Roson讲Qt#17 谈谈Qt QML、Qt Quick、Qt Quick Controls之间的关系
经昱
目录
1.概念
Qt QML:QML是一种用户界面规范和编程语言。它允许开发人员和设计师一样创建高性能、流畅的动画和视觉上吸引人的应用程序。QML提供了高可读性、声明性、类似json的语法，支持命令式JavaScript表达式和动态属性绑定。QML语言和引擎基础结构由Qt QML模块提供。
Qt Quick模块:Qt Quick是QML的类型和功能的标准库。它包括视觉类型，交互类型，动画，模型和视图，粒子效果和着色效果。QML应用程序开发人员可以通过一个导入语句访问所有这些功能。QtQuick QML库由QtQuick模块提供。
Qt Quick Controls模块:提供了一组控件，可用于在Qt Quick中构建完整的接口。
2.关系和区别
QML是一种编程语言，和C++，C#，Java一样，属于一种编程语言。QML提供一些基本的数据类型。
Qt Quick是一个库，作用和我们说的C++标准库一样，如果要编写C++代码，肯定需要C++标准库的支撑。我们在写Qt Quick应用程序时，肯定需要用到一些数据类型，还有一些语法，而这些东西，就是Qt Quick提供的。在QML已经提供的基础数据类型的基础上，Qt Quick又引入了更高级易用的数据类型，这就好比QML中有char*，Qt Quick又搞了个CString。
Qt Quick Controls是Qt Quick的一个子模块，Qt Quick不仅包含Controls，还包含了
Dialogs、Layouts等模块。
3.扩展
3.1QML语言提供的基本数据类型
| date | Date value |
| point | Value with x and y attributes |
| rect | Value with x, y, width and height attributes |
| size | Value with width and height attributes |
3.2QML语言提供的基本对象类型
| Date | Provides date functions |
| Number | Object provides represents a number value |
| String | Object represents a string value |
| Component | Encapsulates a QML component definition |
| Qt | Provides a global object with useful enums and functions from Qt |
| QtObject | A basic QML type |
| Locale | Provides locale specific properties and formatted data |
| LoggingCategory | Defines a logging category in QML |
| Binding | Enables the arbitrary creation of property bindings |
| Connections | Describes generalized connections to signals |
| Instantiator | Dynamically creates objects |
| Timer | Triggers a handler at a specified interval |
3.3Qt Quick的子模块
Qt Quick包含几个子模块，并且这些子模块还包含额外的类型。子模块列举如下：
- XML List Model - contains types for creating models from XML data
- Local Storage - a submodule containing a JavaScript interface for an SQLite database
- Particles - provides a particle system for QML applications
- Window - contains types for creating top-level windows and accessing screen information
- Dialogs - contains types for creating and interacting with system dialogs
- Controls - provides a set of reusable UI components
- Layouts - contains types that are used to arrange items in the user interface
- Tests - types for testing QML applications.
3.4Qt Quick提供的基本数据类型
| color | ARGB color value. The color type refers to an ARGB color value. It can be specified in a number of ways: |
| font | Font value with the properties of QFont. The font type refers to a font value with the properties of QFont |
| matrix4x4 | A matrix4x4 type is a 4-row and 4-column matrix |
| quaternion | A quaternion type has scalar, x, y, and z attributes |
| vector2d | A vector2d type has x and y attributes |
| vector3d | Value with x, y, and z attributes |
| vector4d | A vector4d type has x, y, z and w attributes |
3.5Qt Quick提供的基本对象类型
QtQuick导入提供的所有对象类型都基于Item类型，该类型本身派生自QtObject。在导入QtQuick时，Qt QML模块提供的QML对象类型(如QtObject和Component)也可用。
| Canvas | Provides a 2D canvas item enabling drawing via JavaScript |
| CanvasGradient | Provides an opaque CanvasGradient interface |
| CanvasImageData | Contains image pixel data in RGBA order |
| CanvasPixelArray | Provides ordered and indexed access to the components of each pixel in image data |
| Context2D | Provides 2D context for shapes on a Canvas item |
| Accessible | Enables accessibility of QML items |
| AnimatedImage | Plays animations stored as a series of images |
| AnimatedSprite | Draws a sprite animation |
| BorderImage | Paints a border based on an image |
| Drag | For specifying drag and drop events for moved Items |
| DragEvent | Provides information about a drag event |
| DropArea | For specifying drag and drop handling in an area |
| KeyEvent | Provides information about a key event |
| MouseEvent | Provides information about a mouse event |
| WheelEvent | Provides information about a mouse wheel event |
| Flickable | Provides a surface that can be "flicked" |
| Flipable | Provides a surface that can be flipped |
| FocusScope | Explicitly creates a focus scope |
| GraphicsInfo | Provides information about the used Qt Quick backend |
| GridView | For specifying a grid view of items provided by a model |
| Image | Displays an image |
| EnterKey | Provides a property to manipulate the appearance of Enter key on an on-screen keyboard |
| Item | A basic visual QML type |
| KeyNavigation | Supports key navigation by arrow keys |
| Keys | Provides key handling to Items |
| LayoutMirroring | Property used to mirror layout behavior |
| Transform | For specifying advanced transformations on Items |
| AnchorAnimation | Animates changes in anchor values |
| ParentAnimation | Animates changes in parent values |
| PathAnimation | Animates an item along a path |
| ItemGrabResult | Contains the results from a call to Item::grabToImage() |
| ViewTransition | Specifies items under transition in a view |
| ListView | Provides a list view of items provided by a model |
