Fixes: N#121 - Thumbnails should be cached on disk

This implementation has a number of issues,  but the base functionality now
works. New bugs will be raised.

dirmodel.cpp

@@ -159,7 +159,7 @@ QVariant DirModel::data(const QModelIndex &index, int role) const
 
             if (fileName.endsWith(".jpg") ||
                 fileName.endsWith(".png")) {
-                return QUrl::fromLocalFile(fi.filePath());
+                return "image://nemoThumbnail/" + fi.filePath();
             }
 
             if (fi.isDir())

filethumbnailprovider.cpp

@@ -0,0 +1,114 @@
+/*
+ * Copyright (C) 2012 Robin Burchell <robin+nemo@viroteck.net>
+ *
+ * You may use this file under the terms of the BSD license as follows:
+ *
+ * "Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *   * Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in
+ *     the documentation and/or other materials provided with the
+ *     distribution.
+ *   * Neither the name of Nemo Mobile nor the names of its contributors
+ *     may be used to endorse or promote products derived from this
+ *     software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+ */
+
+#include <QFile>
+#include <QCryptographicHash>
+#include <QDebug>
+#include <QDesktopServices>
+#include <QDir>
+#include <QImageReader>
+
+#include "filethumbnailprovider.h"
+
+QImage FileThumbnailImageProvider::requestImage(const QString &id, QSize *size, const QSize &requestedSize)
+{
+    QSize actualSize;
+
+    if (requestedSize.isValid())
+        actualSize = requestedSize;
+    else
+        actualSize = QSize(64, 64);
+
+    if (size)
+        *size = actualSize;
+
+    qDebug() << Q_FUNC_INFO << "Requested image: " << id;
+    QByteArray baId = id.toLatin1(); // is there a more efficient way than a copy?
+
+    // check if we have it in cache
+    QCryptographicHash hash(QCryptographicHash::Sha1);
+
+    hash.addData(baId.constData(), baId.length());
+    QByteArray hashData = hash.result().toHex() + "nemo";
+
+    QString cachePath = QDesktopServices::storageLocation(QDesktopServices::CacheLocation) + ".nemothumbs";
+
+    // the syscalls make baby jesus cry; but this protects us against sins like users
+    QDir d(cachePath);
+    if (!d.exists())
+        d.mkpath(cachePath);
+    if (!d.exists("raw"))
+        d.mkdir("raw");
+
+    // in the future, we might store a nicer UI version which can blend in with our UI better, but
+    // we'll always want the raw version.
+
+    QFile fi(cachePath + QDir::separator() + "raw" + QDir::separator() + hashData);
+    if (fi.exists() && fi.open(QIODevice::ReadOnly)) {
+        // cached file exists! hooray.
+        qDebug() << Q_FUNC_INFO << "Read " << id << " from cache";
+        QImage img;
+        img.load(&fi, "JPG");
+        qDebug() << img.size();
+        return img;
+    } else {
+        // slow path: read image in, scale it, write to cache, return it
+        QImageReader ir(id);
+        QImage img = ir.read();
+        if (img.size() != actualSize) {
+            // TODO: we should probably handle cropping here too to get better results
+            qDebug() << Q_FUNC_INFO << "Wrote " << id << " to cache";
+            img = img.scaled(actualSize, Qt::KeepAspectRatio, Qt::SmoothTransformation);
+
+            if (fi.open(QIODevice::WriteOnly)) {
+                img.save(&fi, "JPG");
+                fi.flush();
+                fi.close();
+            } else {
+                qWarning() << "Couldn't cache " << id << " to " << fi.fileName();
+            }
+
+            return img;
+        } else {
+            return img;
+        }
+    }
+
+    // should be unreachable
+    Q_ASSERT(false);
+    return QImage();
+
+//    QImage pixmap(requestedSize.width() > 0 ? requestedSize.width() : actualSize.width(),
+//                  requestedSize.height() > 0 ? requestedSize.height() : actualSize.height());
+//    pixmap.fill(QColor(id).rgba());
+
+//    return pixmap;
+}

filethumbnailprovider.h

@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) 2012 Robin Burchell <robin+nemo@viroteck.net>
+ *
+ * You may use this file under the terms of the BSD license as follows:
+ *
+ * "Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *   * Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in
+ *     the documentation and/or other materials provided with the
+ *     distribution.
+ *   * Neither the name of Nemo Mobile nor the names of its contributors
+ *     may be used to endorse or promote products derived from this
+ *     software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+ */
+
+#ifndef FILETHUMBNAILPROVIDER_H
+#define FILETHUMBNAILPROVIDER_H
+
+#include <QDeclarativeImageProvider>
+
+class FileThumbnailImageProvider : public QDeclarativeImageProvider
+{
+public:
+    FileThumbnailImageProvider()
+        : QDeclarativeImageProvider(QDeclarativeImageProvider::Image)
+    {
+    }
+
+    QImage requestImage(const QString &id, QSize *size, const QSize &requestedSize);
+};
+
+#endif // FILETHUMBNAILPROVIDER_H

main.cpp

@@ -42,6 +42,7 @@
 
 #include "dirmodel.h"
 #include "utils.h"
+#include "filethumbnailprovider.h"
 
 Q_DECLARE_METATYPE(QVector<QFileInfo>)
 
@@ -53,6 +54,9 @@ int main(int argc, char **argv)
 
     QDeclarativeView v;
 
+    QDeclarativeEngine *e = v.engine();
+    e->addImageProvider(QLatin1String("nemoThumbnail"), new FileThumbnailImageProvider);
+
     QDeclarativeContext *c = v.rootContext();
     c->setContextProperty("fileBrowserUtils", new Utils);
 

qmlfilemuncher.pro

@@ -26,7 +26,8 @@ SOURCES += main.cpp \
     iorequestworker.cpp \
     iorequest.cpp \
     dirmodel.cpp \
-    utils.cpp
+    utils.cpp \
+    filethumbnailprovider.cpp
 
 RESOURCES += \
     data.qrc
@@ -36,5 +37,6 @@ HEADERS += \
     iorequestworker.h \
     iorequest.h \
     dirmodel.h \
-    utils.h
+    utils.h \
+    filethumbnailprovider.h