Qt: threaded grid image loading

Makefile.common

@@ -338,9 +338,9 @@ OBJ += ui/drivers/ui_qt.o \
 MOC_HEADERS += ui/drivers/ui_qt.h \
 							 ui/drivers/qt/ui_qt_load_core_window.h
 
-DEFINES += $(QT5CORE_CFLAGS) $(QT5GUI_CFLAGS) $(QT5WIDGETS_CFLAGS) -DHAVE_MAIN
+DEFINES += $(QT5CORE_CFLAGS) $(QT5GUI_CFLAGS) $(QT5WIDGETS_CFLAGS) $(QT5CONCURRENT_CFLAGS) -DHAVE_MAIN
 #DEFINES += $(QT5WEBENGINE_CFLAGS)
-LIBS += $(QT5CORE_LIBS) $(QT5GUI_LIBS) $(QT5WIDGETS_LIBS)
+LIBS += $(QT5CORE_LIBS) $(QT5GUI_LIBS) $(QT5WIDGETS_LIBS) $(QT5CONCURRENT_LIBS)
 #LIBS += $(QT5WEBENGINE_LIBS)
 NEED_CXX_LINKER = 1
 

qb/config.libs.sh

@@ -276,14 +276,16 @@ if [ "$HAVE_QT" != 'no' ] && [ "$MOC_PATH" != 'none' ]; then
    check_pkgconf QT5CORE Qt5Core 5.2
    check_pkgconf QT5GUI Qt5Gui 5.2
    check_pkgconf QT5WIDGETS Qt5Widgets 5.2
+   check_pkgconf QT5CONCURRENT Qt5Concurrent 5.2
    #check_pkgconf QT5WEBENGINE Qt5WebEngine 5.4
 
    check_val '' QT5CORE -lQt5Core QT5CORE
    check_val '' QT5GUI -lQt5Gui QT5GUI
    check_val '' QT5WIDGETS -lQt5Widgets QT5WIDGETS
+   check_val '' QT5CONCURRENT -lQt5Widgets QT5CONCURRENT
    #check_val '' QT5WEBENGINE -lQt5WebEngine QT5WEBENGINE
 
-   if [ "$HAVE_QT5CORE" = "no" ] || [ "$HAVE_QT5GUI" = "no" ] || [ "$HAVE_QT5WIDGETS" = "no" ]; then
+   if [ "$HAVE_QT5CORE" = "no" ] || [ "$HAVE_QT5GUI" = "no" ] || [ "$HAVE_QT5WIDGETS" = "no" ] || [ "$HAVE_QT5CONCURRENT" = "no" ]; then
       die : 'Notice: Not building Qt support, required libraries were not found.'
       HAVE_QT=no
    else

ui/drivers/qt/ui_qt_window.cpp

@@ -29,6 +29,7 @@
 #include <QMenu>
 #include <QDockWidget>
 #include <QList>
+#include <QtConcurrentRun>
 
 #include "../ui_qt.h"
 #include "ui_qt_load_core_window.h"
@@ -101,6 +102,16 @@ static void scan_finished_handler(void *task_data, void *user_data, const char *
 }
 #endif
 
+GridItem::GridItem() :
+   widget(NULL)
+   ,label(NULL)
+   ,hash()
+   ,image()
+   ,pixmap()
+   ,imageWatcher()
+{
+}
+
 TreeView::TreeView(QWidget *parent) :
    QTreeView(parent)
 {
@@ -2753,6 +2764,29 @@ void MainWindow::removeGridItems()
    }
 }
 
