BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Print Preview with Printer()->Canvas          BorlandTalk.com Forum Index -> C++ Builder (VCL Components Usage) View previous topic :: View next topic   Author Message Alain Guest Posted: Fri Sep 29, 2006 8:11 am    Post subject: Print Preview with Printer()->Canvas Hello All, How to get a print preview with the "Printer()->Canvas" function ? Thanks Alain Back to top JD Guest Posted: Sat Sep 30, 2006 3:52 pm    Post subject: Re: Print Preview with Printer()->Canvas "Alain" <alainbastien (AT) gmail (DOT) com> wrote: Quote: How to get a print preview with the "Printer()->Canvas" function ? To be clear, the TPrinter::Canvas is not a function. It is a member of the TPrinter class. The first thing is to keep in mind that a TCanvas is a TCanvas no matter what HWND (Handle) it belongs to. It is nothing more than a wrapper for the HDC (Device Context) which Windows uses for drawing operations. Do not confuse the TCanvas::Handle which is an HDC with other VCL object Handles which are HWND's. Since all TCanvas's are the same, you can use the exact same methods to print to a TBitmap's Canvas and then you can display the TBitmap as a print preview and even print it if you like. While it's not difficult, it's not as quite straight forward as it sounds. The biggest issue is that the screen and the printer have radically different DPI (Density of Pixels per Inch) and pixel dimensions (Width and Height in pixels). What I do for my print previews is I size the TBitmap to match the paper dimensions in inches. IOW, if the paper is 8.5 x 11 inches, then I get the screen's DPI, do some math and then set the TBitmap's Width and Height accordingly so that when displayed at 100%, on screen, it measures 8.5 x 11 inches. The result is a WYSIWYG (What You See Is What You Get) preview. Look in the win32.hlp file (you might have to search your hard drive for it) and look up GetDeviceCaps. That API needs to be called several times to gather all of the information that you need to do this correctly. Another issue that needs to be addressed is that no 2 printers are the same (unless their the same make AND model). Each printer has a white space that surrounds the outer edge of the paper where the printer is physically unable to print and this white space is different from printer to printer. What this means to you the programmer is that Canvas(0,0) on one printer might start at absolute pixel (50,10) on one printer and it might be (40,40) on another printer. To compound the situation, not only do printers have varying DPI, the Canvas is never centered on the paper so if you want the printed report to look the same no matter what printer is used, you have to do more calls to GetDeviceCaps and more math. // Get the printer pixels per inch pXPPI = ::GetDeviceCaps( Printer()->Handle, LOGPIXELSX ); pYPPI = ::GetDeviceCaps( Printer()->Handle, LOGPIXELSY ); // Get the printers totals pixels pXPixels = ::GetDeviceCaps( Printer()->Handle, PHYSICALWIDTH ); pYPixels = ::GetDeviceCaps( Printer()->Handle, PHYSICALHEIGHT ); // Determine the printable area of the paper TRect Area; Area.left = ::GetDeviceCaps( Printer()->Handle, PHYSICALOFFSETX ); Area.top = ::GetDeviceCaps( Printer()->Handle, PHYSICALOFFSETY ); Area.right = pXPixels - (Printer()->PageWidth + Area.left); Area.bottom = pYPixels - (Printer()->PageHeight + Area.top); // User defined margines in inches LMargine = 1.0; TMargine = 1.25; RMargine = 1.0; BMargine = 1.25; // Calculate the margines in printer pixels TRect Margines; Margines.left = ((double)LMargine * pXPPI); Margines.top = ((double)TMargine * pYPPI); Margines.right = ((double)RMargine * pXPPI); Margines.bottom = ((double)BMargine * pYPPI); // Adjust printable Area to account for margines if( Margines.left > Area.left ) Area.left = Margines.left; if( Margines.top > Area.top ) Area.top = Margines.top; if( Margines.right > Area.right ) Area.right = Margines.right; if( Margines.bottom > Area.bottom ) Area.bottom = Margines.bottom; // Get the Screen Pixels Per Inch sXPPI = ::GetDeviceCaps( Canvas->Handle, LOGPIXELSX ); sYPPI = ::GetDeviceCaps( Canvas->Handle, LOGPIXELSY ); pBitmap->Width = ((double)(pXPixels - ((Area.right - Area.left) + 1)) / pXPPI) * sXPPI; pBitmap->Height = ((double)(pYPixels - ((Area.bottom - Area.top ) + 1)) / pYPPI) * sYPPI; Now the TBitmap is dimensionally the same as the paper - in inches (excluding margines) - not pixels. As you print, you'll want to ensure that your font sizes are correct. The standard sizes are 6 lines per inch for normal print and 8 lines per inch for condensed print. Now, I never have understood the Font::Size/Height. The docs were confusing to me so I just used the TCanvas::TextHeight method to set the size. For example: int NormalHeight = sYPPI / 6; int CondensedHeight = sYPPI / 8; // set it to an arbitrary number pBitmap->Canvas->Font->Size = 50; while( pBitmap->Canvas->TextHeight("Wg") > NormalHeight ) { // do not try pBitmap->Canvas->Font->Size -= 1 or similar pBitmap->Canvas->Font->Size = pBitmap->Canvas->Font->Size - 1; } Be aware that calls to TextHeight and (especially) TextWidth are very slow and should be limited as much as possible. Also note that the font provides all of the vertical spacing as well so you only need to increment line counters (assuming standard print). As a note, there is a distinct advantage to printing to a TBitmap that you later send to the printer and that is that many printers have a limited font selection when compared to the screen and some printers are severly lacking. This method doesn't care what the printer has. As for displaying the TBitmap, I use a TScrollBox with it's Align property set to alClient and a TPaintBox inside the TScrollBox. All you need to do is position the TPaintBox at (0,0) and add an OnPaint event to paint the TBitmap. I presume that you'll be changing the zoom ratio to allow the user to zoom in and out and for that you'll need a second TBitmap that you size according to the zoom ratio and then draw the original TBitmap to it using StretchDraw. For example: private: // User declarations Graphics::TBitmap *Bitmap1; Graphics::TBitmap *Bitmap2; void __fastcall ChangeZoomRatio( int Percent ); public: // User declarations __fastcall TForm1(TComponent* Owner); __fastcall ~TForm1(); //------------------------------------------------------------- __fastcall TForm1::TForm1(TComponent* Owner) : TForm(Owner) { // set this in the IDE ScrollBox1->Align = alClient; // just need some initialization to prevent AV and so it looks right PaintBox1->Width = ScrollBox1->ClientWidth; PaintBox1->Height = ScrollBox1->ClientHeight; Bitmap1 = new Graphics::TBitmap(); Bitmap1->PixelFormat = pf24bit; Bitmap2 = new Graphics::TBitmap(); Bitmap2->PixelFormat = pf24bit; Bitmap2->Width = PaintBox1->Width; Bitmap2->Height = PaintBox1->Height; Bitmap2->Canvas->Brush->Style = bsClear; // Reported to speed-up bitmap operations Bitmap2->Canvas->Brush->Color = clWhite; Bitmap2->Canvas->FillRect( Rect(0,0,Bitmap2->Width,Bitmap2->Height) ); } //------------------------------------------------------------- __fastcall TForm1::~TForm1() { delete Bitmap1; delete Bitmap2; } //------------------------------------------------------------- void __fastcall TForm1::PaintBox1Paint(TObject *Sender) { TRect R = Rect( 0, 0, Bitmap2->Width, Bitmap2->Height ); PaintBox1->Canvas->CopyRect( R, Bitmap2->Canvas, R ); } //------------------------------------------------------------- void __fastcall TForm1::ChangeZoomRatio( int Percent ) { // disable painting redrawing Bitmap2 ::SendMessage( ScrollBox1->Handle, WM_SETREDRAW, FALSE, 0 ); Bitmap2->Width = (Bitmap1->Width * Percent) / 100; Bitmap2->Height = (Bitmap1->Height * Percent) / 