Bad quality with GIF (and GDI+)

[Enrico Maria Giordano]

On XP and Vista your sample shows a black rectangle.

EMG

https://support.microsoft.com/es-es/kb/958911

Ok, thank you.

EMG

[mastintin]

On XP and Vista your sample shows a black rectangle.

EMG

https://support.microsoft.com/es-es/kb/958911

Ok, thank you.

EMG

first confirm is ok. ...
link this gdiplus.obj file in your code ...
https://www.dropbox.com/s/ah0f235yqbe5a ... s.obj?dl=0

[Enrico Maria Giordano]

It works!!!

EMG

[nageswaragunupudi]

Mr Manuel

Code: Select all  Expand view

Bitmap* newImage  = new Bitmap( nWidth, nHeight, PixelFormat32bppPARGB ) ; //   cambio aqui ---- original->GetPixelFormat() );

This is the change you made. That means this function adopts "PixelFormat32bppPARGB" for "all" image/bitmap files, irrespective of the source and present pixelformat.
Does it have any side effects on other file formats?

[mastintin]

Mr Manuel

Code: Select all  Expand view

Bitmap* newImage  = new Bitmap( nWidth, nHeight, PixelFormat32bppPARGB ) ; //   cambio aqui ---- original->GetPixelFormat() );

This is the change you made. That means this function adopts "PixelFormat32bppPARGB" for "all" image/bitmap files, irrespective of the source and present pixelformat.
Does it have any side effects on other file formats?

I've been using it time and have not had any problems.
actually we assume that all "imported" to gdi+ is 32bit (highest quality) then return HBITMAP not had problem

[nageswaragunupudi]

One of the cases I can now recollect is non-alpha bmp files.
The hBitmap returned is an alpha bmp. We get into problem while rendering.

[Enrico Maria Giordano]

I confirm. All images loaded with GDI+ are "marked" as alphachannel even if they are not.

EMG

[mastintin]

One of the cases I can now recollect is non-alpha bmp files.
The hBitmap returned is an alpha bmp. We get into problem while rendering.

Yes, same case in GDIP_IMAGEFROMFILE -> BitmapFromStream ....

....
PixelFormat pf = original->GetPixelFormat();

if ( pf != PixelFormatUndefined && ( ! IsExtendedPixelFormat( pf ) ) )
{
newImage = new Bitmap( nWidth, nHeight, ( pf == PixelFormat32bppRGB ? PixelFormat32bppPARGB : pf ) );

if ( pf == PixelFormat32bppRGB ) // AlphaBmp: Need to do additional work
....

by now there have been no trouble for it.
another solution is to put a exception for gif.

[Enrico Maria Giordano]

Any news?

EMG

[mastintin]

Nages and this solution?

Code: Select all  Expand view

.....

 int nWidth  = original->GetWidth()  ;
 int nHeight = original->GetHeight() ;

 PixelFormat pf ;
 
 if( strncmp( adr, "GIF", 3 ) != 0 )   // detect if file is a gif type.
       pf = original->GetPixelFormat();
  else
      pf = PixelFormat32bppPARGB ;
   
  Bitmap* newImage  = new Bitmap( nWidth, nHeight, pf ) ;

 Graphics * graphics = new Graphics( newImage );

.....

 

[nageswaragunupudi]

Mr Manuel

So your proposal is to force 32bppPARGB for GIFs.
Done it.

[Enrico Maria Giordano]

I'm ready to test it.

EMG

[mastintin]

Mr Manuel

So your proposal is to force 32bppPARGB for GIFs.
Done it.

yes.
another option ...
pass a new parameter that specifies that we want to use 32 bits

Code: Select all  Expand view

.......

PixelFormat pf ;
     pf = original->GetPixelFormat();
 
bool l32bpp = hb_parl( 2)  

  if (  ( strncmp( adr, "GIF", 3 ) == 0  )  &  ( l32bpp == TRUE )   )
            pf = PixelFormat32bppPARGB ;
   
  Bitmap* newImage  = new Bitmap( nWidth, nHeight, pf ) ;
........

 

[mastintin]

Enrico . For your test ...
https://dl.dropboxusercontent.com/u/132931/gdiplus.obj
Cheers.

[Enrico Maria Giordano]

Probably I'm doing something wrong but it doesn't work (GIFs are still bad rendered).

EMG