CTreeCtrl with CustomDraw Flickering
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Hi basically my problem is how to get rid of flickering when i use customdraw. I know about double bufering, bckgnderase and any other solutions, but all of them do not work in my case, because my customdraw is called for each item (when resizing window(mfc behavior)) and for some of them when multiselection happens. CustomDraw is called from OnNotify(need that because i am extending normal tree with columns like in listView - so it look smth like Grid with expandable rows). Cause of all that behavior that i need, got no idea how to apply double buffering into this, cause there's none notification when to bitblt offscreen bitmap into screen. Would appreciate any ideas.
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Hi basically my problem is how to get rid of flickering when i use customdraw. I know about double bufering, bckgnderase and any other solutions, but all of them do not work in my case, because my customdraw is called for each item (when resizing window(mfc behavior)) and for some of them when multiselection happens. CustomDraw is called from OnNotify(need that because i am extending normal tree with columns like in listView - so it look smth like Grid with expandable rows). Cause of all that behavior that i need, got no idea how to apply double buffering into this, cause there's none notification when to bitblt offscreen bitmap into screen. Would appreciate any ideas.
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Richard MacCutchan wrote:
Same problem like with bitblt there's no proper place to call that one. MFC calls NM_CUSTOMDRAW for each element. So i've got no control over this "message loop".
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Hi basically my problem is how to get rid of flickering when i use customdraw. I know about double bufering, bckgnderase and any other solutions, but all of them do not work in my case, because my customdraw is called for each item (when resizing window(mfc behavior)) and for some of them when multiselection happens. CustomDraw is called from OnNotify(need that because i am extending normal tree with columns like in listView - so it look smth like Grid with expandable rows). Cause of all that behavior that i need, got no idea how to apply double buffering into this, cause there's none notification when to bitblt offscreen bitmap into screen. Would appreciate any ideas.
You might want to look at this article: [A custom-drawn TreeList Control](https://www.codeproject.com/Articles/325/A-custom-drawn-TreeList-Control)
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Hi basically my problem is how to get rid of flickering when i use customdraw. I know about double bufering, bckgnderase and any other solutions, but all of them do not work in my case, because my customdraw is called for each item (when resizing window(mfc behavior)) and for some of them when multiselection happens. CustomDraw is called from OnNotify(need that because i am extending normal tree with columns like in listView - so it look smth like Grid with expandable rows). Cause of all that behavior that i need, got no idea how to apply double buffering into this, cause there's none notification when to bitblt offscreen bitmap into screen. Would appreciate any ideas.
There double buffering technique that is fairly trivial to implement and gives reasonable results for any complex drawing 1.) Your draw routines only draw on a memory context, don't draw to the screen at all in those item draw calls. 2.) You use a standard windows timer which will timeout after a set time and you use that to update the screen. 3.) Anytime you draw to the memory context in step 1 you kill the running any timer and restart it 4.) The timer running out posts off a message and if you use that message to transfer the memory DC to screen, you then dispose of the timer. You should be able to get what happens that each item simply draws itself to the memory DC and will restart the timer. When the last item has been drawn the timer will finally hit it's wait timeout and post off the message which will draw all the items together as one big bitblt draw and no flickering. The requirements 1 memory context (created when window is created), 1 timer which is created and disposed as per above.
In vino veritas
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You might want to look at this article: [A custom-drawn TreeList Control](https://www.codeproject.com/Articles/325/A-custom-drawn-TreeList-Control)
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There double buffering technique that is fairly trivial to implement and gives reasonable results for any complex drawing 1.) Your draw routines only draw on a memory context, don't draw to the screen at all in those item draw calls. 2.) You use a standard windows timer which will timeout after a set time and you use that to update the screen. 3.) Anytime you draw to the memory context in step 1 you kill the running any timer and restart it 4.) The timer running out posts off a message and if you use that message to transfer the memory DC to screen, you then dispose of the timer. You should be able to get what happens that each item simply draws itself to the memory DC and will restart the timer. When the last item has been drawn the timer will finally hit it's wait timeout and post off the message which will draw all the items together as one big bitblt draw and no flickering. The requirements 1 memory context (created when window is created), 1 timer which is created and disposed as per above.
In vino veritas
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There double buffering technique that is fairly trivial to implement and gives reasonable results for any complex drawing 1.) Your draw routines only draw on a memory context, don't draw to the screen at all in those item draw calls. 2.) You use a standard windows timer which will timeout after a set time and you use that to update the screen. 3.) Anytime you draw to the memory context in step 1 you kill the running any timer and restart it 4.) The timer running out posts off a message and if you use that message to transfer the memory DC to screen, you then dispose of the timer. You should be able to get what happens that each item simply draws itself to the memory DC and will restart the timer. When the last item has been drawn the timer will finally hit it's wait timeout and post off the message which will draw all the items together as one big bitblt draw and no flickering. The requirements 1 memory context (created when window is created), 1 timer which is created and disposed as per above.
In vino veritas
So i've found answer to my problem. I think that i got best working solution that's : Fast, easy and makes ALL flickering dissapear. So the trick is to set Ctrl's window Exstyle WS_EX_COMPOSITED and the same time handle ON_WM_ERASEBKGND() (just return true or false doesn't metter from what i've observed) and that do the trick.:cool:
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So i've found answer to my problem. I think that i got best working solution that's : Fast, easy and makes ALL flickering dissapear. So the trick is to set Ctrl's window Exstyle WS_EX_COMPOSITED and the same time handle ON_WM_ERASEBKGND() (just return true or false doesn't metter from what i've observed) and that do the trick.:cool:
You should return true (being a non zero value) otherwise window will remain marked for erasing which somewhere down the track may come back to bite you. Remember the API underworkings aren't fixed you may find an old version of Windows or a new update which decides to use the flag.
In vino veritas