repaint in c++

tommycahir

hi all
i trying to repaint a tpanel but i have added timages to it dynamically and they will not "disappear2 when i call the repaint function the code i am using is shown below i am also using this function for a tpaintbox am it works fine.

mainFrame->Repaint(); //tpaintbox
BackPanel->Repaint(); //tpanel

is there anyway that i can remove these timages i.e blank the tpanel again..

tanx in advance
tommycahir

GUI

u talking about c++ console app now?
or windows app?

tommycahir

i talking bout the windows app
i got it blanking the stuff now but i need it to remove the timages that were there previously.

dazberry

I'm not sure exactly what you're trying to do here, but (guessing) that the TImages are children to the TPanel, when you call Repaint, this causes an Invalidate and then an Update. You need to call update only (avoiding the invalidate) ... why ?

BackPanel->Update();

D.

tommycahir

i am designing a logic gate simulator and i add the timages to the tpanel then i have a tpaintbox on top of that in which to draw the connections i am able to clear the paint box and the tpanel with floodfill but i am not able to remove the timages that were added to the tpanel

dazberry

Ok,

well you could, either:

[1]
Set the TImages.visible = False
In the TPaintBox.OnPaint methods, depending on the specific logic, you could manually draw the TImage contents on to the paint box.
Cons: You will have to deal with transparency as well, if thats a problem.

[2]
Delete all the TImages
Add a TImageList to the form and load all the images in to it.
In the TPaintBox.OnPaint method, again depending on logic, do something like the following (In Delphi):

If (SomeState) then
begin
ImageList1.Draw(PaintBox1.Canvas,10,10,0);
end;

Check out the help on TCustomImageList.Draw.
Cons: All the images need to be the same size, or at least you'll need to use multiple TImageLists.

[3]
or alternately In TPaintBox.OnPaint (Depending on state)

for nLoop:=0 to ComponentCount-1 do
begin
if Components[nLoop] is TImage then
With Components[nLoop] as TImage do
if Parent = Panel1 then
Visible:=False;
end;

Should be similar in BCB.

HTH

D.