QtPlatformSupport: Add QAbstractFileIconEngine

Move the code from QtWidgets/QFileIconEngine into a new class with
virtuals in QtPlatformSupport so that platforms can reuse it.

Prototypically use the class in the Windows and macOS QPA plugins.

Remove QPlatformTheme::fileIconPixmap() and change the type
of the hint QPlatformTheme::IconPixmapSizes from QList<int>
to QList<QSize> so that it fits better with the icon code.

Change-Id: I580e936f3507218757565ca099272cd575b3a779
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>

4 files changed, 104 insertions, 42 deletions

diff --git a/src/plugins/platforms/cocoa/qcocoatheme.h b/src/plugins/platforms/cocoa/qcocoatheme.h
index 282e527b0b..d47e620fbb 100644
--- a/src/plugins/platforms/cocoa/qcocoatheme.h
+++ b/src/plugins/platforms/cocoa/qcocoatheme.h
@@ -70,9 +70,7 @@ public:
     const QPalette *palette(Palette type = SystemPalette) const Q_DECL_OVERRIDE;
     const QFont *font(Font type = SystemFont) const Q_DECL_OVERRIDE;
     QPixmap standardPixmap(StandardPixmap sp, const QSizeF &size) const Q_DECL_OVERRIDE;
-    QPixmap fileIconPixmap(const QFileInfo &fileInfo,
-                           const QSizeF &size,
-                           QPlatformTheme::IconOptions options = 0) const Q_DECL_OVERRIDE;
+    QIcon fileIcon(const QFileInfo &fileInfo, QPlatformTheme::IconOptions options = 0) const override;
 
     QVariant themeHint(ThemeHint hint) const Q_DECL_OVERRIDE;
     QString standardButtonText(int button) const Q_DECL_OVERRIDE;
diff --git a/src/plugins/platforms/cocoa/qcocoatheme.mm b/src/plugins/platforms/cocoa/qcocoatheme.mm
index 01b654af68..3a3d634f5a 100644
--- a/src/plugins/platforms/cocoa/qcocoatheme.mm
+++ b/src/plugins/platforms/cocoa/qcocoatheme.mm
@@ -58,6 +58,7 @@
 #include <QtGui/private/qguiapplication_p.h>
 #include <QtGui/qpainter.h>
 #include <QtPlatformSupport/private/qcoretextfontdatabase_p.h>
+#include <QtPlatformSupport/private/qabstractfileiconengine_p.h>
 #include <qpa/qplatformintegration.h>
 #include <qpa/qplatformnativeinterface.h>
 
@@ -274,16 +275,41 @@ QPixmap QCocoaTheme::standardPixmap(StandardPixmap sp, const QSizeF &size) const
     return QPlatformTheme::standardPixmap(sp, size);
 }
 
-QPixmap QCocoaTheme::fileIconPixmap(const QFileInfo &fileInfo, const QSizeF &size,
-                                    QPlatformTheme::IconOptions iconOptions) const
+class QCocoaFileIconEngine : public QAbstractFileIconEngine
 {
-    Q_UNUSED(iconOptions);
-    QMacAutoReleasePool pool;
+public:
+    explicit QCocoaFileIconEngine(const QFileInfo &info,
+                                  QPlatformTheme::IconOptions opts) :
+        QAbstractFileIconEngine(info, opts) {}
+
+    static QList<QSize> availableIconSizes()
+    {
+        const qreal devicePixelRatio = qGuiApp->devicePixelRatio();
+        const int sizes[] = {
+            qRound(16 * devicePixelRatio), qRound(32 * devicePixelRatio),
+            qRound(64 * devicePixelRatio), qRound(128 * devicePixelRatio)
+        };
+        return QAbstractFileIconEngine::toSizeList(sizes, sizes + sizeof(sizes) / sizeof(sizes[0]));
+    }
+
+    QList<QSize> availableSizes(QIcon::Mode = QIcon::Normal, QIcon::State = QIcon::Off) const override
+    { return QCocoaFileIconEngine::availableIconSizes(); }
 