100; Bitmap2->Canvas->StretchDraw( Rect(0,0,Bitmap1->Width,Bitmap1->Height), Bitmap1 ); // need to set scrollbars before you size the paint box ScrollBox1->HorzScrollBar->Position = 0; ScrollBox1->VertScrollBar->Position = 0; // size the paintbox PaintBox1->SetBounds( 0, 0, Bitmap2->Width, Bitmap2->Height ); // add code here to set scroll positions if desired // enable painting ::SendMessage( ScrollBox1->Handle, WM_SETREDRAW, TRUE, 0 ); // cause the new image to be painted ScrollBox1->Refresh(); } //------------------------------------------------------------- As for printing the TBitmap, not all printer support print a Device Dependent Bitmap (DDB) so you'll need to convert the TBitmap to a Device Independent Bitmap (DIB). Printer()->BeginDoc(); StretchBltBitmap( Printer()->Canvas, Area.left, Area.top, (Area.right - Area.left) + 1, (Area.bottom - Area.top) + 1, Bitmap1 ); Printer()->EndDoc(); //------------------------------------------------------------- void __fastcall TForm1::StretchBltBitmap( TCanvas *pCanvas, int iX, int iY, int iWidth, int iHeight, Graphics::TBitmap *pBitmap ) { char* Buffer = NULL; unsigned int HeaderSize = 0, ImageSize = 0; GetDIBSizes( pBitmap->Handle, HeaderSize, ImageSize ); try { Buffer = new char[ HeaderSize + ImageSize ]; } catch( Exception& E ) { MessageDlg( "Error allocating memory for DIB : " + E.Message, mtError, TMsgDlgButtons() << mbOK, 0 ); return; } BITMAPINFO* pBmi = (BITMAPINFO*) Buffer; unsigned char* pImage = (unsigned char*) Buffer + HeaderSize; if( GetDIB( pBitmap->Handle, pBitmap->Palette, pBmi, pImage ) ) { StretchDIBits( pCanvas->Handle, iX, iY, iWidth, iHeight, 0, 0, pBitmap->Width, pBitmap->Height, pImage, pBmi, DIB_RGB_COLORS, SRCCOPY ); } else { MessageDlg( "Error copying the DIB.", mtError, TMsgDlgButtons() << mbOK, 0 ); } delete [] Buffer; } //------------------------------------------------------------- ~ JD Back to top Daryl Guest Posted: Tue Oct 17, 2006 3:13 pm    Post subject: Re: Print Preview with Printer()->Canvas JD I tried the code example and have a question: Should you call the method ChangeZoomRatio( int Percent ) with Percent set to 100% to get the correct representation of the page on the screen? I ask this because when I ran the code the white area was only about one 12th or less of the screen. I read an article in a Builder 5 Developer guide that TMetafile is better than TBitmap, have you tried the example with TMetafile substituted for TBitmap? Either way can you please let me have a little more info on how this example can be used to print out a block of text? How do you manage more than on page for example? thanks for the link to the example. daryl Back to top JD Guest Posted: Wed Oct 18, 2006 8:11 am    Post subject: Re: Print Preview with Printer()->Canvas "Daryl" <devaccount (AT) hotmail (DOT) com> wrote: Quote: [...] Should you call the method ChangeZoomRatio( int Percent ) with Percent set to 100% to get the correct representation of the page on the screen? Setting it to 100% would result in an image that is dimentionally the same as if it were printed. Quote: [...] when I ran the code the white area was only about one 12th or less of the screen. 1/10th perhaps? I didn't test that code. I simplified a test case for work that was thrown together on a weekend (meaning that it was ugly code). It sounds to me like it's a simple decimal point issue. Quote: I read an article in a Builder 5 Developer guide that TMetafile is better than TBitmap, have you tried the example with TMetafile substituted for TBitmap? No and I don't know that it is. It may be 'better' (always a subjective term) for displaying but ultimately, it would have to be converted to a DIB to print it so what's the point? Quote: Either way can you please let me have a little more info on how this example can be used to print out a block of text? The sample is intended to demonstrate how to setup a print- preview. It was