Fixed icons lookup in QIcon::fromTheme

This commit fixes incorrect logic of icons' lookup if there are
fallbacks or more than one theme's directory.

According to Icon Theme Specification, Directory Layout section, theme
can be spread across several base directories by having subdirectories
of the same name. This makes possible to extend system themes by
application-specific icons without making of collisions with other
applications.

According to Icon Naming Specification, Icon Naming Guidelines section,
icon name may contain dashes to separate levels of specificity in icon
names. This makes possible to set in application very specific icon
which may be not in every theme. So it can fallback to less specific one.

Change-Id: Iafc813902a3646be56e8f1d3a2fdbf8fd32ac542
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@theqtcompany.com>
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>

3 files changed, 89 insertions, 57 deletions

diff --git a/src/gui/image/qicon.cpp b/src/gui/image/qicon.cpp
index d885729cbd..1b99a5d8dc 100644
--- a/src/gui/image/qicon.cpp
+++ b/src/gui/image/qicon.cpp
@@ -1197,7 +1197,7 @@ bool QIcon::hasThemeIcon(const QString &name)
 {
     QIcon icon = fromTheme(name);
 
-    return !icon.isNull();
+    return icon.name() == name;
 }
 
 
diff --git a/src/gui/image/qiconloader.cpp b/src/gui/image/qiconloader.cpp
index 06491f1155..4510125816 100644
--- a/src/gui/image/qiconloader.cpp
+++ b/src/gui/image/qiconloader.cpp
@@ -172,11 +172,15 @@ QIconTheme::QIconTheme(const QString &themeName)
     for ( int i = 0 ; i < iconDirs.size() ; ++i) {
         QDir iconDir(iconDirs[i]);
         QString themeDir = iconDir.path() + QLatin1Char('/') + themeName;
-        themeIndex.setFileName(themeDir + QLatin1String("/index.theme"));
-        if (themeIndex.exists()) {
-            m_contentDir = themeDir;
-            m_valid = true;
-            break;
+        QFileInfo themeDirInfo(themeDir);
+
+        if (themeDirInfo.isDir())
+            m_contentDirs << themeDir;
+
+        if (!m_valid) {
+            themeIndex.setFileName(themeDir + QLatin1String("/index.theme"));
+            if (themeIndex.exists())
+                m_valid = true;
         }
     }
 #ifndef QT_NO_SETTINGS
@@ -239,11 +243,11 @@ QIconTheme::QIconTheme(const QString &themeName)
 #endif //QT_NO_SETTINGS
 }
 
-QThemeIconEntries QIconLoader::findIconHelper(const QString &themeName,
-                                 const QString &iconName,
-                                 QStringList &visited) const
+QThemeIconInfo QIconLoader::findIconHelper(const QString &themeName,
+                                           const QString &iconName,
+                                           QStringList &visited) const
 {
-    QThemeIconEntries entries;
+    QThemeIconInfo info;
     Q_ASSERT(!themeName.isEmpty());
 
     QPixmap pixmap;
@@ -260,34 +264,54 @@ QThemeIconEntries QIconLoader::findIconHelper(const QString &themeName,
         themeList.insert(themeName, theme);
     }
 
-    QString contentDir = theme.contentDir() + QLatin1Char('/');
+    const QStringList contentDirs = theme.contentDirs();
     const QVector<QIconDirInfo> subDirs = theme.keyList();
 
