private double GetIntersectOffset(double curOffset, double pageWidth)
{
//Gets the position of the Control to print on the screen
var mainTranform = ControlToPrint.TransformToVisual(Application.Current.RootVisual);
var mainOffset = mainTranform.Transform(new Point(0, 0));
//Creates a 1 pixel line where the control is going to be paginated
var intersectRect = new Rect(mainOffset.X, curOffset + mainOffset.Y, pageWidth, 1);
//This gets all controls that the intersectRect crosses that are inside of the ControlToPrint
//The coordinates of the intersectRect must be relative to the whole screen not just the control itself
//all the second parameter does is filter the elements that get returned.
var elements = VisualTreeHelper.FindElementsInHostCoordinates(intersectRect, ControlToPrint);
if (elements.Count() == 0)
{
_forceStopPagging = true;
}
var maxOffset = 0.0;
foreach (var uiElement in elements)
{
////Any control that can have children can be paginated (ie. Panels,ContentControls,ItemControls)
////Things that dont have children (ie textblock,textbox,Image) cannot be paginated
if (VisualTreeHelper.GetChildrenCount(uiElement) <= 0)
{
////TODO: possibly take into account other types of controls that can have children but are empty
////what if there is a stackpanel with no children but a hieght of 100, this makes no sense in a UI but it is possible
if (uiElement is Border)
{
////an empty border can be paginated
continue;
}
//Make sure we have the corect size of the object being cut
uiElement.Measure(new Size(pageWidth, double.MaxValue));
//Get the coordinates of the element with respect to the control being printed
var gt = uiElement.TransformToVisual(ControlToPrint);
var offset = gt.Transform(new Point(0, 0));
//Get the Height of the element that is left on the current page, this is used to know the adjustment needed to the overal offset
var elementOffset = (curOffset + intersectRect.Height) - offset.Y;
//Get the max of all controls that are being cut.
maxOffset = Math.Max(maxOffset, elementOffset);
}
}
return(maxOffset);
}
private int GetTotalPages()
{
if (!_totalPages.HasValue)
{
_forceStopPagging = false;
_coverOffsetCache.Clear();
var availableSizeOnPage = _printPage.GetHeightAvailable();
var pageWidth = _printPage.Width;
//Calles measure to make sure we know the full height of the Control to Print
ControlToPrint.Measure(new Size(pageWidth, double.MaxValue));
var controlHeight = ControlToPrint.DesiredSize.Height;
var curOffset = availableSizeOnPage;
var pageCount = 1;
//Loops through control hieght to find how many pages there needs to be
while (curOffset < controlHeight)
{
var coverOffset = GetIntersectOffset(curOffset, pageWidth);
_coverOffsetCache.Add(pageCount, coverOffset);
curOffset -= coverOffset;
if (_forceStopPagging)
{
break;
}
pageCount++;
curOffset += availableSizeOnPage;
}
if (!_forceStopPagging)
{
////for last page, last page was already handled if pagginging was forcably stopped
_coverOffsetCache.Add(pageCount, 0.0);
}
_totalPages = pageCount;
}
return(_totalPages.Value);
}
