More improvements to pixmap cache key generation

HexString is actually more optimal than fromRawData since we dont
need any allocations while using it. Arguably the code is also
a bit nicer.

Task-number: QTBUG-9850
Reviewed-by: ogoffart

4 files changed, 57 insertions, 50 deletions

diff --git a/src/gui/image/qicon.cpp b/src/gui/image/qicon.cpp
index 9f1eea2..7696632 100644
--- a/src/gui/image/qicon.cpp
+++ b/src/gui/image/qicon.cpp
@@ -55,6 +55,7 @@
 #include "qcache.h"
 #include "qdebug.h"
 #include "private/qguiplatformplugin_p.h"
+#include "private/qstylehelper_p.h"
 
 #ifdef Q_WS_MAC
 #include <private/qt_mac_p.h>
@@ -261,24 +262,17 @@ QPixmap QPixmapIconEngine::pixmap(const QSize &size, QIcon::Mode mode, QIcon::St
     if (!actualSize.isNull() && (actualSize.width() > size.width() || actualSize.height() > size.height()))
         actualSize.scale(size, Qt::KeepAspectRatio);
 
-    int digits = sizeof(qint64)/sizeof(QChar);
-    quint64 tkey = pm.cacheKey(),
-            tmode = pe->mode,
-            tpalkey = QApplication::palette().cacheKey(),
-            twidth = actualSize.width(),
-            theight = actualSize.height();
-
     QString key = QLatin1Literal("qt_")
-                  % QString::fromRawData((QChar*)&tkey, digits)
-                  % QString::fromRawData((QChar*)&tmode, digits)
-                  % QString::fromRawData((QChar*)&tpalkey, digits)
-                  % QString::fromRawData((QChar*)&twidth, digits)
-                  % QString::fromRawData((QChar*)&theight, digits);
+                  % HexString<quint64>(pm.cacheKey())
+                  % HexString<uint>(pe->mode)
+                  % HexString<quint64>(QApplication::palette().cacheKey())
+                  % HexString<uint>(actualSize.width())
+                  % HexString<uint>(actualSize.height());
 
     if (mode == QIcon::Active) {
-        if (QPixmapCache::find(key + QString::number(mode), pm))
+        if (QPixmapCache::find(key % HexString<uint>(mode), pm))
             return pm; // horray
-        if (QPixmapCache::find(key + QString::number(QIcon::Normal), pm)) {
+        if (QPixmapCache::find(key % HexString<uint>(QIcon::Normal), pm)) {
             QStyleOption opt(0);
             opt.palette = QApplication::palette();
             QPixmap active = QApplication::style()->generatedIconPixmap(QIcon::Active, pm, &opt);
@@ -287,7 +281,7 @@ QPixmap QPixmapIconEngine::pixmap(const QSize &size, QIcon::Mode mode, QIcon::St
         }
     }
 
-    if (!QPixmapCache::find(key + QString::number(mode), pm)) {
+    if (!QPixmapCache::find(key % HexString<uint>(mode), pm)) {
         if (pm.size() != actualSize)
             pm = pm.scaled(actualSize, Qt::IgnoreAspectRatio, Qt::SmoothTransformation);
         if (pe->mode != mode && mode != QIcon::Normal) {
@@ -297,7 +291,7 @@ QPixmap QPixmapIconEngine::pixmap(const QSize &size, QIcon::Mode mode, QIcon::St
             if (!generated.isNull())
                 pm = generated;
         }
-        QPixmapCache::insert(key + QString::number(mode), pm);
+        QPixmapCache::insert(key % HexString<uint>(mode), pm);
     }
     return pm;
 }
diff --git a/src/gui/styles/qgtkpainter.cpp b/src/gui/styles/qgtkpainter.cpp
index a6686e2..79c53e9 100644
--- a/src/gui/styles/qgtkpainter.cpp
+++ b/src/gui/styles/qgtkpainter.cpp
@@ -47,6 +47,7 @@
 // This class is primarily a wrapper around the gtk painter functions
 // and takes care of converting all such calls into cached Qt pixmaps.
 
+#include <private/qstylehelper_p.h>
 #include <QtGui/QWidget>
 #include <QtGui/QStyleOption>
 #include <QtGui/QPixmapCache>
@@ -154,21 +155,13 @@ QGtkPainter::QGtkPainter(QPainter *_painter)
 static QString uniqueName(const QString &key, GtkStateType state, GtkShadowType shadow,
                           const QSize &size, GtkWidget *widget = 0)
 {
-
-    int digits = sizeof(qint64)/sizeof(QChar);
-    quint64 tstate= state,
-            tshadow = shadow,
-            twidth = size.width(),
-            theight = size.height(),
-            twidget = quint64(widget);
-
     // Note the widget arg should ideally use the widget path, though would compromise performance
     QString tmp = key
-                  % QString::fromRawData((QChar*)&tstate, digits)
-                  % QString::fromRawData((QChar*)&tshadow, digits)
-                  % QString::fromRawData((QChar*)&twidth, digits)
-                  % QString::fromRawData((QChar*)&theight, digits)
-                  % QString::fromRawData((QChar*)&twidget, digits);
+                  % HexString<uint>(state)
+                  % HexString<uint>(shadow)
+                  % HexString<uint>(size.width())
+                  % HexString<uint>(size.height())
+                  % HexString<quint64>(quint64(widget));
     return tmp;
 }
 
