Report construction with the help of a code

The FastReport engine usually is responsible for report’s constructing. It shows report’s bands in a particular order as many times, as the datasource to which it is connected requires, thus forming a finished report. Sometimes it is necessary to create a report of a non-standard form, which FastReport’s engine is unable to produce. In this case, one can use the ability of constructing a report manually, with the help of the TfrxReport.OnManualBuild event. If to define a handler of this event, the FastReport engine sends management to it. At the same time, allocation of responsibilities for forming a report is changed in the following way:

FastReport engine:

• report’s preparation (script, data sources initialization, bands’ tree forming)

• all calculations (aggregate functions, event handlers)

• new pages/columns’ forming (automatic showing a page/column header/footer, report title/summary)

• other routine work

Handler:

• bands’ presentation in a certain order

The OnManualBuild handler’s essence is to issue commands concerning presenting certain bands to the FastReport’s engine. The engine itself will do the rest: a new page will be created, as soon as there is no place in the current one; execution of scripts will be performed, etc.

The engine is represented with the TfrxCustomEngine class. A link to the instance of this class is located in the TfrxReport.Engine property.

Property or method	Description
procedure NewColumn	Creates a new column. If a column is the last one, it creates a new page.
procedure NewPage	Creates a new page.
procedure ShowBand(Band: TfrxBand)	Shows a band.
procedure ShowBand(Band: TfrxBandClass)	Shows a band of the given type.
function FreeSpace: Extended	Returns the amount of free space on the page (in pixels). After the next band is presented, this value descends.
property CurColumn: Integer	Returns/sets the current column’s number
property CurX: Extended	Returns/sets the current X position.
property CurY: Extended	Returns/sets the current Y position. After the next band is presented, this value ascends.
property DoublePass: Boolean	Defines whether a report is a two-pass one.
property FinalPass: Boolean	Defines whether the current pass is the last one.
property FooterHeight: Extended	Returns the page footer height.
property HeaderHeight: Extended	Returns the page header height.
property PageHeight: Extended	Returns the height of the page’s printable region.
property PageWidth: Extended	Returns the width of the page’s printable region.
property TotalPages: Integer	Returns the number of pages in a finished report (only on the second pass of the two-pass report).

Let us give an example of a simple handler. There is two «Master Data» bands in a report, which are not connected to data. The handler presents these bands in an interlaced order, six times each one. After six bands, a small gap is made.

Pascal:

var
  i: Integer;
  Band1, Band2: TfrxMasterData;

{ find required bands }
Band1 := frxReport1.FindObject('MasterData1') as TfrxMasterData;
Band2 := frxReport1.FindObject('MasterData2') as TfrxMasterData;
for i := 1 to 6 do
begin
  { lead/deduce bands one after another }
  frxReport1.Engine.ShowBand(Band1);
  frxReport1.Engine.ShowBand(Band2);
  { make a small gap }
  if i = 3 then
    frxReport1.Engine.CurY := frxReport1.Engine.CurY + 10;
end;

C++:

int i;
TfrxMasterData * Band1;
TfrxMasterData * Band2;

// find required bands 
Band1 := dynamic_cast <TfrxMasterData *> (frxReport1->FindObject("MasterData1"));
Band2 := dynamic_cast <TfrxMasterData *> (frxReport1->FindObject("MasterData2"));
for(i = 1; i <= 6; i++)
{
  // lead/deduce bands one after another 
  frxReport1->Engine->ShowBand(Band1);
  frxReport1->Engine->ShowBand(Band2);
  // make a small gap 
  if(i == 3)
    frxReport1->Engine->CurY += 10;
}

The next example shows two groups of bands alongside each other.

Pascal:

var
  i, j: Integer;
  Band1, Band2: TfrxMasterData;
  SaveY: Extended;

Band1 := frxReport1.FindObject('MasterData1') as TfrxMasterData;
Band2 := frxReport1.FindObject('MasterData2') as TfrxMasterData;
SaveY := frxReport1.Engine.CurY;

for j := 1 to 2 do
begin
  for i := 1 to 6 do
  begin
    frxReport1.Engine.ShowBand(Band1);
    frxReport1.Engine.ShowBand(Band2);
    if i = 3 then
      frxReport1.Engine.CurY := frxReport1.Engine.CurY + 10;
  end;
  frxReport1.Engine.CurY := SaveY;
  frxReport1.Engine.CurX := frxReport1.Engine.CurX + 200;
end;

C++:

int i, j;
TfrxMasterData * Band1;
TfrxMasterData * Band2;
Extended SaveY;

Band1 = dynamic_cast <TfrxMasterData *> (frxReport1->FindObject("MasterData1"));
Band2 = dynamic_cast <TfrxMasterData *> (frxReport1->FindObject("MasterData2"));
SaveY = frxReport1->Engine->CurY;

for(j = 1; j <= 2; j++)
{
  for(i = 1; i <= 6; i++)
  {
    frxReport1->Engine->ShowBand(Band1);
    frxReport1->Engine->ShowBand(Band2);
    if(i == 3)
      frxReport1->Engine->CurY += 10;
  }
  frxReport1->Engine->CurY = SaveY;
  frxReport1->Engine->CurX += 200;
}