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2005-01-18 12:13
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Editor.gif (27,881 bytes) |
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Which version of the JVCL are you using? This remings me of a bug from WinNT with TMemo, TRichEdit and al. |
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JVCL 3 RC1 |
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JvEditorCommon.pas::TJvCustomEditorBase.Scroll() should be the problem. It looks like that Windows NET has problems with the Win32API function ScrollDC(). Win32SDK says to ScrollDC: Minimum operating systems Windows 95, Windows NT 3.1. Does it work if you insert this line before the ScrollDC call? -------- RUpdate := ClientRect; ScrollDC(... -------- |
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No, that line made no apparent difference. But, if I understand the ScrollDC help correctly, RUpdate is an output parameter from ScrollDC. Should I be assigning R or RClip instead? |
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RUpdate contains the correct value. But I just found out that sometimes it return (0,0,0,0). I have committed an update version that does a complete Invalidate if ScrollDC returns (0,0,0,0). Maybe this helps. |
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This does not seem to be the problem. The (0,0,0,0) is returned when there is really nothing to repaint. I think a possible solution would be to disable optimized scrolling for NT<5.0 as the issue only happens on NT. |
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My user tried the latest version, but it didn't seem any different. The problem still occurred. |
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What happens if you remove the whole {$IFDEF ... ENDIF} Block? If this does not work either, then the bug must be somewhere else. |
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Comment from my user: "...display is actually much worse on NT. Still see the same improper redraw. Before, we could use the scrollbar to scroll up and down a couple of times to get a good display. Now, scrolling up and down doesn't help. Pretty much unusable on our NT systems. I checked on updated video drivers - none available. Still looks normal on Win2K" Can I just check I commented out the correct code... in TJvCustomEditorBase.Scroll, the vertical scroll block, I commented out the following code: {$IFDEF VCL} if Abs((OldFTopRow - ScrollPos) * FCellRect.Height) < FEditorClient.Height then begin R := FEditorClient.ClientRect; R.Bottom := R.Top + CellRect.Height * FVisibleRowCount; R.Left := 0; // update gutter RClip := R; Inc(RClip.Bottom, CellRect.Height); ScrollDC( FEditorClient.Canvas.Handle, // handle of device context 0, // horizontal scroll units (OldFTopRow - ScrollPos) * CellRect.Height, // vertical scroll units R, // address of structure for scrolling rectangle RClip, // address of structure for clipping rectangle 0, // handle of scrolling region @RUpdate // address of structure for update rectangle ); // (ahuser) WinNT seams to have problems with ScrollDC in vertical direction. (Mantis 0002528) if (Win32Platform = VER_PLATFORM_WIN32_NT) and (Win32MajorVersion < 5) then Dec(RUpdate.Top, CellRect.Height); Inc(RUpdate.Bottom, CellRect.Height); InvalidateRect(Handle, @RUpdate, False); end else {$ENDIF VCL} |
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Yes, that is the code that seems to not work under NT. |
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Is this still here? |
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Yes, this has not been resolved |
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Any news, anyone? |
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Hello? |
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No answers, I'm assuming this is fixed in the latest SVN version http://homepages.borland.com/jedi/wiki/index.php?title=Repository |
- Anonymous