diff --git a/src/gui/styles/qstylehelper.cpp b/src/gui/styles/qstylehelper.cpp
index 22f2014..d09d7fa 100644
--- a/src/gui/styles/qstylehelper.cpp
+++ b/src/gui/styles/qstylehelper.cpp
@@ -63,30 +63,18 @@ namespace QStyleHelper {
 QString uniqueName(const QString &key, const QStyleOption *option, const QSize &size)
 {
     const QStyleOptionComplex *complexOption = qstyleoption_cast<const QStyleOptionComplex *>(option);
-    int digits = sizeof(qint64)/sizeof(QChar);
-    quint64 state = option->state,
-            direction = option->direction,
-            subcontrols = (complexOption ? uint(complexOption->activeSubControls) : 0u),
-            palettekey = option->palette.cacheKey(),
-            width = size.width(),
-            height = size.height();
-
-    QString tmp = key % QString::fromRawData((QChar*)&state, digits)
-                      % QString::fromRawData((QChar*)&direction, digits)
-                      % QString::fromRawData((QChar*)&subcontrols, digits)
-                      % QString::fromRawData((QChar*)&palettekey, digits)
-                      % QString::fromRawData((QChar*)&width, digits)
-                      % QString::fromRawData((QChar*)&height, digits);
+    QString tmp = key % HexString<uint>(option->state)
+                      % HexString<uint>(option->direction)
+                      % HexString<uint>(complexOption ? uint(complexOption->activeSubControls) : 0u)
+                      % HexString<quint64>(option->palette.cacheKey())
+                      % HexString<uint>(size.width())
+                      % HexString<uint>(size.height());
 
 #ifndef QT_NO_SPINBOX
     if (const QStyleOptionSpinBox *spinBox = qstyleoption_cast<const QStyleOptionSpinBox *>(option)) {
-        quint64 buttonsymbols = spinBox->buttonSymbols,
-                stepEnabled = spinBox->stepEnabled,
-                frame = spinBox->frame;
-
-        tmp = tmp % QString::fromRawData((QChar*)&buttonsymbols, digits)
-                  % QString::fromRawData((QChar*)&stepEnabled, digits)
-                  % QString::fromRawData((QChar*)&frame, digits);
+        tmp = tmp % HexString<uint>(spinBox->buttonSymbols)
+                  % HexString<uint>(spinBox->stepEnabled)
+                  % QLatin1Char(spinBox->frame ? '1' : '0'); ;
     }
 #endif // QT_NO_SPINBOX
     return tmp;
diff --git a/src/gui/styles/qstylehelper_p.h b/src/gui/styles/qstylehelper_p.h
index 31cc4ed..555ad60 100644
--- a/src/gui/styles/qstylehelper_p.h
+++ b/src/gui/styles/qstylehelper_p.h
@@ -41,6 +41,7 @@
 
 #include <QtCore/qglobal.h>
 #include <QtCore/qpoint.h>
+#include <QtCore/qstring.h>
 #include <QtGui/qpolygon.h>
 
 #ifndef QSTYLEHELPER_P_H
@@ -79,6 +80,37 @@ namespace QStyleHelper
                      int bottom = 0);
 }
 
+// internal helper. Converts an integer value to an unique string token
+template <typename T>
+        struct HexString
+{
+    inline HexString(const T t)
+        : val(t)
+    {}
+
+    inline void write(QChar *&dest) const
+    {
+        const ushort hexChars[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
+        const char *c = reinterpret_cast<const char *>(&val);
+        for (uint i = 0; i < sizeof(T); ++i) {
+            *dest++ = hexChars[*c & 0xf];
+            *dest++ = hexChars[(*c & 0xf0) >> 4];
+            ++c;
+        }
+    }
+    const T val;
+};
+
+// specialization to enable fast concatenating of our string tokens to a string
+template <typename T>
+        struct QConcatenable<HexString<T> >
+{
+    typedef HexString<T> type;
+    enum { ExactSize = true };
+    static int size(const HexString<T> &str) { return sizeof(str.val) * 2; }
+    static inline void appendTo(const HexString<T> &str, QChar *&out) { str.write(out); }
+};
+
 QT_END_NAMESPACE
 
 #endif // QSTYLEHELPER_P_H