Fix restore/minimize/close buttons for maximized MDI subwidows

The style code to display the restore/minimize/close buttons in menubar
for maximized MDI subwidows was removed in Qt5 as it was incorrectly
ifdeffed with just QT_NO_WORKSPACE where QT_NO_MDIAREA should
also have been used. Brought back the removed code with proper
ifdeffing.

Task-number: QTBUG-27235
Change-Id: I89607dd54eec00329e576c72b0e8b997f37cdb29
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>

2 files changed, 201 insertions, 0 deletions

diff --git a/src/widgets/styles/qcommonstyle.cpp b/src/widgets/styles/qcommonstyle.cpp
index 52dfc4759d..0460ad69e6 100644
--- a/src/widgets/styles/qcommonstyle.cpp
+++ b/src/widgets/styles/qcommonstyle.cpp
@@ -3567,6 +3567,68 @@ void QCommonStyle::drawComplexControl(ComplexControl cc, const QStyleOptionCompl
         }
         break;
 #endif // QT_NO_GROUPBOX
+#ifndef QT_NO_MDIAREA
+    case CC_MdiControls:
+        {
+            QStyleOptionButton btnOpt;
+            btnOpt.QStyleOption::operator=(*opt);
+            btnOpt.state &= ~State_MouseOver;
+            int bsx = 0;
+            int bsy = 0;
+            if (opt->subControls & QStyle::SC_MdiCloseButton) {
+                if (opt->activeSubControls & QStyle::SC_MdiCloseButton && (opt->state & State_Sunken)) {
+                    btnOpt.state |= State_Sunken;
+                    btnOpt.state &= ~State_Raised;
+                    bsx = proxy()->pixelMetric(PM_ButtonShiftHorizontal);
+                    bsy = proxy()->pixelMetric(PM_ButtonShiftVertical);
+                } else {
+                    btnOpt.state |= State_Raised;
+                    btnOpt.state &= ~State_Sunken;
+                    bsx = 0;
+                    bsy = 0;
+                }
+                btnOpt.rect = proxy()->subControlRect(CC_MdiControls, opt, SC_MdiCloseButton, widget);
+                proxy()->drawPrimitive(PE_PanelButtonCommand, &btnOpt, p, widget);
+                QPixmap pm = standardIcon(SP_TitleBarCloseButton).pixmap(16, 16);
+                proxy()->drawItemPixmap(p, btnOpt.rect.translated(bsx, bsy), Qt::AlignCenter, pm);
+            }
+            if (opt->subControls & QStyle::SC_MdiNormalButton) {
+                if (opt->activeSubControls & QStyle::SC_MdiNormalButton && (opt->state & State_Sunken)) {
+                    btnOpt.state |= State_Sunken;
+                    btnOpt.state &= ~State_Raised;
+                    bsx = proxy()->pixelMetric(PM_ButtonShiftHorizontal);
+                    bsy = proxy()->pixelMetric(PM_ButtonShiftVertical);
+                } else {
+                    btnOpt.state |= State_Raised;
+                    btnOpt.state &= ~State_Sunken;
+                    bsx = 0;
+                    bsy = 0;
+                }
+                btnOpt.rect = proxy()->subControlRect(CC_MdiControls, opt, SC_MdiNormalButton, widget);
+                proxy()->drawPrimitive(PE_PanelButtonCommand, &btnOpt, p, widget);
+                QPixmap pm = standardIcon(SP_TitleBarNormalButton).pixmap(16, 16);
+                proxy()->drawItemPixmap(p, btnOpt.rect.translated(bsx, bsy), Qt::AlignCenter, pm);
+            }
+            if (opt->subControls & QStyle::SC_MdiMinButton) {
