qt-everywhere-src-5.15.1/qtdeclarative/dist/changes-5.15.0 - orbit - Git at Google

 Qt 5.15 introduces many new features and improvements as well as bugfixes
 over the 5.14.x series. For more details, refer to the online documentation
 included in this distribution. The documentation is also available online:

 https://doc.qt.io/qt-5/index.html

 The Qt version 5.15 series is binary compatible with the 5.14.x series.
 Applications compiled for 5.14 will continue to run with 5.15.

 Some of the changes listed in this file include issue tracking numbers
 corresponding to tasks in the Qt Bug Tracker:

   https://bugreports.qt.io/

 Each of these identifiers can be entered in the bug tracker to obtain more
 information about a particular change.

 ****************************************************************************
 *                   Important Behavior Changes                             *
 ****************************************************************************

  - [QTBUG-74137] CMake: Added a Qt6 forward compatible CMake API. Using this,
    you can define projects that work with either Qt5 or Qt6, without further
    changes.

  - [QTBUG-79331] If you register the same revision of the same type multiple
    times, the last registration is the one QML will use. This allows you to
    override qmlRegisterSingleton*() calls, for example in order to register a
    singleton instance for a type tagged with QML_SINGLETON. Previously, the
    first registration would take effect.

  - [QTBUG-79868] Using instanceof to check whether an instance has the type of
    QObject or one of its derived classes used to raise a TypeError, if the
    instance was not derived from QObject. Now, it instead returns false, which
    is more in line with the ECMAScript semantic.

  - The QML ObjectModel type had an undocumented "feature" which made it sort
    items in list views into sections according to context properties of the QML
    context the created objects belong to. Instead of context properties, object
    properties are used now.

  - [QTBUG-73669] Using the Qt Quick Compiler would exclude the original .qml
    files from the resource system. This made it impossible to change the Qt
    library binary later as the program binary was tied the to the exact Qt
    version. In addition sometimes unrelated files (QTBUG-73669) were removed.
    For the latter scenario, retain and skip options were added for the Qt
    Quick Compiler. In Qt 5.15 the Qt Quick Compiler does not remove the input
    files anymore. All files are retained and the compiler merely adds the
    more efficient binary representation to the application.

 ****************************************************************************
 *                            Deprecation Notice                            *
 ****************************************************************************

  - The qmlmin tool is deprecated and not needed anymore. The built-in caching of
    qml files addresses the needs and unfortunately the tool does not work with
    more advanced concepts such as required properties or the ES 7 yield
    statement. It will be removed in Qt 6.

  - qmlRegisterExtendedType() without URI or version, is deprecated. You should
    state the module the type belongs to, by supplying a URI and version.

  - qmlRegisterInterface(const char *typeName) without URI or version, is
    deprecated. You should state the module the type belongs to, but supplying a
    URI and version. Conversely, the typeName is redundant as the type itself
    is already supplied as template parameter. None of the other registration
    functions allow overriding the name for the metatype registration.

  - QQmlIncubationController::incubateWhile(volatile bool *flag, int msecs) is
    deprecated. The volatile parameter is used as a poor man's atomic bool, with
    all the well known downsides of such a practice. A replacement method
    taking an actual atomic is provided.

  - In QML Connections elements, the handlers should be defined as plain
    JavaScript functions, not as "onPropertyChanged properties".

  - You can currently access local files from QML via XMLHttpRequest using
    "file://..." URLs. This will not be allowed by default anymore in Qt6. If
    you actually need this behavior, you can set the environment variables
    QML_XHR_ALLOW_FILE_READ and/or QML_XHR_ALLOW_FILE_WRITE to 1. You can also
    set them to 0 when using Qt 5.15 to prevent local file access.

  - [QTBUG-78596] The class QSGEngine is now deprecated.

 ****************************************************************************
 *                                  QtQml                                   *
 ****************************************************************************

  - QML allows a new attribute "required" to be attached to properties. Such
    properties have to be set when instantiating a component. The various models
    and views use this as the preferred way of communicating model data to
    delegates. The old way of passing model data via context properties should
    be avoided in new code.

