[Kst] Progress indication when loading from file...

[Nicolas Brisset]

Hi,

I've been looking at this issue that there was no longer any progress feedback when loading a .kst file.
As already discussed here, I am not sure what we should do with this progress status. What I had first implemented was simple:
- progress bar from 0 to 100 % while parsing lines (slow)
- status message for each variable being read (fairly fast for each variable)
I found it sufficient and it had the benefit that it didn't require too many API changes.

Now Peter went one step further and extended the datasource vector API with a prepareRead(int) method informing the datasource how many vectors will be read, and the first 50 % of the progress bar correspond to the line parsing step, the rest being vector loading. The issue I have with that is that it works well only when using the datawizard, not the other dialogs used to create a datasource (loading from file, change data file, create vector).
In the past I had got it to work for all by connecting the progress signal to the status bar from the datasourcepluginfactory. I got it to work again by adding a dummy call to prepareRead() as follows. The issue is that at this stage the code does not have any idea how many vectors will be read.

diff --git a/src/libkstapp/datasourcepluginfactory.cpp b/src/libkstapp/datasourcepluginfactory.cpp
index 63f641e..a476213 100644
--- a/src/libkstapp/datasourcepluginfactory.cpp
+++ b/src/libkstapp/datasourcepluginfactory.cpp
@@ -80,6 +80,7 @@ DataSourcePtr DataSourcePluginFactory::generateDataSource(ObjectStore *store, QX
     dataSource = DataSourcePluginManager::loadSource(store, fileName, fileType);
     if (dataSource) {
       QObject::connect(dataSource, SIGNAL(progress(int,QString)), kstApp->mainWindow(), SLOT(updateProgress(int,QString)));
+      dataSource->vector().prepareRead(0);
       dataSource->parseProperties(propertyAttributes);
       if (fileName != alternate_filename) {
         dataSource->setAlternateFilename(alternate_filename);

So now my question: what should we do?
1) Add the above call, where 50% does not really mean 50%
2) Put the call elsewhere to cover all cases where a datasource is created
3) Modify the code so that prepareRead(-1) means "I don't know how many vectors will be read" and then we scale the progress differently
4) Revert to the previous "naive" approach of indicating line parsing progress with the bar and the vector reading with only a status message

Thoughts?

Nicolas

P.S.: I'm getting worried about the complexity of the ASCII source... We have to be careful to keep it maintainable!