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Is there a way to prevent checkered bitmaps from flickering.


Checkered patterned backgrounds with 1 pixel by 1 pixel squares flicker regardless or how they are loaded.  Is there a way to prevent these bitmaps from flickering?


Capture.bmp
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mlcarey1959
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mlcarey1959
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1 Solution
 
TommySzalapskiCommented:
They aren't flickering any more than any other pattern. It just appears to flicker more because of the way our eyes try to adjust. Making each pixel the same color for a background works much better.
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sentnerCommented:
If the image is flickering, it is due to the type of monitor you have and/or its settings.  

See:  http://www.lagom.nl/lcd-test/


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sarabandeCommented:
did you try to load the bitmap into a compatible memory dc (device context) and call BitBlt to copy it from compatible dc to screen dc?

Sara
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sarabandeCommented:
you also might test how often your bitmap actually was drawn (increment a static integer and write it to logfile with a timestamp, always open and close the file with each write). if for any reason it is more than once when the screen was freshly drawn, you need to find the reason for that. if the reason comes from controls which are placed on the bitmap you could try to prevent multiple drawings by calling LockWindowUpdate.

Sara
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mlcarey1959Author Commented:
It does not matter how the image is loaded or how many times it is drawn.
If the image has a 1x1 pixel checkered pattern, it will flicker regardless of the overall size.  
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sarabandeCommented:
do you know for sure? i would try to make a form that only contains one big bitmap button with the checkered bitmapfile as surface. if you are right it also should flicker (or seems to flicker according to TommySzalapski).

Sara
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sentnerCommented:
As I said, this flickering is almost certainly due to the monitor, not the image itself or the way you draw it.  The sample image you posted does not flicker at all on my screen.  

What kind of monitor do you have (Is it LCD?  What brand and model?)
What is the refresh rate set to in your graphics card's properties for the monitor?
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mlcarey1959Author Commented:
HP Pavilion g7 laptop
Intel HD Graphics adapter

Refresh Rate 60hz
Resolution 1600 x 900
Color Depth 32 Bit

Laptop LCD Screen Size: 17.3 Inches
Laptop LCD Screen Resolution: WXGA++
Laptop LCD Screen Type: LED
Laptop LCD Screen Lamp: DIODE
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TommySzalapskiCommented:
If you just copy a large checkered bitmap into Paint it appears to flicker there as well, right?
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sentnerCommented:
Ah, laptop screens can often have some flickering, as they are designed to use less power than a standalone monitor.  The refresh rate of 60hz is low, but with an LCD what's more important is the refresh of the backlight, which in this case is an LED based one.  That refresh can be out of sync very slightly with the lcd refresh, which can cause flicker.  If you have the option to use a higher refresh rate, that can help.

Go through the tests on that website I listed earlier, particularly the clock and phase test as well as the Inversion (Pixel walk) test.  If you have severe flickering on these, it may be that your screen has a problem.

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sarabandeCommented:
i see no flickering with the bitmap shown at top of that thread. i neither have flickering when i view the bitmap with a standard viewer.

if these pictures do flicker for you, then indeed it is a problem of individual eyesight or individual monitors or both.

Sara
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mlcarey1959Author Commented:
Although Windows Help and Support says LCD moniters do not create flicker, laptop LCD monitors do create flicker.
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