/// <summary>
/// Given a range of pages, adds the pages to the existing row cache,
/// adding new rows where necessary.
/// </summary>
/// <param name="startPage">The first page to add to the layout</param>
/// <param name="count">The number of pages to add.</param>
private RowCacheChange AddPageRange(int startPage, int count)
{
if (!_isLayoutCompleted)
{
throw new InvalidOperationException(SR.Get(SRID.RowCacheCannotModifyNonExistentLayout));
}
int currentPage = startPage;
int lastPage = startPage + count;
int startRow = 0;
int rowCount = 0;
//First we check to see if startPage is such that we'd end up skipping
//pages in the document -- that is, if the last page in our layout is currently
//10 and start is 15, we need to fill in pages 11-14 as well.
if (startPage > LastPageInCache + 1)
{
currentPage = LastPageInCache + 1;
}
//Get the last row in the layout
RowInfo lastRow = _rowCache[_rowCache.Count - 1];
//Now we need to check to see if we can add any pages to this row
//without exceeding the current layout's pivot row width.
//Get the size of the page to add
Size pageSize = GetScaledPageSize(currentPage);
//Get the pivot row
RowInfo pivotRow = GetRow(_pivotRowIndex);
bool lastRowUpdated = false;
//Add new pages to the last row until we run out of pages or space.
while (currentPage < lastPage &&
lastRow.RowSize.Width + pageSize.Width <= pivotRow.RowSize.Width)
{
//Add the current page
lastRow.AddPage(pageSize);
currentPage++;
//Get the size of the next page.
pageSize = GetScaledPageSize(currentPage);
//Note that we updated this row so we'll update the cache when we're done here.
lastRowUpdated = true;
}
//If we actually made a change to the last row, then we need to update the row cache.
if (lastRowUpdated)
{
startRow = _rowCache.Count - 1;
//Update the last row
UpdateRow(startRow, lastRow);
}
else
{
startRow = _rowCache.Count;
}
//Now we add more rows to the layout, if we have any pages left.
while (currentPage < lastPage)
{
//Build a new row.
RowInfo newRow = new RowInfo();
newRow.FirstPage = currentPage;
//Add pages until we either run out of pages or need to start a new row.
do
{
//Get the size of the next page
pageSize = GetScaledPageSize(currentPage);
//Add it.
newRow.AddPage(pageSize);
currentPage++;
} while (newRow.RowSize.Width + pageSize.Width <= pivotRow.RowSize.Width
&& currentPage < lastPage);
//Add this new row to our cache
AddRow(newRow);
rowCount++;
}
return new RowCacheChange(startRow, rowCount);
}
/// <summary>
/// Creates a "dynamic" row -- that is, given a maximum width for the row, it will fit as
/// many pages on said row as possible.
/// </summary>
/// <param name="startPage">The first page to put on this row.</param>
/// <param name="rowWidth">The requested width of this row.</param>
/// <param name="createForward">Whether to create this row using the next N pages or the
/// previous N.</param>
/// <returns></returns>
private RowInfo CreateDynamicRow(int startPage, double rowWidth, bool createForward)
{
if (startPage >= PageCache.PageCount)
{
throw new ArgumentOutOfRangeException("startPage");
}
//Given a starting page for this row, and the specified
//width for each row, figure out how many pages will fit on this row
//and return the resulting RowInfo object.
//Populate the struct with initial data.
RowInfo newRow = new RowInfo();
//Each row is guaranteed to have at least one page, even if it’s wider
//than the allotted size, so we add it here.
