BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Get size of an image Goto page 1, 2, 3  Next          BorlandTalk.com Forum Index -> comp.lang.pascal.delphi.misc View previous topic :: View next topic   Author Message QS Computing Guest Posted: Thu Jan 27, 2005 11:35 am    Post subject: Get size of an image I'm looking for some code that will allow me to get the pixel dimensions of an image in JPG, PNG or GIF format in Delphi 7 Personal. Obviously I can load a JPG into a TImage with AutoSize=true and check the size of the TImage afterwards, but that won't work with PNG or GIF. Any ideas? Thanks, - QS Computing. Back to top Maarten Wiltink Guest Posted: Thu Jan 27, 2005 2:08 pm    Post subject: Re: Get size of an image "QS Computing" <qscomputing (AT) gmail (DOT) com> wrote Quote: I'm looking for some code that will allow me to get the pixel dimensions of an image in JPG, PNG or GIF format in Delphi 7 Personal. Obviously I can load a JPG into a TImage with AutoSize=true and check the size of the TImage afterwards, but that won't work with PNG or GIF. Any ideas? Loading the entire image to know its size is overkill. Just find out the file format, load the first sixteen bytes or so, and get the ones that are the size. It's not as easy, but it saves rather a lot on bloat if you're not otherwise loading the entire image. Groetjes, Maarten Wiltink Back to top Dodgy Guest Posted: Thu Jan 27, 2005 3:07 pm    Post subject: Re: Get size of an image On 27 Jan 2005 03:35:46 -0800, [email]qscomputing (AT) gmail (DOT) com[/email] (QS Computing) waffled on about something: Quote: I'm looking for some code that will allow me to get the pixel dimensions of an image in JPG, PNG or GIF format in Delphi 7 Personal. Obviously I can load a JPG into a TImage with AutoSize=true and check the size of the TImage afterwards, but that won't work with PNG or GIF. Any ideas? Thanks, - QS Computing. Do as Maarten suggests. The file format specs can be found via www.wotsit.org Basically a GIF will always have GIF as the first 3 chars of the file. Followed by the version number of the GIF format. This doesn't matter though, as the width/height are always in the same place IIRC. The width is at offset 6,7 (low byte high byte) The height is at offset 8,9 (low/high) The jpeg mehod is a little trickier. Add efg to your delphi bookmarks. http://www.efg2.com/Lab/Library/Delphi/Graphics/FileFormatsAndConversion.htm D0d6y. -- MUSHROOMS ARE THE OPIATE OF THE MOOSES Back to top qscomputing@gmail.com Guest Posted: Thu Jan 27, 2005 6:50 pm    Post subject: Re: Get size of an image @Dodgy: OK, so how do I read the binary data in a file like this? Back to top Maarten Wiltink Guest Posted: Thu Jan 27, 2005 8:59 pm    Post subject: Re: Get size of an image <qscomputing (AT) gmail (DOT) com> wrote Quote: @Dodgy: OK, so how do I read the binary data in a file like this? Do you mind terribly if I butt in? Using a TFileStream, you can Seek to the right place and ReadBuffer straight into a variable. Using an untyped file, BlockRead those sixteen bytes into a buffer and Move bytes into the same variable. Using a typed file (for which you need to declare a record type), you can read those same sixteen bytes, or however many, into a record type variable and have the interesting bits (bytes) available as fields in it. Groetjes, Maarten Wiltink Back to top QS Computing Guest Posted: Fri Jan 28, 2005 11:30 am    Post subject: Re: Get size of an image Quote: Do you mind terribly if I butt in? <g> Not at all! I looked at the page on efg and found a sample program that reads header information from JPEGs. I think I can adapt this just to read the info I'm looking for and to read the width and height from a GIF. Now the problem I have is with PNG. I looked on wotsit.org and couldn't find anything useful? Any suggestions? TIA, - QS Computing. Back to top Maarten Wiltink Guest Posted: Fri Jan 28, 2005 6:48 pm    Post subject: Re: Get size of an image "QS Computing" <qscomputing (AT) gmail (DOT) com> wrote Quote: Do you mind terribly if I butt in? g> Not at all! I looked at the page on efg and found a sample program that reads header information from JPEGs. I think I can adapt this just to read the info I'm looking for and to read the width and height from a GIF. Now the problem I have is with PNG. I looked on wotsit.org and couldn't find anything useful? http://www.libpng.org/pub/png/spec/1.2/PNG-Contents.html Groetjes, Maarten