Qt 5.7 Beta发布，C++跨平台界面库

Qt 5.7不再兼容C++98，是一个全面体现C++11优势的版本，从底层实现到api设计，充分使用C++11特性，比如非常方便的auto和 lambda函数。由于Qt5.6是一个LTS版本，所以设计时向C++98靠拢，使用了少量的C++11特性。Qt5.7将是更加令人期待的版本。

Qt5.7的新特性：

C++11 Support Required from the compiler

Qt has enabled usage of C++11 in Qt applications for a long time, but with Qt 5.7 we are also enabling use of C++11 in the Qt modules. Therefore Qt 5.7 requires C++11 support from the compiler, and has removed support from older compilers not providing adequate C++11 support.

New Features (within existing modules)

• Qt Core

• Added qAsConst function to help using non-const Qt containers in C++11 range for loops

• Qt event dispatchers use the poll() function on Unix now, making it possible for applications to have file descriptors > 1024

• Added the ability to convert a floating point to its shortest, exact string form, without having to pre-calculate how many digits that is; QVariant uses this

• Many clean-ups related to C++11, including using std::atomic as backend for QAtomic classes and adding QTypeInfo for char16_t and char32_t

• QIODevice now supports multistreaming

• QPluginLoader now works even if QT_NO_LIBRARY is set (e.g., linking against a static libc)

• Qt GUI

• QImage smooth scale optimized for NEON.

• Optimized the OpenGL function wrappers for speed and code size. QtGui library size has been significantly reduced due to a massive reduction in symbols.

• Qt Widgets

• QTabBar now delegates placement of tab scroll buttons to the style.

• Qt Style Sheets can now optionally let widgets inherit font and palette from their parents.

• Qt WebEngine

• Based on Chromium 49

• Drag'n'Drop

• Printing to PDF

• Spellchecking

• Audio played in tab notification.

• Support for DRM-protected HTML5 video using Widevine pepper plugin

• API for evaluating javascript or installing qwebchannel in secure isolated javascript worlds

• Qt QML

• Added JIT support for WinRT on x86 and x64.

• Enabled JIT for 64-bit ARM Linux platforms.

• All debug services now work with QJSEngine rather than QQmlEngine, which allows for non-QML JavaScript debugging or profiling.

• The JavaScript debug service now supports debugging of multiple QJSEngine instances at the same time.

• Qt Quick

• The inspector service now supports all subclasses of QQuickWindow, which makes Qt Creator's inspection feature useful.

• Embedded platforms

• Added support for NVIDIA DRIVE CX boards (Tegra X1, AArch64)

• Improved theming support with eglfs

• Desktop platforms

• X11: QMenuBar uses the unified D-Bus AppMenu menubar when the desktop environment supports it (e.g. Ubuntu Unity)

• Mobile platforms

• Android: Qt can now be used to easily create Android Services.

• Qt Canvas 3D

• New version of three.js

• Qt NFC

• API ported to Android.

• Qt Multimedia

• Added support for tvOS.

• Extended QML playlist API.

• Qt Bluetooth

• Technical preview for Qt Bluetooth Low Energy peripheral role feature (Bluez only)

New Modules

• Qt 3D

• Support for Compute Shaders on supported hardware

• Support for loading multi-image DDS and KTX textures including cubemaps, mip chains, array textures

• Improved support for compressed texture formats

• Render surface made explicit - will later allow for multiple renders of the same scene to different surfaces and other use cases

• Extended Input API and support for device plugins

• Picking support improved

• Qt Quick Controls 2

• Default style - a simple and minimal all-round style that offers the maximum performance

• Material style - a style based on the Google Material Design Guidelines

• Universal style - a style based on the Microsoft Universal Design Guidelines

• A new light-weight set of embedded and mobile oriented controls

• Based on a flexible template system that enables rapid development of entire custom styles and user experiences

• Built-in styles:

• Can be mixed with Qt Quick Controls 1.0, but the APIs are not compatible

• Qt Charts

• Previously commercial-only Qt Charts module is now included in Qt under also GPLv3 license for open source users

• Qt Data Visualization

• Previously commercial-only Qt Data Visualization module is now included in Qt under also GPLv3 license for open source users

• Qt Virtual Keyboard

• Previously commercial-only Qt Virtual Keyboard module is now included in Qt under also GPLv3 license for open source users

• Qt Purchasing

• Previously commercial-only Qt Purchasing module is now included in Qt under also LGPLv3 and GPLv3 license for open source users

• Qt Quick 2D Renderer

• Previously commercial-only Qt Quick 2D Renderer module is now included in Qt under also GPLv3 license for open source users

Technology Preview Modules

• Qt Wayland Compositor

• Pure QML API

• Improved C++ API with added convenience

• New convenient API for making extensions and using them from both QML and C++

• Qt SCXML

• Completely new module for C++ and QML

• Static and runtime integration of SCXML models into Qt code

• Qt Gamepad

• New module to process input from gamepads in C++ and QML applications.

• Supports Windows (XInput), Linux (evdev), Android, iOS.

• Qt Serial Bus

• New module for C++

• Supports Modbus and CAN bus

Deprecated Modules

The following modules are part of Qt 5.6 release, but deprecated and considered for removal in subsequent releases of Qt:

• Qt Script

Removed Modules

With Qt 5.7 the following modules are no longer part of the final release packages:

• Qt Enginio

Configurations

• Qt 5.7 has deprecated configurations that do not provide adequate C++11 support. For details, please see Qt 5.7 Tools and Versions in the wiki.

• Mobile platforms: Minimum required versions upgraded to iOS 7 and Android 4.1