Size pageSize = GetScaledPageSize( startPage );
newRow.AddPage(pageSize);
//Keep adding pages until we either:
// - run out of pages to add
// - run out of space in the row
for(;;)
{
if( createForward )
{
//Grab the next page.
pageSize = GetScaledPageSize(startPage + newRow.PageCount);
//We’re out of pages, or out of space.
if (startPage + newRow.PageCount >= PageCache.PageCount ||
newRow.RowSize.Width + pageSize.Width > rowWidth )
{
break;
}
}
else
{
//Grab the previous page.
pageSize = GetScaledPageSize( startPage - newRow.PageCount );
//We’re out of pages, or out of space.
if( startPage - newRow.PageCount < 0 ||
newRow.RowSize.Width + pageSize.Width > rowWidth )
{
break;
}
}
newRow.AddPage(pageSize);
//If we've hit the hard upper limit for pages on a row then we're done with this row.
if (newRow.PageCount == DocumentViewerConstants.MaximumMaxPagesAcross)
{
break;
}
}
if (!createForward)
{
newRow.FirstPage = startPage - (newRow.PageCount - 1);
}
else
{
newRow.FirstPage = startPage;
}
return newRow;
}
/// <summary>
/// Creates a "fixed" row -- that is, a row with a specific number of columns on it.
/// </summary>
/// <param name="startPage">The first page to live on this row.</param>
/// <param name="columns">The number of columns on this row.</param>
/// <returns></returns>
private RowInfo CreateFixedRow(int startPage, int columns)
{
if (startPage >= PageCache.PageCount)
{
throw new ArgumentOutOfRangeException("startPage");
}
if (columns < 1 )
{
throw new ArgumentOutOfRangeException("columns");
}
//Given a starting page for this row and the number of columns in the row
//calculate the width & height and return the resulting RowInfo struct
//Populate the struct with initial data
RowInfo newRow = new RowInfo();
newRow.FirstPage = startPage;
//Keep adding pages until we either:
// - run out of pages to add
// - add the appropriate number of pages
for (int i = startPage; i < startPage + columns; i++)
{
//We’re out of pages.
if (i > PageCache.PageCount - 1)
break;
//Get the size of the page
Size pageSize = GetScaledPageSize(i);
//Add this page to the row
newRow.AddPage(pageSize);
}
return newRow;
}
/// <summary>
/// Updates the cache entry at the given index with the new RowInfo supplied.
/// If the new row has a different height than the old one, we need to update
/// the offsets of all the rows below this one and adjust the vertical extent appropriately.
/// If it has a different width, we just need to update the horizontal extent appropriately.
/// </summary>
/// <param name="index">The index of the row to update</param>
/// <param name="newRow">The new RowInfo to replace the old</param>
private void UpdateRow(int index, RowInfo newRow)
{
if (!_isLayoutCompleted)
{
throw new InvalidOperationException(SR.Get(SRID.RowCacheCannotModifyNonExistentLayout));
}
//Check for invalid indices. If it's out of range then we just return.
if (index > _rowCache.Count)
{
Debug.Assert(false, "Requested to update a non-existent row.");
return;
}
//Get the current entry.
RowInfo oldRowInfo = _rowCache[index];
//Replace the old with the new.
_rowCache[index] = newRow;
//Compare the heights -- if they differ we need to update the rows beneath it.
if (oldRowInfo.RowSize.Height != newRow.RowSize.Height)
{
//The new row has a different height, so we add the delta
//between the old and the new to every row below this one.
double delta = newRow.RowSize.Height - oldRowInfo.RowSize.Height;
for(int i = index + 1; i < _rowCache.Count; i++)
{
RowInfo row = _rowCache[i];
row.VerticalOffset += delta;
_rowCache[i] = row;
}
//Add the delta for this row to our vertical extent.
_extentHeight += delta;
}
//If the new row is wider than the current document's width, then we
//can just update the document width now.
if (newRow.RowSize.Width > _extentWidth)
{
_extentWidth = newRow.RowSize.Width;
}
//Otherwise, if the widths differ we need to recalculate the width
//of the document again.
//(The logic is that this particular row could have defined the extent width,
//and now that it's changed size the extent may change as well.)
else if (oldRowInfo.RowSize.Width != newRow.RowSize.Width)
{
//The width of this row has changed.
//This means we need to recalculate the width of the entire document
//by walking through each row.
_extentWidth = 0;
for (int i = 0; i < _rowCache.Count; i++)
{
RowInfo row = _rowCache[i];
//Update the extent width.