-    NSImage *iconImage = [[NSWorkspace sharedWorkspace] iconForFile:QCFString::toNSString(fileInfo.canonicalFilePath())];
-    if (!iconImage)
-        return QPixmap();
-    return qt_mac_toQPixmap(iconImage, size);
+protected:
+    QPixmap filePixmap(const QSize &size, QIcon::Mode, QIcon::State) override
+    {
+        QMacAutoReleasePool pool;
+
+        NSImage *iconImage = [[NSWorkspace sharedWorkspace] iconForFile:QCFString::toNSString(fileInfo().canonicalFilePath())];
+        if (!iconImage)
+            return QPixmap();
+        return qt_mac_toQPixmap(iconImage, size);
+    }
+};
+
+QIcon QCocoaTheme::fileIcon(const QFileInfo &fileInfo, QPlatformTheme::IconOptions iconOptions) const
+{
+    return QIcon(new QCocoaFileIconEngine(fileInfo, iconOptions));
 }
 
 QVariant QCocoaTheme::themeHint(ThemeHint hint) const
@@ -298,15 +324,8 @@ QVariant QCocoaTheme::themeHint(ThemeHint hint) const
     case TabFocusBehavior:
         return QVariant([[NSApplication sharedApplication] isFullKeyboardAccessEnabled] ?
                     int(Qt::TabFocusAllControls) : int(Qt::TabFocusTextControls | Qt::TabFocusListControls));
-    case IconPixmapSizes: {
-        qreal devicePixelRatio = qGuiApp->devicePixelRatio();
-        QList<int> sizes;
-        sizes << 16 * devicePixelRatio
-              << 32 * devicePixelRatio
-              << 64 * devicePixelRatio
-              << 128 * devicePixelRatio;
-        return QVariant::fromValue(sizes);
-    }
+    case IconPixmapSizes:
+        return QVariant::fromValue(QCocoaFileIconEngine::availableIconSizes());
     case QPlatformTheme::PasswordMaskCharacter:
         return QVariant(QChar(kBulletUnicode));
     case QPlatformTheme::UiEffects:
diff --git a/src/plugins/platforms/windows/qwindowstheme.cpp b/src/plugins/platforms/windows/qwindowstheme.cpp
index 2c3ffd45d9..79befc56c2 100644
--- a/src/plugins/platforms/windows/qwindowstheme.cpp
+++ b/src/plugins/platforms/windows/qwindowstheme.cpp
@@ -68,6 +68,7 @@
 #include <QtGui/QPainter>
 #include <QtGui/QPixmapCache>
 #include <qpa/qwindowsysteminterface.h>
+#include <QtPlatformSupport/private/qabstractfileiconengine_p.h>
 #include <private/qhighdpiscaling_p.h>
 #include <private/qsystemlibrary_p.h>
 
@@ -314,6 +315,7 @@ const char *QWindowsTheme::name = "windows";
 QWindowsTheme *QWindowsTheme::m_instance = 0;
 
 QWindowsTheme::QWindowsTheme()
+    : m_threadPoolRunner(new QWindowsThreadPoolRunner)
 {
     m_instance = this;
     std::fill(m_fonts, m_fonts + NFonts, static_cast<QFont *>(0));
@@ -384,7 +386,7 @@ QVariant QWindowsTheme::themeHint(ThemeHint hint) const
     case UiEffects:
         return QVariant(uiEffects());
     case IconPixmapSizes:
-        return m_fileIconSizes;
+        return QVariant::fromValue(m_fileIconSizes);
     case DialogSnapToDefaultButton:
         return QVariant(booleanSystemParametersInfo(SPI_GETSNAPTODEFBUTTON, false));
     case ContextMenuOnMouseRelease:
@@ -492,15 +494,14 @@ void QWindowsTheme::refreshIconPixmapSizes()
     fileIconSizes[ExtraLargeFileIcon] =
         fileIconSizes[LargeFileIcon] + fileIconSizes[LargeFileIcon] / 2;
     fileIconSizes[JumboFileIcon] = 8 * fileIconSizes[LargeFileIcon]; // empirical, has not been observed to work
-    QList<int> sizes;
-    sizes << fileIconSizes[SmallFileIcon] << fileIconSizes[LargeFileIcon];
+
 #ifdef USE_IIMAGELIST
-    sizes << fileIconSizes[ExtraLargeFileIcon]; // sHIL_EXTRALARGE
-    if (QSysInfo::WindowsVersion >= QSysInfo::WV_VISTA)
-        sizes << fileIconSizes[JumboFileIcon]; // SHIL_JUMBO
+    int *availEnd = fileIconSizes + JumboFileIcon + 1;
+#else
+    int *availEnd = fileIconSizes + LargeFileIcon + 1;
 #endif // USE_IIMAGELIST
-    qCDebug(lcQpaWindows) << __FUNCTION__ << sizes;
-    m_fileIconSizes = QVariant::fromValue(sizes);
+    m_fileIconSizes = QAbstractFileIconEngine::toSizeList(fileIconSizes, availEnd);
+    qCDebug(lcQpaWindows) << __FUNCTION__ << m_fileIconSizes;
 }
 
