|
|
| Line 1: |
Line 1: |
| =<span class="caps">FAQ</span> on How to implement Qt Hardware Support=
| |
|
| |
|
| ==What is the difference between Qt 4.8.x and Qt 5?==
| |
|
| |
| * 4.8: QtQuick1, Javascript core, <span class="caps">QWS</span> (good) and <span class="caps">QPA</span> (not good)
| |
| * 5.0: QtQuick2, v8, <span class="caps">QPA</span>, no <span class="caps">QWS</span>, <span class="caps">QPA</span> only supporting OpenGL and DirectFB backends
| |
|
| |
| ==What is the difference between <span class="caps">QPA</span> and <span class="caps">QWS</span> and when should I use which?==
| |
|
| |
| * In general use <span class="caps">QWS</span> on 4.8 and <span class="caps">QPA</span> on 5.0
| |
| * Depending on the use-case <span class="caps">QPA</span> on 4.8 is a valid choice as well. Some important limitations and requirements are necessary to consider:
| |
| ** <span class="caps">QPA</span> on Qt4.8 only makes sense on OpenGL Hardware! If you don’t have OpenGL HW there is absolutely no point in choosing Qt4.8-<span class="caps">QPA</span> over Qt4.8-<span class="caps">QWS</span>
| |
| ** If you have OpenGL HW, there are two distinct use-cases to consider:
| |
| *** single-process: The features and limits of <span class="caps">QWS</span> and <span class="caps">QPA</span> are similar. <span class="caps">QWS</span> is older, is therefor considered more stable. Arguments for <span class="caps">QPA</span> could be:
| |
| **** you have to work on the graphcis/platform-plugin because your OpenGL implementation need special threadment, and(!):
| |
| **** you’re thinking about moving to Qt5
| |
| *** multi-process: There is currently no officially supported embedded(!) OpenGL-multi-process offering in Qt4.8. Implementing a platform-plugin for <span class="caps">QPA</span> is considered to be way simpler then writing <span class="caps">QWS</span>-graphics-plugins. Therefor Qt 4.8 <span class="caps">QPA</span> is the primary choice if you start your own platform-plugin or work on an existing platform plugin (e.g. the wayland-platform-plugin)
| |
|
| |
| ==What are the technical differences between QtQuick 1 and QtQuick 2?==
| |
|
| |
| * QtQuick 1 is the only choice for Qt4.7 and Qt4.8
| |
| * QtQuick 2 comes with and is the primary choice for Qt5.x
| |
| * QtQuick 2 is based on a complete new and tailor made graphics stack called scenegraph.
| |
| ** This leads to rendering performance of QtQuick2 which is a multiple of the rendering performance of QtQuick1
| |
| * Both use the same language (<span class="caps">QML</span>) to declare a user interface
| |
| * Although the language is the same, QtQuick2 comes with more and improved UI-elements (e.g. a complete new particle-engine)
| |
|
| |
| ==When should I use OpenGL, OpenVG, DirectFB versus software rendering?==
| |
|
| |
| * Use OpenGL and DirectFB for hardware acceleration in 4.8 or 5.0. OpenVG only works on 4.8 (it’s a graphics system only tested on Symbian). Be aware of the hardware acceleration capabilities of your device: if you do something it can’t accelerate you will end up with software rendering (not great performance).
| |
|
| |
| ==What is the difference between Webkit 1 and Webkit 2 and how are they supported on Qt 4 and Qt 5?==
| |
|
| |
| * Webkit 1 runs on both 4.8 and 5.0, Webkit2 only runs on 5.0. Qt Webkit2 is staying up to date with HTML5 features in webkit.org (Qt Webkit 1 is not).
| |
|
| |
| ==What are the options for implementing multimedia playback in Qt 4 and Qt 5?==
| |
|
| |
| * The options are in-process and out-of-process. Most demos are using out-of-process today but if you implement in-process you can apply QtQuick effects to your media. (more from Bhooshan).