Wiltink Back to top QS Computing Guest Posted: Fri Jan 28, 2005 10:45 pm    Post subject: Re: Get size of an image OK, I've tried out some code for JPEGs that works fine. Then, using the info from Wotsit's Format, I've tried to edit the code to read from a GIF, but it isn't working. I think I'm just reading in the wrong place, but I'm not sure. (code below) Any suggestions? TIA, - QS Computing. Code is as follows (trimmed): inferface .... type ByteRA = array [1..1] of byte; Bytep = ^ByteRA; .... implementation function GetFileSize(AFileName: string): integer; var FileStream: TFileStream; begin try FileStream:=TFileStream.Create(AFileName, fmOPENREAD + fmSHAREDENYNONE); Result:=FileStream.Size; FileStream.Free(); except Result:=(-1); end; end; function ReadWord(const lRawRA: byteP; lRawPos: integer): word; var lbtL1, lbtL2: byte; begin lbtL1 := lRawRA[lRawPos]; Inc(lRawPos); lbtL2 := lRawRA[lRawPos]; Result := (256 * lbtL1 + lbtL2) end; procedure GetJPEGDimensions(AFileName: string; var Width, Height, FileSize: integer); var Size: integer; RawRA: byteP; InFile: file; begin Size:=GetFileSize(AFileName); try AssignFile(InFile, AFileName); Reset(InFile, 1); GetMem(RawRA, 170); BlockRead(InFile, RawRA^, 170); CloseFile(InFile); Height:=ReadWord(RawRA, 164); Width:=ReadWord(RawRA, 166); FileSize:=Size; FreeMem(RawRA); except FileSize:=(-1); Width:=(-1); Height:=(-1); end; end; procedure GetGIFDimensions(AFileName: string; var Width, Height, FileSize: integer); var Size: integer; RawRA: byteP; InFile: file; begin Size:=GetFileSize(AFileName); try AssignFile(InFile, AFileName); Reset(InFile, 1); GetMem(RawRA, 20); BlockRead(InFile, RawRA^, 20); CloseFile(InFile); Width:=ReadWord(RawRA, 6); Height:=ReadWord(RawRA, ; FileSize:=Size; FreeMem(RawRA); except FileSize:=(-1); Width:=(-1); Height:=(-1); end; end; Back to top J French Guest Posted: Sat Jan 29, 2005 8:02 am    Post subject: Re: Get size of an image On 28 Jan 2005 14:45:10 -0800, "QS Computing" <qscomputing (AT) gmail (DOT) com> wrote: Quote: OK, I've tried out some code for JPEGs that works fine. Then, using the info from Wotsit's Format, I've tried to edit the code to read from a GIF, but it isn't working. I think I'm just reading in the wrong place, but I'm not sure. (code below) Any suggestions? TIA, - QS Computing. Code is as follows (trimmed): Ouch Why don't you simply read the header of the file into a Record directly from the TFileStream ? Back to top QS Computing Guest Posted: Sat Jan 29, 2005 9:47 am    Post subject: Re: Get size of an image J French wrote on Saturday 29 Jan 2005 08:02: Quote: Why don't you simply read the header of the file into a Record directly from the TFileStream ? Could you tell me how to do this please, or point me to some useful info on the web. Sorry if I seem like a newbie here - I haven't programmed anything like this before! -- QS Computing http://www.qscomputing.plus.com [email]postmaster (AT) qscomputing (DOT) plus.com[/email] Back to top J French Guest Posted: Sat Jan 29, 2005 11:08 am    Post subject: Re: Get size of an image On Sat, 29 Jan 2005 09:47:18 +0000, QS Computing <postmaster (AT) qscomputing (DOT) plus.com> wrote: Quote: J French wrote on Saturday 29 Jan 2005 08:02: Why don't you simply read the header of the file into a Record directly from the TFileStream ? Could you tell me how to do this please, or point me to some useful info on the web. I could see that one coming ! Here you go, I've not bothered with error handling or checking that it really is a GIF file Type TGifHeader = Packed Record Sig :Array[0 ..2] Of Char; Ver :Array[0 ..2] Of Char; PixW :WORD; PixH :WORD; End; Function GifStats( Const FileSpec :String ; Var PixW, PixH, FileSize :Integer ):Boolean; Var FS :TFileStream; HeaderRec :TGifHeader; Begin Result := False; If Not FileExists( FileSpec ) Then Exit; // FS := TFileStream.Create( FileSpec, fmOpenRead Or fmShareDenyNone ); FileSize := FS.Size; FS.Read( HeaderRec, SizeOf( HeaderRec ) ); FS.Free; // See what we have read ShowMessage( HeaderRec.Sig + #13 + HeaderRec.Ver ); PixW := HeaderRec.PixW; PixH := HeaderRec.PixH; Result := True; End; procedure TForm1.Button1Click(Sender: TObject); Var W, H, FileSize :Integer; begin If Not GifStats( 'c:downloadlogo.gif', W, H, FileSize ) Then Begin ShowMessage( 'Check file name' ); Exit; // Function Failed End; // ShowMessage( IntToStr(W) + ' ' + IntToStr(H) + #13 + IntToStr(FileSize) ); end; ====================================== Ok, getting