用服务器组件解决WEB交叉报表问题(2)

用服务器组件解决WEB交叉报表问题
——修改FastReport源码，支持内存流导出


Fast Report是一个经典的报表控件，不过其导出功能只支持导出到磁盘文件，而此项目为了避开权限的限制和出于服务器安全的需要，要求将Fast Report生成的报表导出到内存流，所以要修改Fast Report源码。{========================================================================
DESIGN BY : 彭国辉
DATE: 2007-09-15
SITE: http://kacarton.yeah.net/
BLOG: http://blog.csdn.net/nhconch
EMAIL: kacarton[A T]sohu.com 文章为作者原创，转载请注明文章出处、保留作者信息，谢谢支持！
=========================================================================}

Fast Report2.5的导出函数在FR_Class文件中声明，参考此函数，可以很轻易的写出导出到内存流的函数：
//添加导出到内存流的支持 --Conch 2007-09-10--
procedure TfrReport.ExportToStream(Filter: TfrExportFilter; Stream: TMemoryStream);
var
s: String;
Flag, NeedConnect: Boolean;
begin
DocMode := dmPrinting;
FCurrentFilter := Filter;
if (Preview <> nil) and (EMFPages.Count = 0) then
begin
Preview.Disconnect;
NeedConnect := True;
end
else
NeedConnect := False;{========================================================================
DESIGN BY : 彭国辉
DATE: 2007-09-15
SITE: http://kacarton.yeah.net/
BLOG: http://blog.csdn.net/nhconch
EMAIL: kacarton[A T]sohu.com 文章为作者原创，转载请注明文章出处、保留作者信息，谢谢支持！
=========================================================================}

Flag := True;
if Assigned(FCurrentFilter.OnBeforeExport) then
FCurrentFilter.OnBeforeExport(FCurrentFilter.FileName, Flag);
FCurrentFilter.Stream := Stream;

CurReport := Self;
MasterReport := Self;
SavedAllPages := EMFPages.Count;

FCurrentFilter.OnBeginDoc;
ExportBeforeModal(Self);

if Assigned(FCurrentFilter.OnAfterExport) then
FCurrentFilter.OnAfterExport(FCurrentFilter.FileName);

if NeedConnect then
Preview.Connect(Self);
FCurrentFilter := nil;
end;

同样，TfrHTML2Export控件是将CSS文件与HTML分开保存的，这样使得内存流中的HTML内容因缺少CSS而无法显示，故此要修改TfrHTML2Export.OnEndDoc函数。从该函数中找到SaveStringToFile(ImageFolderFull + '/' + CSSFile, s)这一句（FR2.5在第461行），改为：
if FileName <> '' then
SaveStringToFile(ImageFolderFull + '/' + CSSFile, s)
else begin
s := '<style type=''text/css''>' + LF + s + LF + '</style>' + LF;
Stream.Write(s[1], Length(s));
end;{========================================================================
DESIGN BY : 彭国辉
DATE: 2007-09-15
SITE: http://kacarton.yeah.net/
BLOG: http://blog.csdn.net/nhconch
EMAIL: kacarton[A T]sohu.com 文章为作者原创，转载请注明文章出处、保留作者信息，谢谢支持！
=========================================================================}
其它版本或其它导出控件可按此方法修改（导出Excel控件因使用OLE技术调用Excel组件，只能保存到磁盘文件），修改后的OnEndDoc函数如下：
procedure TfrHTML2Export.OnEndDoc;
var
s : string;
i, j : integer;
Page : THPage;
LastBottom : integer;
CSSFile : string;
CSSFilePrint : string;
NavFile : string;
// DefaultStyle : THStyle;
// Style : THStyle;
h1, h2 : string;
MaxWidth : integer;
MinLeftMargin : integer;

begin
if Navigator = nil then Exit;
if FPages.Count = 0 then Exit;

if FStyles.Count > 0 then
begin
s := '';
CSSFilePrint := ChangeFileExt(ExtractFileName(FileName), '_print.css');

if Navigator.Position <> [] then
s := s + Navigator.GetStyleHTML(true);

if s <> '' then
SaveStringToFile(ImageFolderFull + '/' + CSSFilePrint, s);
{----------------------------}

CSSFile := ChangeFileExt(ExtractFileName(FileName), '.css');

{DefaultStyle := nil;
for i := 0 to FStyles.Count - 1 do
begin
Style := THStyle(FStyles[i]);
if not (Style is THStyleFrame) or
(THStyleFrame(Style).FFillColor = $1FFFFFFF) then
if (DefaultStyle = nil) or (Style.FCount > DefaultStyle.FCount) then
DefaultStyle := THStyle(FStyles[i]);
end;

if DefaultStyle <> nil then
DefaultStyle.SetDefault;}

//s := 'img' + LF + '{' + LF + 'border: 0px solid #000000;' + LF + '}' + LF;

s := 'span' + LF + '{' + LF + 'position: absolute;' + LF + '}' + LF +
'img' + LF + '{' + LF + 'position: absolute;' + LF + '}' + LF +
'.page_break' + LF + '{' + LF + 'page-break-before: always;' + LF + '}' + LF;

for i := 0 to FStyles.Count - 1 do
s := s + THStyle(FStyles[i]).GetHtml + LF;

if {(FPages.Count > 1) and} (Navigator.Position <> []) then
s := s + Navigator.GetStyleHTML(false);
//配合导出到内存流功能，将CSS内容直接写到流中 --Conch--
if FileName <> '' then
SaveStringToFile(ImageFolderFull + '/' + CSSFile, s)
else begin
s := '<style type=''text/css''>' + LF + s + LF + '</style>' + LF;
Stream.Write(s[1], Length(s));
end;
{----------------------------}
end;

if FMultiPage and (FNavigator.Position <> []) then
begin
if Navigator.InFrame and Navigator.WideInFrame then
begin
MaxWidth := Screen.Width - 20;
MinLeftMargin := 0;
end
else begin
MaxWidth := 0;
MinLeftMargin := High(integer);
for j := 0 to FPages.Count - 1 do
begin
Page := THPage(FPages[j]);
if Page.Width - Page.RightMargin > MaxWidth then
MaxWidth := Page.Width - Page.RightMargin;
if Page.LeftMargin < MinLeftMargin then
MinLeftMargin := Page.LeftMargin;
end;
if MaxWidth + MinLeftMargin > Screen.Width then
MaxWidth := Screen.Width - MinLeftMargin;
end;

