TAtlasPrintDocument

Create constructor

constructor Create(AOwner: TComponent); override;

Creates an empty document with Title set to Atlas report and no pages (PageCount is 0 until Prepare succeeds).

PageCount property

property PageCount: Integer read GetPageCount;

Number of pages in the snapshot: 0 before a successful Prepare, otherwise at least 1 (a table without rows gives a header-only page).

Title property

property Title: string read FTitle write FTitle;

Text drawn in bold at the top of every page and used as the print job name. Defaults to Atlas report. Changing it after Prepare affects subsequent rendering; it is not part of the snapshot.

Prepare method

procedure Prepare(Table: TAtlasTable; PageWidth: Integer = 794; PageHeight: Integer = 1123; Margin: Integer = 48; RowHeight: Integer = 28);

Snapshots the visible rows of Table (its current filtered and sorted view, via ExportCSV(True)) together with the column widths, and fixes the page geometry. Rows per page is (PageHeight - 2 * Margin - 3 * RowHeight) div RowHeight: the space left after the margins, the title line, the header row and the footer line. Raises EAtlasPrintError when Table is nil or has no columns, when PageWidth or PageHeight is below 100, Margin is negative or more than a third of either dimension, RowHeight is below 8, or no data row fits. On failure the previous snapshot is kept. A table without rows still produces one page (header only).

Document.Title := 'Invoices / September';
Document.Prepare(Table);              // A4 portrait at 96 dpi, 33 rows per page
Document.Prepare(Table, 1123, 794);   // landscape: 21 rows per page

FirstRow method

function FirstRow(Page: Integer): Integer;

Zero-based index, into the snapshot's data rows, of the first row printed on the zero-based Page. It equals Page * rows per page. Raises EAtlasPrintError when Page is outside 0..PageCount - 1, including on an unprepared document.

RowsOnPage method

function RowsOnPage(Page: Integer): Integer;

Number of data rows printed on Page: the rows per page on every page except the last, which carries the remainder. Summing RowsOnPage over all pages gives the number of snapshot rows. Raises EAtlasPrintError for a page out of range.

Total := 0;
for I := 0 to Document.PageCount - 1 do
  Inc(Total, Document.RowsOnPage(I));   // Total = number of rows in the snapshot

RenderPage method

procedure RenderPage(Canvas: TCanvas; const Bounds: TRect; Page: Integer);

Draws Page onto Canvas, scaling the page geometry to fit Bounds exactly (both axes are scaled independently, so keep the aspect ratio of Bounds equal to the page's to avoid distortion). Fills the background white, draws the title in bold Segoe UI, the header row on a light shade, cell borders, ellipsized cell text and the page footer. Raises EAtlasPrintError when Page is out of range or Bounds has no positive width and height. Use it for thumbnails, custom preview controls or your own printing loop.

Thumb := TBitmap.Create;
try
  Thumb.SetSize(397, 562);   // half of an A4 page at 96 dpi
  Document.RenderPage(Thumb.Canvas, Rect(0, 0, 397, 562), 0);
finally
  Thumb.Free;
end;

Preview method

function Preview(Page: Integer): TBitmap;

Returns a new TBitmap of PageWidth × PageHeight pixels (794 × 1123 by default) with Page rendered on it. The caller owns and frees the bitmap. Raises EAtlasPrintError for a page out of range.

Page := Document.Preview(0);
try
  Image.Picture.Bitmap.Assign(Page);
finally
  Page.Free;
end;

Print method

procedure Print;

Sends every page to the default Windows printer through Vcl.Printers: sets Printer.Title to Title, calls BeginDoc, renders each page scaled to the printer's page size with NewPage in between, then EndDoc. If rendering raises, the print job is aborted and the exception propagates. Raises EAtlasPrintError when no document has been prepared. Requires an installed printer; actual printer output is listed as pending manual acceptance in the product's validation record.

Preview the first page as a PNG file

Prepares a report from a table and saves page 1 at A4 size; the caller owns the preview bitmap.

uses System.SysUtils, Vcl.Graphics, Vcl.Imaging.pngimage, Atlas.Data, Atlas.Printing;

procedure SaveFirstPage(Table: TAtlasTable; const FileName: string);
var
  Document: TAtlasPrintDocument;
  Page: TBitmap;
  Png: TPngImage;
begin
  Document := TAtlasPrintDocument.Create(nil);
  try
    Document.Title := 'Invoices / September';
    Document.Prepare(Table);            // snapshot of the current view, A4 at 96 dpi
    Page := Document.Preview(0);        // caller owns the bitmap
    try
      Png := TPngImage.Create;
      try
        Png.Assign(Page);
        Png.SaveToFile(FileName);
      finally
        Png.Free;
      end;
    finally
      Page.Free;
    end;
    Writeln(Format('%d pages, %d rows on the first', [Document.PageCount, Document.RowsOnPage(0)]));
  finally
    Document.Free;
  end;
end;