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Dive pictures: Introduce thumbnailer class

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Create a new class, which performs all thumbnailing code.
This is mostly code reshuffling. Thumbnails are extracted
either from a cache or thumbnail calculation is started in
a worker thread.

Since getHashedImage() is called from a worker thread it
makes no sense to call subfunctions in yet another worker
thread. Remove these calls.

In contrast to the previous code, on error the background
thread produces a failure image, but it is not yet shown.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
This commit is contained in:
Berthold Stoeger 2018-03-10 14:15:50 +01:00 • committed by Dirk Hohndel
parent f60343eebb
commit 3967b1fd4d
4 changed files with 141 additions and 68 deletions
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68
qt-models/divepicturemodel.cpp
View file

@ -5,73 +5,11 @@
#include "core/divelist.h"
#include "core/imagedownloader.h"
#include "core/qthelper.h"
#include "core/metadata.h"
#include <QtConcurrent>
#include <QFileInfo>
static const int maxZoom = 3; // Maximum zoom: thrice of standard size
static QImage getThumbnailFromCache(const PictureEntry &entry)
{
// First, check if we know a hash for this filename
QString filename = thumbnailFileName(entry.filename);
if (filename.isEmpty())
return QImage();
QFile file(filename);
if (!file.open(QIODevice::ReadOnly))
return QImage();
QDataStream stream(&file);
// Each thumbnail file is composed of a media-type and an image file.
// Currently, the type is ignored. This will be used to mark videos.
quint32 type;
QImage res;
stream >> type;
stream >> res;
return res;
}
static void addThumbnailToCache(const QImage &thumbnail, const PictureEntry &entry)
{
if (thumbnail.isNull())
return;
QString filename = thumbnailFileName(entry.filename);
// If we got a thumbnail, we are guaranteed to have its hash and therefore
// thumbnailFileName() should return a filename.
if (filename.isEmpty()) {
qWarning() << "Internal error: can't get filename of recently created thumbnail";
return;
}
QSaveFile file(filename);
if (!file.open(QIODevice::WriteOnly))
return;
QDataStream stream(&file);
// For format of the file, see comments in getThumnailForCache
quint32 type = MEDIATYPE_PICTURE;
stream << type;
stream << thumbnail;
file.commit();
}
static void scaleImages(PictureEntry &entry, int maxSize)
{
QImage thumbnail = getThumbnailFromCache(entry);
// If thumbnails were written by an earlier version, they might be smaller than needed.
// Rescale in such a case to avoid resizing artifacts.
if (thumbnail.isNull() || (thumbnail.size().width() < maxSize && thumbnail.size().height() < maxSize)) {
qDebug() << "No thumbnail in cache for" << entry.filename;
thumbnail = getHashedImage(QString(entry.picture->filename));
addThumbnailToCache(thumbnail, entry);
}
entry.image = thumbnail;
}
DivePictureModel *DivePictureModel::instance()
{
static DivePictureModel *self = new DivePictureModel();
@ -121,7 +59,8 @@ void DivePictureModel::updateThumbnails()
{
int maxSize = defaultSize * maxZoom;
updateZoom();
QtConcurrent::blockingMap(pictures, [maxSize](PictureEntry &entry){scaleImages(entry, maxSize);});
for (PictureEntry &entry: pictures)
entry.image = Thumbnailer::instance()->fetchThumbnail(entry, maxSize);
}
void DivePictureModel::updateDivePictures()
@ -131,6 +70,7 @@ void DivePictureModel::updateDivePictures()
pictures.clear();
endRemoveRows();
rowDDStart = rowDDEnd = 0;
Thumbnailer::instance()->clearWorkQueue();
}
// if the dive_table is empty, quit