FNavigator.BuildItems(MaxWidth);

if FNavigator.InFrame then
begin
NavFile := ChangeFileExt(ExtractFileName(FileName), '') + '_' +
NavigatorFilePostfix + '_0.html';
if npTop in Navigator.Position then
h1 := Format('%dpx,', [Navigator.GetHeight])
else
h1 := '';

if npBottom in Navigator.Position then
h2 := Format(', %dpx', [Navigator.GetHeight])
else
h2 := '';

s := Format(HTMLHeader, [CurReport.Title, CSSFile, CSSFilePrint]) +
Format('<frameset rows="%s *%s" framespacing="0" frameborder="0" border="0">',
[h1, h2]) + LF;

if npTop in Navigator.FPosition then
s := s + Format('<frame src="%s" name="N***IGATOR_TOP" scrolling="no" ' +
'marginwidth="0" marginheight="0">', [ImageFolder + '/' + NavFile]) + LF;

s := s + Format('<frame src="%s" name="%s" scrolling="yes" marginwidth="0" ' +
'marginheight="0">', [ImageFolder + '/' + THPage(FPages[0]).GetName,
PageFrame]) + LF;

if npBottom in Navigator.FPosition then
s := s + Format('<frame src="%s" name="N***IGATOR_BOTTOM" scrolling="no" ' +
'marginwidth="0" marginheight="0">', [ImageFolder + '/' + NavFile]) + LF;

s := s + '</frameset>' + LF + HTMLFooter;
Stream.Write(s[1], Length(s));

for j := 0 to FNavigator.FItems.Count - 1 do
begin
s := Format(HTMLHeader, [CurReport.Title, CSSFile, CSSFilePrint]);
s := s + Navigator.GetHTML(TNavigatorItem(FNavigator.FItems[j]).MinPage,
0, MinLeftMargin, MaxWidth, true) + HTMLFooter;
NavFile := ChangeFileExt(ExtractFileName(FileName), '') + '_' +
NavigatorFilePostfix + '_' + IntToStr(j) + '.html';
SaveStringToFile(ImageFolderFull + '/' + NavFile, s);
end;
end;
end;

LastBottom := 5;
for j := 0 to FPages.Count - 1 do
begin
Page := THPage(FPages[j]);

if FMultiPage then
begin
if (j = 0) and (not Navigator.InFrame or (Navigator.Position = [])) then
s := Format(HTMLHeader, [CurReport.Title, ImageFolder + '/' + CSSFile,
ImageFolder + '/' + CSSFilePrint])
else
s := Format(HTMLHeader, [CurReport.Title, CSSFile, CSSFilePrint]);

LastBottom := 5;
if (FNavigator.Position <> []) and FNavigator.InFrame then
begin
s := s + Page.GetHTML(LastBottom, 0) + HTMLFooter; //!!!!!!!!!!!!!!!!!!!!
SaveStringToFile(ImageFolderFull + '/' + Page.GetName, s);
end
else begin
if (FPages.Count > 1) and (npTop in Navigator.Position) then
begin
s := s + Navigator.GetHTML(Page.ID, LastBottom, Page.LeftMargin,
Page.Width - Page.RightMargin, false);
Inc(LastBottom, Navigator.GetHeight + 15);
end;

s := s + Page.GetHTML(LastBottom, 0);

if (FPages.Count > 1) and (npBottom in Navigator.Position) then
s := s + Navigator.GetHTML(Page.ID, Page.Height + LastBottom +
{Page.BottomMargin} + 5, Page.LeftMargin, Page.Width - Page.RightMargin, false);

s := s + HTMLFooter;

if j = 0 then
Stream.Write(s[1], Length(s))
else
SaveStringToFile(ImageFolderFull + '/' + Page.GetName, s);
end;
end
else begin
s := Page.GetHTML(LastBottom, 0);
if j = 0 then
s := Format(HTMLHeader, [CurReport.Title, ImageFolder + '/' + CSSFile,
ImageFolder + '/' + CSSFilePrint]) + s;
Stream.Write(s[1], Length(s));
Inc(LastBottom, Page.Height);
end;
end;

if not FMultiPage then
begin
s := HTMLFooter;
Stream.Write(s[1], Length(s));
end;

ClearListWithFree(FNavigator.FItems);
ClearListWithFree(FStyles);
ClearListWithFree(FPages);
end;{========================================================================
DESIGN BY : 彭国辉
DATE: 2007-09-15
SITE: http://kacarton.yeah.net/
BLOG: http://blog.csdn.net/nhconch
EMAIL: kacarton[A T]sohu.com 文章为作者原创，转载请注明文章出处、保留作者信息，谢谢支持！
=========================================================================}

经修改后就可以直接用FrReport1.ExportToStream(ex{TfrHTML2Export}, Stream{TMemoryStream});将报表导出到内存流了。

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