  - The qmllint tool has been extended to check for patterns considered to be
    potentially problematic in Qt6, and suggest better solutions. Pass the -U
    command line option to enable the checks.

  - The new qmlformat tool can be used to pretty-print a QML file according to
    the recommended code style.

  - QML supports type assertions similar to typescript. So far this is only used
    to make the intended type of an expression known to qmllint. At run time,
    type assertions are ignored.

  - C++ types can and should be registered to QML at compile time now. For this
    purpose there are a number of macros available in qqml.h that can be added
    to a class declaration. A new tool, qmltyperegistrar, will evaluate them and
    generate the actual registrations. You should not need to call any
    qmlRegister* function manually anymore in new code.

  - New classes QQmlEngineExtensionInterface and QQmlEngineExtensionPlugin are
    available and should be used in place of QQmlExtensionInterface and
    QQmlExtensionPlugin. The new classes do not offer a virtual registerTypes()
    method as types should be registered at compile time.

  - [QTBUG-81631] Qt.formatDateTime, Qt.formatDate and Qt.formatTime now support
    formatting according to a locale and an optional locale format type. If
    locale dependent formatting is desired, this method should be used instead
    of the locale-related DateFormat enum members.

  - [QTBUG-77926] Nullish coalescing is now implemented as specified in
    https://github.com/tc39/proposal-nullish-coalescing.

  - It is now possible to declare new QML components in a QML file via the
    component keyword. They can be used just as if they were declared in another
    file, with the only difference that the type name needs to be prefixed with
    the name of the containing type outside of the file were the inline
    component has been declared.

  - The Qt.uiLanguage and QJSEngine::uiLanguage properties were added. They can
    be used to dynamically change the translation language from both QML and C++.
    QQmlApplicationEngine does this automatically. When using other engines, you
    need to listen for changes of QJSEngine::uiLanguage and load the respective
    translator in response.

  - [QTBUG-82743] Assigning to a QSet property from JS works again.

  - [QTBUG-74087] There is now an option to disable the (necessarily)
    conservative stack size checks when parsing and executing JavaScript. If the
    environment variable QV4_CRASH_ON_STACKOVERFLOW is set, JavaScript stack
    overflows crash the program the same way C++ stack overflows do. On the flip
    side, more stack space is made available that way.

  - [QTBUG-81714] You can add annotations, prefixed by "@" to QML elements now,
    similar to Java type annotations. These annotations have to be written in QML
    and are ignored by the QML interpreter. Tools processing QML can evaluate
    them.

  - [QTBUG-82843] Fixed a crash caused by creating QQmlValueTypeWrapper from
    an invalid Q_GADGET type.

  - [QTBUG-82150] QML Debugger now shows correct values for color objects.

  - [QTBUG-81970] QQmlCustomParser now resolves import namespaces.

  - [QTBUG-81678] Fixed qml loading problems caused by cycles.

  - [QTBUG-81825] Array.includes now works with value types such as point.

  - [QTBUG-79263] QQmlListProperty now has replace and removeLast functions.

  - [QTBUG-81123] Fixed a crash in QQmlListProperty if a contained object is deleted.

  - [QTBUG-58858] The path for storing QML cache files can now be customized.

  - [QTBUG-80030] Implemented TypedArray.from()

  - [QTBUG-80413] WorkerScript now has a ready property.

  - [QTBUG-75110] Locale NumberOptions are now exposed to QML.

  - [QTBUG-41087] Primitive self-references in composite types are now supported.

  - [QTBUG-76074] Custom QML types can now be freed when unloading plugins.

  - [QTBUG-73669] Fixed link errors when enabling CONFIG+=qtquickcompiler
    on non-QML projects.

  - [QTBUG-60908] Removed an unnecessary assert when setting a binding to alias.

  - qml: The QML Runtime tool --selector option now allows defining a custom
    QQmlFileSelector.

