RemoveGadgetItem on ComboBoxGadget Bug

Comfort · **Joined:** Thu Jul 05, 2018 11:52 pm **Posts:** 2

Hello,

There seems to be a problem with the RemoveGadgetItem command when used on a ComboBoxGadget.

It occurs when #PB_ComboBox_Image flag is set, but no image has been applied to list item.

Tested on V5.73 (x86) and (x64) when using PB's example (with ImageID removed):

Code:

UsePNGImageDecoder()
LoadImage(0, #PB_Compiler_Home + "examples/sources/Data/world.png")
  
If OpenWindow(0, 0, 0, 270, 180, "ComboBoxGadget", #PB_Window_SystemMenu | #PB_Window_ScreenCentered)
  ComboBoxGadget(0, 10, 10, 250, 21, #PB_ComboBox_Editable)
    AddGadgetItem(0, -1, "ComboBox editable...")

  ComboBoxGadget(1, 10, 40, 250, 21, #PB_ComboBox_Image)
    AddGadgetItem(1, -1, "ComboBox item with image") ;, ImageID(0)  -<<<< IMAGEID REMOVED

  ComboBoxGadget(2, 10, 70, 250, 21)
    For a = 1 To 5
      AddGadgetItem(2, -1,"ComboBox item " + Str(a))
    Next

  SetGadgetState(0, 0)
  SetGadgetState(1, 0)
  SetGadgetState(2, 2)   
    
  RemoveGadgetItem(1, 0)  ; -<<<< ERROR HERE
    
  Repeat : Until WaitWindowEvent() = #PB_Event_CloseWindow
EndIf

BarryG · **Joined:** Thu Apr 18, 2019 8:17 am **Posts:** 1337

Confirmed. Crashes here with an "Invalid memory access" error on the RemoveGadgetItem() line.

And here's another related bug: When an image is assigned to the added item, but then the item is removed before the event loop, the item is still visible (image and text) until the mouse is moved over it. But you can make it go away correctly with InvalidateRect_() API call. Try this:

Code:

UsePNGImageDecoder()
LoadImage(0, #PB_Compiler_Home + "examples/sources/Data/world.png")

If OpenWindow(0, 0, 0, 270, 180, "ComboBoxGadget", #PB_Window_SystemMenu | #PB_Window_ScreenCentered)
  ComboBoxGadget(0, 10, 10, 250, 21, #PB_ComboBox_Editable)
  AddGadgetItem(0, -1, "ComboBox editable...")
  
  ComboBoxGadget(1, 10, 40, 250, 21, #PB_ComboBox_Image)
  AddGadgetItem(1, -1, "ComboBox item with image", ImageID(0))
  
  ComboBoxGadget(2, 10, 70, 250, 21)
  For a = 1 To 5
    AddGadgetItem(2, -1,"ComboBox item " + Str(a))
  Next
  
  SetGadgetState(0, 0)
  SetGadgetState(1, 0)
  SetGadgetState(2, 2)   
  
  RemoveGadgetItem(1, 0) ; Item with image is still visible until the mouse is moved over it.
  ;InvalidateRect_(GadgetID(1),0,1) ; Uncomment this line to fix the bug.
  
  Repeat : Until WaitWindowEvent() = #PB_Event_CloseWindow
EndIf

mk-soft · **Posted:** Sat Dec 05, 2020 6:36 pm

Very old mistake. Does not work with v5.46 already.

Comfort · **Joined:** Thu Jul 05, 2018 11:52 pm **Posts:** 2

Quote:

RemoveGadgetItem(1, 0) ; Item with image is still visible until the mouse is moved over it.
; InvalidateRect_(GadgetID(1),0,1) ; Uncomment this line to fix the bug.

SetGadgetState(1, 0) also fixes that issue... even though item 0 should no longer exist.

mk-soft · **Posted:** Sat Dec 05, 2020 11:11 pm

Macro Workaround ...

Code:

;-TOP
CompilerIf #PB_Compiler_OS = #PB_OS_Windows
  Macro _PB_(Function)
    Function
  EndMacro
  
  Macro FixRemoveGadgetItem(Gadget, Position)
    If GadgetType(Gadget) = #PB_GadgetType_ComboBox
      SetGadgetItemImage(Gadget, Position, 0)
      _PB_(RemoveGadgetItem)(Gadget, Position)
      SetGadgetState(Gadget, 0)
    Else
      _PB_(RemoveGadgetItem)(Gadget, Position)
    EndIf  
  EndMacro
  
  Macro RemoveGadgetItem(Gadget, Position)
    FixRemoveGadgetItem(Gadget, Position)
  EndMacro
CompilerEndIf

UsePNGImageDecoder()
LoadImage(0, #PB_Compiler_Home + "examples/sources/Data/world.png")
  
If OpenWindow(0, 0, 0, 270, 180, "ComboBoxGadget", #PB_Window_SystemMenu | #PB_Window_ScreenCentered)
  ComboBoxGadget(0, 10, 10, 250, 21, #PB_ComboBox_Editable)
    AddGadgetItem(0, -1, "ComboBox editable...")

  ComboBoxGadget(1, 10, 40, 250, 21, #PB_ComboBox_Image)
    AddGadgetItem(1, -1, "ComboBox item with image"); ImageID(0)) ; -<<<< IMAGEID REMOVED

  ComboBoxGadget(2, 10, 70, 250, 21)
    For a = 1 To 5
      AddGadgetItem(2, -1,"ComboBox item " + Str(a))
    Next

  SetGadgetState(0, 0)
  SetGadgetState(1, 0)
  SetGadgetState(2, 2)   
  
  RemoveGadgetItem(1, 0)  ; -<<<< ERROR HERE
  
  Repeat : Until WaitWindowEvent() = #PB_Event_CloseWindow
EndIf

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RemoveGadgetItem on ComboBoxGadget Bug

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