VB/WinAPI/Graphics, Access VBA Flicker

Access VBA Flicker

Author	Message
Ian Eale #1 / 8	Access VBA Flicker Hello, I have inherited an Access 2000 application that has many [~15] subforms on a main form. These forms have a label whose caption is updated with the current display value. The sub forms also have a Line which is moved to display the value graphically, like an analog gauge. These sub forms have an Image control containing a bitmap of the gauge The problem is if the update is done more quickly than ~250ms, the labels and the lines flicker, showing the underlying screen color, even through the Image control. It makes little difference if only the changes are written to the 'controls' I tried some OCX controls, but the 'pointer' is drawn and the 'dial' is not until the form is refreshed by choosing another application and then coming back to Access. The same controls, using the same update code show no problems in VB6. No response yet from control vendors. I tried using an image control and moving a new image to the image control on the subforms, but moving the .PictureData is abysmally slow. Changing the .PictureData minimum change is about 100ms, judged by the update of the forms on the screen. I tested changing the .Picture property and can change the .Picture very rapidly, perhaps less than 5ms. I expected the .PictureData to be much faster. The DoEvents have no effect. Private Sub Form_Timer() Static lngDir As Long lngDir = lngDir Xor True If lngDir Then Forms("zzzfrmG2Test").Controls("imgBMP").Picture = Forms("zzzfrmG0Test").Controls("imgBMP").Picture DoEvents Forms("zzzfrmG0Test").Controls("imgBMP").Picture = Forms("zzzfrmG1Test").Controls("imgBMP").Picture DoEvents Forms("zzzfrmG1Test").Controls("imgBMP").Picture = Forms("zzzfrmG2Test").Controls("imgBMP").Picture DoEvents Else Forms("zzzfrmG2Test").Controls("imgBMP").Picture = Forms("zzzfrmG1Test").Controls("imgBMP").Picture DoEvents Forms("zzzfrmG1Test").Controls("imgBMP").Picture = Forms("zzzfrmG0Test").Controls("imgBMP").Picture DoEvents Forms("zzzfrmG0Test").Controls("imgBMP").Picture = Forms("zzzfrmG2Test").Controls("imgBMP").Picture DoEvents End If SysCmd acSysCmdSetStatus, Me.TimerInterval DoEvents End Sub The timing issue does not appear to be related to the graphics card. I tried the application on 2 machines : 1 with a 32MB SIS 305 video and another with an old Trident 9750. Both machines running Win2k 1.8GHz 512MB and 2GHz 256MB. The only change that had any effect at reducing the artifact is setting the ColorDepth in the Display Properties to 32Bit. Any help will be most appreciated.
Wed, 23 Mar 2005 00:21:12 GMT

Mike D Sutto #2 / 8	Access VBA Flicker Quote: > I have inherited an Access 2000 application that has many [~15] subforms on > a main form. These forms have a label whose caption is updated with the > current display value. The sub forms also have a Line which is moved to > display the value graphically, like an analog gauge. These sub forms have an > Image control containing a bitmap of the gauge > The problem is if the update is done more quickly than ~250ms, the labels > and the lines flicker, showing the underlying screen color, even through the > Image control. It makes little difference if only the changes are written to > the 'controls' > I tried some OCX controls, but the 'pointer' is drawn and the 'dial' is not > until the form is refreshed by choosing another application and then coming > back to Access. The same controls, using the same update code show no > problems in VB6. No response yet from control vendors. > I tried using an image control and moving a new image to the image control > on the subforms, but moving the .PictureData is abysmally slow. Changing the > .PictureData minimum change is about 100ms, judged by the update of the > forms on the screen. I tested changing the .Picture property and can change > the .Picture very rapidly, perhaps less than 5ms. I expected the > .PictureData to be much faster. The problem here is that the Label, Line and Image controls (Among others) are what's known as 'Windowless' controls (Well, technically everything is in Access, but that's another story..) and as such they don't exist at runtime - They're drawn over the background when it updates which sounds fine but first the background is drawn, then each of the subsequent controls are drawn on top if that directly to screen. This leads to the undesired flickering since the screen is updating faster than the drawing is and you see the in-between stages, you will get the same problems in VB too although not quite so badly. Unfortunately in Access you get very little access (No pun intended ;) to what's actually going on behind the scenes visually as most of it's hidden from you. What I've done in the past for our Access developers it to write these visual components in VB where you get full control over the drawing, then compile it to an ActiveX OCX which can be embedded on an Access form. Hope this helps, Mike -- EDais -- - Microsoft Visual Basic MVP - WWW: Http://EDais.earlsoft.co.uk/
Wed, 23 Mar 2005 01:20:27 GMT

