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Author Topic: Flicker and Flash  (Read 229 times)

rick2691

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Flicker and Flash
« on: June 11, 2022, 02:36:56 pm »
RichMemo

At every key-up and mouse-up event, the RTF screen is redrawn. So while typing, the screen flickers white  (I notice the flicker because my background is set to clCream), but with images there is a white flash; due to the size of the image, and that I have a clCream background.

If you hold a key down for repetition, it does not redraw until you release the key ... though it shows your cursor tracking across the screen. It does the same when you hold down the left-button on the mouse. Implicating that a redraw is not always necessary.

I have tried to duplicate this on WordPad, but I don't notice any flicker or flash. However, I also can't find a way to set a background color on WordPad.

But I changed the RichMemo background to clWindow (white), and the flicker was not noticeable on text. Yet still, because the images are in color and large, I still saw the flash. Moreover, BeginUpdate & EndUpdate do not change the behavior.

So why should it always redraw, causing text line flickers and image flashes? And ... can it be suppressed? ie. such as when you have pressed a non-printing key, or you have clicked the screen with your mouse. Then likewise, can a redraw be triggered when you need one? Is it the same as a repaint?
« Last Edit: June 12, 2022, 01:03:56 pm by rick2691 »
Windows 10, LAZ 2.0.12, FPC 3.2.0, SVN 64642, i386-win32-win32/win64, using windows unit

 

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