tdf#150451 Fix borders in Editbox controls (kf5)

The bounding rectangle calculated for an Editbox in
QtGraphics_Controls::getNativeControlRegion was not
always enough to accommodate content and the borders.

The KDE Breeze does not draw any borders if the total
height of the bounding rectangle is smaller than the
minimum size needed for content + frame at top and bottom,
s. Style::drawFrameLineEditPrimitive in the Breeze
style [1].

Therefore, ensure a minimum height of that size.
The Breeze style also considers the type of the
passed widget when retrieving the frame width using
QStyle::pixelMetric [2], so pass a dummy `QLineEdit`
in order to get the actual frame width of 6
that the Breeze style uses for line edits, rather
than the default value of 2 that is returned when not
passing any widget.

Just do that for the minimum size calculation for now
and not everywhere, because the handling for edit boxes
here in the qt VCL plugins and in the calling code
currently does all kinds of "interesting" things like doing
extra size adjustments or passing the content rect where the
bounding rect would be expected,...

Ideally this should be cleaned up in the callers and all
platform integrations in a follow-up commit
to adhere to what the doc in vcl/inc/WidgetDrawInterface.hxx
says, but this here keeps it working with existing code for now.

(s.a. discussion in the Gerrit change for more details)

Tested using various scaling factors: 1, 1.25, 1.5, 1.75 and 2.0.

[1] https://invent.kde.org/plasma/breeze/-/blob/144ea45018d28758db07afd987d97318d56c4981/kstyle/breezestyle.cpp#L3527
[2] https://invent.kde.org/plasma/breeze/-/blob/144ea45018d28758db07afd987d97318d56c4981/kstyle/breezestyle.cpp#L555

Co-authored-by: Michael Weghorn <m.weghorn@posteo.de>

Change-Id: If8cb4794c7f3ce1be4d1ee421c9c27ad5adf5da2
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/146516
Tested-by: Jenkins
Reviewed-by: Michael Weghorn <m.weghorn@posteo.de>

2 files changed, 30 insertions, 3 deletions

diff --git a/vcl/inc/qt5/QtGraphics_Controls.hxx b/vcl/inc/qt5/QtGraphics_Controls.hxx
index 17039f9d6038..dd1865e34008 100644
--- a/vcl/inc/qt5/QtGraphics_Controls.hxx
+++ b/vcl/inc/qt5/QtGraphics_Controls.hxx
@@ -59,7 +59,8 @@ public:
                                 tools::Rectangle& rNativeContentRegion) override;
 
 private:
-    static int pixelMetric(QStyle::PixelMetric metric, const QStyleOption* option = nullptr);
+    static int pixelMetric(QStyle::PixelMetric metric, const QStyleOption* option = nullptr,
+                           const QWidget* pWidget = nullptr);
     static QSize sizeFromContents(QStyle::ContentsType type, const QStyleOption* option,
                                   const QSize& contentsSize);
     static QRect subControlRect(QStyle::ComplexControl control, const QStyleOptionComplex* option,
diff --git a/vcl/qt5/QtGraphics_Controls.cxx b/vcl/qt5/QtGraphics_Controls.cxx
index e08b84719e61..f2e48f655149 100644
--- a/vcl/qt5/QtGraphics_Controls.cxx
+++ b/vcl/qt5/QtGraphics_Controls.cxx
@@ -23,6 +23,7 @@
 #include <QtWidgets/QApplication>
 #include <QtWidgets/QFrame>
 #include <QtWidgets/QLabel>
+#include <QtWidgets/QLineEdit>
 
 #include <QtTools.hxx>
 #include <QtGraphicsBase.hxx>
@@ -129,9 +130,10 @@ bool QtGraphics_Controls::isNativeControlSupported(ControlType type, ControlPart
     return false;
 }
 
-inline int QtGraphics_Controls::pixelMetric(QStyle::PixelMetric metric, const QStyleOption* option)
+inline int QtGraphics_Controls::pixelMetric(QStyle::PixelMetric metric, const QStyleOption* option,
+                                            const QWidget* pWidget)
 {
-    return QApplication::style()->pixelMetric(metric, option);
+    return QApplication::style()->pixelMetric(metric, option, pWidget);
 }
 
 inline QSize QtGraphics_Controls::sizeFromContents(QStyle::ContentsType type,
@@ -759,6 +761,30 @@ bool QtGraphics_Controls::getNativeControlRegion(ControlType type, ControlPart p
             int nRight = qMax(nLine, upscale(fo.rect.right() - aSubRect.right(), Round::Ceil));
             int nBottom = qMax(nLine, upscale(fo.rect.bottom() - aSubRect.bottom(), Round::Ceil));
             boundingRect.adjust(nLeft, nTop, nRight, nBottom);
+
+            // tdf#150451: ensure a minimium size that fits text content + frame at top and bottom.
+            // Themes may use the widget type for determining the actual frame width to use,
+            // so pass a dummy QLineEdit
+            //
+            // NOTE: This is currently only done here for the minimum size calculation and
+            // not above because the handling for edit boxes here and in the calling code
+            // currently does all kinds of "interesting" things like doing extra size adjustments
+            // or passing the content rect where the bounding rect would be expected,...
+            // Ideally this should be cleaned up in the callers and all platform integrations
+            // to adhere to what the doc in vcl/inc/WidgetDrawInterface.hxx says, but this
+            // here keeps it working with existing code for now.
+            // (s.a. discussion in https://gerrit.libreoffice.org/c/core/+/146516 for more details)
+            QLineEdit aDummyEdit;
+            const int nFrameWidth = pixelMetric(QStyle::PM_DefaultFrameWidth, nullptr, &aDummyEdit);
+            QFontMetrics aFontMetrics(QApplication::font());
+            const int minHeight = upscale(aFontMetrics.height() + 2 * nFrameWidth, Round::Floor);
+            if (boundingRect.height() < minHeight)
+            {
+                const int nDiff = minHeight - boundingRect.height();
+                boundingRect.setHeight(boundingRect.height() + nDiff);
+                contentRect.setHeight(contentRect.height() + nDiff);
+            }
+
             retVal = true;
             break;
         }