Transparent TCustomcontrol

 

#2   11-21-2002, 03:31 AM

Ted On The NeT Senior Member   Join Date: Apr 2001 Posts: 2,182

RE: Transparent TCustomcontrol Transparent TCustomcontrol hi to all, I have a problems with making a TCustomcontrol transparent. I added: Procedure CreateParams(var Params: TCreateParams); override; implenmentation procedure TDSPTransparentPanel.CreateParams(var Params: TCreateParams); begin { call the create of the params } inherited CreateParams(Params); Params.ExStyle := Params.ExStyle + WS_EX_Transparent; ControlStyle := ControlStyle - [csOpaque] + [csAcceptsControls] end; This makes the Component transparent, but when I place an Imagebox on it and I'am moveing the Imagebox per runtime, the background of the TCustomcontrol losess it's tranzparency . When I minimize and maximize the Form or when I move an other Window over it (e.g. explorer) , the transparency will be back. So here is my Question: What must I do to get this effect by code, to get the transparency back? I called self.redraw , self.invalidate but without effect. Please help me solve this Problem Best Regards BT Try this: Override its CreateParam method like this: private // in control declaration Procedure CreateParams( Var params: TCreateParams ); override; Procedure TTransparentXXX.CreateParams( Var params: TCreateParams ); begin inherited CreateParams( params ); params.ExStyle := params.ExStyle or WS_EX_TRANSPARENT; end; Add a handler for the WM_ERASEBKGND message: Procedure WMEraseBkGnd( Var msg: TWMEraseBkGnd ); message WM_ERASEBKGND; Procedure TTransparentXXX.WMEraseBkGnd( Var msg: TWMEraseBkGnd ); begin SetBkMode( msg.DC, TRANSPARENT ); msg.result := 1; end; That is the basic frame for a TWinControl descendent. For a TGraphicsControl you would drop the CreateParams (since only WinControls have that method) and override the create constructor. After calling the inherited constructor you modify the ControlStyle of the control: ControlStyle := ControlStyle - [csOpaque]; Transparency actually works better for TGraphicControls than for TWinControls. The latter have problems if the control is moved or the background needs to change. Delphi container controls (like form or panel) are always created with the WS_CLIPCHILDREN style, which automatically excludes the area under child controls from updates, so the background will not be updated if required. Removing the WS_CLIPCHILDREN style from a controls parent is possible with SetWindowLong( parent.handle, GWL_STYLE, GetWIndowLong( parent.handle, GWL_STYLE ) and not WS_CLIPCHILDREN ); Greetz, ::TeD On The NeT:: =[ QUESTIONS ]========================================= please click Accept as Answer if my reply helped you. =[ EXTRA INFO ]======================================== Location : Netherlands (GMT +01.00) Languages : English, Dutch, German Age : 25 ICQ : Be smart and figure out what my UIN is... ------------------------------------------------------- Used OS : Win2k SR2 | Win2k SR3 Delphi # : Enterprise 5 SP2 | Enterprise 6 SP2 ================================================== =====

#3   11-21-2002, 06:07 AM

blacktrip Member   Join Date: Nov 2001 Posts: 55

Transparent TCustomcontrol I added a TImage to the create proedure in my Transparent Component (TCustumcontrol) Create procedure: Ibar := TImage.create(self); Ibar.parent := self; SetWindowLong(Ibar.parent.handle, GWL_STYLE, GetWIndowLong(Ibar.parent.handle, GWL_STYLE ) and not WS_CLIPCHILDREN ); but when I move the Ibar per runtime the background of my Component will not updated. What can be wrong? Please Help Best Regards BT

Ibar.parent := self.parent可以解决！;