example: Add an example about using stylesheets

2021-09-08 23:14:47 +01:00
parent 83c8c22736
commit b5c11ce199
2 changed files with 82 additions and 1 deletions
--- a/examples/dockwidgets/MyTitleBar_CSS.h
+++ b/examples/dockwidgets/MyTitleBar_CSS.h
@@ -0,0 +1,79 @@
+/*
+  This file is part of KDDockWidgets.
+
+  SPDX-FileCopyrightText: 2019-2021 Klarälvdalens Datakonsult AB, a KDAB Group company <info@kdab.com>
+  Author: Sérgio Martins <sergio.martins@kdab.com>
+
+  SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only
+
+  Contact KDAB at <info@kdab.com> for commercial licensing options.
+*/
+
+#include <kddockwidgets/private/widgets/TitleBarWidget_p.h>
+
+/**
+ * @brief Shows how to implement a custom titlebar which uses "Qt StyleSheets".
+ * 
+ * Derive from KDDockWidgets::DefaultWidgetFactory and override the two createTitleBar() methods.
+ * 
+ * To try it out, modify examples/dockwidgets/MyFrameworkWidgetFactory.cpp to return a MyTitleBar_CSS instance.
+ * Run the example with: ./bin/kddockwidgets_example -p
+ *
+ * WARNINGS:
+ *   - Qt StyleSheets are not recommended for new applications. Often you are able to style 90% of
+ *   the application but then hit a road block. QStyle is much more powerful and flexible.
+ *   - The Qt maintainers have manifested intention to deprecated stylesheets.
+ *   - Stylesheets are supported for built-in QWidgets (QPushButton, QComboBox, etc.), any widget
+ *   that's not in Qt needs to be crafted by the user, that includes, for example, having to paint
+ *   your background manually. KDDockWidget::TitleBarWidget does this for your convenience though.
+ *   - Qt stylesheets don't react to property changes (known old bug in Qt), for example:
+ *     QLineEdit[readOnly="true"] { color: gray }
+ *     this won't trigger when readOnly changes to false, you need to set/unset. This is QTBUG-51236
+ *   - KDDockWidgets::TitleBarWidget::isFocused is a property, there for needs to workaround the
+ *   above bug by unsetting the sheet and setting it again.
+ */
+class MyTitleBar_CSS : public KDDockWidgets::TitleBarWidget
+{
+public:
+    explicit MyTitleBar_CSS(KDDockWidgets::Frame *frame)
+        : KDDockWidgets::TitleBarWidget(frame)
+    {
+        init();
+    }
+
+    explicit MyTitleBar_CSS(KDDockWidgets::FloatingWindow *fw)
+        : KDDockWidgets::TitleBarWidget(fw)
+    {
+        init();
+    }
+
+    ~MyTitleBar_CSS() override;
+
+    void initStyleSheet()
+    {
+        // Or use qApp->setStyleSheet(), as you prefer
+        setStyleSheet(QStringLiteral("KDDockWidgets--TitleBarWidget {"
+                                     "background: blue"
+                                     "}"
+                                     "KDDockWidgets--TitleBarWidget:hover {"
+                                     "background: red"
+                                     "}"
+                                     "KDDockWidgets--TitleBarWidget[isFocused=true] {"
+                                     "background: green"
+                                     "}"));
+    }
+
+    void init()
+    {
+        initStyleSheet();
+        connect(this, &KDDockWidgets::TitleBar::isFocusedChanged, this, [this] {
+            // Workaround QTBUG-51236, this makes the [isFocused=true] syntax useful
+            setStyleSheet(QString());
+            initStyleSheet();
+        });
+    }
+};
+
+MyTitleBar_CSS::~MyTitleBar_CSS()
+{
+}