 ****************************************************************************
 *                                 QtQuick                                  *
 ****************************************************************************

  - Animations:
    * [QTBUG-48193] Fixed signal emission order for zero-duration animations.

  - AnimatedSprite:
    * [QTBUG-59090] Added finishBehavior to allow a sprite to finish on the
      last frame.

  - Behavior:
    * [QTBUG-70964] Behavior now has a targetProperty property to allow custom
      logic based on the target property's object or name.

  - Event handlers:
    * [QTBUG-68073] Pointer Handlers now have a cursorShape property to set the
      cursor when the handler is active and the mouse or a tablet stylus is hovering,
      and restore to the previous cursor when the pointing device leaves.
    * [QTBUG-79660] QTabletEvents are now delivered to pointer handlers.
      For example PointHandler { acceptedPointerTypes: PointerDevice.Pen }
      is one way of receiving stroke information for drawing via Canvas or Shapes,
      and HoverHandler can use the new cursorShape property to show when a
      stylus is in use.
    * [QTBUG-68075] Pointer Handlers now have a dragThreshold property to
      define the distance at which DragHandler will activate and TapHandler
      will deactiveate, for example.

  - FolderListModel:
    * [QTBUG-82298] The fileUrl property was added to replace the fileURL
      property, which is now deprecated.

  - Image:
    * Image now has a sourceClipRect property to render a clipped image from a
      region of the sourceSize.
    * [QTBUG-80616] Image now has a colorSpace property.

  - Item:
    * Item.mapToItem() and mapFromItem() now work with QPointF and QRectF types
      as well as with raw numbers.
    * Item.mapToGlobal() and mapFromGlobal() now work with QPointF as well as
      with raw numeric coordinates.

  - Item Views:
    * [QTBUG-81580] DelegateChooser now supports using a property name as
      roleValue when an array of QObject instances is used as the model for a
    * [QTBUG-74046] ListView no longer allows the user to press on an Overlay or
      PullBack header or footer and start scrolling, but only on the content
      delegates.
    * [QTBUG-80507] ListView now has support for reusing delegate items. This can
      be switched on by setting the reuseItems property of ListView to true.

  - MouseArea:
    * [QTBUG-74987] MouseArea no longer gets stuck in pressed state if it
      is set invisible on press.

  - MultiPointTouchArea:
    * [QTBUG-81944] The TouchPoint.x and y properties are updated together
      before the change signals are emitted.

  - Particles:
    * [QTBUG-76827] QQuickItemParticle::give() is now implemented.

  - RHI / scene graph:
    * [QTBUG-82927] QSGRenderNode is now usable in Quick3D.
    * [QTBUG-78570] Added API to get the platform specific texture handle.
    * [QTBUG-80690] Fixed invalid core profile shader code.
    * [QTBUG-80498] We now avoid unnecessary rendering of an extra frame with QSG_RHI=1
    * [QTBUG-80365] Initialization failure now results in a sensible error dialog
      rather than an infinite loop.
    * [QTBUG-82988] QSGSimpleMaterial and QSGSimpleMaterialShader are now
      deprecated.

  - Shapes:
    * Added PathText path element which can be used together with Qt Quick Shapes
      to get text rendering that does not cache glyphs in a texture, but
      triangulates the outlines of the glyphs instead.

  - Text:
    * [QTBUG-78277] Added new API that exposes implicitWidth, and isLast on the
      QQuickTextLine for use in the lineLaidOut signal. This allows the user to
      layout other items relative to the lines of text.
    * [QTBUG-80759] Reduced redundant renderering of glyphs, thus fixing incorrect
      rendering of superscripts.

  - TextInput:
    * [QTBUG-76320] Inputmask X character now requires non-blank input.

  - QQuickItem:
    * [QTBUG-68176] ParentChange now avoids roundoff error when restoring the old position.

  - QQuickWidget:
    * [QTBUG-78323] When QQuickWidget is resized, an in-scene dialog or other
      content that is rendered into an offscreen window is now resized correctly.