_extentWidth = Math.Max(row.RowSize.Width, _extentWidth);
}
}
}
/// <summary>
/// Trims any pages (and rows) from the end of the layout, starting with the specified page.
/// </summary>
/// <param name="startPage">The first page to remove.</param>
private RowCacheChange TrimPageRange(int startPage)
{
//First, we find the row the last page is on.
int rowIndex = GetRowIndexForPageNumber(startPage);
//Now we replace this row with a new row that has the deleted pages
//removed, if there are pages on this row that aren't going to be deleted.
RowInfo oldRow = GetRow(rowIndex);
if (oldRow.FirstPage < startPage)
{
RowInfo updatedRow = new RowInfo();
updatedRow.VerticalOffset = oldRow.VerticalOffset;
updatedRow.FirstPage = oldRow.FirstPage;
for (int i = oldRow.FirstPage; i < startPage; i++)
{
//Get the page we're interested in.
Size pageSize = GetScaledPageSize(i);
//Add it.
updatedRow.AddPage(pageSize);
}
UpdateRow(rowIndex, updatedRow);
//Increment the rowIndex, since we're going to keep this row.
rowIndex++;
}
int removeCount = _rowCache.Count - rowIndex;
//Now remove all the rows below this one.
if(rowIndex < _rowCache.Count )
{
_rowCache.RemoveRange( rowIndex, removeCount);
}
//Update our extents
_extentHeight = oldRow.VerticalOffset;
return new RowCacheChange(rowIndex, removeCount);
}
/// <summary>
/// Adds a new row onto the end of the layout and updates the current layout
/// measurements.
/// </summary>
/// <param name="newRow">The new row to add to the layout</param>
private void AddRow(RowInfo newRow)
{
//If this is the first row in the document we just put it at the beginning
if (_rowCache.Count == 0)
{
newRow.VerticalOffset = 0.0;
//The width of the document is just the width of the first row.
_extentWidth = newRow.RowSize.Width;
}
else
{
//This is not the first row, so we put it at the end of the last row.
RowInfo lastRow = _rowCache[_rowCache.Count - 1];
//The new row needs to be positioned at the bottom of the last row
newRow.VerticalOffset = lastRow.VerticalOffset + lastRow.RowSize.Height;
//Update the document's width
_extentWidth = Math.Max(newRow.RowSize.Width, _extentWidth);
}
//Update the layout
_extentHeight += newRow.RowSize.Height;
//Add the row.
_rowCache.Add(newRow);
}
/// <summary>
/// Given a preexisting page range, updates the dimensions of the rows containing said
/// pages from the Page Cache.
/// If any row's height changes as a result, all rows below have their offsets updated.
/// </summary>
/// <param name="startPage">The first page changed</param>
/// <param name="count">The number of pages changed</param>
private RowCacheChange UpdatePageRange(int startPage, int count)
{
if (!_isLayoutCompleted)
{
throw new InvalidOperationException(SR.Get(SRID.RowCacheCannotModifyNonExistentLayout));
}
//Get the row that contains the first page
int startRowIndex = GetRowIndexForPageNumber(startPage);
int rowIndex = startRowIndex;
int currentPage = startPage;
//Recalculate the rows affected by the changed pages.
while (currentPage < startPage + count && rowIndex < _rowCache.Count)
{
//Get the current row
RowInfo currentRow = _rowCache[rowIndex];
//Create a new row and copy pertinent data
//from the old one.
RowInfo updatedRow = new RowInfo();
updatedRow.VerticalOffset = currentRow.VerticalOffset;
updatedRow.FirstPage = currentRow.FirstPage;
//Now rebuild this row, thus recalculating the row's size
//based on the new page sizes.
for (int i = currentRow.FirstPage; i < currentRow.FirstPage + currentRow.PageCount; i++)
{
//Get the updated page size and add it to our updated row
Size pageSize = GetScaledPageSize(i);
updatedRow.AddPage(pageSize);
}
//Update the row layout with this new row.
