Flicker reduction drawing strategy

[LiaoMi]

Hi jj2007,

when scrolling the text has at least 3 additional frames, the text is displayed with a soapy effect. The top border causes flickering at the bottom region of the window when resized. With general resizing, there is a green flicker in the background of the program 

[LiaoMi]

We can visually see the flicker, if we use the program screentogif, in this program, you can change the recording rate and view the rendering by frame. By combining this data with the obtained measurements, then we can draw conclusions about the performance.
https://www.screentogif.com/
https://github.com/NickeManarin/ScreenToGif/releases/download/2.30/ScreenToGif.2.30.Portable.zip

@jj2007
Flickering of the text while scrolling could not be confirmed. This is probably an optical illusion - https://en.wikipedia.org/wiki/Optical_illusion
The rest of the flickering was confirmed, you can look at the picture.

[LiaoMi]

Hi Biterider,

here is the test ...

[LiaoMi]

If you compare both results, you can see that there are the same patterns. The sequence of drawing is visible, areas that were processed separately are visible. The new concept shows black artifacts and more shifts in the transform window. In the regular form, this effect appears less often and the transformation of the window is more often limited to one drawing, if we consider this event to be atomic. Visually, I did not see any difference with my own eyes.

The only technique that can remove flicker is double buffering 

[jj2007]

https://github.com/NickeManarin/ScreenToGif/releases/download/2.30/ScreenToGif.2.30.Portable.zip

That one asks for dotnot 4.8

Flickering of the text while scrolling could not be confirmed. This is probably an optical illusion - https://en.wikipedia.org/wiki/Optical_illusion
The rest of the flickering was confirmed, you can look at the picture.

I didn't say the text flickers. The RichEdit control is quite good at that, actually. The embedded simple edit control does flicker a bit, and this is normal for edit controls.

[daydreamer]

If you compare both results, you can see that there are the same patterns. The sequence of drawing is visible, areas that were processed separately are visible. The new concept shows black artifacts and more shifts in the transform window. In the regular form, this effect appears less often and the transformation of the window is more often limited to one drawing, if we consider this event to be atomic. Visually, I did not see any difference with my own eyes.

The only technique that can remove flicker is double buffering 

there are some more advanced api's that let you wait for vertical retrace,disadvantage to draw in order opposite direction than screen output to monitor

[HSE]

Tested, no effect. I bet that SetWindowPos uses MoveWindow under the hood

SetWindowPos allow a lot of flags, but apparently nothing for this problem.

If I take away the vertical scrollbar by omitting WS_VSCROLL from the style during CreateWindowEx, and then enable it afterwards with SetWindowLong

[HSE]

Perhaps is for here?:

The DeferWindowPos function updates the specified multiple-window - position structure for the specified window. The function then returns the handle to the updated structure. The EndDeferWindowPos function uses the information in this structure to change the position and size of a number of windows simultaneously. The BeginDeferWindowPos function creates the structure.

[Biterider]

Hi HSE
Dynamic layouts use DeferWindowPos to reposition all controls at once.

Biterider

[LiaoMi]

Perhaps is for here?:

The DeferWindowPos function updates the specified multiple-window - position structure for the specified window. The function then returns the handle to the updated structure. The EndDeferWindowPos function uses the information in this structure to change the position and size of a number of windows simultaneously. The BeginDeferWindowPos function creates the structure.

Hi HSE,

Wm_size Edit flicker - http://masm32.com/board/index.php?topic=7668.msg83761#msg83761 and http://masm32.com/board/index.php?topic=7668.msg83780#msg83780

Code Select Expand

case WM_ENTERSIZEMOVE:
SendMessage(hEdit, WM_SETREDRAW, 0, 0);
return TRUE;
case WM_EXITSIZEMOVE: {
SendMessage(hEdit, WM_SETREDRAW, 1, 0);
RedrawWindow(hwndDlg, NULL, NULL, RDW_INVALIDATE | RDW_ERASE);
}
return TRUE;

[HSE]

Dynamic layouts use DeferWindowPos to reposition all controls at once.

Ok. Then that don't solve very much.

Wm_size Edit flicker

That could be usefull  , just I don't know how 

[jj2007]

Dynamic layouts use DeferWindowPos to reposition all controls at once.

That's an interesting option. I use MoveWindow, ..., 1 to reposition all controls in a loop. Perhaps DeferWindowPos is faster or less flickery, I'll have to look into that - thanks for the hint

Attached a debug version of my demo, demonstrating why the richedit's vertical scrollbar is jumping up and down - btw only for horizontal sizing. The cause is found (it's a bug in the control) but so far no therapy in sight

Btw invoke SendMessage, hMyEdit, WM_SETREDRAW, 0, 0 is not a valid option, it just looks ugly

Code Select Expand

Event Message
  .if uMsg_==WM_ENTERSIZEMOVE
invoke GetScrollInfo, hMyEdit, SB_VERT, addr sinf
fdeb 4, "start sizing", sinf.nMin, sinf.nMax, sinf.nPage, sinf.nPos, sinf.nTrackPos
  .elseif uMsg_==WM_SIZING
invoke GetScrollInfo, hMyEdit, SB_VERT, addr sinf
fdeb 4, "GetScrollInfo", sinf.nMax
  .elseif uMsg_==WM_EXITSIZEMOVE
invoke GetScrollInfo, hMyEdit, SB_VERT, addr sinf
fdeb 4, "end sizing", sinf.nMin, sinf.nMax, sinf.nPage, sinf.nPos, sinf.nTrackPos
  .endif

[hutch--]

There is a magic rule, do not layer windows that independently update their client area. A bare window with the background colour set in the WNDCLASSEX does not flicker. If you put another window over it, then set the base window to 0 or a transparent background. If you need to have multiple windows, ensure that what is under them has the update turned off. It makes the layout a bit more complicated but done right, you will have no flicker at all.

[jj2007]

Hutch,

That is all correct, but the WS_CLIPCHILDREN style should take care of that. My experience is that certain controls behave worse than others. The RichEdit control, for example, remains pretty smooth, except that there is that jumping vertical scrollbar. Edit and static controls, otoh, do flicker when you resize them. Not much, but it's clearly visible.

Code Select Expand

GuiParas equ xr0, y0, w880, h-1, b Red ; right-aligned, on top, 88% width, red background
GuiMenu equ @File, &Open, &Save, -, E&xit, @Edit, Undo, Copy, Paste
include \masm32\MasmBasic\Res\MbGui.asm
  GuiControl MyEdit, "richedit", FileRead$(98), bcol LiteBlueGreen, x100, w800, y50, h250, wrap
  GuiControl MyRich, "edit", FileRead$(99), bcol White, x100, w800, y350, h250
  GuiControl MyStatic, "static", FileRead$(99), bcol LiteYellow, x100, w800, y650, h250
GuiEnd

The attached executables are built once with the WS_CLIPCHILDREN style, once without. The difference is obvious. Still, even with WS_CLIPCHILDREN set, the ordinary edit and static controls do flicker a little bit, only the RichEdit control stays smooth.