 // Defined in qpixmap_win.cpp
@@ -714,8 +715,46 @@ static QPixmap pixmapFromShellImageList(int iImageList, const SHFILEINFO &info)
     return result;
 }
 
-QPixmap QWindowsTheme::fileIconPixmap(const QFileInfo &fileInfo, const QSizeF &size,
-                                      QPlatformTheme::IconOptions iconOptions) const
+class QWindowsFileIconEngine : public QAbstractFileIconEngine
+{
+public:
+    explicit QWindowsFileIconEngine(const QFileInfo &info,
+                                    QPlatformTheme::IconOptions opts,
+                                    const QSharedPointer<QWindowsThreadPoolRunner> &runner) :
+        QAbstractFileIconEngine(info, opts), m_threadPoolRunner(runner) {}
+
+    QList<QSize> availableSizes(QIcon::Mode = QIcon::Normal, QIcon::State = QIcon::Off) const override
+    { return QWindowsTheme::instance()->availableFileIconSizes(); }
+
+protected:
+    QString cacheKey() const override;
+    QPixmap filePixmap(const QSize &size, QIcon::Mode mode, QIcon::State) override;
+
+private:
+    const QSharedPointer<QWindowsThreadPoolRunner> m_threadPoolRunner;
+};
+
+QString QWindowsFileIconEngine::cacheKey() const
+{
+    // Cache directories unless custom or drives, which have custom icons depending on type
+    if ((options() & QPlatformTheme::DontUseCustomDirectoryIcons) && fileInfo().isDir() && !fileInfo().isRoot())
+        return QStringLiteral("qt_/directory/");
+    if (!fileInfo().isFile())
+        return QString();
+    // Return "" for .exe, .lnk and .ico extensions.
+    // It is faster to just look at the file extensions;
+    // avoiding slow QFileInfo::isExecutable() (QTBUG-13182)
+    const QString &suffix = fileInfo().suffix();
+    if (!suffix.compare(QLatin1String("exe"), Qt::CaseInsensitive)
+        || !suffix.compare(QLatin1String("lnk"), Qt::CaseInsensitive)
+        || !suffix.compare(QLatin1String("ico"), Qt::CaseInsensitive)) {
+        return QString();
+    }
+    return QLatin1String("qt_.")
+        + (suffix.isEmpty() ? fileInfo().fileName() : suffix.toUpper()); // handle "Makefile"                                    ;)
+}
+
+QPixmap QWindowsFileIconEngine::filePixmap(const QSize &size, QIcon::Mode, QIcon::State)
 {
     /* We don't use the variable, but by storing it statically, we
      * ensure CoInitialize is only called once. */
@@ -725,10 +764,10 @@ QPixmap QWindowsTheme::fileIconPixmap(const QFileInfo &fileInfo, const QSizeF &s
     static QCache<QString, FakePointer<int> > dirIconEntryCache(1000);
     static QMutex mx;
     static int defaultFolderIIcon = -1;
-    const bool useDefaultFolderIcon = iconOptions & QPlatformTheme::DontUseCustomDirectoryIcons;
+    const bool useDefaultFolderIcon = options() & QPlatformTheme::DontUseCustomDirectoryIcons;
 
