This will colourize your UI to show you the different clipping regions. In order to visualize how many clipping regions your application has, set the environment variable QSG_VISUALIZE to clip. The take away here is that you should try your best not to use clipping if you can help it this will allow the renderer to batch draw commands together and speed up performance. If we set both items clipping property to false on the other hand both sub trees would be able to be placed within the same OpenGL state and therefore drawn together with one call to glDrawArray(). If we had two Item elements side by side our Item (Item A)’s children would be rendered with one call to glDrawArray() and the other Item (Item B)’s child elements would be rendered by a second call to glDrawArray(). This means that the child elements can’t be drawn at the same time with the same call to glDrawArrays() as child elements of Items siblings. its child elements) needs to be in its own OpenGL state preventing the ability to batch multiple components together into the same state. This sounds great and all and you would expect greater performance however any items with its clipping property set to true means that its sub tree (i.e. Because the Rectangles parent (Item) has its clipping set to true the scene graph renderer will not draw the right most 100px of the child Rectangle. Now that Item has a child Rectangle with a width of 200. This property tells the scene graph not to render any child elements which extend beyond its parent boarders.Įxample Say we have an Item with its clipping property set to true and a width of 100. QDeclarativeItem ) has a property called clipping.

In this post let’s talk about Clipping.Īll QML components that extend from Item ( i.e.

In this blog series I’m listing out different performance tips and tricks for Qt Quick to make sure you’re getting the best performance out of the scene graph renderer.

Qt clips