never intended to demonstrate how to actually print anything (except a TBitmap). As for printing text, you should understand that no matter what method is used, the text is drawn onto an HDC. When that HDC is the TPrinter's Canvas, up until the moment that you cause the printer to actually print the page, any pixel in that HDC can be changed. So ... printing is one thing, drawing the text is another. The 2 usual methods to draw text are to use TCanvas's TextOut method or to use the win32 API DrawText and each have their own advantages. For example, TextOut will work with rotated fonts and DrawText will not. OTOH, DrawText is much more flexible (look in the win32.hlp file for details). Quote: How do you manage more than on page for example? You build it as the user requests (remember that the sample is for a print-preview) just as you would if you were printing a multiple page report. The difference being that you would use the TPrinter::Canvas instead of the TBitmap::Canvas and you would call TPrinter::NewPage between pages. The sample included printing the TBitmap because we found that some users wanted fonts that their printer didn't support. In these cases, we draw the text using the desired font onto a bitmap and print that (it's a simple test to see if the printer supports the selected fonts). Quote: thanks for the link to the example. NP ~ JD Back to top george Guest Posted: Thu Oct 19, 2006 5:19 pm    Post subject: Re: Print Preview with Printer()->Canvas An alternative approach to Print Preview is to put your text to be printed into a RichEdit and then use->Print from there. You have to do some maths to ensure you have the same lines per page and columns per line in the RE and the Printer, but I don't think as much as you seem to need otherwise. The facilities may not be as sophisticated, but it serves all my purposes. George "JD" <nospam (AT) nospam (DOT) com> wrote: Quote: "Daryl" <devaccount (AT) hotmail (DOT) com> wrote: Either way can you please let me have a little more info on how this example can be used to print out a block of text? The sample is intended to demonstrate how to setup a print- preview. It was never intended to demonstrate how to actually print anything (except a TBitmap). As for printing text, you should understand that no matter what method is used, the text is drawn onto an HDC. When that HDC is the TPrinter's Canvas, up until the moment that you cause the printer to actually print the page, any pixel in that HDC can be changed. So ... printing is one thing, drawing the text is another. The 2 usual methods to draw text are to use TCanvas's TextOut method or to use the win32 API DrawText and each have their own advantages. For example, TextOut will work with rotated fonts and DrawText will not. OTOH, DrawText is much more flexible (look in the win32.hlp file for details). How do you manage more than on page for example? Back to top JD Guest Posted: Fri Oct 20, 2006 2:00 am    Post subject: Re: Print Preview with Printer()->Canvas "george" <zombacity (AT) apl (DOT) com> wrote: Quote: Please trim your posts. Quote: An alternative approach to Print Preview is to put your text to be printed into a RichEdit Ever try to add a bitmap to a TRichEdit? How about column spanning or zooming in and out or user defined margins? They can all be done but not easily with a TRichEdit but the bottom line is that the print-preview still isn't WYSIWYG. ~ JD Back to top Alain Guest Posted: Fri Oct 20, 2006 8:11 am    Post subject: Re: Print Preview with Printer()->Canvas Not that easy. I am going to use this to print barcodes on a A4 size paper with 3.5X2.5 cm detachable stickers. In order to avoid wastage, need to have preview with if possible dotted lines showing the position of the stickers relative to the printing to check any overlaps. Back to top george Guest Posted: Sun Oct 22, 2006 12:52 am    Post subject: