OpenEuphoria

Win32Lib getPixel problem revised

• Posted by Andy Drummond <andy at kestreltele.com> Dec 16, 2005
• 543 views

I posted a query about getPixel() in Win32Lib recently. But when I tried 
the test here at work I couldn't replicate the problem. Now I have.

The problem is this. I have two bitmaps. They overlay one another. I 
click on the top, visible, one with the mouse. I can then read the value 
of the top bitmap, which picked up the mouse events, fine. But using the 
same coordinates for the other bitmap I get -1 returned.

I attach a sample program which shows the problem - left clicks use 
getPixel on one bitmap, right clicks on the other.

So ...... now, does anyone have the answer to this?  What have I 
missed?  Why are you saying "What a dork!"?

---------------------------------------------------------------
include Win32Lib.ew
without warning
with trace

constant Test = createEx( Window, "Left-Click samples 'Page' and 
right-click samples 'Copy' - see program details", 0, Center, Center, 
756, 526, 0, 0 )
constant Page = createEx( Bitmap, "", Test, 0, 0, 750, 500, 0, 0 )
constant Copy = createEx( Bitmap, "", Test, 0, 0, 750, 500, 0, 0 )

integer  Status        Status = 0
integer     Request    Request = 0
object      res

sequence Drawing    Drawing = {}
sequence Start, Stop

--    Two "identical" bitmaps set to either Red or Green
--    Page will have its mouse events monitored, Copy won't

setPenColor(Copy, Red)
drawRectangle(Copy, w32True, 0,0,750,500)

setPenColor(Page, Green)
drawRectangle(Page, w32True, 0,0,750,500)

--    Collect mouse events on 'Page' only (topmost control)

procedure Page_onMouse (integer self, integer event, sequence params)
    sequence pos
   
    event = params[1]                             -- Replace this with 
the mouse event
    pos = getPointerRelPos(Page)                  -- Get coordinate on 
'Page' - same on 'Copy'
   
    if event = RightDown then
        event = getPixel(Copy, pos[1], pos[2])    -- Sample bitmap NOT 
clicked on
    elsif event = LeftDown then
        event = getPixel(Page, pos[1], pos[2])    -- Sample bitmap 
clicked on
    else
        return                                    -- Any other event
    end if   

    res = message_box("getPixel returned "&sprint(event), "getPixel()", 
MB_ICONEXCLAMATION)

end procedure

setHandler( Page, w32HMouse, routine_id("Page_onMouse"))
WinMain( Test,Normal )
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