Bug in HasAlpha()

[Antonio Linares]

If we paint it into a memory hDC then we will just check if it works or not

Nothing will be seen

[Enrico Maria Giordano]

So, why not to make a function HasAlpha( hBmp ) using ABPaint() inside it?

EMG

[Antonio Linares]

Enrico,

Lets check if it works.

I have modified FWH function ABPaint() to return the result of the call to AlphaBlend()

Code: Select all  Expand view  RUN

function HasAlpha( hBitmap )

   local hDC := CreateDC( "DISPLAY", "", "" )
   local lHasAlpha := ABPaint( hDC, 0, 0, hBitmap )

   DeleteDC( hDC )
   
return lHasAlpha

I am emailing you the modified FWH library. I appreciate if you can test it

[Enrico Maria Giordano]

I get this:

Code: Select all  Expand view  RUN

Harbour 3.2.0dev (r1605041350)
Copyright (c) 1999-2016, http://harbour-project.org/
Embarcadero C++ 7.20 for Win32 Copyright (c) 1993-2016 Embarcadero Technologies, Inc.
ALPHA.c:
Turbo Incremental Link 6.75 Copyright (c) 1997-2016 Embarcadero Technologies, Inc.
Error: Unresolved external '_pcre_config' referenced from E:\HARBOUR\LIB\HBRTL.LIB|hbregex
Error: Unresolved external '_pcre_stack_malloc' referenced from E:\HARBOUR\LIB\HBRTL.LIB|hbregex
Error: Unresolved external '_pcre_stack_free' referenced from E:\HARBOUR\LIB\HBRTL.LIB|hbregex
Error: Unable to perform link

Can you send me the libs for xHarbour, please?

EMG

[Antonio Linares]

Are you linking hbpcre.lib ?

[nageswaragunupudi]

Function HasAlpha() has never been changed and works the same way it was working all the time.

Code: Select all  Expand view  RUN

cFile := "c:\fwh\bitmaps\olga1.jpg"
hBmp := FILOADIMG( cFile ) // Source of function image.prg. Requires Freeimage.dll
? HasAlpha( hBmp ) // --> .F.
 

In the first post in this thread, hBmp is read wth the function GDIP_IMAGEFROMFILE(). This function uses GDI+. This does not require freeimage.dll, but the side-effect is this function converts even jpeg image as an alpha image and returns hBmp which has Alpha. Naturally HasAlpha( hBmp ) returns .T., because this hBitmap has Alpha channel. Even if the alpha channel is added ( 32-bit bitmap instead of 24-bit bitmap) there is no change in the content or rendering when painted with abpaint(). We knew this behavior from the time we started using GDI+.

[Enrico Maria Giordano]

Function HasAlpha() has never been changed and works the same way it was working all the time.

Code: Select all  Expand view  RUN

cFile := "c:\fwh\bitmaps\olga1.jpg"
hBmp := FILOADIMG( cFile ) // Source of function image.prg. Requires Freeimage.dll
? HasAlpha( hBmp ) // --> .F.
 

In the first post in this thread, hBmp is read wth the function GDIP_IMAGEFROMFILE(). This function uses GDI+. This does not require freeimage.dll, but the side-effect is this function converts even jpeg image as an alpha image and returns hBmp which has Alpha. Naturally HasAlpha( hBmp ) returns .T., because this hBitmap has Alpha channel. Even if the alpha channel is added ( 32-bit bitmap instead of 24-bit bitmap) there is no change in the content or rendering when painted with abpaint(). We knew this behavior from the time we started using GDI+.

Thank you. This could explain why HasAlpha() is not working fine. Unfortunately there is another problem: images loaded with GDIP_IMAGEFROMFILE() seems to not paint correctly using ABPAINT(), at least with TPrinter's hDCOut.

EMG