+                if (opt->activeSubControls & QStyle::SC_MdiMinButton && (opt->state & State_Sunken)) {
+                    btnOpt.state |= State_Sunken;
+                    btnOpt.state &= ~State_Raised;
+                    bsx = proxy()->pixelMetric(PM_ButtonShiftHorizontal);
+                    bsy = proxy()->pixelMetric(PM_ButtonShiftVertical);
+                } else {
+                    btnOpt.state |= State_Raised;
+                    btnOpt.state &= ~State_Sunken;
+                    bsx = 0;
+                    bsy = 0;
+                }
+                btnOpt.rect = proxy()->subControlRect(CC_MdiControls, opt, SC_MdiMinButton, widget);
+                proxy()->drawPrimitive(PE_PanelButtonCommand, &btnOpt, p, widget);
+                QPixmap pm = standardIcon(SP_TitleBarMinButton).pixmap(16, 16);
+                proxy()->drawItemPixmap(p, btnOpt.rect.translated(bsx, bsy), Qt::AlignCenter, pm);
+            }
+        }
+        break;
+#endif // QT_NO_MDIAREA
     default:
         qWarning("QCommonStyle::drawComplexControl: Control %d not handled", cc);
     }
@@ -4091,6 +4153,50 @@ QRect QCommonStyle::subControlRect(ComplexControl cc, const QStyleOptionComplex
         break;
     }
 #endif // QT_NO_GROUPBOX
+#ifndef QT_NO_MDIAREA
+    case CC_MdiControls:
+    {
+        int numSubControls = 0;
+        if (opt->subControls & SC_MdiCloseButton)
+            ++numSubControls;
+        if (opt->subControls & SC_MdiMinButton)
+            ++numSubControls;
+        if (opt->subControls & SC_MdiNormalButton)
+            ++numSubControls;
+        if (numSubControls == 0)
+            break;
+
+        int buttonWidth = opt->rect.width() / numSubControls - 1;
+        int offset = 0;
+        switch (sc) {
+        case SC_MdiCloseButton:
+            // Only one sub control, no offset needed.
+            if (numSubControls == 1)
+                break;
+            offset += buttonWidth + 2;
+            //FALL THROUGH
+        case SC_MdiNormalButton:
+            // No offset needed if
+            // 1) There's only one sub control
+            // 2) We have a close button and a normal button (offset already added in SC_MdiClose)
+            if (numSubControls == 1 || (numSubControls == 2 && !(opt->subControls & SC_MdiMinButton)))
+                break;
+            if (opt->subControls & SC_MdiNormalButton)
+                offset += buttonWidth;
+            break;
+        default:
+            break;
+        }
+
+        // Subtract one pixel if we only have one sub control. At this point
+        // buttonWidth is the actual width + 1 pixel margin, but we don't want the
+        // margin when there are no other controllers.
+        if (numSubControls == 1)
+            --buttonWidth;
+        ret = QRect(offset, 0, buttonWidth, opt->rect.height());
+        break;
+    }
+#endif // QT_NO_MDIAREA
      default:
         qWarning("QCommonStyle::subControlRect: Case %d not handled", cc);
     }
diff --git a/src/widgets/styles/qwindowsxpstyle.cpp b/src/widgets/styles/qwindowsxpstyle.cpp
index e576e414ae..e20b85e209 100644
--- a/src/widgets/styles/qwindowsxpstyle.cpp
+++ b/src/widgets/styles/qwindowsxpstyle.cpp
@@ -3274,6 +3274,63 @@ void QWindowsXPStyle::drawComplexControl(ComplexControl cc, const QStyleOptionCo
         }
         break;
 