Ian Eale #3 / 8	Access VBA Flicker Quote: > > I have inherited an Access 2000 application that has many [~15] subforms > on > > a main form. These forms have a label whose caption is updated with the > > current display value. The sub forms also have a Line which is moved to > > display the value graphically, like an analog gauge. These sub forms have > an > > Image control containing a bitmap of the gauge > > The problem is if the update is done more quickly than ~250ms, the labels > > and the lines flicker, showing the underlying screen color, even through > the > > Image control. It makes little difference if only the changes are written > to > > the 'controls' > > I tried some OCX controls, but the 'pointer' is drawn and the 'dial' is > not > > until the form is refreshed by choosing another application and then > coming > > back to Access. The same controls, using the same update code show no > > problems in VB6. No response yet from control vendors. > > I tried using an image control and moving a new image to the image control > > on the subforms, but moving the .PictureData is abysmally slow. Changing > the > > .PictureData minimum change is about 100ms, judged by the update of the > > forms on the screen. I tested changing the .Picture property and can > change > > the .Picture very rapidly, perhaps less than 5ms. I expected the > > .PictureData to be much faster. > The problem here is that the Label, Line and Image controls (Among others) > are what's known as 'Windowless' controls (Well, technically everything is > in Access, but that's another story..) and as such they don't exist at > runtime - They're drawn over the background when it updates which sounds > fine but first the background is drawn, then each of the subsequent controls > are drawn on top if that directly to screen. This leads to the undesired > flickering since the screen is updating faster than the drawing is and you > see the in-between stages, you will get the same problems in VB too although > not quite so badly. > Unfortunately in Access you get very little access (No pun intended ;) to > what's actually going on behind the scenes visually as most of it's hidden > from you. What I've done in the past for our Access developers it to write > these visual components in VB where you get full control over the drawing, > then compile it to an ActiveX OCX which can be embedded on an Access form. > Hope this helps, > Mike > -- EDais -- > - Microsoft Visual Basic MVP - > WWW: Http://EDais.earlsoft.co.uk/ I think I may have some additional information. If I have the subforms open as forms and write to the labels and , I can make the lines and labels update without any artifacts at all. I can make the lines look like windshield wipers on Hi. Could this have anything to do with the 'control' being on a sub form and the form below is showing through. TIA
Wed, 23 Mar 2005 03:01:15 GMT

Mike D Sutto #4 / 8	Access VBA Flicker Quote: > I think I may have some additional information. If I have the subforms open > as forms and write to the labels and , I can make the lines and labels > update without any artifacts at all. I can make the lines look like > windshield wipers on Hi. Could this have anything to do with the 'control' > being on a sub form and the form below is showing through. From what I understand, only the top-most window in Access is actually a true window, the rest are just images drawn on the main Access window. Controls created in VB will have their own window though that you can repaint if and when you wish. Hope this helps, Mike -- EDais -- - Microsoft Visual Basic MVP - WWW: Http://EDais.earlsoft.co.uk/
Wed, 23 Mar 2005 03:26:29 GMT

Ian Eale #5 / 8	Access VBA Flicker Quote: > > I think I may have some additional information. If I have the subforms > open > > as forms and write to the labels and , I can make the lines and labels > > update without any artifacts at all. I can make the lines look like > > windshield wipers on Hi. Could this have anything to do with the 'control' > > being on a sub form and the form below is showing through. > From what I understand, only the top-most window in Access is actually a > true window, the rest are just images drawn on the main Access window. > Controls created in VB will have their own window though that you can > repaint if and when you wish. > Hope this helps, > Mike > -- EDais -- > - Microsoft Visual Basic MVP - > WWW: Http://EDais.earlsoft.co.uk/ When you say top most, do you mean the application or the top most form?
Wed, 23 Mar 2005 07:33:56 GMT