| Loader | Allows dynamic loading of a subtree from a URL or Component |
| MouseArea | Enables simple mouse handling |
| GestureEvent | Parameter given with the gestureStarted signal |
| MultiPointTouchArea | Enables handling of multiple touch points |
| TouchPoint | Describes a touch point in a MultiPointTouchArea |
| PathView | Lays out model-provided items on a path |
| PinchArea | Enables simple pinch gesture handling |
| PinchEvent | For specifying information about a pinch event |
| Column | Positions its children in a column |
| Flow | Positions its children side by side, wrapping as necessary |
| Grid | Positions its children in grid formation |
| Positioner | Provides attached properties that contain details on where an item exists in a positioner |
| Row | Positions its children in a row |
| Gradient | Defines a gradient fill |
| GradientStop | Defines the color at a position in a Gradient |
| Rectangle | Paints a filled rectangle with an optional border |
| Repeater | Instantiates a number of Item-based components using a provided model |
| ShaderEffect | Applies custom shaders to a rectangle |
| BorderImageMesh | Defines a mesh with vertices arranged like those of a BorderImage |
| GridMesh | Defines a mesh with vertices arranged in a grid |
| ShaderEffectSource | Renders a Qt Quick item into a texture and displays it |
| Sprite | Specifies sprite animations |
| SpriteSequence | Draws a sprite animation |
| AnchorChanges | Specifies how to change the anchors of an item in a state |
| ParentChange | Specifies how to reparent an Item in a state change |
| Text | Specifies how to add formatted text to a scene |
| TextEdit | Displays multiple lines of editable formatted text |
| TextInput | Displays an editable line of text |
| Matrix4x4 | Provides a way to apply a 4x4 tranformation matrix to an Item |
| Rotation | Provides a way to rotate an Item |
| Scale | Provides a way to scale an Item |
| Translate | Provides a way to move an Item without changing its x or y properties |
| Animation | Is the base of all QML animations |
| ColorAnimation | Animates changes in color values |
| NumberAnimation | Animates changes in qreal-type values |
| ParallelAnimation | Enables animations to be run in parallel |
| PauseAnimation | Provides a pause for an animation |
| PropertyAction | Specifies immediate property changes during animation |
| PropertyAnimation | Animates changes in property values |
| RotationAnimation | Animates changes in rotation values |
| ScriptAction | Defines scripts to be run during an animation |
| SequentialAnimation | Allows animations to be run sequentially |
| Vector3dAnimation | Animates changes in QVector3d values |
| AnimationController | Enables manual control of animations |
| Animator | Is the base of all QML animators |
| OpacityAnimator | Type animates the opacity of an Item |
| RotationAnimator | Type animates the rotation of an Item |
| ScaleAnimator | Type animates the scale factor of an Item |
| UniformAnimator | Type animates a uniform of a ShaderEffect |
| XAnimator | Type animates the x position of an Item |
| YAnimator | Type animates the y position of an Item |
| Behavior | Defines a default animation for a property change |
| FontLoader | Allows fonts to be loaded by name or URL |
| FontMetrics | Provides metrics for a given font |
| Path | Defines a path for use by PathView |
| PathArc | Defines an arc with the given radius |
| PathAttribute | Specifies how to set an attribute at a given position in a Path |
| PathCubic | Defines a cubic Bezier curve with two control points |
| PathCurve | Defines a point on a Catmull-Rom curve |
| PathElement | The base path type |
| PathLine | Defines a straight line |
| PathPercent | Manipulates the way a path is interpreted |
| PathQuad | Defines a quadratic Bezier curve with a control point |
| PathSvg | Defines a path using an SVG path data string |
| PathInterpolator | Specifies how to manually animate along a path |
| PropertyChanges | Describes new property bindings or values for a state |
| Shortcut | Provides keyboard shortcuts |
| SmoothedAnimation | Allows a property to smoothly track a value |
| SpringAnimation | Allows a property to track a value in a spring-like motion |
| State | Defines configurations of objects and properties |
| StateChangeScript | Specifies how to run a script in a state |
| StateGroup | Provides built-in state support for non-Item types |
| SystemPalette | Provides access to the Qt palettes |
| TextMetrics | Provides metrics for a given font and text |
| Transition | Defines animated transitions that occur on state changes |
| DoubleValidator | Defines a validator for non-integer numbers |
| IntValidator | Defines a validator for integer values |
| RegExpValidator | Provides a string validator |
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