| |
|
| |
| ==When should I use DirectFB versus Wayland?==
| |
|
| |
| * In general this questions shouldn’t be answered by “Qt” but by the silicon-vender (which should also be the one providing the <span class="caps">BSP</span>)
| |
| * The questions is only valid if you want to use OpenGL-HW-acceleration (and you need multi-process)
| |
| * Qt has wayland-platform-plugins for Qt4.8 and Qt5
| |
| * The Qt5-wayland-plugin get more attention (then the one for Qt4.8) and should be on a par with wayland-development
| |
| * [for holder: please comment the directfb-opengl state in Qt4/Qt5]
| |
|
| |
| ==How do I implement <span class="caps">QML</span> 1 or <span class="caps">QML</span> 2 in a single process? In multiple processes? Can I implement QML1 and QML2 in the same process?==
| |
|
| |
| * foo
| |
|
| |
| ==What is the difference between in-process multimedia play back versus out-of-process multimedia playback?==
| |
|
| |
| * foo
| |
|
| |
| ==What do I implement differently using <span class="caps">QML</span> in full screen versus windowed user interfaces?==
| |
|
| |
| * foo
| |
|
| |
| ==What is the list of issues and their sequence in which I should check them when encountering less than satisfactory performance on my hardware?==
| |
|
| |
| * foo
| |
|
| |
| ==Is OpenVG supported in Qt5?==
| |
|
| |
| * No (at least not unless you contribute it).
| |
|
| |
| ==Where does <span class="caps">JIT</span> work in Webkit? (e.g <span class="caps">MIPS</span>, <span class="caps">ARM</span>, IA)==
| |
|
| |
| * foo
| |
| * (Holger)
| |
|
| |
| ==From what and in what sequence should I build my Qt software stack?==
| |
|
| |
| * foo
| |
| * (e.g. always pull from Webkit trunk because it is moving so fast)
| |
| * How do I get Qt running on my board? (Also a session at <span class="caps">QCS</span>)
| |
| * X86, <span class="caps">ARM</span>, <span class="caps">MIPS</span>,
| |
| * GL/notGL (<span class="caps">DFB</span>, OpenVG, Direct3D)
| |
|
| |
| ==How much time is a Qt port to new hardware going to take?==
| |
|
| |
| * foo
| |
| * How can I make it faster/easier?
| |
| * What thinks are '''critical'''? What things are “nice to have”?
| |
| * What do I need to do first? Can I do things in stages?
| |
| * When doing a Qt port, what technical issues are critical to watch out for?
| |
|
| |
| ==What tools can I use when and where across Qt4 and Qt5?==
| |
|
| |
| * Foo
| |
| * QtCreator does not yet work on Qt5.
| |
| * How do I get the Tools ready?
| |
| * How do I deal with version changes?
| |
| * What license issues do I need to consider?
| |
| * Do I need to do anything to work well with 3rd party (and/or system) tools?
| |
|
| |
| ==Performance: How do I identify and resolve driver performance issues?==
| |
|
| |
| * foo
| |
|
| |
| ==Performance: How do I identify code that should be running on the <span class="caps">GPU</span> and isn’t?==
| |
|
| |
| * foo
| |
|
| |
| ==Performance: How do I identify and resolve multimedia performance issues?==
| |
|
| |
| * foo
| |
|
| |
| ==Performance: What issues can I safely ignore?==
| |
|
| |
| * foo
| |
| * Features? Modules? Qt Add Ons?
| |
|
| |
| ==How do I package and document a fix to upstream it? How do I upstream it?==
| |
|
| |
| * foo
| |
| * How should I package my work?
| |
| * How should I document my work?
| |
| * Where / how should I upstream?
| |
| * What do I do if a fix cannot be up streamed?
| |
| * What testing should I do?
| |
| * How should I test?
| |
| * Should I do unit tests?
| |
| * What are the pros/cons of unit testing?
| |
|
| |
| ==What is the status of Qt Components for embedded? For Desktop?==
| |
|
| |
| * foo
| |
|
| |
| ===There is only one article in "hardware faq":===
| |
|
| |
| ===D===
| |
| * [[:Category:Devices|Category:Devices]]
| |