-    const QString svgext(QLatin1String(".svg"));
-    const QString pngext(QLatin1String(".png"));
-
-    // Add all relevant files
-    for (int i = 0; i < subDirs.size() ; ++i) {
-        const QIconDirInfo &dirInfo = subDirs.at(i);
-        QString subdir = dirInfo.path;
-        QDir currentDir(contentDir + subdir);
-        if (currentDir.exists(iconName + pngext)) {
-            PixmapEntry *iconEntry = new PixmapEntry;
-            iconEntry->dir = dirInfo;
-            iconEntry->filename = currentDir.filePath(iconName + pngext);
-            // Notice we ensure that pixmap entries always come before
-            // scalable to preserve search order afterwards
-            entries.prepend(iconEntry);
-        } else if (m_supportsSvg &&
-            currentDir.exists(iconName + svgext)) {
-            ScalableEntry *iconEntry = new ScalableEntry;
-            iconEntry->dir = dirInfo;
-            iconEntry->filename = currentDir.filePath(iconName + svgext);
-            entries.append(iconEntry);
+    QString iconNameFallback = iconName;
+
+    // Iterate through all icon's fallbacks in current theme
+    while (info.entries.isEmpty()) {
+        const QString svgIconName = iconNameFallback + QLatin1String(".svg");
+        const QString pngIconName = iconNameFallback + QLatin1String(".png");
+
+        // Add all relevant files
+        for (int i = 0; i < contentDirs.size(); ++i) {
+            QString contentDir = contentDirs.at(i) + QLatin1Char('/');
+            for (int j = 0; j < subDirs.size() ; ++j) {
+                const QIconDirInfo &dirInfo = subDirs.at(j);
+                QString subdir = dirInfo.path;
+                QDir currentDir(contentDir + subdir);
+                if (currentDir.exists(pngIconName)) {
+                    PixmapEntry *iconEntry = new PixmapEntry;
+                    iconEntry->dir = dirInfo;
+                    iconEntry->filename = currentDir.filePath(pngIconName);
+                    // Notice we ensure that pixmap entries always come before
+                    // scalable to preserve search order afterwards
+                    info.entries.prepend(iconEntry);
+                } else if (m_supportsSvg &&
+                    currentDir.exists(svgIconName)) {
+                    ScalableEntry *iconEntry = new ScalableEntry;
+                    iconEntry->dir = dirInfo;
+                    iconEntry->filename = currentDir.filePath(svgIconName);
+                    info.entries.append(iconEntry);
+                }
+            }
+        }
+
+        if (!info.entries.isEmpty()) {
+            info.iconName = iconNameFallback;
+            break;
         }
+
+        // If it's possible - find next fallback for the icon
+        const int indexOfDash = iconNameFallback.lastIndexOf(QLatin1Char('-'));
+        if (indexOfDash == -1)
+            break;
+
+        iconNameFallback.truncate(indexOfDash);
     }
 
-    if (entries.isEmpty()) {
+    if (info.entries.isEmpty()) {
         const QStringList parents = theme.parents();
         // Search recursively through inherited themes
         for (int i = 0 ; i < parents.size() ; ++i) {
@@ -295,23 +319,23 @@ QThemeIconEntries QIconLoader::findIconHelper(const QString &themeName,
             const QString parentTheme = parents.at(i).trimmed();
 
             if (!visited.contains(parentTheme)) // guard against recursion
-                entries = findIconHelper(parentTheme, iconName, visited);
+                info = findIconHelper(parentTheme, iconName, visited);
 
-            if (!entries.isEmpty()) // success
+            if (!info.entries.isEmpty()) // success
                 break;
         }
     }
-    return entries;
+    return info;
 }
 
-QThemeIconEntries QIconLoader::loadIcon(const QString &name) const
+QThemeIconInfo QIconLoader::loadIcon(const QString &name) const
 {
     if (!themeName().isEmpty()) {
         QStringList visited;
         return findIconHelper(themeName(), name, visited);
     }
 
-    return QThemeIconEntries();
+    return QThemeIconInfo();
 }
 
 
@@ -325,7 +349,7 @@ QIconLoaderEngine::QIconLoaderEngine(const QString& iconName)
 
 QIconLoaderEngine::~QIconLoaderEngine()
 {
-    qDeleteAll(m_entries);
+    qDeleteAll(m_info.entries);
 }
 
 QIconLoaderEngine::QIconLoaderEngine(const QIconLoaderEngine &other)
@@ -353,17 +377,19 @@ bool QIconLoaderEngine::write(QDataStream &out) const
 
 bool QIconLoaderEngine::hasIcon() const
 {
-    return !(m_entries.isEmpty());
+    return !(m_info.entries.isEmpty());
 }
 
 // Lazily load the icon
 void QIconLoaderEngine::ensureLoaded()
 {
     if (!(QIconLoader::instance()->themeKey() == m_key)) {
+        qDeleteAll(m_info.entries);
+        m_info.entries.clear();
+        m_info.iconName.clear();
 
-        qDeleteAll(m_entries);
-
-        m_entries = QIconLoader::instance()->loadIcon(m_iconName);
+        Q_ASSERT(m_info.entries.size() == 0);
+        m_info = QIconLoader::instance()->loadIcon(m_iconName);
         m_key = QIconLoader::instance()->themeKey();
     }
 }
@@ -433,14 +459,14 @@ QIconLoaderEngineEntry *QIconLoaderEngine::entryForSize(const QSize &size)
 {
     int iconsize = qMin(size.width(), size.height());
 
-    // Note that m_entries are sorted so that png-files
+    // Note that m_info.entries are sorted so that png-files
     // come first
 
