Re: [PyQt] QGraphicsScene background
>> in long-running >> programs >> >> when many many items have been added, the >> scene >> >> starts to slow down. > Did you checked the navigation pad example? It uses some tricks, e.g. by > (optionally) using OpenGL and various transformations, that might be > helpful for your issue, too. Thanks Pete. I will take a deeper look at that example. I am a bit worried at the start, though. Running that example on my old laptop locked up the whole system (required a hard reboot) and on my desktop it fails with OpenGL errors: QGLShader: could not create shader Vertex shader for simpleShaderProg (MainVertexShader & PositionOnlyVertexShader) failed to compile QGLShader: could not create shader Fragment shader for simpleShaderProg (MainFragmentShader & ShockingPinkSrcFragmentShader) failed to compile QGLShaderProgram: could not create shader program Errors linking simple shader: "" QGLShader: could not create shader Vertex shader for blitShaderProg (MainWithTexCoordsVertexShader & UntransformedPositionVertexShader) failed to compile QGLShader: could not create shader Fragment shader for blitShaderProg (MainFragmentShader & ImageSrcFragmentShader) failed to compile QGLShaderProgram: could not create shader program Errors linking blit shader: "" QGLShader: could not create shader Warning: "" failed to compile! Commenting out the QGLWidget viewport allows the program to run, but I'd be leery of using something in my application that can fail so spectacularly. ___ PyQt mailing listPyQt@riverbankcomputing.com http://www.riverbankcomputing.com/mailman/listinfo/pyqt
Re: [PyQt] QGraphicsScene background
On Friday 22 July 2011, 21:04:44 Lee Harr wrote: > I work on a turtle graphics application written using > PyQt (pynguin.googlecode.com) and I am stuck on one > particular feature that I would like to add. > > Right now, I am using QGraphicsScene and when the > turtle draws, it uses QGraphicsItem based objects to > show the results. Mostly QGraphicsPathItem, > QGraphicsEllipseItem and QGraphicsSimpleTextItem. > > It works quite well, but in long-running programs > when many many items have been added, the scene > starts to slow down. > > > Two options I have looked at are: > > Re-implementing drawBackground. I save a QPixmap as > self.bg in my QGraphicsScene subclass, then do > painter.drawPixmap(rect, self.bg, sourcerect) > in drawBackground. It works, but when the zoom > level is anything but 1:1 it gets very slow. > > The other way was to add a QGraphicsPixmapItem as > the lowest item on the stack. That also seems like it > might work, but again, as soon as the zoom level is > anything but 1:1 the speed goes way down instantly. > > > What I think I want to be able to do is to take > all of those graphics items and flatten them down on > to the background and then delete those items. > > Is there any way that an approach like this will > be able to speed up the application (including the > ability to zoom to arbitrary levels...)? > > > Any suggestions greatly appreciated! Did you checked the navigation pad example? It uses some tricks, e.g. by (optionally) using OpenGL and various transformations, that might be helpful for your issue, too. Pete ___ PyQt mailing listPyQt@riverbankcomputing.com http://www.riverbankcomputing.com/mailman/listinfo/pyqt
[PyQt] QGraphicsScene background
I work on a turtle graphics application written using PyQt (pynguin.googlecode.com) and I am stuck on one particular feature that I would like to add. Right now, I am using QGraphicsScene and when the turtle draws, it uses QGraphicsItem based objects to show the results. Mostly QGraphicsPathItem, QGraphicsEllipseItem and QGraphicsSimpleTextItem. It works quite well, but in long-running programs when many many items have been added, the scene starts to slow down. Two options I have looked at are: Re-implementing drawBackground. I save a QPixmap as self.bg in my QGraphicsScene subclass, then do painter.drawPixmap(rect, self.bg, sourcerect) in drawBackground. It works, but when the zoom level is anything but 1:1 it gets very slow. The other way was to add a QGraphicsPixmapItem as the lowest item on the stack. That also seems like it might work, but again, as soon as the zoom level is anything but 1:1 the speed goes way down instantly. What I think I want to be able to do is to take all of those graphics items and flatten them down on to the background and then delete those items. Is there any way that an approach like this will be able to speed up the application (including the ability to zoom to arbitrary levels...)? Any suggestions greatly appreciated! ___ PyQt mailing listPyQt@riverbankcomputing.com http://www.riverbankcomputing.com/mailman/listinfo/pyqt
