Chapter4 VCL Printing within Delphi

ProEssentials Charting Library

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Chapter 4: VCL Printing within Delphi

You can print ProEssentials based images either via simple DLL function calls or via low level API calls.

NOTE: To call DLL calls within Delphi, you need to add the "Pegrpapi" unit to your uses clause.

Simple Printing with Dialog Intervention:

BOOL PElaunchprintdialog(hObject, bFullPage, lpPoint)

HWND	hObject	* Use PEGraph1.hObject property.
BOOL	bFullPage	Controls page size. Use 0 or 1
POINT FAR*	lpPoint	Pointer to TPoint struct holding size.

This function invokes a modal print dialog. If bFullPage equals TRUE then lpPoint is ignored. If bFullPage equals FALSE then lpPoint must point to a TPoint that holds the size (in 1/100th millimeter units) of the image to export. Note that HWND, and BOOL are really 32 bit long integers within Delphi.

PrintStyleControl

This property controls the visibility of radio buttons and the option selected for printing on the print dialog. Type of ePrintStyleControl.

Constant	Description
xNoPrintStyleControl	No control over Viewing Style
xPrintCurrentStyle	Current Viewing Style
xPrintDefaultMono	Switch to Mono Viewing Style

Replace the x prefix with either g(graph), sg(scientific graph), td(3D scientific graph), ps(polar/smith), or pc(pie chart).

DefOrientation

This property controls the default orientation of the printer paper when printing a ProEssentials object. Type of eDefOrientation.

Constant	Description
xDriverDefault	Use the printer driver
xLandscape	Landscape orientation.
xPortrait	Portrait orientation.

Replace the x prefix with either g(graph), sg(scientific graph), td(3D scientific graph), ps(polar/smith), or pc(pie chart).

PrintDpi

Controls the target resolution in DotsPerInch when printing. If set to Zero, graphic commands are sent directly to the printer:

Value	Description
0	If zero, the chart's image is sent to the printer via the actual graphic primitives and final resolution is based upon the printer's driver settings. This produces the sharpest graphics and may be the best setting when printing with ViewingStyle set to MonoChrome, BitmapGradientMode = False
100 --- 600	If non zero, the chart image is prepared as a bitmap (at the specified PrintDpi) and this bitmap is sent to the printer. The default and recommend setting is 300. 300 produces a good looking image while not requiring a huge amount of memory to be sent to the printer.

HidePrintDpi

This property controls the visibility of the above PrintDpi end-user setting shown within the ProEssentials built-in print dialog:

Value	Description
TRUE	The End-User can not adjust the PrintDpi setting.
FALSE	The End-User can adjust the PrintDpi setting.

Simple Printing without Dialog Intervention:

BOOL PEprintgraph(hObject, nWidth, nHeight, nOrient)

HWND	hObject	* Use PEGraph1.hObject.
INT	nWidth	Width in 1/100th millimeters.
INT	nHeight	Height in 1/100th millimeters.
INT	nOrient	0=Driver Default, 1=Landscape, 2=Portrait.

This function prints the objects image to the default printer.

If nWidth and nHeight are both zero, the image will print full page.

Lower Level Printing:

The following example shows how to place multiple images on a page. You can also add other graphics and text as needed providing full control over the printed page.

The recommended method uses PEprintgraphEx which is a new v6 feature to simplify printing:

PEprintgraphEx(nDC:Integer; nWidth:Integer; nHeight:Integer; nOriginX:Integer; nOriginY:Integer)

Parameter	Description
nDC	Handle to target device context.
nWidth	Width in 1/100th millimeters.
nHeight	Height in 1/100th millimeters.
nOriginX	Top-Left horizontal location in 1/100th millimeters.
nOriginY	Top-Left vertical location in 1/100th millimeters.

This function sends GDI or GDIPLUS commands to the target device context (hDC) to place the object's image within the printer's page at the size and position specified. The current state of PrintDpi and PrintTechnology properties will control which system calls are used to transfer the image.

Be sure to remember to add "Math", "Printers" and "Pegrpapi" to your uses clause.

{******************************************************************
** Method of printing using PEprintgraphEx.
******************************************************************}

procedure TForm1.FormClick(Sender: TObject);
var
nLogPx: Integer;
nLogPy: Integer;
ChartSizeX: Single;
ChartSizeY: Single;

begin

Printer.Title := 'Printing ProEssentials';
Printer.BeginDoc;
Printer.Canvas.TextOut(100,100, 'Hello World!');

{'** Get DPI info **'}
nLogPx := GetDeviceCaps(Printer.Handle, LOGPIXELSX);
nLogPy := GetDeviceCaps(Printer.Handle, LOGPIXELSY);

{'** Get Size in Inches **'}
ChartSizeX := Printer.PageWidth / nLogPx;
ChartSizeY := Printer.PageHeight / nLogPy;

{'** Convert to Himetrics, 1/100th millimeters **'}
ChartSizeX := ChartSizeX * 2540.0 / 2.0;
ChartSizeY := ChartSizeY * 2540.0 / 2.0;
ChartSizeX := ChartSizeX - 1270; {reduce horz size by margin, 1270 is 1/2 inch}

{'** Output image #1 **'}
PEprintgraphEx(PESGraph1.hObject, Printer.Handle, Floor(ChartSizeX), Floor(ChartSizeY), 1270, 1270);

{'** just place same image, but could be from another control**}
PEprintgraphEx(PESGraph1.hObject, Printer.Handle, Floor(ChartSizeX), Floor(ChartSizeY), Floor(ChartSizeX) + 1270, Floor(ChartSizeY));

Printer.EndDoc;

{' ** reset image to current aspect ratio **'}
PEresetimage(PESGraph1.hObject, 0, 0);

end;

{******************************************************************
** Lowest level, plays metafile to device context.
** Above code internally calls similar code when PrintDpi = 0
******************************************************************}

procedure TForm1.FormClick(Sender: TObject);

var

hMeta: Integer;

oldMM: Integer;

lresult: Longbool;

wSize: Integer;

hSize: Integer;

pt: TPoint;

begin

Printer.BeginDoc;

Printer.Canvas.TextOut(100,100, 'Hello World!');

{'** set mapping mode MM_TEXT **'}

oldMM := SetMapMode(Printer.Handle, 1);

{'** Set viewport org and extents **'}

hSize := Printer.PageHeight div 2;

wSize := Printer.PageWidth div 2;

lresult := SetViewportOrgEx(Printer.Handle, 0, hSize, @pt);

lresult := SetViewportExtEx(Printer.Handle, wSize, hSize, @pt);

{'** reset image shape to match shape defined by SetViewportExt **'}

PEresetimageEx(PESGraph1.hObject, wSize, hSize, 0, hsize);

hMeta := PEgetmeta(PESGraph1.hObject);

PEplaymetafile(PESGraph1.hObject, Printer.Handle, hMeta);

{'** just place same image, but could be from another control**}

lresult := SetViewportOrgEx(Printer.Handle, wSize, hSize, @pt);

lresult := SetViewportExtEx(Printer.Handle, wSize, hSize, @pt);

PEplaymetafile(PESGraph1.hObject, Printer.Handle, hMeta);

Printer.EndDoc;

{' ** reset mapping mode **'}

SetMapMode(Printer.Handle, oldMM);

{' ** reset image to current aspect ratio **'}

PEresetimage(PESGraph1.hObject, 0, 0);

end;

An important tip regarding low level printing and working with text and graphic mapping modes. It's best to first do a SaveDC Windows API call, output either your graphics or text, perform a RestoreDC call, output other graphics and or text, followed by a RestoreDC when completed with the DC.


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