824c594816
git-svn-id: https://svn.code.sf.net/p/lazarus-ccr/svn@6090 8e941d3f-bd1b-0410-a28a-d453659cc2b4
112 lines
3.8 KiB
Plaintext
112 lines
3.8 KiB
Plaintext
================================================================================
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fpexif
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================================================================================
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Overview
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fpexif is an fpc/Lazarus library for displaying and manipulating meta data in
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image files.
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fpexif works without the LCL.
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Meta data systems supported are
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- EXIF (including thumbnail, GPS, and manufacturer notes (partially) )
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- IPTC
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Image formats
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- JPEG
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- TIFF
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The majority of meta data tags can be modified and written back to file. It
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should be emphasized, however, that the EXIF maker notes are poorly documented
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and often become unreadable after editing an EXIF structure.
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Some examples in which fpexif can be applied:
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- add user comments, keywords and other documentation
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- fix date/time information (incorrect time/zone at camera when travelling
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in foreign countries)
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- adding GPS information to scanned photographs
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- remember exposure settings of difficult photos
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- extract thumbnails for a super-fast thumbnail viewer
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Quick introduction
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The basic class is TImgInfo (in unit fpeMetaData). It has properties to read
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meta data from file/stream (LoadFromFile, LoadFromStream) and to write them
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back (SaveToFile).
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EXIF data found in the file are stored by the object ExifData from which every
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tag can be acessed as TagByID[ATagID: TTagID] or TagByName[AName: String].
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(TTagID is a DWord value containing the numerical ID of a tag in the low-word,
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and the ID of the "directory" to which the tag belongs in the highword.)
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The properties TagByID and TagByName return a TTag instance in which the tag
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value is stored. The type of the value depends on the type of the tag and can
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be accessed by calling AsString, AsInteger, Asfloat, AsIntegerArray,
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AsFloatArray etc. TTag is declared in unit fpeTags.
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Example
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Read meta data from a file, write a particular tag, modify a tag, write back.
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See also "console_demo".
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uses
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fpeMetadata, fpeTags;
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var
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imgInfo: TImgInfo;
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tag: TTag;
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begin
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imgInfo := TImgInfo.Create;
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try
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// Read file
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imgInfo.LoadFromFile('MyImage.jpg');
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// Check for EXIF meta data
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if imgInfo.HasEXIF then begin
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// Read the shutter speed used when taking an image from EXIF data
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WriteLn(
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'ShutterSpeed: ',
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imgInfo.ExifData.TagByName['ShutterSpeed'].AsString
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);
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// or better (to avoid the exception if this particular tag does not exist):
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tag := imgInfo.ExifData.TagByName['ShutterSpeed'];
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if tag <> nil then WriteLn('ShutterSpeed: ', tag.AsString);
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// Add a user comment to the EXIF data
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imgInfo.ExifData.TagByName['UserComment'].AsString := 'My best photo';
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// Save the modified meta data to file
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imgInfo.SaveToFile('MyImage_edited.jpg');
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// or: imgInfo.Save; // overwrite currently loaded file
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end;
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finally
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imgInfo.Free;
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end;
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end;
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Tested systems
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* Lazarus 1.0/fpc 2.6.0 up to Lazarus 1.9/fpc 3.0.4
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* Delphi 7.0
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* Delphi XE2
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* Delphi 10.2 Tokyo
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--------------------------------------------------------------------------------
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License
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--------------------------------------------------------------------------------
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Modified LGPL (like Lazarus)
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