Qt 5.8 Alpha版发布，C++跨平台界面库

Qt 5.8 Alpha 版发布了，Qt 是一个跨平台的C++图形用户界面应用程序框架。它提供给开发者建立图形用户界面所需的功能，广泛用于开发GUI程序，也可用于开发非GUI程序。Qt是完全面向对象的，很容易扩展，并且允许真正地组件编程。

一些新特性：

• Qt Core

• Added at(), operator[], mid(), right() and left() to QLatin1String

• Qt GUI

• QTouchEvent now has uniqueId and rotation

• Support for dithering when converting to all QImage formats

• Previously private QOpenGLTextureBlitter API is made public, to help QtWayland in particular

• Added capHeight() to QFontMetrics, QFontMetricsF, and QRawFont

• Selection handles on Android,  with edit menu for copy/paste)

• Qt Quick

• Refactored the Qt Quick scene graph to remove its OpenGL dependency and make it possible to create rendering backends based on other graphics APIs, such as Vulkan or Direct3D.

• Integrated the software renderer for the Qt Quick scene graph as a proper backend for the scene graph (previously known as the Qt Quick 2D Renderer.)

• Implemented support for partial updates in the software backend for the scene graph (2D Renderer) to prevent expensive fullscreen updates when only small areas are changing.

• Added an experimental Direct3D 12 backend

• Implemented caching of code and data structures generated from .qml/.js files to disk to reduce start-up time and memory consumption. The resulting .qmlc and .jsc cache files are memory mapped.

• Cleaned up touch and mouse event delivery and added a new internal class QQuickPointerEvent which is used for that purpose. This is the foundation for further improvements with regards to input event handling, but does not affect any code using Qt Quick yet.

• Qt Quick Controls 2

• Added new QML types: Dialog, DialogButtonBox, MenuSeparator, RoundButton, and ToolSeparator

• Added ripple effects to the Material style

• Added hover effects to the Material and Universal styles

• Added a 'System' theme to the Material and Universal styles

• Added new experimental "platform" QML types: MenuBar, Menu, SystemTrayIcon, ColorDialog, FontDialog, MessageDialog, FileDialog and FolderDialog

• Qt Widgets

• Qt WebEngine

• Based on Chromium 51+ (probably 53)

• Windows: Requires MSVC 2015 Update 2 or later

• view-source: scheme is supported

• Spellchecking with custom .bdic files

• Tooltips (HTML5 global tile attribute) are shown

• User scripts now support metadata (@include, @exclude, @match)

• Qt WebEngine (QML) allows defining custom dialogs / context menu's

• Qt WebEngine (QML) on eglfs uses builtin dialogs based on Qt Quick Controls 2

• Added setting to enable printing of CSS backgrounds

• Support for printing

• Qt Bluetooth

• Bluetooth Low Energy Peripheral support on OS X, iOS & WinRT

• Qt Multimedia

• Added QAudio::convertVolume() (and matching QML API)  function to convert an audio volume from one scale to another, e.g. logarithmic to linear.

• VideoOutput (QML) now supports rendering YUV 4:2:2 (YUYV, UYVY) video frames.

• Qt Network

• Support for TLS PSK ciphersuites on server side

• Support for configurable diffie hellman parameters

• Support for HTTP/2 in Network Access Manager

• Qt WebSockets

• Support for TLS PSK ciphersuites on client and server side

• Qt Charts

• Candlestick chart type added.

• Qt 3D

• Main focus on maturation (improving performance, bug fixing and improving test coverage)

• Paint to texture using QPainter from Weiland

• Optional support for issuing commands to Qt3D aspects (e.g. from profiler)

• (Screenshot framegraph node STILL UNDER REVIEW)

• Embedded platforms

• Enhanced multi-screen capabilities and configurability with eglfs when running on KMS/DRM, both with GBM and EGLDevice/Stream

• Added support for 90 or 180 degrees rotation of software-rendered content (QWidget) in eglfs