+void MainWindow::onDeferredImageLoaded()
+{
+   const QFutureWatcher<GridItem*> *watcher = static_cast<QFutureWatcher<GridItem*>*>(sender());
+   GridItem *item = watcher->result();
+
+   if (!item->image.isNull())
+      item->label->setPixmap(QPixmap::fromImage(item->image));
+}
+
+void MainWindow::loadImageDeferred(GridItem *item, QString path)
+{
+   connect(&item->imageWatcher, SIGNAL(finished()), this, SLOT(onDeferredImageLoaded()), Qt::QueuedConnection);
+   item->imageWatcher.setFuture(QtConcurrent::run<GridItem*>(this, &MainWindow::doDeferredImageLoad, item, path));
+}
+
+GridItem* MainWindow::doDeferredImageLoad(GridItem *item, QString path)
+{
+   /* this runs in another thread */
+   item->image = QImage(path);
+
+   return item;
+}
+
 void MainWindow::addPlaylistItemsToGrid(QString pathString)
 {
    QList<QHash<QString, QString> > items = getPlaylistItems(pathString);
@@ -2764,7 +2798,6 @@ void MainWindow::addPlaylistItemsToGrid(QString pathString)
       const QHash<QString, QString> &hash = items.at(i);
       GridItem *item = new GridItem();
       ThumbnailLabel *label = NULL;
-      QPixmap pixmap;
       QString thumbnailFileNameNoExt;
       QLabel *newLabel = NULL;
 
@@ -2779,9 +2812,7 @@ void MainWindow::addPlaylistItemsToGrid(QString pathString)
 
       label = new ThumbnailLabel(item->widget);
 
-      pixmap = QPixmap(QString(settings->paths.directory_thumbnails) + "/" + hash.value("db_name") + "/" + THUMBNAIL_BOXART + "/" + thumbnailFileNameNoExt + ".png");
+      item->label = label;
-
-      label->setPixmap(pixmap);
 
       item->widget->layout()->addWidget(label);
 
@@ -2793,6 +2824,8 @@ void MainWindow::addPlaylistItemsToGrid(QString pathString)
 
       m_gridLayout->addWidget(item->widget);
       m_gridItems.append(item);
+
+      loadImageDeferred(item, QString(settings->paths.directory_thumbnails) + "/" + hash.value("db_name") + "/" + THUMBNAIL_BOXART + "/" + thumbnailFileNameNoExt + ".png");
    }
 }
 

ui/drivers/ui_qt.h

@@ -28,6 +28,8 @@
 #include <QRegularExpression>
 #include <QPalette>
 #include <QPlainTextEdit>
+#include <QFutureWatcher>
+#include <QImage>
 
 extern "C" {
 #include <retro_common_api.h>
@@ -58,12 +60,19 @@ class QScrollArea;
 class LoadCoreWindow;
 class MainWindow;
 class ThumbnailWidget;
+class ThumbnailLabel;
 class FlowLayout;
 
 struct GridItem
 {
+   GridItem();
+
    ThumbnailWidget *widget;
+   ThumbnailLabel *label;
    QHash<QString, QString> hash;
+   QImage image;
+   QPixmap pixmap;
+   QFutureWatcher<GridItem*> imageWatcher;
 };
 
 class ThumbnailWidget : public QWidget
@@ -255,6 +264,7 @@ public:
    bool setCustomThemeFile(QString filePath);
    void setCustomThemeString(QString qss);
    const QString& customThemeString() const;
+   GridItem* doDeferredImageLoad(GridItem *item, QString path);
 
 signals:
    void thumbnailChanged(const QPixmap &pixmap);
@@ -309,6 +319,7 @@ private slots:
    void onFileBrowserTreeContextMenuRequested(const QPoint &pos);
    void onPlaylistWidgetContextMenuRequested(const QPoint &pos);
    void onStopClicked();
+   void onDeferredImageLoaded();
 
 private:
    void setCurrentCoreLabel();
@@ -316,6 +327,7 @@ private:
    bool isCoreLoaded();
    bool isContentLessCore();
    void removeGridItems();
+   void loadImageDeferred(GridItem *item, QString path);
    QList<QHash<QString, QString> > getPlaylistItems(QString pathString);
 
    LoadCoreWindow *m_loadCoreWindow;