+#ifndef QT_NO_MDIAREA
+    case CC_MdiControls:
+        {
+            QRect buttonRect;
+            XPThemeData theme(widget, p, QWindowsXPStylePrivate::WindowTheme, WP_MDICLOSEBUTTON, CBS_NORMAL);
+
+            if (option->subControls & SC_MdiCloseButton) {
+                buttonRect = proxy()->subControlRect(CC_MdiControls, option, SC_MdiCloseButton, widget);
+                if (theme.isValid()) {
+                    theme.partId = WP_MDICLOSEBUTTON;
+                    theme.rect = buttonRect;
+                    if (!(flags & State_Enabled))
+                        theme.stateId = CBS_INACTIVE;
+                    else if (flags & State_Sunken && (option->activeSubControls & SC_MdiCloseButton))
+                        theme.stateId = CBS_PUSHED;
+                    else if (flags & State_MouseOver && (option->activeSubControls & SC_MdiCloseButton))
+                        theme.stateId = CBS_HOT;
+                    else
+                        theme.stateId = CBS_NORMAL;
+                    d->drawBackground(theme);
+                }
+            }
+            if (option->subControls & SC_MdiNormalButton) {
+                buttonRect = proxy()->subControlRect(CC_MdiControls, option, SC_MdiNormalButton, widget);
+                if (theme.isValid()) {
+                    theme.partId = WP_MDIRESTOREBUTTON;
+                    theme.rect = buttonRect;
+                    if (!(flags & State_Enabled))
+                        theme.stateId = CBS_INACTIVE;
+                    else if (flags & State_Sunken && (option->activeSubControls & SC_MdiNormalButton))
+                        theme.stateId = CBS_PUSHED;
+                    else if (flags & State_MouseOver && (option->activeSubControls & SC_MdiNormalButton))
+                        theme.stateId = CBS_HOT;
+                    else
+                        theme.stateId = CBS_NORMAL;
+                    d->drawBackground(theme);
+                }
+            }
+            if (option->subControls & QStyle::SC_MdiMinButton) {
+                buttonRect = proxy()->subControlRect(CC_MdiControls, option, SC_MdiMinButton, widget);
+                if (theme.isValid()) {
+                    theme.partId = WP_MDIMINBUTTON;
+                    theme.rect = buttonRect;
+                    if (!(flags & State_Enabled))
+                        theme.stateId = CBS_INACTIVE;
+                    else if (flags & State_Sunken && (option->activeSubControls & SC_MdiMinButton))
+                        theme.stateId = CBS_PUSHED;
+                    else if (flags & State_MouseOver && (option->activeSubControls & SC_MdiMinButton))
+                        theme.stateId = CBS_HOT;
+                    else
+                        theme.stateId = CBS_NORMAL;
+                    d->drawBackground(theme);
+                }
+            }
+        }
+        break;
+#endif //QT_NO_MDIAREA
 #ifndef QT_NO_DIAL
     case CC_Dial:
         if (const QStyleOptionSlider *dial = qstyleoption_cast<const QStyleOptionSlider *>(option))
@@ -3661,6 +3718,44 @@ QRect QWindowsXPStyle::subControlRect(ComplexControl cc, const QStyleOptionCompl
             }
         }
         break;
+#ifndef QT_NO_MDIAREA
+    case CC_MdiControls:
+    {
+        int numSubControls = 0;
+        if (option->subControls & SC_MdiCloseButton)
+            ++numSubControls;
+        if (option->subControls & SC_MdiMinButton)
+            ++numSubControls;
+        if (option->subControls & SC_MdiNormalButton)
+            ++numSubControls;
+        if (numSubControls == 0)
+            break;
+
+        int buttonWidth = option->rect.width() / numSubControls;
+        int offset = 0;
+        switch (subControl) {
+        case SC_MdiCloseButton:
+            // Only one sub control, no offset needed.
+            if (numSubControls == 1)
+                break;
+            offset += buttonWidth;
+            //FALL THROUGH
+        case SC_MdiNormalButton:
+            // No offset needed if
+            // 1) There's only one sub control
+            // 2) We have a close button and a normal button (offset already added in SC_MdiClose)
+            if (numSubControls == 1 || (numSubControls == 2 && !(option->subControls & SC_MdiMinButton)))
+                break;
+            if (option->subControls & SC_MdiNormalButton)
+                offset += buttonWidth;
+            break;
+        default:
+            break;
+        }
+        rect = QRect(offset, 0, buttonWidth, option->rect.height());
+        break;
+    }
+#endif // QT_NO_MDIAREA
 
     default:
         rect = visualRect(option->direction, option->rect,