UpdateRow(rowIndex, updatedRow);
//Move to the next group of pages.
currentPage = updatedRow.FirstPage + updatedRow.PageCount;
//Move to the next row.
rowIndex++;
}
return new RowCacheChange(startRowIndex, rowIndex - startRowIndex);
}
/// <summary>
/// Helper function that calculates the Horizontal offset of the given page.
/// </summary>
/// <param name="row">The row which the desired page lives on</param>
/// <param name="pageNumber">The page to find the offset for</param>
/// <returns>The Horizontal offset of the page in the document.</returns>
private double GetHorizontalOffsetForPage( RowInfo row, int pageNumber )
{
if (row == null)
{
throw new ArgumentNullException("row");
}
if (pageNumber < row.FirstPage ||
pageNumber > row.FirstPage + row.PageCount)
{
throw new ArgumentOutOfRangeException("pageNumber");
}
//Rows are centered if the content has varying page sizes,
//Left-aligned otherwise.
double horizontalOffset = _pageCache.DynamicPageSizes ?
Math.Max(0.0, (ExtentWidth - row.RowSize.Width) / 2.0) : 0.0;
//Add the widths of the pages (and spacing) prior to this one on the row
for (int i = row.FirstPage; i < pageNumber; i++)
{
Size pageSize = _pageCache.GetPageSize(i);
horizontalOffset += pageSize.Width * Scale + HorizontalPageSpacing;
}
return horizontalOffset;
}
private double CalculateScaleFactor(RowInfo pivotRow)
{
//Determine the dimensions of this row minus any spacing between the pages.
//We use this as the baseline for our scale factor as page spacing does not scale.
double rowWidth;
//If the page sizes vary, we use the width of the pivot row,
//otherwise we use the overall width of the document (ExtentWidth).
//(For uniform page sizes, we always use the width of the document, even
//for the last row which may not have the same width as the rest of the document).
if (_pageCache.DynamicPageSizes)
{
rowWidth = pivotRow.RowSize.Width - pivotRow.PageCount * HorizontalPageSpacing;
}
else
{
rowWidth = ExtentWidth - MaxPagesAcross * HorizontalPageSpacing;
}
double rowHeight = pivotRow.RowSize.Height - VerticalPageSpacing;
//If we have row dimensions of zero or less, there's no reason to scale anything.
//So just return 1.0 to indicate no change.
if (rowWidth <= 0.0 || rowHeight <= 0.0)
{
return 1.0;
}
//The dimensions of our Viewport minus any spacing. We use this as the baseline for our
//scale factor as page spacing does not scale.
double compensatedViewportWidth;
if (_pageCache.DynamicPageSizes)
{
compensatedViewportWidth = ViewportWidth - pivotRow.PageCount * HorizontalPageSpacing;
}
else
{
compensatedViewportWidth = ViewportWidth - MaxPagesAcross * HorizontalPageSpacing;
}
double compensatedViewportHeight = ViewportHeight - VerticalPageSpacing;
//If we have no space to display pages, there's nothing to scale.
//So just return 1.0 to indicate no change.
if (compensatedViewportWidth <= 0.0 ||
compensatedViewportHeight <= 0.0)
{
return 1.0;
}
double scaleFactor = 1.0;
//Based on the previously determined ViewMode (set in SetColumns(), FitToWidth(), etc..
//scale the pages appropriately.
switch (_documentLayout.ViewMode)
{
case ViewMode.SetColumns:
//We leave the scale factor as is -- this is not a "page-fit" mode.
break;
case ViewMode.FitColumns:
//Update the scale factor so that the pivot row is completely visible.
scaleFactor = Math.Min(compensatedViewportWidth / rowWidth, compensatedViewportHeight / rowHeight);
break;
case ViewMode.PageWidth:
//Update the scale factor so that the pivot row is as wide as the viewport.
scaleFactor = compensatedViewportWidth / rowWidth;
break;
case ViewMode.PageHeight:
//Update the scale factor so that the pivot row is as tall as the viewport.
scaleFactor = compensatedViewportHeight / rowHeight;
break;
case ViewMode.Thumbnails:
//Update the scale factor so that the _entire layout_ is completely visible. As in previous
//cases we must compensate for the fact that the spacing between pages does not scale.
