Long live QSize(F)::grownBy/shrunkBy()

These functions tighten the integration of QMargins(F) with the rest
of the geometry classes by providing a way to apply margins to sizes
(and later, rects).

Apply them in a few obvious cases across QtWidgets.

[ChangeLog][QtCore][QSize/QSizeF] Added grownBy(QMargin(F))/shrunkBy(QMargin(F)).

Change-Id: I8a549436824cdb7fb6125a8cde89d5bf02826934
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

4 files changed, 38 insertions, 19 deletions

diff --git a/src/corelib/tools/qsize.cpp b/src/corelib/tools/qsize.cpp
index fe508ad459..2cbaae117d 100644
--- a/src/corelib/tools/qsize.cpp
+++ b/src/corelib/tools/qsize.cpp
@@ -390,7 +390,25 @@ QSize QSize::scaled(const QSize &s, Qt::AspectRatioMode mode) const noexcept
     \sa expandedTo(), scale()
 */
 
+/*!
+    \fn QSize QSize::grownBy(QMargins margins) const
+    \fn QSizeF QSizeF::grownBy(QMarginsF margins) const
+    \since 5.14
+
+    Returns the size that results from growing this size by \a margins.
+
+    \sa shrunkBy()
+*/
 
+/*!
+    \fn QSize QSize::shrunkBy(QMargins margins) const
+    \fn QSizeF QSizeF::shrunkBy(QMarginsF margins) const
+    \since 5.14
+
+    Returns the size that results from shrinking this size by \a margins.
+
+    \sa grownBy()
+*/
 
 /*****************************************************************************
   QSize stream functions
diff --git a/src/corelib/tools/qsize.h b/src/corelib/tools/qsize.h
index 4114609856..06de1cd63f 100644
--- a/src/corelib/tools/qsize.h
+++ b/src/corelib/tools/qsize.h
@@ -41,6 +41,7 @@
 #define QSIZE_H
 
 #include <QtCore/qnamespace.h>
+#include <QtCore/qmargins.h>
 
 #if defined(Q_OS_DARWIN) || defined(Q_QDOC)
 struct CGSize;
@@ -74,6 +75,11 @@ public:
     Q_REQUIRED_RESULT Q_DECL_CONSTEXPR inline QSize expandedTo(const QSize &) const noexcept;
     Q_REQUIRED_RESULT Q_DECL_CONSTEXPR inline QSize boundedTo(const QSize &) const noexcept;
 
+    Q_REQUIRED_RESULT Q_DECL_CONSTEXPR QSize grownBy(QMargins m) const noexcept
+    { return {width() + m.left() + m.right(), height() + m.top() + m.bottom()}; }
+    Q_REQUIRED_RESULT Q_DECL_CONSTEXPR QSize shrunkBy(QMargins m) const noexcept
+    { return {width() - m.left() - m.right(), height() - m.top() - m.bottom()}; }
+
     Q_DECL_RELAXED_CONSTEXPR inline int &rwidth() noexcept;
     Q_DECL_RELAXED_CONSTEXPR inline int &rheight() noexcept;
 
@@ -238,6 +244,11 @@ public:
     Q_REQUIRED_RESULT Q_DECL_CONSTEXPR inline QSizeF expandedTo(const QSizeF &) const noexcept;
     Q_REQUIRED_RESULT Q_DECL_CONSTEXPR inline QSizeF boundedTo(const QSizeF &) const noexcept;
 
+    Q_REQUIRED_RESULT Q_DECL_CONSTEXPR QSizeF grownBy(QMarginsF m) const noexcept
+    { return {width() + m.left() + m.right(), height() + m.top() + m.bottom()}; }
+    Q_REQUIRED_RESULT Q_DECL_CONSTEXPR QSizeF shrunkBy(QMarginsF m) const noexcept
+    { return {width() - m.left() - m.right(), height() - m.top() - m.bottom()}; }
+
     Q_DECL_RELAXED_CONSTEXPR inline qreal &rwidth() noexcept;
     Q_DECL_RELAXED_CONSTEXPR inline qreal &rheight() noexcept;
 
diff --git a/src/widgets/widgets/qdockarealayout.cpp b/src/widgets/widgets/qdockarealayout.cpp
index 55ae42db04..8844a85987 100644
--- a/src/widgets/widgets/qdockarealayout.cpp
+++ b/src/widgets/widgets/qdockarealayout.cpp
@@ -138,11 +138,8 @@ bool QDockAreaLayoutItem::skip() const
 
 QSize QDockAreaLayoutItem::minimumSize() const
 {
-    if (widgetItem != 0) {
-        int left, top, right, bottom;
-        widgetItem->widget()->getContentsMargins(&left, &top, &right, &bottom);
-        return widgetItem->minimumSize() + QSize(left+right, top+bottom);
-    }
+    if (widgetItem)
+        return widgetItem->minimumSize().grownBy(widgetItem->widget()->contentsMargins());
     if (subinfo != 0)
         return subinfo->minimumSize();
     return QSize(0, 0);
@@ -150,11 +147,8 @@ QSize QDockAreaLayoutItem::minimumSize() const
 
 QSize QDockAreaLayoutItem::maximumSize() const
 {
-    if (widgetItem != 0) {
-        int left, top, right, bottom;
-        widgetItem->widget()->getContentsMargins(&left, &top, &right, &bottom);
-        return widgetItem->maximumSize()+ QSize(left+right, top+bottom);
-    }
+    if (widgetItem)
+        return widgetItem->maximumSize().grownBy(widgetItem->widget()->contentsMargins());
     if (subinfo != 0)
         return subinfo->maximumSize();
     return QSize(QWIDGETSIZE_MAX, QWIDGETSIZE_MAX);
@@ -180,11 +174,8 @@ QSize QDockAreaLayoutItem::sizeHint() const
 {
     if (placeHolderItem != 0)
         return QSize(0, 0);
-    if (widgetItem != 0) {
-        int left, top, right, bottom;
-        widgetItem->widget()->getContentsMargins(&left, &top, &right, &bottom);
-        return widgetItem->sizeHint() + QSize(left+right, top+bottom);
-    }
+    if (widgetItem)
+        return widgetItem->sizeHint().grownBy(widgetItem->widget()->contentsMargins());
     if (subinfo != 0)
         return subinfo->sizeHint();
     return QSize(-1, -1);
diff --git a/src/widgets/widgets/qdockwidget.cpp b/src/widgets/widgets/qdockwidget.cpp
index 28a7cee2a0..a7010f9260 100644
--- a/src/widgets/widgets/qdockwidget.cpp
+++ b/src/widgets/widgets/qdockwidget.cpp
@@ -381,11 +381,10 @@ QSize QDockWidgetLayout::sizeFromContent(const QSize &content, bool floating) co
     if (content.height() < 0)
         result.setHeight(-1);
 
-    int left, top, right, bottom;
-    w->getContentsMargins(&left, &top, &right, &bottom);
+    const QMargins margins = w->contentsMargins();
     //we need to subtract the contents margin (it will be added by the caller)
-    QSize min = w->minimumSize() - QSize(left + right, top + bottom);
-    QSize max = w->maximumSize() - QSize(left + right, top + bottom);
+    QSize min = w->minimumSize().shrunkBy(margins);
+    QSize max = w->maximumSize().shrunkBy(margins);
 
     /* A floating dockwidget will automatically get its minimumSize set to the layout's
        minimum size + deco. We're *not* interested in this, we only take minimumSize()