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Skapa en förhandsgranskning
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Kategori: Skrivare
Inlagt: 2003-11-13
Läst: 1761
Inlagt av: Staffan Berg
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Beskrivning |
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Detta exempel använder sig av en TPanel för att skapa en förhandsgranskning (innan utskrift).
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Kod |
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 ): Double;
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;
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;
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 * 1000)));
//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.
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