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To report bugs or for general questions on the JPEG components
please send an EMail to
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or
look at our forums. Please do not try and phone as we do not provide telephone support.
When new upgrades are released, our policy so far has
been to let all registered users know by EMail and to provide free upgrades.
We do, however, reserve the right to charge for a major upgrade.
Issues and Known Problems
| | Problem | Fixed in | | 1. | The data aware control does not support use in a DB control grid.
This is because special support is required by the VCL for this
feature that is in addition to that normally required for data aware
controls. This will be added in the next update. | 1.6 | | 2. | If a corrupt JPEG image is found when decompressing a jpeg file
via the TImage.Picture.LoadFromFile method, then decompression of
a subsequent image may result in an access violation. This is caused
by too many recovery actions being placed in the same try..finally
clause. This will be fixed in the next release. | 1.6 | | 3. | If an exception occurs in when processing a user provided OnProgressReport
event handler, the jpeg Abort method is not called, resulting in
an error being reported on the next call to the JPEG compressor/decompressor
- although any further calls are unaffected. This will be fixed
in the next release. | 1.6 | | 4. | A memory leak may be detected when decompressing JPEG's using
the TJPEGFileDecompressor's LoadPictureFromFile, LoadPictureFromStream,
LoadPictureFromResource methods. These methods are also used by
the data aware JPEG control but not by the TJPEGBitmap class that
is used for decompressing JPEG's when calling TImage.Picture's LoadFileFile
method. This will be fixed in the next release. | 1.6 | | 5. | In the Delphi 4 version, the error message "image too wide
for this implementation" may be generated when saving a metafile
to a jpeg image. This only occurs when the compiler is running without
optimisation and is due to a bug in the code generation process.This
will be fixed in the next release. | 1.6 | | 6. | Error message: "Improper Call
to JPEG library in state 205" when using the data
aware JPEG control and trying to replace a picture by calling Picture.LoadFromFile
or similar . This is caused by a race condition between the DBGrid
refreshing its images (and calling the JPEG decompressor to do this)
and separately calling the JPEG decompressor to load an image. To
avoid this problem the TDBJPEGImage in a DBGrid must use a dedicated
JPEG decompressor and not share it with any other purpose.
However, the current library does not allow this to readily be
done because when you call TPicture.LoadFromFile (or similar)
the code will choose an existing decompressor object (if available)
and call that to do the decompression. Generally this is the most
efficient way to work but causes the above problem.
To allow this problem to be fixed in a deterministic manner,
the JPEG decompression object needs a new property (DefaultDecompressor).
Only when this property is set to true will it be a candidate
for use by TPicture.LoadFromFile. This will ensure that a JPEG
decompressor can be exclusively used by a TDBJPEGImage. | 1.7 | | 7. | C++Builder Update 1: We have had reports of an
included unit conflict when compiling applications that use the
JPEG Component Library under C++Builder Update 1 - the error message
usually refers to a unit called "outline" that is present
in too many .bpl files. It seems that Borland may have re-organised
some of the library dependencies and which is causing this problem.
Registered users can avoid this problem by undertaking the following
procedure:
- From the Component|Install dialog, remove the current "MWA
JPEG Component Library".
- From File|Open, open the "mwajpgc4.bpk" file that
should be found in your JPEG directory. The "Install Package"
dialog box should now appear.
- Click on the install button. The install should fail but C++Builder
will offer to update the package file to contain the correct
dependencies. Click on "OK" to do this and then click
on the install button again. The package should now be installed
correctly and the JPEG component library should now work correctly.
If there is any problem in the build process, it's probably due
to not having the library path set up correctly. Refer to the
original installation instructions to set up the library path. | 1.7 |
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