     QPixmap pixmap;
-    const QString filePath = QDir::toNativeSeparators(fileInfo.filePath());
+    const QString filePath = QDir::toNativeSeparators(fileInfo().filePath());
     const int width = int(size.width());
     const int iconSize = width > fileIconSizes[SmallFileIcon] ? SHGFI_LARGEICON : SHGFI_SMALLICON;
     const int requestedImageListSize =
@@ -739,7 +778,7 @@ QPixmap QWindowsTheme::fileIconPixmap(const QFileInfo &fileInfo, const QSizeF &s
 #else
         0;
 #endif // !USE_IIMAGELIST
-    bool cacheableDirIcon = fileInfo.isDir() && !fileInfo.isRoot();
+    bool cacheableDirIcon = fileInfo().isDir() && !fileInfo().isRoot();
     if (cacheableDirIcon) {
         QMutexLocker locker(&mx);
         int iIcon = (useDefaultFolderIcon && defaultFolderIIcon >= 0) ? defaultFolderIIcon
@@ -758,9 +797,9 @@ QPixmap QWindowsTheme::fileIconPixmap(const QFileInfo &fileInfo, const QSizeF &s
         SHGFI_ICON|iconSize|SHGFI_SYSICONINDEX|SHGFI_ADDOVERLAYS|SHGFI_OVERLAYINDEX;
 
     const bool val = cacheableDirIcon && useDefaultFolderIcon
-        ? shGetFileInfoBackground(m_threadPoolRunner, L"dummy", FILE_ATTRIBUTE_DIRECTORY,
+        ? shGetFileInfoBackground(*m_threadPoolRunner.data(), L"dummy", FILE_ATTRIBUTE_DIRECTORY,
                                   &info, flags | SHGFI_USEFILEATTRIBUTES)
-        : shGetFileInfoBackground(m_threadPoolRunner, reinterpret_cast<const wchar_t *>(filePath.utf16()), 0,
+        : shGetFileInfoBackground(*m_threadPoolRunner.data(), reinterpret_cast<const wchar_t *>(filePath.utf16()), 0,
                                   &info, flags);
 
     // Even if GetFileInfo returns a valid result, hIcon can be empty in some cases
@@ -800,9 +839,12 @@ QPixmap QWindowsTheme::fileIconPixmap(const QFileInfo &fileInfo, const QSizeF &s
         DestroyIcon(info.hIcon);
     }
 
-    if (!pixmap.isNull())
-        return pixmap;
-    return QPlatformTheme::fileIconPixmap(fileInfo, size);
+    return pixmap;
+}
+
+QIcon QWindowsTheme::fileIcon(const QFileInfo &fileInfo, QPlatformTheme::IconOptions iconOptions) const
+{
+    return QIcon(new QWindowsFileIconEngine(fileInfo, iconOptions, m_threadPoolRunner));
 }
 
 QT_END_NAMESPACE
diff --git a/src/plugins/platforms/windows/qwindowstheme.h b/src/plugins/platforms/windows/qwindowstheme.h
index fa1fb4d998..0384899efa 100644
--- a/src/plugins/platforms/windows/qwindowstheme.h
+++ b/src/plugins/platforms/windows/qwindowstheme.h
@@ -43,6 +43,7 @@
 #include "qwindowsthreadpoolrunner.h"
 #include <qpa/qplatformtheme.h>
 
+#include <QtCore/QSharedPointer>
 #include <QtCore/QVariant>
 
 QT_BEGIN_NAMESPACE
@@ -66,12 +67,14 @@ public:
         { return m_fonts[type]; }
 
     QPixmap standardPixmap(StandardPixmap sp, const QSizeF &size) const Q_DECL_OVERRIDE;
-    QPixmap fileIconPixmap(const QFileInfo &fileInfo, const QSizeF &size,
-                           QPlatformTheme::IconOptions iconOptions = 0) const Q_DECL_OVERRIDE;
+
+    QIcon fileIcon(const QFileInfo &fileInfo, QPlatformTheme::IconOptions iconOptions = 0) const override;
 
     void windowsThemeChanged(QWindow *window);
     void displayChanged() { refreshIconPixmapSizes(); }
 
+    QList<QSize> availableFileIconSizes() const { return m_fileIconSizes; }
+
     static const char *name;
 
 private:
@@ -85,8 +88,8 @@ private:
     static QWindowsTheme *m_instance;
     QPalette *m_palettes[NPalettes];
     QFont *m_fonts[NFonts];
-    mutable QWindowsThreadPoolRunner m_threadPoolRunner;
-    QVariant m_fileIconSizes;
+    const QSharedPointer<QWindowsThreadPoolRunner> m_threadPoolRunner;
+    QList<QSize> m_fileIconSizes;
 };
 
 QT_END_NAMESPACE