  - QQuickWindow:
    * [QTBUG-78141] LanguageChange events are now delivered to items to enable
      them to update translations.
    * [QTBUG-79268] createTextureFromId() is now deprecated.
	Qt 5.15 introduces many new features and improvements as well as bugfixes
	over the 5.14.x series. For more details, refer to the online documentation
	included in this distribution. The documentation is also available online:

	https://doc.qt.io/qt-5/index.html

	The Qt version 5.15 series is binary compatible with the 5.14.x series.
	Applications compiled for 5.14 will continue to run with 5.15.

	Some of the changes listed in this file include issue tracking numbers
	corresponding to tasks in the Qt Bug Tracker:

	https://bugreports.qt.io/

	Each of these identifiers can be entered in the bug tracker to obtain more
	information about a particular change.

	****************************************************************************
	* Important Behavior Changes *
	****************************************************************************

	- [QTBUG-74137] CMake: Added a Qt6 forward compatible CMake API. Using this,
	you can define projects that work with either Qt5 or Qt6, without further
	changes.

	- [QTBUG-79331] If you register the same revision of the same type multiple
	times, the last registration is the one QML will use. This allows you to
	override qmlRegisterSingleton*() calls, for example in order to register a
	singleton instance for a type tagged with QML_SINGLETON. Previously, the
	first registration would take effect.

	- [QTBUG-79868] Using instanceof to check whether an instance has the type of
	QObject or one of its derived classes used to raise a TypeError, if the
	instance was not derived from QObject. Now, it instead returns false, which
	is more in line with the ECMAScript semantic.

	- The QML ObjectModel type had an undocumented "feature" which made it sort
	items in list views into sections according to context properties of the QML
	context the created objects belong to. Instead of context properties, object
	properties are used now.

	- [QTBUG-73669] Using the Qt Quick Compiler would exclude the original .qml
	files from the resource system. This made it impossible to change the Qt
	library binary later as the program binary was tied the to the exact Qt
	version. In addition sometimes unrelated files (QTBUG-73669) were removed.
	For the latter scenario, retain and skip options were added for the Qt
	Quick Compiler. In Qt 5.15 the Qt Quick Compiler does not remove the input
	files anymore. All files are retained and the compiler merely adds the
	more efficient binary representation to the application.

	****************************************************************************
	* Deprecation Notice *
	****************************************************************************

	- The qmlmin tool is deprecated and not needed anymore. The built-in caching of
	qml files addresses the needs and unfortunately the tool does not work with
	more advanced concepts such as required properties or the ES 7 yield
	statement. It will be removed in Qt 6.

	- qmlRegisterExtendedType() without URI or version, is deprecated. You should
	state the module the type belongs to, by supplying a URI and version.

	- qmlRegisterInterface(const char *typeName) without URI or version, is
	deprecated. You should state the module the type belongs to, but supplying a
	URI and version. Conversely, the typeName is redundant as the type itself
	is already supplied as template parameter. None of the other registration
	functions allow overriding the name for the metatype registration.

	- QQmlIncubationController::incubateWhile(volatile bool *flag, int msecs) is
	deprecated. The volatile parameter is used as a poor man's atomic bool, with
	all the well known downsides of such a practice. A replacement method
	taking an actual atomic is provided.

	- In QML Connections elements, the handlers should be defined as plain
	JavaScript functions, not as "onPropertyChanged properties".

	- You can currently access local files from QML via XMLHttpRequest using
	"file://..." URLs. This will not be allowed by default anymore in Qt6. If
	you actually need this behavior, you can set the environment variables
	QML_XHR_ALLOW_FILE_READ and/or QML_XHR_ALLOW_FILE_WRITE to 1. You can also
	set them to 0 when using Qt 5.15 to prevent local file access.

	- [QTBUG-78596] The class QSGEngine is now deprecated.

	****************************************************************************
	* QtQml *
	****************************************************************************

	- QML allows a new attribute "required" to be attached to properties. Such
	properties have to be set when instantiating a component. The various models
	and views use this as the preferred way of communicating model data to
	delegates. The old way of passing model data via context properties should
	be avoided in new code.

