On 02/06/2022 12:53, Shawn Rutledge wrote:
In Qt Quick the strategy has been to build a complete scene graph for all the contents of all visible items that you declared, and during rending, the SG nodes that are not visible get culled; so we didn’t have anything like QPaintEvent::region() to tell you what part of an Item is “dirty”
I don't think that this is the problem here (i.e. partial updates within _one_ Item); rather, the fact that if any item in a scene needs to update, there's no damage-tracking mechanism to tell the underlying graphics layers that only a specific screen region has been damaged.
... or is there? QSG_VISUALIZE=changes does (used to do) exactly this. (I no longer remember if it shows an Item's bounding rectangle taking transformations into account, or an Item's actual geometry -- how does it do so in the presence of arbitrary vertex shaders?).
Properly signalling damage areas has a lot of interesting use cases, from compositors to efficiently enable remoting solutions (frame streaming/VNC/etc.).
My 2 c, -- Giuseppe D'Angelo | [email protected] | Senior Software Engineer KDAB (France) S.A.S., a KDAB Group company Tel. France +33 (0)4 90 84 08 53, http://www.kdab.com KDAB - The Qt, C++ and OpenGL Experts
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