Article:7

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Applies To:

VB5

VB6

Author:

Steve McMahon

BugTrak

Bugs: 12 / 13

Issues: 0 / 0

Questions: 0 / 0

Updated:6 February 2004

23 Apr 2003

If an menu was used as a drop-down from a vbAccelerator Toolbar control, and it contained infrequently used items which were hidden, once the items were exposed they did not respond when clicked. Now all items click correctly.

When showing as a chevron in a menu, if you customised which buttons were visible they could incorrectly appear in the chevron menu.

Disabled items now draw in the correct colour when XP style is in effect.

Update History >

Subclassing Without The Crashes

Flicker in OwnerDraw Control

Summary

Id:	7.10
Type:	Bug
Current Status:	Open

Detail

The icq menu generates a large amount of flicker on mouse movement. I traced it down to this snippet of code...

If (m_tMI(lIndex).bOwnerDraw) Then ' this is unfortunate LSet tTR = tDIS.rcItem Dim lW As Long, lH As Long lW = tTR.Right - tTR.Left + 1 lH = tTR.Bottom - tTR.Top + 1 tTR.Top = tTR.Top - 1 tTR.Bottom = tTR.Bottom + 1 BitBlt tDIS.hdc, tDIS.rcItem.Left, tDIS.rcItem.Top, lW, lH, lHDC, 0, 0, vbSrcCopy RaiseEvent DrawItem(tDIS.hdc, lIndex, tTR.Left, tTR.Top, tTR.Right, tTR.Bottom, bHighlighted, bChecked, bDisabled, bDoDefault) BitBlt lHDC, 0, 0, lW, lH, tDIS.hdc, tDIS.rcItem.Left, tDIS.rcItem.Top, vbSrcCopy tR.Left = tTR.Left - tDIS.rcItem.Left tR.Top = tTR.Top - tDIS.rcItem.Top + 1 End If

I notice that the event handler draws to the onscreen hDC, I guess this is because the lHDC (offscreen hdc) is just the hdc to the actual menu item itself (a small rectangle?)

Can you recommend a method where I can reduce the flicker by drawing to an offscreen hDC?