内容

• 方法
• 详细描述
• 枚举
• 类型
• 日期/时间格式化程序
• 动态对象创建

Qt QML Element

The QML global Qt object provides useful enums and functions from Qt. 更多...

• 所有成员列表，包括继承成员

方法

• string atob (data)
• string btoa (data)
• 对象 createComponent (url)
• 对象 createQmlObject (string qml , object parent , string filepath )
• color darker (color baseColor , real factor )
• list<string> fontFamilies ()
• string formatDate (datetime date , variant format )
• string formatDateTime (datetime dateTime , variant format )
• string formatTime (datetime time , variant format )
• color hsla (real hue , real saturation , real lightness , real alpha )
• 对象 包括 (string url , jsobject callback )
• bool isQtObject (object)
• color lighter (color baseColor , real factor )
• string md5 (data)
• bool openUrlExternally (url target )
• point point (int x , int y )
• quit ()
• rect rect (int x , int y , int width , int height )
• url resolvedUrl (url url )
• color rgba (real red , real green , real blue , real alpha )
• size (int width , int height )
• color tint (color baseColor , color tintColor )
• vector3d (real x , real y , real z )

详细描述

The Qt 对象是具有实用函数、特性及枚举的全局对象。

它不可实例化；要使用它，调用成员来自全局 Qt 对象直接。例如：

import QtQuick 1.0
Text {
    color: Qt.rgba(1, 0, 0, 1)
    text: Qt.md5("hello, world")
}
					
					

枚举

Qt 对象包含的枚举可用于 Qt 名称空间 。例如，可以访问 Qt::LeftButton and Qt::RightButton enum values as Qt.LeftButton and Qt.RightButton .

类型

The Qt object also contains helper functions for creating objects of specific data types. This is primarily useful when setting the properties of an item when the property has one of the following types:

• color - use Qt.rgba(), Qt.hsla(), Qt.darker(), Qt.lighter() or Qt.tint()
• rect - use Qt.rect()
• point - use Qt.point()
• size - use Qt.size()
• vector3d - use Qt.vector3d()

There are also string based constructors for these types. See QML 基本类型 了解更多信息。

日期/时间格式化程序

The Qt object contains several functions for formatting QDateTime , QDate and QTime 值。

• string Qt.formatDateTime(datetime date, variant format)
• string Qt.formatDate(datetime date, variant format)
• string Qt.formatTime(datetime date, variant format)

The format specification is described at Qt.formatDateTime.

动态对象创建

The following functions on the global object allow you to dynamically create QML items from files or strings. See Dynamic Object Management in QML for an overview of their use.

• object Qt.createComponent(url)
• object Qt.createQmlObject(string qml, object parent, string filepath)

方法文档编制

string atob ( data )

ASCII to binary - this function returns a base64 decoding of data .

string btoa ( data )

Binary to ASCII - this function returns a base64 encoding of data .

对象 createComponent ( url )

返回 Component object created using the QML file at the specified url ，或 null if an empty string was given.

The returned component's Component::status property indicates whether the component was successfully created. If the status is Component.Error ，见 Component::errorString() for an error description.

调用 Component.createObject() on the returned component to create an object instance of the component.

例如：

import QtQuick 1.0
Item {
    id: container
    width: 300; height: 300
    function loadButton() {
        var component = Qt.createComponent("Button.qml");
        if (component.status == Component.Ready) {
            var button = component.createObject(container);
            button.color = "red";
        }
    }
    Component.onCompleted: loadButton()
}
								

见 Dynamic Object Management in QML for more information on using this function.

To create a QML object from an arbitrary string of QML (instead of a file), use Qt.createQmlObject().

对象 createQmlObject ( string qml , 对象 parent , string filepath )

Returns a new object created from the given string of QML which will have the specified parent ，或 null if there was an error in creating the object.

若 filepath is specified, it will be used for error reporting for the created object.