	- The qmllint tool has been extended to check for patterns considered to be
	potentially problematic in Qt6, and suggest better solutions. Pass the -U
	command line option to enable the checks.

	- The new qmlformat tool can be used to pretty-print a QML file according to
	the recommended code style.

	- QML supports type assertions similar to typescript. So far this is only used
	to make the intended type of an expression known to qmllint. At run time,
	type assertions are ignored.

	- C++ types can and should be registered to QML at compile time now. For this
	purpose there are a number of macros available in qqml.h that can be added
	to a class declaration. A new tool, qmltyperegistrar, will evaluate them and
	generate the actual registrations. You should not need to call any
	qmlRegister* function manually anymore in new code.

	- New classes QQmlEngineExtensionInterface and QQmlEngineExtensionPlugin are
	available and should be used in place of QQmlExtensionInterface and
	QQmlExtensionPlugin. The new classes do not offer a virtual registerTypes()
	method as types should be registered at compile time.

	- [QTBUG-81631] Qt.formatDateTime, Qt.formatDate and Qt.formatTime now support
	formatting according to a locale and an optional locale format type. If
	locale dependent formatting is desired, this method should be used instead
	of the locale-related DateFormat enum members.

	- [QTBUG-77926] Nullish coalescing is now implemented as specified in
	https://github.com/tc39/proposal-nullish-coalescing.

	- It is now possible to declare new QML components in a QML file via the
	component keyword. They can be used just as if they were declared in another
	file, with the only difference that the type name needs to be prefixed with
	the name of the containing type outside of the file were the inline
	component has been declared.

	- The Qt.uiLanguage and QJSEngine::uiLanguage properties were added. They can
	be used to dynamically change the translation language from both QML and C++.
	QQmlApplicationEngine does this automatically. When using other engines, you
	need to listen for changes of QJSEngine::uiLanguage and load the respective
	translator in response.

	- [QTBUG-82743] Assigning to a QSet property from JS works again.

	- [QTBUG-74087] There is now an option to disable the (necessarily)
	conservative stack size checks when parsing and executing JavaScript. If the
	environment variable QV4_CRASH_ON_STACKOVERFLOW is set, JavaScript stack
	overflows crash the program the same way C++ stack overflows do. On the flip
	side, more stack space is made available that way.

	- [QTBUG-81714] You can add annotations, prefixed by "@" to QML elements now,
	similar to Java type annotations. These annotations have to be written in QML
	and are ignored by the QML interpreter. Tools processing QML can evaluate
	them.

	- [QTBUG-82843] Fixed a crash caused by creating QQmlValueTypeWrapper from
	an invalid Q_GADGET type.

	- [QTBUG-82150] QML Debugger now shows correct values for color objects.

	- [QTBUG-81970] QQmlCustomParser now resolves import namespaces.

	- [QTBUG-81678] Fixed qml loading problems caused by cycles.

	- [QTBUG-81825] Array.includes now works with value types such as point.

	- [QTBUG-79263] QQmlListProperty now has replace and removeLast functions.

	- [QTBUG-81123] Fixed a crash in QQmlListProperty if a contained object is deleted.

	- [QTBUG-58858] The path for storing QML cache files can now be customized.

	- [QTBUG-80030] Implemented TypedArray.from()

	- [QTBUG-80413] WorkerScript now has a ready property.

	- [QTBUG-75110] Locale NumberOptions are now exposed to QML.

	- [QTBUG-41087] Primitive self-references in composite types are now supported.

	- [QTBUG-76074] Custom QML types can now be freed when unloading plugins.

	- [QTBUG-73669] Fixed link errors when enabling CONFIG+=qtquickcompiler
	on non-QML projects.

	- [QTBUG-60908] Removed an unnecessary assert when setting a binding to alias.

	- qml: The QML Runtime tool --selector option now allows defining a custom
	QQmlFileSelector.

	****************************************************************************
	* QtQuick *
	****************************************************************************

	- Animations:
	* [QTBUG-48193] Fixed signal emission order for zero-duration animations.

