QPdf: Extract Method is_monochrome()

The old code repeatedly evaluated QImage::colorTable(), which returns
a vector by value.

Instead, factor the checks performed on the color table into
a helper function and pass the color table to it, reducing
the number of evaluations from three to one.

Also makes the code more readable, because the condition now
fits on a single line.

Change-Id: I82773c235047e76b87c8a9d630f7df9440430351
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@digia.com>

1 files changed, 9 insertions, 4 deletions

diff --git a/src/gui/painting/qpdf.cpp b/src/gui/painting/qpdf.cpp
index 0c888d645d..c7f3c0fd5b 100644
--- a/src/gui/painting/qpdf.cpp
+++ b/src/gui/painting/qpdf.cpp
@@ -2323,6 +2323,14 @@ int QPdfEnginePrivate::addBrushPattern(const QTransform &m, bool *specifyColor,
     return patternObj;
 }
 
+static inline bool is_monochrome(const QVector<QRgb> &colorTable)
+{
+    return colorTable.size() == 2
+        && colorTable.at(0) == QColor(Qt::black).rgba()
+        && colorTable.at(1) == QColor(Qt::white).rgba()
+        ;
+}
+
 /*!
  * Adds an image to the pdf and return the pdf-object id. Returns -1 if adding the image failed.
  */
@@ -2337,10 +2345,7 @@ int QPdfEnginePrivate::addImage(const QImage &img, bool *bitmap, qint64 serial_n
 
     QImage image = img;
     QImage::Format format = image.format();
-    if (image.depth() == 1 && *bitmap && img.colorTable().size() == 2
-        && img.colorTable().at(0) == QColor(Qt::black).rgba()
-        && img.colorTable().at(1) == QColor(Qt::white).rgba())
-    {
+    if (image.depth() == 1 && *bitmap && is_monochrome(img.colorTable())) {
         if (format == QImage::Format_MonoLSB)
             image = image.convertToFormat(QImage::Format_Mono);
         format = QImage::Format_Mono;