Windows: Introduce QFileDialog::DontUseCustomDirectoryIcons

Folders can have a custom icon, set by the user. Some system
folders also have one, for example c:\windows\fonts.

This option allows you to disable this behavior, you'll get the
folder directory icon.

As a side-effect, you'll get a very big performance improvement
on removable/network media: 2 seconds vs 60 seconds on a SDCard
with 10000 folders.

Change-Id: Id55ea628186e0a6523585ec7a4ff622d6f5da505
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>

4 files changed, 75 insertions, 9 deletions

diff --git a/src/widgets/dialogs/qfiledialog.cpp b/src/widgets/dialogs/qfiledialog.cpp
index e6b6c2b73f..657c8cc7c2 100644
--- a/src/widgets/dialogs/qfiledialog.cpp
+++ b/src/widgets/dialogs/qfiledialog.cpp
@@ -255,6 +255,11 @@ Q_WIDGETS_EXPORT _qt_filedialog_save_file_url_hook qt_filedialog_save_file_url_h
     static functions will always be an application modal dialog. If
     you want to use sheets, use QFileDialog::open() instead.
 
+    \value DontUseCustomDirectoryIcons Always use the default directory icon.
+    Some platforms allow the user to set a different icon. Custom icon lookup
+    cause a big performance impact over network or removable drives.
+    Setting this will enable the QFileIconProvider::DontUseCustomDirectoryIcons
+    option in the icon provider. This enum value was added in Qt 5.2.
 */
 
 /*!
@@ -754,6 +759,15 @@ void QFileDialog::setOptions(Options options)
 
     if (changed & ShowDirsOnly)
         setFilter((options & ShowDirsOnly) ? filter() & ~QDir::Files : filter() | QDir::Files);
+
+    if (changed & DontUseCustomDirectoryIcons) {
+        QFileIconProvider::Options providerOptions = iconProvider()->options();
+        if (options & DontUseCustomDirectoryIcons)
+            providerOptions |= QFileIconProvider::DontUseCustomDirectoryIcons;
+        else
+            providerOptions &= ~QFileIconProvider::DontUseCustomDirectoryIcons;
+        iconProvider()->setOptions(providerOptions);
+    }
 }
 
 QFileDialog::Options QFileDialog::options() const
diff --git a/src/widgets/dialogs/qfiledialog.h b/src/widgets/dialogs/qfiledialog.h
index 2b276be8f1..6b12a00ae6 100644
--- a/src/widgets/dialogs/qfiledialog.h
+++ b/src/widgets/dialogs/qfiledialog.h
@@ -84,13 +84,14 @@ public:
 
     enum Option
     {
-        ShowDirsOnly          = 0x00000001,
-        DontResolveSymlinks   = 0x00000002,
-        DontConfirmOverwrite  = 0x00000004,
-        DontUseSheet          = 0x00000008,
-        DontUseNativeDialog   = 0x00000010,
-        ReadOnly              = 0x00000020,
-        HideNameFilterDetails = 0x00000040
+        ShowDirsOnly                = 0x00000001,
+        DontResolveSymlinks         = 0x00000002,
+        DontConfirmOverwrite        = 0x00000004,
+        DontUseSheet                = 0x00000008,
+        DontUseNativeDialog         = 0x00000010,
+        ReadOnly                    = 0x00000020,
+        HideNameFilterDetails       = 0x00000040,
+        DontUseCustomDirectoryIcons = 0x00000080
     };
     Q_DECLARE_FLAGS(Options, Option)
 
diff --git a/src/widgets/itemviews/qfileiconprovider.cpp b/src/widgets/itemviews/qfileiconprovider.cpp
index b435639390..f03d9fb81b 100644
--- a/src/widgets/itemviews/qfileiconprovider.cpp
+++ b/src/widgets/itemviews/qfileiconprovider.cpp
@@ -83,6 +83,16 @@ QT_BEGIN_NAMESPACE
   \value File
 */
 
+
+/*!
+    \enum QFileIconProvider::Option
+    \since 5.2
+
+    \value DontUseCustomDirectoryIcons Always use the default directory icon.
+    Some platforms allow the user to set a different icon. Custom icon lookup
+    cause a big performance impact over network or removable drives.
+*/
+
 class QFileIconProviderPrivate
 {
     Q_DECLARE_PUBLIC(QFileIconProvider)
@@ -94,6 +104,7 @@ public:
 
