QItemDelegate::doLayout: only call QStyle::pixelMetric() once

QStyle::pixelMetric(QStyle::PM_FocusFrameHMargin) was called three times
in the worst case but it returns a constant value. Therefore cache this
value and call pixelMetric() only once.
Since this code is duplicated from QCommonStylePrivate::viewItemLayout()
also change it there.

Change-Id: I6d5f0a8d2b1373bd36f0520f404e6a3cb0794f12
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@qt.io>
Reviewed-by: Thorbjørn Lund Martsum <tmartsum@gmail.com>

2 files changed, 16 insertions, 10 deletions

diff --git a/src/widgets/itemviews/qitemdelegate.cpp b/src/widgets/itemviews/qitemdelegate.cpp
index df5f9afb0e..e1089e3158 100644
--- a/src/widgets/itemviews/qitemdelegate.cpp
+++ b/src/widgets/itemviews/qitemdelegate.cpp
@@ -803,11 +803,14 @@ void QItemDelegate::doLayout(const QStyleOptionViewItem &option,
     const bool hasCheck = checkRect->isValid();
     const bool hasPixmap = pixmapRect->isValid();
     const bool hasText = textRect->isValid();
-    const int textMargin = hasText ? style->pixelMetric(QStyle::PM_FocusFrameHMargin, 0, widget) + 1 : 0;
-    const int pixmapMargin = hasPixmap ? style->pixelMetric(QStyle::PM_FocusFrameHMargin, 0, widget) + 1 : 0;
-    const int checkMargin = hasCheck ? style->pixelMetric(QStyle::PM_FocusFrameHMargin, 0, widget) + 1 : 0;
-    int x = option.rect.left();
-    int y = option.rect.top();
+    const bool hasMargin = (hasText | hasPixmap | hasCheck);
+    const int frameHMargin = hasMargin ?
+                style->pixelMetric(QStyle::PM_FocusFrameHMargin, 0, widget) + 1 : 0;
+    const int textMargin = hasText ? frameHMargin : 0;
+    const int pixmapMargin = hasPixmap ? frameHMargin : 0;
+    const int checkMargin = hasCheck ? frameHMargin : 0;
+    const int x = option.rect.left();
+    const int y = option.rect.top();
     int w, h;
 
     textRect->adjust(-textMargin, 0, textMargin, 0); // add width padding
diff --git a/src/widgets/styles/qcommonstyle.cpp b/src/widgets/styles/qcommonstyle.cpp
index 36cc6a22da..9f51a6b9d6 100644
--- a/src/widgets/styles/qcommonstyle.cpp
+++ b/src/widgets/styles/qcommonstyle.cpp
@@ -994,11 +994,14 @@ void QCommonStylePrivate::viewItemLayout(const QStyleOptionViewItem *opt,  QRect
     const bool hasCheck = checkRect->isValid();
     const bool hasPixmap = pixmapRect->isValid();
     const bool hasText = textRect->isValid();
-    const int textMargin = hasText ? proxyStyle->pixelMetric(QStyle::PM_FocusFrameHMargin, opt, widget) + 1 : 0;
-    const int pixmapMargin = hasPixmap ? proxyStyle->pixelMetric(QStyle::PM_FocusFrameHMargin, opt, widget) + 1 : 0;
-    const int checkMargin = hasCheck ? proxyStyle->pixelMetric(QStyle::PM_FocusFrameHMargin, opt, widget) + 1 : 0;
-    int x = opt->rect.left();
-    int y = opt->rect.top();
+    const bool hasMargin = (hasText | hasPixmap | hasCheck);
+    const int frameHMargin = hasMargin ?
+                proxyStyle->pixelMetric(QStyle::PM_FocusFrameHMargin, opt, widget) + 1 : 0;
+    const int textMargin = hasText ? frameHMargin : 0;
+    const int pixmapMargin = hasPixmap ? frameHMargin : 0;
+    const int checkMargin = hasCheck ? frameHMargin : 0;
+    const int x = opt->rect.left();
+    const int y = opt->rect.top();
     int w, h;
 
     if (textRect->height() == 0 && (!hasPixmap || !sizehint)) {