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Skapa en förhandsgranskning Kategori: Skrivare
Inlagt: 2003-11-13
Läst: 1397
Inlagt av: Staffan Berg
Beskrivning
Detta exempel använder sig av en TPanel för att skapa en förhandsgranskning (innan utskrift). 
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.

 
 
© Copyright 2005 - Staffan Berg
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