     QFileIconProvider *q_ptr;
     const QString homePath;
+    QFileIconProvider::Options options;
 
 private:
     mutable QIcon file;
@@ -193,6 +204,31 @@ QFileIconProvider::~QFileIconProvider()
 }
 
 /*!
+    \since 5.2
+    Sets \a options that affect the icon provider.
+    \sa options()
+*/
+
+void QFileIconProvider::setOptions(QFileIconProvider::Options options)
+{
+    Q_D(QFileIconProvider);
+    d->options = options;
+}
+
+/*!
+    \since 5.2
+    Returns all the options that affect the icon provider.
+    By default, all options are disabled.
+    \sa setOptions()
+*/
+
+QFileIconProvider::Options QFileIconProvider::options() const
+{
+    Q_D(const QFileIconProvider);
+    return d->options;
+}
+
+/*!
   Returns an icon set for the given \a type.
 */
 
@@ -228,6 +264,7 @@ static bool isCacheable(const QFileInfo &fi)
 #ifdef Q_OS_WIN
     // On windows it's faster to just look at the file extensions. QTBUG-13182
     const QString fileExtension = fi.suffix();
+    // Will return false for .exe, .lnk and .ico extensions
     return fileExtension.compare(QLatin1String("exe"), Qt::CaseInsensitive) &&
            fileExtension.compare(QLatin1String("lnk"), Qt::CaseInsensitive) &&
            fileExtension.compare(QLatin1String("ico"), Qt::CaseInsensitive);
@@ -247,7 +284,6 @@ QIcon QFileIconProviderPrivate::getIcon(const QFileInfo &fi) const
     if (sizes.isEmpty())
         return retIcon;
 
-    const QString fileExtension = fi.suffix().toUpper();
     const QString keyBase = QLatin1String("qt_.") + fi.suffix().toUpper();
 
     bool cacheable = isCacheable(fi);
@@ -269,8 +305,12 @@ QIcon QFileIconProviderPrivate::getIcon(const QFileInfo &fi) const
         }
     }
 
+    QPlatformTheme::IconOptions iconOptions;
+    if (options & QFileIconProvider::DontUseCustomDirectoryIcons)
+        iconOptions |= QPlatformTheme::DontUseCustomDirectoryIcons;
+
     Q_FOREACH (int size, sizes) {
-        QPixmap pixmap = theme->fileIconPixmap(fi, QSizeF(size, size));
+        QPixmap pixmap = theme->fileIconPixmap(fi, QSizeF(size, size), iconOptions);
         if (!pixmap.isNull()) {
             retIcon.addPixmap(pixmap);
             if (cacheable)
diff --git a/src/widgets/itemviews/qfileiconprovider.h b/src/widgets/itemviews/qfileiconprovider.h
index cac135fe71..ed270619ed 100644
--- a/src/widgets/itemviews/qfileiconprovider.h
+++ b/src/widgets/itemviews/qfileiconprovider.h
@@ -59,10 +59,19 @@ public:
     QFileIconProvider();
     virtual ~QFileIconProvider();
     enum IconType { Computer, Desktop, Trashcan, Network, Drive, Folder, File };
+
+    enum Option {
+        DontUseCustomDirectoryIcons = 0x00000001
+    };
+    Q_DECLARE_FLAGS(Options, Option)
+
     virtual QIcon icon(IconType type) const;
     virtual QIcon icon(const QFileInfo &info) const;
     virtual QString type(const QFileInfo &info) const;
 
+    void setOptions(Options options);
+    Options options() const;
+
 private:
     Q_DECLARE_PRIVATE(QFileIconProvider)
     QScopedPointer<QFileIconProviderPrivate> d_ptr;
@@ -71,6 +80,8 @@ private:
 
 #endif // QT_NO_FILEICONPROVIDER
 
+Q_DECLARE_OPERATORS_FOR_FLAGS(QFileIconProvider::Options)
+
 QT_END_NAMESPACE
 
 #endif // QFILEICONPROVIDER_H