Mike D Sutto #6 / 8	Access VBA Flicker Quote: > When you say top most, do you mean the application or the top most form? The top most form, most other windows will have their own window objects. Mike -- EDais -- - Microsoft Visual Basic MVP - WWW: Http://EDais.earlsoft.co.uk/
Wed, 23 Mar 2005 07:38:25 GMT

Stephen Leban #7 / 8	Access VBA Flicker I wrote a class to encapsulate the standard Access Image control extending it to resemble the basic functionality of the VB PictureBox control. Perhaps you could give it a try and eliminate the Line controls. http://www.lebans.com/imageclass.htm Manipulating the PictureData prop is inherently much faster than loading a new Image via the Picture prop. WIthout seeing your code I'm not sure why your testing results do not support this. I think you are running into Form/SubForm repainting issues when you manipulate the Line controls. -- HTH Stephen Lebans http://www.lebans.com Access Code, Tips and Tricks Please respond only to the newsgroups so everyone can benefit. Quote: > Hello, > I have inherited an Access 2000 application that has many [~15] subforms on > a main form. These forms have a label whose caption is updated with the > current display value. The sub forms also have a Line which is moved to > display the value graphically, like an analog gauge. These sub forms have an > Image control containing a bitmap of the gauge > The problem is if the update is done more quickly than ~250ms, the labels > and the lines flicker, showing the underlying screen color, even through the > Image control. It makes little difference if only the changes are written to > the 'controls' > I tried some OCX controls, but the 'pointer' is drawn and the 'dial' is not > until the form is refreshed by choosing another application and then coming > back to Access. The same controls, using the same update code show no > problems in VB6. No response yet from control vendors. > I tried using an image control and moving a new image to the image control > on the subforms, but moving the .PictureData is abysmally slow. Changing the > .PictureData minimum change is about 100ms, judged by the update of the > forms on the screen. I tested changing the .Picture property and can change > the .Picture very rapidly, perhaps less than 5ms. I expected the > .PictureData to be much faster. > The DoEvents have no effect. > Private Sub Form_Timer() > Static lngDir As Long > lngDir = lngDir Xor True > If lngDir Then > Forms("zzzfrmG2Test").Controls("imgBMP").Picture = > Forms("zzzfrmG0Test").Controls("imgBMP").Picture > DoEvents > Forms("zzzfrmG0Test").Controls("imgBMP").Picture = > Forms("zzzfrmG1Test").Controls("imgBMP").Picture > DoEvents > Forms("zzzfrmG1Test").Controls("imgBMP").Picture = > Forms("zzzfrmG2Test").Controls("imgBMP").Picture > DoEvents > Else > Forms("zzzfrmG2Test").Controls("imgBMP").Picture = > Forms("zzzfrmG1Test").Controls("imgBMP").Picture > DoEvents > Forms("zzzfrmG1Test").Controls("imgBMP").Picture = > Forms("zzzfrmG0Test").Controls("imgBMP").Picture > DoEvents > Forms("zzzfrmG0Test").Controls("imgBMP").Picture = > Forms("zzzfrmG2Test").Controls("imgBMP").Picture > DoEvents > End If > SysCmd acSysCmdSetStatus, Me.TimerInterval > DoEvents > End Sub > The timing issue does not appear to be related to the graphics card. I tried > the application on 2 machines : 1 with a 32MB SIS 305 video and another with > an old Trident 9750. Both machines running Win2k 1.8GHz 512MB and 2GHz > 256MB. The only change that had any effect at reducing the artifact is > setting the ColorDepth in the Display Properties to 32Bit. > Any help will be most appreciated.
Wed, 23 Mar 2005 12:06:43 GMT

Tony Toew #8 / 8	Access VBA Flicker Quote: >The problem is if the update is done more quickly than ~250ms, the labels >and the lines flicker, showing the underlying screen color, even through the >Image control. It makes little difference if only the changes are written to >the 'controls' I'm not at all sure this is applicable in your situation but what about Echo Method? Tony -- Tony Toews, Microsoft Access MVP Please respond only in the newsgroups so that others can read the entire thread of messages. Microsoft Access Links, Hints, Tips & Accounting Systems at http://www.granite.ab.ca/accsmstr.htm
Thu, 24 Mar 2005 07:42:28 GMT

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