[Boost-users] [gil] Using gil with windows bitmaps

Subject: [Boost-users] [gil] Using gil with windows bitmaps
From: Dan Bloomquist (danb_at_[hidden])
Date: 2011-11-10 13:26:30

Hi,
Yesterday I went on a bend to understand memory images, so far I've just 
taken them for granted. I have a situation where I need to resample 
photos at print time. If a client uses their 37 gigapixel camera and I 
print that to pdf it bloats the size of the pdf so as they can't email 
them. My old hack was with GDI+, code I barely understood. So I've 
gotten to the code below and for all I know it is not a good start, but 
it works. With gil I could do more like crop and rotate without 
modifying the source image.

Right now I'm at a loss as to how to attach a bitmap to a gil view. 
(Over ride the allocator?) In my test I've got two extra memcpy calls I 
should not have to do. I'd like to use gil directly on the windows 
bitmap memory.

BTW, that one hour flash at Adobe was great. Now I want to 'Gilify' my code.
Note HEImage::g_image is a rgb8_image_t;

HBITMAP test_gil( HBITMAP hBitmap )
{
     DIBSECTION d;

     //testing, assume rgb8_image_t in object
     int nBytes = ::GetObject( hBitmap, sizeof( DIBSECTION ), &d );
     HEImage image( d.dsBm.bmWidth, d.dsBm.bmHeight );//, d.dsBm.bmBits, 
0 ); should just be able to attach bits
     memcpy( &image.g_image._view[ 0 ], d.dsBm.bmBits, 
d.dsBmih.biSizeImage );
    //gil::jpeg_read_image( 
"C:\\cpp\\HE_9\\jpeg-8c\\GIL_test\\In\\IMG_0006.JPG", image.g_image );

     HEImage image2( d.dsBm.bmWidth, d.dsBm.bmHeight );
     //testing, just flip image...
     gil::copy_pixels( gil::rotated180_view( image.g_image._view ), 
image2.g_image._view );

     BITMAPINFO bi24BitInfo; //testing, populate to match rgb8_image_t
     memset( &bi24BitInfo, 0, sizeof( BITMAPINFO ) );
     bi24BitInfo.bmiHeader.biSize = sizeof(bi24BitInfo.bmiHeader);
     bi24BitInfo.bmiHeader.biBitCount = 24; // rgb 8 bytes for each 
component(3)
     bi24BitInfo.bmiHeader.biCompression = BI_RGB;// rgb = 3 components
     bi24BitInfo.bmiHeader.biPlanes = 1;
     bi24BitInfo.bmiHeader.biWidth = d.dsBm.bmWidth;
     bi24BitInfo.bmiHeader.biHeight = d.dsBm.bmHeight;

     HBITMAP oBitmap = ::CreateDIBSection( NULL, &bi24BitInfo, 
DIB_RGB_COLORS, 0, 0, 0 );

     nBytes = ::GetObject( oBitmap, sizeof( DIBSECTION ), &d );

     memcpy( d.dsBm.bmBits, &image2.g_image._view[ 0 ], 
d.dsBmih.biSizeImage );

     return oBitmap;
}

In test used like:
                 bResamplePhoto= true; //TODO testing....
                 if( bResamplePhoto )
                 {
                     for( size_t i= 0; i < photoWnd.size( ); ++i )
                     {
                         HBITMAP hB= test_gil( photoWnd.at( i ) );
                         photoWnd.at( i ).Destroy( );
                         photoWnd.at( i ).Attach( hB );
                     }
                 }