### Paint title bar outline

Source: https://github.com/kde/kdecoration/blob/master/doc/KDecoration 3 porting guide.md

Examples of painting a 1px wide outline, comparing incorrect integer-based clipping with the recommended floating-point approach.

```cpp
painter->setClipRect(titleBarRect.x(), titleBarRect.y(), titleBarRect.width(), titleBarRect.height(), Qt::IntersectClip)
painter->setBrush(QPen(QColor::red, 1));
painter->paintRect(rect());
```

```cpp
painter->setClipRect(titleBarRect, Qt::IntersectClip);
const qreal width = KDecoration3::pixelSize(window()->scale());
painter->setBrush(QPen(QColor::red, width));
painter->paintRect(rect().adjusted(width / 2, width / 2, -width / 2, -width / 2));
```

--------------------------------

### Configure Decoration Shadow Test

Source: https://github.com/kde/kdecoration/blob/master/autotests/CMakeLists.txt

Defines the decorationShadowTest executable and registers it as a test using ECM.

```cmake
set(decorationShadowTest_SRCS
    shadowtest.cpp
    )
add_executable(decorationShadowTest ${decorationShadowTest_SRCS})
target_link_libraries(decorationShadowTest kdecorations3 Qt::Test)
add_test(NAME kdecoration3-decorationShadowTest COMMAND decorationShadowTest)
ecm_mark_as_test(decorationShadowTest)
```

--------------------------------

### Configure Decoration Button Test

Source: https://github.com/kde/kdecoration/blob/master/autotests/CMakeLists.txt

Defines the decorationButtonTest executable and registers it as a test using ECM.

```cmake
set(decorationButtonTest_SRCS
    mockbridge.cpp mockbridge.h
    mockbutton.cpp mockbutton.h
    mockwindow.cpp mockwindow.h
    mockdecoration.cpp mockdecoration.h
    mocksettings.cpp mocksettings.h
    decorationbuttontest.cpp
    )
add_executable(decorationButtonTest ${decorationButtonTest_SRCS})
target_link_libraries(decorationButtonTest kdecorations3 kdecorations3private Qt::Test)
add_test(NAME kdecoration3-decorationButtonTest COMMAND decorationButtonTest)
ecm_mark_as_test(decorationButtonTest)
```

--------------------------------

### Snap geometry to pixel grid

Source: https://github.com/kde/kdecoration/blob/master/doc/KDecoration 3 porting guide.md

Use these helpers to ensure geometry values align with the pixel grid based on the window scale factor.

```cpp
KDecoration3::snapToPixelGrid(value, scale)
```

```cpp
std::max(KDecoration3::snapToPixelGrid(value, scale), KDecoration3::pixelSize(scale))
```

--------------------------------

### Register KDecoration3 Plugin Factory

Source: https://github.com/kde/kdecoration/blob/master/README.md

Macro usage to register the decoration implementation using the KCoreAddons framework.

```cpp
K_PLUGIN_FACTORY_WITH_JSON(
    MyAwesomeDecorationFactory,
    "deco.json",
    registerPlugin<MyAwesomeDecoration::Decoration>();
)
```

--------------------------------

### Configure Decoration Test

Source: https://github.com/kde/kdecoration/blob/master/autotests/CMakeLists.txt

Defines the decorationTest executable and registers it as a test using ECM.

```cmake
set(decorationTest_SRCS
    mockbridge.cpp mockbridge.h
    mockbutton.cpp mockbutton.h
    mockwindow.cpp mockwindow.h
    mockdecoration.cpp mockdecoration.h
    mocksettings.cpp mocksettings.h
    decorationtest.cpp
    )
add_executable(decorationTest ${decorationTest_SRCS})
target_link_libraries(decorationTest kdecorations3 kdecorations3private Qt::Test)
add_test(NAME kdecoration3-decorationTest COMMAND decorationTest)
ecm_mark_as_test(decorationTest)
```

--------------------------------

### Define KDecoration3 Plugin Metadata

Source: https://github.com/kde/kdecoration/blob/master/README.md

JSON metadata file required for the framework to discover and load the decoration plugin.

```json
{
    "KPlugin": {
        "Id": "org.kde.myAweseomeDecoration",
        "ServiceTypes": [
            "org.kde.kdecoration3"
        ]
    },
    "X-KDE-ConfigModule": "kcm_name", /* comes with a configuration module */
    "org.kde.kdecoration3": {
        "blur": false, /* blur behind not needed */
    }
}
```

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