Phantom Carets

[raleeper]

What could cause a non-blinking image of a caret to appear on the line below?


Assume this is the line ¦with the real, blinking caret
  And this is the line be¦low.

(imagine they line up and don't occupy spaces)

This occurs only when I switch from an underline caret to a line caret, and only if there is not already a phantom caret just below the real one - if there is, it disappears.

Of course, the phantoms disappear when the line is repainted, but repainting lines that should not have changed without understanding the necessity is something I'd like to avoid.

This is the code I use to manipulate carets:

   In the initialization:

crecar:
   bts   [flge], 3   ;caret exists
   bt   [flge], 5   ;strikeover mode
     jc   @F
   mov   BY [csrtyp], 18   ;CurSoRTYPe
   xor   edx, edx
   inc   edx
     jmp   crecar_e

@@:
   mov   BY [csrtyp], 2
   mov   edx, [cszh]   ;Cursor SiZe Horizontal

crecar_e:
   invoke   CreateCaret, hwnd, 0, edx, 2
   invoke   SetCaretBlinkTime, 100
   retn

   To change type or position:

;;   EINS, CRM

eins:      ;Toggle caret type
   xor   BY [csrtyp], 2 xor 18
   btc   [flge], 5
     jc   @F
   mov   edx, [cszh]
   invoke   CreateCaret, hwnd, 0, edx, 2
     jmp   eins_e

@@:
   invoke   CreateCaret, hwnd, 0, 1, 14

eins_e:
   invoke   ShowCaret, hwnd
   retn

crm:      ;Caret move
   push   edx
   movzx   eax, [crposh]
   mul   BY [cszh]
   mov   edx, eax
   mov   al, [crposv]
   mul   BY [cszv]
   sub   eax, [csrtyp]
   invoke   SetCaretPos, edx, eax
   bts   [flge], 4
     jc   crm_end
   invoke   ShowCaret, hwnd

crm_end:
   pop   edx
   retn


The variables not explained are set elsewhere, and I'm pretty sure they're not causing the problem.
cszh   DD   ?   ;Char cell SiZe Horizontal
cszv   DD   ?   ;Char cell SiZe Vertical
csrtyp   DD   18   ;flip 2 <-> 18   0000 0010   0001 1000
crposv   DB   0   ;CuRsor POSition Vertical - line - 0..24
   DB   3 DUP (0)
cphdw   LABEL   DWORD   ;dword version of crposh
crposh   DB   0   ;CuRsor POSition Horiz - column - 0..4F
   DB   3 DUP (0)
flge   DW   20      ;FLaG - Edit-input
;   7    6       5         4          3      2        1         0
;   seb   caplk   stkvr   csrsh   csrex   in edit   rfsh   in input
;      caplock on   cursorshow on      rfsh ??
;         strikeover mode on


I would greatly appreciate any suggestions or thoughts.

[jj2007]

BTS: Are you sure you don't mean BT, Bit Test?

[raleeper]

BTS: Are you sure you don't mean BT, Bit Test?

Yes. In each case the purpose is to set the flag.  The caret is going to exist, [flge], 3 or be shown, [flge], 4, after the next few lines of code.

Incidently, the flge chart didn't copy correctly. It should be:

flge   DW   20      ;FLaG - Edit-input
;   7       6         5          4         3         2           1       0
;   seb   caplk   stkvr   csrsh   csrex   in edit   rfsh   in input

[hutch--]

raleeper,

> What could cause a non-blinking image of a caret to appear on the line below?

Its usually a screen update issue, I have seen the effect the most in web browwers.

[Tedd]

It's just a repaint thing.. The old caret isn't erased before the new one is moved and drawn. It seems to happen at random in various programs.
If it's happening specifically when changing the caret shape or position, try hiding the caret first, then changing it, and show again. I don't know if that will give enough chance for it to be erased though, so you may need to force a repaint (at least of the line containing the 'old' caret.)

[raleeper]

It's just a repaint thing.. The old caret isn't erased before the new one is moved and drawn. It seems to happen at random in various programs.
If it's happening specifically when changing the caret shape or position, try hiding the caret first, then changing it, and show again. I don't know if that will give enough chance for it to be erased though, so you may need to force a repaint (at least of the line containing the 'old' caret.)

Thanks. I'll try that.

But just to clarify, this is not a matter of on old caret persisting; it's a new non-blinking line caret popping up on the line just below the real, blinking one.

Later - Neither HideCaret nor DestroyCaret has any discernible effect; the phantom still appears.

[Tedd]

Okay, that's even more strange :bdg

Want to post a slimmed-down version of your code that still does it? - then we can have a poke :wink

[jj2007]

This occurs only when I switch from an underline caret to a line caret, and only if there is not already a phantom caret just below the real one - if there is, it disappears.

Are you bitblitting something with one of the DSTINVERT etc modes?