Speed up creation of the pixmap cache key

As discussed with Jens and Joao

Reviewed-by: Robert Griebl

1 files changed, 55 insertions, 9 deletions

diff --git a/src/gui/styles/qstylehelper.cpp b/src/gui/styles/qstylehelper.cpp
index 071ec23..359e7e1 100644
--- a/src/gui/styles/qstylehelper.cpp
+++ b/src/gui/styles/qstylehelper.cpp
@@ -44,6 +44,7 @@
 #include <qstyleoption.h>
 #include <qpainter.h>
 #include <qpixmapcache.h>
+#include <qstringbuilder.h>
 #include <private/qmath_p.h>
 #include <private/qstyle_p.h>
 #include <qmath.h>
@@ -56,22 +57,67 @@
 
 QT_BEGIN_NAMESPACE
 
+// 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); }
+};
+
 namespace QStyleHelper {
 
 QString uniqueName(const QString &key, const QStyleOption *option, const QSize &size)
 {
     const QStyleOptionComplex *complexOption = qstyleoption_cast<const QStyleOptionComplex *>(option);
-    QString tmp = QString::fromLatin1("%1-%2-%3-%4-%5-%6x%7").arg(key).arg(uint(option->state)).arg(option->direction)
-                   .arg(complexOption ? uint(complexOption->activeSubControls) : uint(0))
-                   .arg(option->palette.cacheKey()).arg(size.width()).arg(size.height());
+
+    QString tmp = key
+                  % QLatin1Char('-')
+                  % HexString<uint>(option->state)
+                  % QLatin1Char('-')
+                  % HexString<uint>(option->direction)
+                  % QLatin1Char('-')
+                  % HexString<uint>(complexOption ? uint(complexOption->activeSubControls) : 0u)
+                  % QLatin1Char('-')
+                  % HexString<quint64>(option->palette.cacheKey())
+                  % QLatin1Char('-')
+                  % HexString<uint>(size.width())
+                  % QLatin1Char('x')
+                  % HexString<uint>(size.height());
+
 #ifndef QT_NO_SPINBOX
     if (const QStyleOptionSpinBox *spinBox = qstyleoption_cast<const QStyleOptionSpinBox *>(option)) {
-        tmp.append(QLatin1Char('-'));
-        tmp.append(QString::number(spinBox->buttonSymbols));
-        tmp.append(QLatin1Char('-'));
-        tmp.append(QString::number(spinBox->stepEnabled));
-        tmp.append(QLatin1Char('-'));
-        tmp.append(QLatin1Char(spinBox->frame ? '1' : '0'));
+        tmp = tmp
+              % QLatin1Char('-')
+              % HexString<uint>(spinBox->buttonSymbols)
+              % QLatin1Char('-')
+              % HexString<uint>(spinBox->stepEnabled)
+              % QLatin1Char('-')
+              % QLatin1Char(spinBox->frame ? '1' : '0');
     }
 #endif // QT_NO_SPINBOX
     return tmp;