	- AnimatedSprite:
	* [QTBUG-59090] Added finishBehavior to allow a sprite to finish on the
	last frame.

	- Behavior:
	* [QTBUG-70964] Behavior now has a targetProperty property to allow custom
	logic based on the target property's object or name.

	- Event handlers:
	* [QTBUG-68073] Pointer Handlers now have a cursorShape property to set the
	cursor when the handler is active and the mouse or a tablet stylus is hovering,
	and restore to the previous cursor when the pointing device leaves.
	* [QTBUG-79660] QTabletEvents are now delivered to pointer handlers.
	For example PointHandler { acceptedPointerTypes: PointerDevice.Pen }
	is one way of receiving stroke information for drawing via Canvas or Shapes,
	and HoverHandler can use the new cursorShape property to show when a
	stylus is in use.
	* [QTBUG-68075] Pointer Handlers now have a dragThreshold property to
	define the distance at which DragHandler will activate and TapHandler
	will deactiveate, for example.

	- FolderListModel:
	* [QTBUG-82298] The fileUrl property was added to replace the fileURL
	property, which is now deprecated.

	- Image:
	* Image now has a sourceClipRect property to render a clipped image from a
	region of the sourceSize.
	* [QTBUG-80616] Image now has a colorSpace property.

	- Item:
	* Item.mapToItem() and mapFromItem() now work with QPointF and QRectF types
	as well as with raw numbers.
	* Item.mapToGlobal() and mapFromGlobal() now work with QPointF as well as
	with raw numeric coordinates.

	- Item Views:
	* [QTBUG-81580] DelegateChooser now supports using a property name as
	roleValue when an array of QObject instances is used as the model for a
	* [QTBUG-74046] ListView no longer allows the user to press on an Overlay or
	PullBack header or footer and start scrolling, but only on the content
	delegates.
	* [QTBUG-80507] ListView now has support for reusing delegate items. This can
	be switched on by setting the reuseItems property of ListView to true.

	- MouseArea:
	* [QTBUG-74987] MouseArea no longer gets stuck in pressed state if it
	is set invisible on press.

	- MultiPointTouchArea:
	* [QTBUG-81944] The TouchPoint.x and y properties are updated together
	before the change signals are emitted.

	- Particles:
	* [QTBUG-76827] QQuickItemParticle::give() is now implemented.

	- RHI / scene graph:
	* [QTBUG-82927] QSGRenderNode is now usable in Quick3D.
	* [QTBUG-78570] Added API to get the platform specific texture handle.
	* [QTBUG-80690] Fixed invalid core profile shader code.
	* [QTBUG-80498] We now avoid unnecessary rendering of an extra frame with QSG_RHI=1
	* [QTBUG-80365] Initialization failure now results in a sensible error dialog
	rather than an infinite loop.
	* [QTBUG-82988] QSGSimpleMaterial and QSGSimpleMaterialShader are now
	deprecated.

	- Shapes:
	* Added PathText path element which can be used together with Qt Quick Shapes
	to get text rendering that does not cache glyphs in a texture, but
	triangulates the outlines of the glyphs instead.

	- Text:
	* [QTBUG-78277] Added new API that exposes implicitWidth, and isLast on the
	QQuickTextLine for use in the lineLaidOut signal. This allows the user to
	layout other items relative to the lines of text.
	* [QTBUG-80759] Reduced redundant renderering of glyphs, thus fixing incorrect
	rendering of superscripts.

	- TextInput:
	* [QTBUG-76320] Inputmask X character now requires non-blank input.

	- QQuickItem:
	* [QTBUG-68176] ParentChange now avoids roundoff error when restoring the old position.

	- QQuickWidget:
	* [QTBUG-78323] When QQuickWidget is resized, an in-scene dialog or other
	content that is rendered into an offscreen window is now resized correctly.

	- QQuickWindow:
	* [QTBUG-78141] LanguageChange events are now delivered to items to enable
	them to update translations.
	* [QTBUG-79268] createTextureFromId() is now deprecated.