Announcement

**Andreas Kosch** · 15.01.2000, 14:03

Hallo,

das folgende Beispiel aus einer der Borland-Newsgroups demonstriert eine Implementierung der Druckvorschau:
<pre>
unit printpreview;

interface

uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
StdCtrls, ExtCtrls, ComCtrls;

type
TForm1 = class(TForm)
Panel1: TPanel;
Panel2: TPanel;
PreviewPaintbox: TPaintBox;
Label1: TLabel;
Label2: TLabel;
LeftMarginEdit: TEdit;
TopMarginEdit: TEdit;
Label3: TLabel;
Label4: TLabel;
RightMarginEdit: TEdit;
Label5: TLabel;
BottomMarginEdit: TEdit;
ApplyMarginsButton: TButton;
OrientationRGroup: TRadioGroup;
Label6: TLabel;
ZoomEdit: TEdit;
ZoomUpDown: TUpDown;
procedure LeftMarginEditKeyPress(Sender: TObject; var Key: Char);
procedure FormCreate(Sender: TObject);
procedure PreviewPaintboxPaint(Sender: TObject);
procedure ApplyMarginsButtonClick(Sender: TObject);
private
{ Private declarations }
PreviewText: String;
public
{ Public declarations }
end;

var
Form1: TForm1;

implementation

uses printers;
{$R *.DFM}

procedure TForm1.LeftMarginEditKeyPress(Sender: TObject; var Key: Char);
begin
If not (Key in ['0'..'9',#9,DecimalSeparator]) Then
Key := #0;
end;

procedure TForm1.FormCreate(Sender: TObject);
var
S: String;
procedure loadpreviewtext;
var
sl: TStringlist;
begin
sl:= Tstringlist.Create;
try
sl.Loadfromfile(Extractfilepath( application.exename )+'printpreview.pas');
PreviewText := sl.Text;
finally
sl.free
end;
end;
begin
// Initialize the margin edits with a margin of 0.75 inch
S:= FormatFloat('0.00',0.75);
LeftMarginEdit.Text := S;
TopMarginEdit.Text := S;
RightMarginEdit.Text := S;
BottomMarginEdit.Text := S;

// Initialize the orientation radio group
If Printer.Orientation = poPortrait Then
OrientationRGroup.ItemIndex := 0
Else
OrientationRGroup.ItemIndex := 1;

// load test text for display
LoadPreviewtext;
end;

procedure TForm1.PreviewPaintboxPaint(Sender: TObject);
var
pagewidth, pageheight: Double; // printer page dimension in inch
printerResX, printerResY: Integer; // printer resolution in dots/inch
minmarginX, minmarginY: Double; // nonprintable margin in inch
outputarea: TRect; // print area in 1/1000 inches
scale: Double; // conversion factor, pixels per 1/1000 inch

procedure InitPrintSettings;
function GetMargin( S: String; inX: Boolean )

ouble;
begin
Result := StrToFloat(S);
if InX then begin
if Result < minmarginX then
Result := minmarginX;
end
else begin
if Result < minmarginY then
Result := minmarginY;
end;
end;
begin
printerResX := GetDeviceCaps( printer.handle, LOGPIXELSX );
printerResY := GetDeviceCaps( printer.handle, LOGPIXELSY );
pagewidth := GetDeviceCaps( printer.handle, PHYSICALWIDTH ) / printerResX;
pageheight := GetDeviceCaps( printer.handle, PHYSICALHEIGHT) / printerResY;
minmarginX := GetDeviceCaps( printer.handle, PHYSICALOFFSETX)/ printerResX;
minmarginY := GetDeviceCaps( printer.handle, PHYSICALOFFSETY)/ printerResY;

outputarea.Left := Round( GetMargin( LeftMarginEdit.Text, true ) * 1000);
outputarea.Top := Round( GetMargin( TopMarginEdit.Text, false ) * 1000);
outputarea.Right := Round(( pagewidth -
GetMargin( RightMarginEdit.Text, true )) * 1000);
outputarea.Bottom := Round(( pageheight -
GetMargin( BottomMarginEdit.Text, false ))
* 1000);
end; { InitPrintSettings }
</pre>

2. Teil folgt

**Andreas Kosch** · 15.01.2000, 14:05

2. Teil der <b>Druckvorschau</b>:
<pre>
procedure ScaleCanvas( Canvas: TCanvas; widthavail, heightavail: Integer );
var
needpixelswidth, needpixelsheight: Integer;
// dimensions of preview at current zoom factor in pixels
orgpixels: TPoint; // origin of preview in pixels
begin
// set up a coordinate system for the canvas that uses 1/1000 inch as unit,
// honors the zoom factor and maintains the MM_TEXT orientation of the
// coordinate axis (origin in top left corner, positive Y axis points
// down.
scale := Screen.PixelsPerInch / 1000;
// Apply zoom factor
scale := scale * StrToInt(Zoomedit.text) / 100;
// figure out size of preview
needpixelswidth := Round(pagewidth * 1000 * scale);
needpixelsheight := Round(pageheight * 1000 * scale);

if needpixelswidth >= widthavail then
orgpixels.X := 0
else
orgpixels.X := (widthavail - needpixelswidth) div 2;
if needpixelsheight >= heightavail then
orgpixels.Y := 0
else
orgpixels.Y := (heightavail - needpixelsheight) div 2;

// change mapping mode to MM_ISOTROPIC
SetMapMode( canvas.handle, MM_ISOTROPIC );
// move viewport origin to orgpixels
SetViewportOrgEx( canvas.handle, orgpixels.x, orgpixels.y, Nil );
// scale the window
SetViewportExtEx( canvas.handle, Round( 1000 * scale ),
Round( 1000 * scale ), Nil );
SetWindowExtEx( canvas.handle, 1000, 1000, Nil );
end; { ScaleCanvas }
begin
if OrientationRGroup.ItemIndex = 0 then
Printer.Orientation := poPortrait
else
Printer.Orientation := poLandscape;
InitPrintsettings;
With Sender As TPaintBox Do Begin
ScaleCanvas( Canvas, ClientWidth, ClientHeight );
// specify font height in 1/1000 inch
Canvas.Font.Height := Round(font.height / font.pixelsperinch * 1000);
// paint page white
Canvas.Brush.Color := clWindow;
Canvas.Brush.Style := bsSolid;
Canvas.FillRect( Rect(0,0,Round(pagewidth*1000),Round(pageheight*10 00)));
// draw the text
DrawText( canvas.handle, PChar(PreviewText), Length( PreviewText ),
outputarea, DT_WORDBREAK or DT_LEFT );
// Draw thin gray lines to mark borders
Canvas.Pen.Color := clGray;
Canvas.Pen.Style := psSolid;
Canvas.Pen.Width := 10;
with Canvas do begin
MoveTo( outputarea.left - 100, outputarea.top );
LineTo( outputarea.right + 100, outputarea.top );
MoveTo( outputarea.left - 100, outputarea.bottom );
LineTo( outputarea.right + 100, outputarea.bottom );
MoveTo( outputarea.left, outputarea.top - 100 );
LineTo( outputarea.left, outputarea.bottom + 100 );
MoveTo( outputarea.right, outputarea.top - 100 );
LineTo( outputarea.right, outputarea.bottom + 100 );
end;
End;
end;

procedure TForm1.ApplyMarginsButtonClick(Sender: TObject);
begin
PreviewPaintbox.Invalidate;
end;

end.
<pre&gt

Announcement

wie programmiere ich ein druckvorschau????

wie programmiere ich ein druckvorschau????

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