Delete a line in gdi

[nend]

Hoi all,

How can a delete a line which I made with gdi?

See the codebox

#include <GuiConstantsEx.au3>
#include <GDIPlus.au3>
Local $hGUI, $hGraphic, $hPen
_GDIPlus_Startup ()
$hGUI = GUICreate("GDI+ test", 400, 300)
$make = GUICtrlCreateButton("Make line", 10, 10, 100, 20)
$delete = GUICtrlCreateButton("Delete line", 120, 10, 100, 20)
GUISetState()
 
While 1
$msg = GUIGetMsg()
Switch $msg
  Case $make
   $hGraphic = _GDIPlus_GraphicsCreateFromHWND ($hGUI)
   $hPen = _GDIPlus_PenCreate ()
   _GDIPlus_GraphicsDrawLine ($hGraphic, 10, 150, 390, 150, $hPen)
  Case $delete
   ;code ???
  Case $GUI_EVENT_CLOSE
   _GDIPlus_PenDispose ($hPen)
   _GDIPlus_GraphicsDispose ($hGraphic)
   _GDIPlus_Shutdown ()
   Exit
EndSwitch
Sleep(20)
WEnd

[Ramzes]

Try this:

_GDIPlus_GraphicsClear

[nend]

@ramzes,

I've already looked at this function but I don't see how I insert this into the code.

I already thought it had something to do with that function but i don't see how to insert it into my code.

Edited October 8, 2011 by nend

[Ramzes]

Replace 'code ???' with function.

#include <GuiConstantsEx.au3>
#include <GDIPlus.au3>
Local $hGUI, $hGraphic, $hPen
_GDIPlus_Startup()
$hGUI = GUICreate("GDI+ test", 400, 300)
$make = GUICtrlCreateButton("Make line", 10, 10, 100, 20)
$delete = GUICtrlCreateButton("Delete line", 120, 10, 100, 20)
GUISetState()
While 1
$msg = GUIGetMsg()
Switch $msg
  Case $make
   $hGraphic = _GDIPlus_GraphicsCreateFromHWND($hGUI)
   $hPen = _GDIPlus_PenCreate()
   _GDIPlus_GraphicsDrawLine($hGraphic, 10, 150, 390, 150, $hPen)
  Case $delete
   _GDIPlus_GraphicsClear($hGraphic)
  Case $GUI_EVENT_CLOSE
   _GDIPlus_PenDispose($hPen)
   _GDIPlus_GraphicsDispose($hGraphic)
   _GDIPlus_Shutdown()
   Exit
EndSwitch
Sleep(20)
WEnd

You should change color.

[nend]

@ramzes,

I've I used this function he fills up my complete gui with one color.

This code is a small piece of a lot bigger code and I use a picture at the background.

I've I fills this up with one color the picture is not visible anymore.

Have got a other idea?

[ahmet]

If you know coordinates of line you can draw new line with background color.

[nend]

@ahmet,

The background is a picture from a scanner with a lot of different colors so I don't think this can help me.

I thinks it has something to do with layers, so you can draw on a layer and delete the layer with the button deleted, but I don't know how to do this.

Anyway thanks for your help.

[martin]

You would need to have some way to redraw all the lines except the line you want to delete, or you save a copy of every new version and have an UNDO/REDO otion.

You can store the picture as a bitmap, and have the lines drawn on another bitmap. You could have another bitmap for another layer. When a change is made you change the relevant layer(bitmap) and then recombine them all again and redraw the result.

[nend]

@Martin,

Thanks for your suggestions, it's a bit harder than I expected but I follow your directions and see where I get.

I hoped that there where a function for.

Thanks alot guys for all your support!