-    const int numEntries = m_entries.size();
+    const int numEntries = m_info.entries.size();
 
     // Search for exact matches first
     for (int i = 0; i < numEntries; ++i) {
-        QIconLoaderEngineEntry *entry = m_entries.at(i);
+        QIconLoaderEngineEntry *entry = m_info.entries.at(i);
         if (directoryMatchesSize(entry->dir, iconsize)) {
             return entry;
         }
@@ -450,7 +476,7 @@ QIconLoaderEngineEntry *QIconLoaderEngine::entryForSize(const QSize &size)
     int minimalSize = INT_MAX;
     QIconLoaderEngineEntry *closestMatch = 0;
     for (int i = 0; i < numEntries; ++i) {
-        QIconLoaderEngineEntry *entry = m_entries.at(i);
+        QIconLoaderEngineEntry *entry = m_info.entries.at(i);
         int distance = directorySizeDistance(entry->dir, iconsize);
         if (distance < minimalSize) {
             minimalSize  = distance;
@@ -554,13 +580,13 @@ void QIconLoaderEngine::virtual_hook(int id, void *data)
         {
             QIconEngine::AvailableSizesArgument &arg
                     = *reinterpret_cast<QIconEngine::AvailableSizesArgument*>(data);
-            const int N = m_entries.size();
+            const int N = m_info.entries.size();
             QList<QSize> sizes;
             sizes.reserve(N);
 
             // Gets all sizes from the DirectoryInfo entries
             for (int i = 0; i < N; ++i) {
-                int size = m_entries.at(i)->dir.size;
+                int size = m_info.entries.at(i)->dir.size;
                 sizes.append(QSize(size, size));
             }
             arg.sizes.swap(sizes); // commit
@@ -569,7 +595,7 @@ void QIconLoaderEngine::virtual_hook(int id, void *data)
     case QIconEngine::IconNameHook:
         {
             QString &name = *reinterpret_cast<QString*>(data);
-            name = m_iconName;
+            name = m_info.iconName;
         }
         break;
     default:
diff --git a/src/gui/image/qiconloader_p.h b/src/gui/image/qiconloader_p.h
index 50a6e6d3a7..8ee730f307 100644
--- a/src/gui/image/qiconloader_p.h
+++ b/src/gui/image/qiconloader_p.h
@@ -106,6 +106,12 @@ struct PixmapEntry : public QIconLoaderEngineEntry
 
 typedef QList<QIconLoaderEngineEntry*> QThemeIconEntries;
 
+struct QThemeIconInfo
+{
+    QThemeIconEntries entries;
+    QString iconName;
+};
+
 class QIconLoaderEngine : public QIconEngine
 {
 public:
@@ -126,7 +132,7 @@ private:
     void virtual_hook(int id, void *data);
     QIconLoaderEngineEntry *entryForSize(const QSize &size);
     QIconLoaderEngine(const QIconLoaderEngine &other);
-    QThemeIconEntries m_entries;
+    QThemeIconInfo m_info;
     QString m_iconName;
     uint m_key;
 
@@ -140,11 +146,11 @@ public:
     QIconTheme() : m_valid(false) {}
     QStringList parents() { return m_parents; }
     QVector<QIconDirInfo> keyList() { return m_keyList; }
-    QString contentDir() { return m_contentDir; }
+    QStringList contentDirs() { return m_contentDirs; }
     bool isValid() { return m_valid; }
 
 private:
-    QString m_contentDir;
+    QStringList m_contentDirs;
     QVector<QIconDirInfo> m_keyList;
     QStringList m_parents;
     bool m_valid;
@@ -154,7 +160,7 @@ class Q_GUI_EXPORT QIconLoader
 {
 public:
     QIconLoader();
-    QThemeIconEntries loadIcon(const QString &iconName) const;
+    QThemeIconInfo loadIcon(const QString &iconName) const;
     uint themeKey() const { return m_themeKey; }
 
     QString themeName() const { return m_userTheme.isEmpty() ? m_systemTheme : m_userTheme; }
@@ -169,9 +175,9 @@ public:
     void ensureInitialized();
 
 private:
-    QThemeIconEntries findIconHelper(const QString &themeName,
-                                     const QString &iconName,
-                                     QStringList &visited) const;
+    QThemeIconInfo findIconHelper(const QString &themeName,
+                                  const QString &iconName,
+                                  QStringList &visited) const;
     uint m_themeKey;
     bool m_supportsSvg;
     bool m_initialized;