Diagnostic style for layout debugging

Less use than I'd hoped it would be.

tablet_qt/camcops.pro

@@ -648,6 +648,7 @@ SOURCES += \
     lib/css.cpp \
     lib/datetime.cpp \
     lib/debugfunc.cpp \
+    lib/diagnosticstyle.cpp \
     lib/errorfunc.cpp \
     lib/filefunc.cpp \
     lib/flagguard.cpp \
@@ -1136,6 +1137,7 @@ HEADERS += \
     lib/css.h \
     lib/datetime.h \
     lib/debugfunc.h \
+    lib/diagnosticstyle.h \
     lib/errorfunc.h \
     lib/filefunc.h \
     lib/flagguard.h \

tablet_qt/lib/diagnosticstyle.cpp

@@ -0,0 +1,42 @@
+/*
+    Copyright (C) 2012, University of Cambridge, Department of Psychiatry.
+    Created by Rudolf Cardinal (rnc1001@cam.ac.uk).
+
+    This file is part of CamCOPS.
+
+    CamCOPS is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    CamCOPS is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with CamCOPS. If not, see <https://www.gnu.org/licenses/>.
+*/
+
+// https://stackoverflow.com/questions/5909907/drawing-an-overlay-on-top-of-an-applications-window
+
+#include "diagnosticstyle.h"
+#include <QBrush>
+#include <QPainter>
+#include <QWidget>
+
+void DiagnosticStyle::drawControl(ControlElement element, const QStyleOption* option, QPainter* painter, const QWidget* widget) const
+{
+    QCommonStyle::drawControl(element, option, painter, widget);
+    if (widget && painter) {
+        // draw a border around the widget
+        painter->setPen(QColor("red"));
+        painter->drawRect(widget->rect());
+
+        // show the classname of the widget
+        QBrush translucentBrush(QColor(255,246,240, 100));
+        painter->fillRect(widget->rect(), translucentBrush);
+        painter->setPen(QColor("darkblue"));
+        painter->drawText(widget->rect(), Qt::AlignLeft | Qt::AlignVCenter, widget->metaObject()->className());
+    }
+};

tablet_qt/lib/diagnosticstyle.h

@@ -0,0 +1,31 @@
+/*
+    Copyright (C) 2012, University of Cambridge, Department of Psychiatry.
+    Created by Rudolf Cardinal (rnc1001@cam.ac.uk).
+
+    This file is part of CamCOPS.
+
+    CamCOPS is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    CamCOPS is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with CamCOPS. If not, see <https://www.gnu.org/licenses/>.
+*/
+
+#pragma once
+#include <QCommonStyle>
+
+class DiagnosticStyle : public QCommonStyle
+{
+Q_OBJECT
+
+public:
+void drawControl(ControlElement element, const QStyleOption* option, QPainter* painter, const QWidget* widget) const;
+    typedef QStyle BaseStyle;
+};

tablet_qt/main.cpp

@@ -23,6 +23,8 @@
 #define FULL_LOG_FORMAT  // Include time and thread ID.
 // #define DISABLE_ANDROID_NATIVE_DIALOGS  // For a bug fixed in Qt 5.2.1.
 // #define QT_OPENGL_IN_SOFTWARE  // Unnecessary once proper OpenGL detection added.
+// #define DEBUG_WITH_DIAGNOSTIC_STYLE
+
 
 #include <QApplication>
 #include <QDebug>
@@ -31,6 +33,7 @@
 #include "common/preprocessor_aid.h"
 #include "core/camcopsapp.h"
 #include "crypto/cryptofunc.h"
+#include "lib/diagnosticstyle.h"
 
 #ifdef FULL_LOG_FORMAT
     #ifdef QT_DEBUG
@@ -119,8 +122,15 @@ VISIBLE_SYMBOL int main(int argc, char* argv[])
         created. See https://bugreports.qt.io/browse/QTBUG-45517
     */
 
+#ifdef DEBUG_WITH_DIAGNOSTIC_STYLE
+    // Overlay widgets with bounding box and class name
+    auto style = new DiagnosticStyle();
+#else
     QStyle* style = QStyleFactory::create("Fusion");
+#endif
+
     // QProxyStyle* proxy_style = new TreeViewProxyStyle(style);
+
     QApplication::setStyle(style);
     // ... https://stackoverflow.com/questions/41184723/i-want-qt-app-to-look-like-qt-app-rather-than-android-native