Example (where parentItem is the id of an existing QML item):

var newObject = Qt.createQmlObject('import QtQuick 1.0; Rectangle {color: "red"; width: 20; height: 20}',
    parentItem, "dynamicSnippet1");
									

In the case of an error, a QtScript Error object is thrown. This object has an additional property, qmlErrors , which is an array of the errors encountered. Each object in this array has the members lineNumber , columnNumber , fileName and message . For example, if the above snippet had misspelled color as 'colro' then the array would contain an object like the following: { "lineNumber" : 1, "columnNumber" : 32, "fileName" : "dynamicSnippet1", "message" : "Cannot assign to non-existent property "colro""}.

Note that this function returns immediately, and therefore may not work if the qml string loads new components (that is, external QML files that have not yet been loaded). If this is the case, consider using Qt.createComponent() instead.

见 Dynamic Object Management in QML for more information on using this function.

color darker ( color baseColor , real factor )

Returns a color darker than baseColor 通过 factor provided.

If the factor is greater than 1.0, this function returns a darker color. Setting factor to 3.0 returns a color that has one-third the brightness. If the factor is less than 1.0, the return color is lighter, but we recommend using the Qt. lighter() function for this purpose. If the factor is 0 or negative, the return value is unspecified.

The function converts the current RGB color to HSV, divides the value (V) component by factor and converts the color back to RGB.

若 factor is not supplied, returns a color 50% darker than baseColor (factor 2.0).

list < string > fontFamilies ()

Returns a list of the font families available to the application.

string formatDate ( datetime date , variant format )

Returns a string representation of date , optionally formatted according to format .

The date parameter may be a JavaScript Date 对象， date 特性， QDate ，或 QDateTime 值。 format parameter may be any of the possible format values as described for Qt.formatDateTime().

若 format 未指定， date is formatted using Qt.DefaultLocaleShortDate .

string formatDateTime ( datetime dateTime , variant format )

Returns a string representation of datetime , optionally formatted according to format .

The date parameter may be a JavaScript Date 对象， date 特性， QDate , QTime ，或 QDateTime 值。

若 format is not provided, dateTime is formatted using Qt.DefaultLocaleShortDate 。否则， format should be either.

• One of the Qt::DateFormat enumeration values, such as Qt.DefaultLocaleShortDate or Qt.ISODate
• A string that specifies the format of the returned string, as detailed below.

若 format specifies a format string, it should use the following expressions to specify the date:

表达式	输出
d	the day as number without a leading zero (1 to 31)
dd	the day as number with a leading zero (01 to 31)
ddd	the abbreviated localized day name (e.g. 'Mon' to 'Sun'). Uses QDate::shortDayName() .
dddd	the long localized day name (e.g. 'Monday' to ' Qt::Sunday '). Uses QDate::longDayName() .
M	the month as number without a leading zero (1-12)
MM	the month as number with a leading zero (01-12)
MMM	the abbreviated localized month name (e.g. 'Jan' to 'Dec'). Uses QDate::shortMonthName() .
MMMM	the long localized month name (e.g. 'January' to 'December'). Uses QDate::longMonthName() .
yy	the year as two digit number (00-99)
yyyy	the year as four digit number

In addition the following expressions can be used to specify the time:

表达式	输出
h	the hour without a leading zero (0 to 23 or 1 to 12 if AM/PM display)
hh	the hour with a leading zero (00 to 23 or 01 to 12 if AM/PM display)
m	the minute without a leading zero (0 to 59)
mm	the minute with a leading zero (00 to 59)
s	the second without a leading zero (0 to 59)
ss	the second with a leading zero (00 to 59)
z	the milliseconds without leading zeroes (0 to 999)
zzz	the milliseconds with leading zeroes (000 to 999)
AP	use AM/PM display. AP will be replaced by either "AM" or "PM".
ap	use am/pm display. ap will be replaced by either "am" or "pm".

All other input characters will be ignored. Any sequence of characters that are enclosed in single quotes will be treated as text and not be used as an expression. Two consecutive single quotes ("''") are replaced by a single quote in the output.