//However, unlike in previous cases, we must exclude the space between all rows rather
//merely one space, so we must recalculate the compensated values. Furthermore we must
//also compensate for the ExtentHeight as well since it includes the spaces.
double thumbnailCompensatedExtentHeight = ExtentHeight - VerticalPageSpacing * _rowCache.RowCount;
double thumbnailCompensatedViewportHeight = ViewportHeight - VerticalPageSpacing * _rowCache.RowCount;
//If we have no space to display pages, there's nothing to scale.
//So just return 1.0 to indicate no change.
if (thumbnailCompensatedViewportHeight <= 0.0)
{
scaleFactor = 1.0;
}
else
{
scaleFactor = Math.Min(compensatedViewportWidth / rowWidth,
thumbnailCompensatedViewportHeight / thumbnailCompensatedExtentHeight);
}
break;
case ViewMode.Zoom:
//We will not change the scale here, as this is not a "page-fit" mode.
break;
default:
throw new InvalidOperationException(SR.Get(SRID.DocumentGridInvalidViewMode));
}
return scaleFactor;
}
/// <summary>
/// Given a pivot row and a previously set ViewMode, the scale is adjusted so as
/// to cause the pivot row to be fit based on the specified ViewMode.
/// </summary>
/// <param name="pivotRow"></param>
private void ApplyViewParameters(RowInfo pivotRow)
{
//Update our MaxPagesAcross property to the number of rows on the pivot row
//if page sizes vary. (If page sizes are uniform, this value will not change as a result of
//a layout change)
if (_pageCache.DynamicPageSizes)
{
_maxPagesAcross = pivotRow.PageCount;
}
//Get the scale factor necessary to fit the given row into the Viewport.
double scaleFactor = CalculateScaleFactor(pivotRow);
//Calculate the new scale. We multiply our scale factor by the old scale factor to cancel out any
//previously applied scale.
double newScale = scaleFactor * _rowCache.Scale;
//Clip the value into the acceptable range
newScale = Math.Max(newScale, CurrentMinimumScale);
newScale = Math.Min(newScale, DocumentViewerConstants.MaximumScale);
//Update the Row Layout's scale.
UpdateLayoutScale(newScale);
}
/// <summary>
/// Checks that the current scale factor is optimal for the passed in row.
/// </summary>
/// <param name="pivotRow">The Row to pass to the Delegate</param>
private void EnsureFit(RowInfo pivotRow)
{
//Get the scale factor necessary to fit this row into view.
//If the result is not 1.0 (within a certain margin of error)
//then we need to re-layout, alas.
double neededScaleFactor = CalculateScaleFactor(pivotRow);
double newScale = neededScaleFactor * _rowCache.Scale;
//If the neededScaleFactor would require DocumentGrid scale the pages
//below the minimum allowed zoom, or above the maximum, then we won't
//do anything here.
if (newScale < CurrentMinimumScale ||
newScale > DocumentViewerConstants.MaximumScale)
{
return;
}
if (!DoubleUtil.AreClose(1.0, neededScaleFactor))
{
//Rescale the row.
ApplyViewParameters( pivotRow );
//Make the row visible again -- the offsets may have
//changed due to the above rescaling.
SetVerticalOffsetInternal(pivotRow.VerticalOffset);
}
}
/// <summary>
/// Helper function that indicates whether all the pages on the specified
/// row point to clean cache entries.
/// </summary>
/// <param name="row"></param>
/// <returns></returns>
private bool RowIsClean(RowInfo row)
{
bool clean = true;
for (int i = row.FirstPage; i < row.FirstPage + row.PageCount; i++)
{
if (_pageCache.IsPageDirty(i))
{
clean = false;
break;
}
}
return clean;
}