the file size like that is Ok, but it is a PITA to open a file if one just wants to get its size - also it is asking for problems if the file is locked Here is how I do it :- Function FileLen( Fle:String ):Integer; var L9 : Integer; Handle: THandle; FindData: TWin32FindData; begin Result := -1; { Check for '*' and '?' } For L9 := 1 To Length( Fle ) Do If ( Fle[L9] = '*' ) Or ( Fle[L9] = '?' ) Then Exit; Handle := FindFirstFile(PChar(Fle), FindData); if Handle <> INVALID_HANDLE_VALUE then begin Windows.FindClose(Handle); if (FindData.dwFileAttributes and FILE_ATTRIBUTE_DIRECTORY) = 0 then begin Result := FindData.nFileSizeLow ; // Note - Up to 2 Gb Exit; end; end; End; Back to top QS Computing Guest Posted: Mon Jan 31, 2005 11:24 am    Post subject: Re: Get size of an image That's great thanks! Any ideas how to do something similar for PNG? Back to top J French Guest Posted: Mon Jan 31, 2005 2:17 pm    Post subject: Re: Get size of an image On 31 Jan 2005 03:24:45 -0800, "QS Computing" <qscomputing (AT) gmail (DOT) com> wrote: Quote: That's great thanks! Any ideas how to do something similar for PNG? You go off and find me a website with the PNG format - and I'll run up another example I trust you have implemented the method I posted for BMP and JPG The real point is that you need to forget about all the old native Pascal file access stuff - Wurth simply got it wrong - the BCD/Unix (?) people got it right with Streams Those were nicked by MSDOS in (IRRC) MSDOS 3.0 (?? 2.1 ??) when they augmented File Control Blocks with something a lot less block headed. It all goes back to the very old days when programmers were acutely aware of the physical layout of the disk drives. Learn about TStream - and you'll be impressed by how well the concept has been implemented in Delphi Back to top Maarten Wiltink Guest Posted: Mon Jan 31, 2005 2:30 pm    Post subject: Re: Get size of an image "J French" <erewhon (AT) nowhere (DOT) uk> wrote Quote: On 31 Jan 2005 03:24:45 -0800, "QS Computing" wrote: Any ideas how to do something similar for PNG? You go off and find me a website with the PNG format - and I'll run up another example I posted a link to one. PNG is fairly easy at this level; an eight-byte file header followed by several chunks. The first chunk is always IHDR and starts with a four-byte header ("IHDR") and image size as two signed 32-bit integers. (All this IIRC.) [...] Quote: The real point is that you need to forget about all the old native Pascal file access stuff - Wurth simply got it wrong Who is this Wurth character? Wirth's design for Pascal I/O wasn't all that bad if you see it as a platform-independent abstraction of punch card I/O. Which it was. Groetjes, Maarten Wiltink Back to top Marco van de Voort Guest Posted: Mon Jan 31, 2005 2:56 pm    Post subject: Re: Get size of an image On 2005-01-31, J French <erewhon (AT) nowhere (DOT) uk> wrote: Quote: On 31 Jan 2005 03:24:45 -0800, "QS Computing" wrote: That's great thanks! Any ideas how to do something similar for PNG? You go off and find me a website with the PNG format - and I'll run up another example No need, see the fpimage collection: http://www.freepascal.org/cgi-bin/viewcvs.cgi/fpc/fcl/image/ Free (LGPL), used enough to be sure that it works. Quote: The real point is that you need to forget about all the old native Pascal file access stuff - Wurth simply got it wrong Assuming you mean Wirth. What exactly did he get wrong. Quote: - the BCD/Unix (?) people got it right with Streams BCD=BSD I assume. BSD doesn't have streams, and SysV OS level streams are different from application streams. Quote: Those were nicked by MSDOS in (IRRC) MSDOS 3.0 (?? 2.1 ??) when they augmented File Control Blocks with something a lot less block headed. POSIX read/write are exactly the same in functionality as blockread/write. The only artefact is the default size of an untyped file. So what are you actually trying to say? Quote: Learn about TStream - and you'll be impressed by how well the concept has been implemented in Delphi Dog slow for large amounts of data, unless you buffer, and then the result is the same as blockread/write (what TStream calls internally probably anyway) Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         BorlandTalk.com Forum Index -> comp.lang.pascal.delphi.misc All times are GMT Goto page 1, 2, 3  Next Page 1 of 3   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.