For example, if the following date/time value was specified:

// 21 May 2001 14:13:09
var dateTime = new Date(2001, 5, 21, 14, 13, 09)
													

This dateTime value could be passed to Qt.formatDateTime() , Qt.formatDate() or Qt.formatTime() with the format values below to produce the following results:

格式	结果
"dd.MM.yyyy"	21.05.2001
"ddd MMMM d yy"	Tue May 21 01
"hh:mm:ss.zzz"	14:13:09.042
"h:m:s ap"	2:13:9 pm

string formatTime ( datetime time , variant format )

Returns a string representation of time , optionally formatted according to format .

The time parameter may be a JavaScript Date 对象， QTime ，或 QDateTime 值。 format parameter may be any of the possible format values as described for Qt.formatDateTime().

若 format 未指定， time is formatted using Qt.DefaultLocaleShortDate .

color hsla ( real hue , real saturation , real lightness , real alpha )

Returns a color with the specified hue , saturation , lightness and alpha components. All components should be in the range 0-1 inclusive.

对象 包括 ( string url , jsobject callback )

Includes another JavaScript file. This method can only be used from within JavaScript files, and not regular QML files.

This imports all functions from url into the current script's namespace.

Qt.include() returns an object that describes the status of the operation. The object has a single property, status , that is set to one of the following values:

Symbol	值	描述
result.OK	0	The include completed successfully.
result.LOADING	1	Data is being loaded from the network.
result.NETWORK_ERROR	2	A network error occurred while fetching the url.
result.EXCEPTION	3	A JavaScript exception occurred while executing the included code. An additional exception property will be set in this case.

The status property will be updated as the operation progresses.

If provided, callback is invoked when the operation completes. The callback is passed the same object as is returned from the Qt.include() call.

bool isQtObject ( 对象 )

返回 true 若 对象 is a valid reference to a Qt or QML object, otherwise false.

color lighter ( color baseColor , real factor )

Returns a color lighter than baseColor 通过 factor provided.

If the factor is greater than 1.0, this functions returns a lighter color. Setting factor to 1.5 returns a color that is 50% brighter. If the factor is less than 1.0, the return color is darker, but we recommend using the Qt. darker() function for this purpose. If the factor is 0 or negative, the return value is unspecified.

The function converts the current RGB color to HSV, multiplies the value (V) component by factor and converts the color back to RGB.

若 factor is not supplied, returns a color 50% lighter than baseColor (factor 1.5).

string md5 ( data )

Returns a hex string of the md5 hash of data .

bool openUrlExternally ( url target )

Attempts to open the specified target url in an external application, based on the user's desktop preferences. Returns true if it succeeds, and false otherwise.

point point ( int x , int y )

Returns a Point with the specified x and y 坐标。

quit ()

此函数导致 QDeclarativeEngine::quit() signal to be emitted. Within the QML 查看器 , this causes the launcher application to exit; to quit a C++ application when this method is called, connect the QDeclarativeEngine::quit() 信号到 QCoreApplication::quit() 槽。

rect rect ( int x , int y , int width , int height )

返回 rect with the top-left corner at x , y and the specified width and height .

The returned object has x , y , width and height attributes with the given values.

url resolvedUrl ( url url )

返回 url resolved relative to the URL of the caller.

color rgba ( real red , real green , real blue , real alpha )

Returns a color with the specified red , green , blue and alpha components. All components should be in the range 0-1 inclusive.

size ( int width , int height )

Returns a Size with the specified width and height .

color tint ( color baseColor , color tintColor )

This function allows tinting one color with another.

The tint color should usually be mostly transparent, or you will not be able to see the underlying color. The below example provides a slight red tint by having the tint color be pure red which is only 1/16th opaque.

Item {
    Rectangle {
        x: 0; width: 80; height: 80
        color: "lightsteelblue"
    }
    Rectangle {
        x: 100; width: 80; height: 80
        color: Qt.tint("lightsteelblue", "#10FF0000")
    }
}
																											

Tint is most useful when a subtle change is intended to be conveyed due to some event; you can then use tinting to more effectively tune the visible color.

vector3d ( real x , real y , real z )

Returns a Vector3D with the specified x , y and z .