From: Stalkern 2 <stalkern2 at tin.it>
Reply-To: stalkern2 at tin.it
To: lablgtk at kaba.or.jp
Subject: Re: animation: pixmap transparency?
Date: Tue, 8 Jul 2003 09:26:20 +0200
References: <200307021756.22997.stalkern2 at tin.it> <200307071941.13532.stalkern2 at tin.it> <20030708093841E.garrigue at kurims.kyoto-u.ac.jp>
In-Reply-To: <20030708093841E.garrigue at kurims.kyoto-u.ac.jp>
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Il  Tuesday 08 July 2003 02:38, Jacques Garrigue ha scritto:
[...]
> Did you set a mask on your pixmap?
> Transparency is controlled by the mask. If there is no mask, there is
> no transparency. By the way, alpha-blending at the X11 level is not
> supported.

OK, I've been merging this by a previous code sample from Claude Marché and 
now I get transparency: but it seems that setting the clip mask fools the 
callback that restores the background.
So, before having transparency I had a background that could recover from 
exposure, now it can not. 
Another buggy feature is that I have to hide the footprints of the moving 
pixmap by hand.

To test this code, one can download the images bkg.xpm and fly.xpm from 
http://www.connettivo.net/cntdownload/XPMs/

Any commentary, suggestion, hint is welcome.
Thank you
Ernesto

------------------------------------------------------------------------------------
animate.ml
------------------------------------------------------------------------------------

let (theRefBkgPixmap:(GDraw.pixmap option ref) ) = ref None;;
let (theRefMovingPixmap:(GDraw.pixmap option ref) ) = ref None;;

let (windowWidth,windowHeight) = (300,300);;
let (movingImgWidth,movingImgHeight) = (22,21);;

let refCounter = ref 0;;

let (baseX,baseY) = (10,100);;

let aXUnit = 10;;

let m_pi = acos (-1.);; (*from J.Garrigues' lissajous.ml*)
let c = ref 0.;; (*from J.Garrigues' lissajous.ml*)

(**)

open GMain;;


let window = GWindow.window ~width:windowWidth ~height:windowHeight ();;
let area = GMisc.drawing_area ~packing:window#add ();;

let (w:Gdk.window) = 
  (area#misc#realize (); 
   area#misc#window);;

let (theDrawing:[ `window] GDraw.drawable) = new GDraw.drawable w;;

theRefBkgPixmap := Some (GDraw.pixmap_from_xpm "bkg.xpm" ());;

theRefMovingPixmap := Some (GDraw.pixmap_from_xpm "fly.xpm" ());;


let redraw_on_exposure (aDrawing:[ `window] GDraw.drawable) aConnectEventArea 
=
  match !theRefBkgPixmap with
  | None -> false
  | Some bkgpxm ->
      (   

       let exposedAreaX = (Gdk.Rectangle.x aConnectEventArea) in
       let exposedAreaY = (Gdk.Rectangle.y aConnectEventArea) in
       let exposedAreaWidth = (Gdk.Rectangle.width aConnectEventArea) in
       let exposedAreaHeight = (Gdk.Rectangle.height aConnectEventArea) in

       (*use ~xsrc:0 ~ysrc:0 for checking the behaviour*)
       let () = aDrawing#put_pixmap ~x:exposedAreaX ~y:exposedAreaY 
~xsrc:exposedAreaX ~ysrc:exposedAreaY ~width:exposedAreaWidth 
~height:exposedAreaHeight bkgpxm#pixmap
       in
       false
      );;



let move_on_expose (aDrawing:[ `window] GDraw.drawable) aRefCounter _ = 
  match (!theRefBkgPixmap,!theRefMovingPixmap) with  
  | (Some bkgpxm, Some movpxm) ->
      (
       (*hiding the footprints... let's restore the background after passage*)
       let pastX = (windowWidth - ((baseX + ((!aRefCounter - 1) * aXUnit)) mod 
(windowWidth + movingImgWidth))) in
       let pastY = baseY in
       let () = aDrawing#put_pixmap ~x:pastX ~y:pastY ~xsrc:pastX ~ysrc:baseY   
~width:movingImgWidth ~height:movingImgHeight bkgpxm#pixmap 
       in

       let newX = (windowWidth - ((baseX + (!aRefCounter * aXUnit)) mod 
(windowWidth + movingImgWidth))) in
       let newY = baseY in
       let () = 
	 match movpxm#mask with (*mask is for transparency; thanks also to Claude 
Marché*)
	 | None -> ()
	 | Some m -> 
             (aDrawing#set_clip_origin ~x:newX ~y:newY;
              aDrawing#set_clip_mask m)
       in
       let () = aDrawing#put_pixmap ~x:newX ~y:newY ~xsrc:0 ~ysrc:0  
~width:movingImgWidth ~height:movingImgHeight movpxm#pixmap
       in

       let () = incr aRefCounter 
       in
       
       false
      )
  | _ -> false
;;
	

let init_gui () =
  let () = ignore (window#connect#destroy ~callback:Main.quit) in 
  let () = ignore 
      (area#event#connect#expose 
	 ~callback:
	 (fun event -> redraw_on_exposure theDrawing (GdkEvent.Expose.area event))) 
in 

  let () = ignore 
      (area#event#connect#expose 
	 ~callback:
	 (fun event -> move_on_expose theDrawing refCounter () )
      ) in
  let timeout _ = (c := !c +. 0.01 *. m_pi; (*J.Garrigues'*)
		   move_on_expose theDrawing refCounter () ;
		   true) in 
  let () = ignore (Timeout.add ~ms:500 ~callback:timeout) in

  let () = window#show () in
  Main.main ();;


let _ = init_gui ();;
------------------------------------------------------------------------------------