Re: Print Preview with Printer()->Canvas OK, but does the enquirer want all that stuff? I can do margins if I want and I am only talking about text. I can see how it will fit in the printed page, which is what is important to me. George "JD" <nospam (AT) nospam (DOT) com> wrote: Quote: Ever try to add a bitmap to a TRichEdit? How about column spanning or zooming in and out or user defined margins? They can all be done but not easily with a TRichEdit but the bottom line is that the print-preview still isn't WYSIWYG. ~ JD Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         BorlandTalk.com Forum Index -> C++ Builder (VCL Components Usage) All times are GMT Page 1 of 1   Jump to: Select a forum C++ Builder Newsgroups----------------C++ BuilderC++ Builder (ActiveX)C++ Builder (Announcements)C++ Builder (Command Line Tools)C++ Builder DatabasesC++ Builder Databases (ADO)C++ Builder Databases (Desktop)C++ Builder Databases (InterBase Express)C++ Builder Databases (Multi-Tier)C++ Builder Databases (SQL Servers)C++ Builder (Graphics)C++ Builder (IDE)C++ Builder (Internet)C++ Builder (Internet Socket)C++ Builder (Internet Web)C++ Builder (Jobs)C++ Builder (Language)C++ Builder (Language C++)C++ Builder (Compatibility with MFC)C++ Builder (Native API)C++ Builder (Non-Technical)C++ Builder (Students)C++ Builder (Third Party Tools)C++ Builder (Upgrade)C++ Builder (VCL)C++ Builder (VCL Components Usage)C++ Builder (VCL Components Development)C++ Builder (VCL Usage)C++ Builder (WinAPI)C++ Builder Installation Delphi Newsgroups----------------Delphi (General)Delphi ActiveX Controls UsageDelphi ActiveX Controls DevelopmentDelphi As400Delphi DatabasesDelphi Databases (ADO)Delphi Databases (dbExpress)Delphi Databases (Desktop)Delphi Databases (InterBase Express)Delphi Databases (Multi-Tier)Delphi Databases (SQL Servers)Delphi DeploymentDelphi GraphicsDelphi IDEDelphi InternationalizationDelphi InternetDelphi Internet Isapi-WebBrokerDelphi Internet WebSnapDelphi Internet WinsockDelphi JobsDelphi Language BASMDelphi Language ObjectPascalDelphi Model Driven Architecture (General)Delphi Model Driven Architecture (Third Party)Delphi MultimediaDelphi Native APIDelphi Non-TechnicalDelphi ObjectPascalDelphi OLE AutomationDelphi OO designDelphi OpenToolsAPIDelphi Reporting-ChartingDelphi RTLDelphi StudentsDelphi TeamSourceDelphi Thirdparty ToolsDelphi Thirdparty Tools (General)Delphi Thirdparty Tools (IntraWeb)Delphi Thirdparty Tools (RaveReports)Delphi UpgradeDelphi VCLDelphi VCL ComponentsDelphi VCL Components UsingDelphi VCL Components WritingDelphi WebServices SOAPDelphi WinAPIDelphi XMLDelphi Installationcomp.lang.pascal.delphi.components.misccomp.lang.pascal.delphi.components.usagecomp.lang.pascal.delphi.components.writingcomp.lang.pascal.delphi.databasescomp.lang.pascal.delphi.misccomp.sources.delphi JBuilder Newsgroups----------------JBuilderJBuilder AnnouncementsJBuilder Applet IssuesJBuilder As400JBuilder CompilerJBuilder CORBA/RMIJBuilder DatabasesJBuilder DB SwingJBuilder DebuggerJBuilder DeploymentJBuilder DocumentationJBuilder EnterpriseJBuilder HandheldJBuilder IDEJBuilder JavaJBuilder JavaAPIJBuilder Java LanguageJBuilder Java SwingJBuilder Java BeansJBuilder Java Beans UsageJBuilder Java Beans DevelopmentJBuilder JBCLJBuilder JDataStoreJBuilder JobsJBuilder LinuxJBuilder MacintoshJBuilder & MobileSetJBuilder MultiLingual AppsJBuilder Non-TechnicalJBuilder OpenToolsJBuilder Servlets (JSP)JBuilder StudentsJBuilder Team DevelopmentJBuilder Thirdparty ToolsJBuilder UpgradeJBuilder Installation InterBase Newsgroups----------------InterBaseInterBase Bug DiscussionInterBase GeneralInterBase IBConsoleInterBase OpenSourceInterBase ReplicationInterBase SQLInterBase ThirdpartyInterBase Installation Miscellaneous Borland Newsgroups----------------AppCenterAppServerEnteraVisiBroker  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.