Review Request: Internal viewer: improve handling of unknown MIME types

[Raphael Kubo da Costa]

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I like the idea of the patch, but some issues need to be solved first:

 - The coding style issues:
   - if (foo) bar();
     needs to become
     if (foo) {
         bar();
     }
     as we follow kdelibs' coding style.
   - Single-letter variable names (such as `s') should be avoided.
   - Aren't "mime" and "type" separate words? If so, camel-casing them as such (`mimeType' instead of `mimetype') makes sense.
   - The code won't compile in master without some calls to QLatin1String.

 - The code solving the TODO item about the dialog size should go into a separate review request/commit.

 - I had not noticed we probe the file for its mimetype in so many places. My suggestion: determine the file's mimetype once in ArkViewer::view() and turn ArkViewer::getViewer(const QString &filename) into ArkViewer::getViewer(const KMimeType::Ptr &mimeType). The `asMimetype' argument you added to ArkViewer::viewInInternalViewer() can then be made mandatory, saving us another KMimeType::find*() call.

 - The changes in ArkViewer::view() could check whether an external viewer is needed first and save some indentation and logic in the rest of the method. The logic would look like this:

   void ArkViewer::view(...)
   {
       // Determine mimetype, call getViewer().

       const bool needsExternalViewer = (!viewer.isNull()) && (viewer->hasServiceType(QL1S("KParts/ReadOnlyPart")));
       if (needsExternalViewer) {
           // Call the KRun::run/runUrl() code, yadda yadda.
           return;
       }

       bool viewInInternalViewer = true;
       if (viewer.isNull()) {
           // Ask the user if the file should be previewed as text/plain
           if (response == KMessageBox::Cancel) {
               viewInInternalViewer = false;
           }
       }

       if (viewInInternalViewer) {
           // The ArkViewer::viewInInternalViewer() dance.
       }

       QFile::remove(...);
   }



part/arkviewer.cpp
<http://git.reviewboard.kde.org/r/103110/#comment7657>

    - It'd be good to use i18nc() here to give translators some context.
    - Semantic markup would be good too.
    - Don't you need to close the <qt> tag (if it is needed at all)?
    - I feel that information such as the mimetype should be kept away from the user, or at most visible in a "more details" part of the dialog. Do you have strong feelings for showing the mimetype here?



part/arkviewer.cpp
<http://git.reviewboard.kde.org/r/103110/#comment7656>

    This sounds like a good idea, but it is not directly related to the purpose of this request. I'd rather review it (and have it committed) separately.



part/arkviewer.cpp
<http://git.reviewboard.kde.org/r/103110/#comment7655>

    Does this change from KRun::runUrl bring any benefits?



part/arkviewer.cpp
<http://git.reviewboard.kde.org/r/103110/#comment7654>

    Why have the calls to QFile::remove been changed? It looks like the file is not being removed when it is previewed by the internal viewer anymore?



part/arkviewer.cpp
<http://git.reviewboard.kde.org/r/103110/#comment7653>

    Not needed.



part/arkviewer.cpp
<http://git.reviewboard.kde.org/r/103110/#comment7652>

    Why?


- Raphael Kubo da Costa


On Nov. 11, 2011, 10:02 p.m., Jonathan Marten wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> http://git.reviewboard.kde.org/r/103110/
> -----------------------------------------------------------
> 
> (Updated Nov. 11, 2011, 10:02 p.m.)
> 
> 
> Review request for KDE Utils and Raphael Kubo da Costa.
> 
> 
> Description
> -------
> 
> Archives often contain files which contain and are viewable as plain text, but either resolve to a MIME type that does not have a suitable viewer KPart available, or the default MIME type application/octet-stream.  Trying to view such a file is simply rejected - and there is no "Open with" operation, so it is not easily possible to open the file in KWrite or another application.
> 
> This change gives the user the option, in this case, of viewing the file as plain text - whether this is will result in a sensible display for the file is their decision.  If they want to do that, ArkViewer::viewInInternalViewer() is forced to display the file as text/plain and not to try to detect the MIME type from the file name.
> 
> The size of the internal viewer window is also saved and restored, as per the TODO comment.
> 
> This change does introduce some new GUI strings, so it will not be able to be committed until after the KDE SC 4.8 release.
> 
> 
> Diffs
> -----
> 
>   part/arkviewer.h b810e17 
>   part/arkviewer.cpp 9bfd651 
> 
> Diff: http://git.reviewboard.kde.org/r/103110/diff/diff
> 
> 
> Testing
> -------
> 
> Built ark with these changes, attempted to preview archive file contents for a variety of file types.  The extremely annoying "The internal viewer cannot preview this file" error message is now a thing of the past.
> 
> 
> Thanks,
> 
> Jonathan Marten
> 
>

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