PageComponent.PageCount)
{
// We don't have required information.
return(DeterminePagesToRenderVirtual(topLine, bottomLine, pageMargin, zoomFactor));
}
// Height of viewport.
var height = bottomLine - topLine;
// Let's say, the middle point of height is on position 0. Create virtual top line.
var virtualTopLine = -1d * (bottomLine - topLine) / 2d;
// List of all pages to render.
var list = new List <IPDFPageRenderInfo>();
// Let's take the page witch vertical center on it has this point on position 0.
// We'll correct all top and bottom lines later.
var pageOnMiddle = new PDFPageRenderInfo(pageOnCenter.Page)
{
Left = 0,
Right = PageWidth(pageOnCenter.Page) * zoomFactor,
Top = -1d * pageOnCenter.PagePositionOnCenter * PageHeight(pageOnCenter.Page) * zoomFactor,
Bottom = (1d - pageOnCenter.PagePositionOnCenter) * PageHeight(pageOnCenter.Page) * zoomFactor,
IsOnCenter = pageOnCenter.IsOnCenter,
PagePositionOnCenter = pageOnCenter.PagePositionOnCenter,
};
// Add this page to the list.
list.Add(pageOnMiddle);
// Current position on Y-axis.
var currentPositionOnY = pageOnMiddle.Top;
currentPositionOnY -= pageMargin;
// Iterate through pages from 'page on middle' to the first page.
// Iterate through all of them, don't break on page above virtual top line.
for (var index = pageOnCenter.Page.PageIndex - 1; index >= 0; index--)
{
// Get page to check.
var page = PageComponent.Pages[index];
// Check the curreint position on y relative to the virtual top line.
if (currentPositionOnY > virtualTopLine)
{
// This page is still visible.
var nextPageToAdd = new PDFPageRenderInfo(page)
{
Left = 0,
Right = PageWidth(page) * zoomFactor,
Top = currentPositionOnY - (PageHeight(page) * zoomFactor),
Bottom = currentPositionOnY,
};
// Insert this page to the first position of list.
list.Insert(0, nextPageToAdd);
}
// Adjust current position on y.
currentPositionOnY -= PageHeight(page) * zoomFactor;
currentPositionOnY -= pageMargin;
}
// Set new top and bottom line returned back.
topLine = (-1d * currentPositionOnY) - (height / 2d);
bottomLine = topLine + height;
// A negative top line means that the first page is displayed and not positioned at the top.
if (topLine < 0d)
{
topLine = 0d;
bottomLine = topLine + height;
currentPositionOnY = pageMargin;
// Adjust top and bottom line of all already added pages to render.
foreach (var pageRenderInfo in list)
{
pageRenderInfo.Top = currentPositionOnY;
pageRenderInfo.Bottom = currentPositionOnY + (PageHeight(pageRenderInfo.Page) * zoomFactor);
// Adjust current position on y axis.
currentPositionOnY += pageMargin + (PageHeight(pageRenderInfo.Page) * zoomFactor);
}
}
else
{
// Adjust top and bottom line of all already added pages to render.
foreach (var pageRenderInfo in list)
{
pageRenderInfo.Top += topLine + (height / 2d);
pageRenderInfo.Bottom += topLine + (height / 2d);
currentPositionOnY = pageRenderInfo.Bottom;
}
// Adjust current position on y axis.
currentPositionOnY += pageMargin;
}
// Iterate through pages from 'page on middle' to the last page.
for (var index = pageOnCenter.Page.PageIndex + 1; index < PageComponent.Pages.Count; index++)
{
// Filter out all pages below bottom line.
if (currentPositionOnY > bottomLine)
{
// Page is below bottom line.
// End foreach.
break;
}
// Part of this page is between top and bottom line.
// Add this page to the list.
var nextPageToAdd = new PDFPageRenderInfo(PageComponent.Pages[index])
{
Left = 0,
Right = PageWidth(PageComponent.Pages[index]) * zoomFactor,
Top = currentPositionOnY,
Bottom = currentPositionOnY + (PageHeight(PageComponent.Pages[index]) * zoomFactor),
};
// Add the page to the list.
list.Add(nextPageToAdd);
// Adjust current position on y axis.
currentPositionOnY += pageMargin + (PageHeight(PageComponent.Pages[index]) * zoomFactor);
}
return(list);
}
/// <summary>
/// Gets all pages to be drawn in specified region.
/// </summary>
/// <param name="topLine">Top line of viewport.</param>
/// <param name="bottomLine">Bottom line of viewport.</param>
/// <param name="pageMargin">Margin around the page.</param>
/// <param name="zoomFactor">Zoom factor to use for pages. Not for page margin.</param>
/// <param name="setCurrentPageIndex">If <c>true</c>, page on middle of height will be set as current page.</param>
/// <returns>Pages to draw in required region.</returns>
protected virtual IList <IPDFPageRenderInfo> DeterminePagesToRenderVirtual(double topLine, double bottomLine, double pageMargin, double zoomFactor, bool setCurrentPageIndex = false)
{
// List of all pages to render.
var list = new List <IPDFPageRenderInfo>();
// Current position on Y-axis.
var currentPositionOnY = pageMargin;
// Center line on viewport
var centerLine = (topLine + bottomLine) / 2;
var isCenterSet = false;
// Iterate through all pages.
foreach (var page in PageComponent.Pages)
{
// Filter out all pages above top line.
if (currentPositionOnY + (PageHeight(page) * zoomFactor) < topLine)
{
// Page is above top line.
// Adjust the current position on y and continue.
currentPositionOnY += pageMargin + (PageHeight(page) * zoomFactor);
continue;
}
// Filter out all pages below bottom line.
if (currentPositionOnY > bottomLine)
{
// Page is below bottom line.
// End foreach.
break;
}
// Part of this page is between top and bottom line.
// Add this page to the list.
var pageToAdd = new PDFPageRenderInfo(page)
{
Left = 0,
Right = PageWidth(page) * zoomFactor,
Top = currentPositionOnY,
Bottom = currentPositionOnY + (PageHeight(page) * zoomFactor),
};
// Check if the middle point of height of viewport is over this page.
if (pageToAdd.Top < centerLine && pageToAdd.Bottom > centerLine)
{
// Middle point of height of viewport is over this page.
// Store thid information to use it later during zoom manipulation.
pageToAdd.IsOnCenter = true;
pageToAdd.PagePositionOnCenter = (centerLine - pageToAdd.Top) / (pageToAdd.Bottom - pageToAdd.Top);
isCenterSet = true;
if (setCurrentPageIndex)
{
PageComponent.SetCurrentInformation(pageToAdd.Page);
}
}
// Special behaviour. Middle point of height of viewport may be between to pages.
// In this case use current page to add.
if (!isCenterSet && pageToAdd.Top > centerLine)
{
pageToAdd.IsOnCenter = true;
pageToAdd.PagePositionOnCenter = 0d;
isCenterSet = true;
if (setCurrentPageIndex)
{
PageComponent.SetCurrentInformation(pageToAdd.Page);
}
}
// Add the page to the list.
list.Add(pageToAdd);
// Adjust current position on y.
currentPositionOnY += pageMargin + (PageHeight(page) * zoomFactor);
}
return(list);
}
