iea has asked for the wisdom of the Perl Monks concerning the following question:

Hi,

i´m trying to use the CopyToGD function to "convert" a DIBitmap to a GD

Win32-GUI-DIBitmap

Here is what i've got.
use Win32::API;
use Win32::GUI::DIBitmap;
use GD;

$GetDC                 = new Win32::API('user32','GetDC',['N'],'N');

my $dc      = $GetDC->Call(0);
my $dib     = newFromDC Win32::GUI::DIBitmap ($dc);
my $width   = $dib->GetWidth() ;
my $height  = $dib->GetHeight() ;
my $GDimage = new GD::Image($w,$h);
$dib->CopyToGD($GDimage,$dib) ;

#do something with the gd object 
#....

open (DISPLAY, ">test.png");
binmode DISPLAY;
print DISPLAY $GDimage->png;
close (DISPLAY);

[download]

I keep getting the error:
gd-png:  fatal libpng error: Image width or height is zero in IHDR
gd-png error: setjmp returns error condition

Any ideas what i´m missing?
Thanks

Replies are listed 'Best First'.
Re: Convert DIBitmap to GD
by BrowserUk (Patriarch) on Apr 10, 2010 at 09:51 UTC

    I suspect it is this line causing the problem: 

    $dib->CopyToGD($GDimage,$dib);
........................^^^ 
## should be a boolean indicating whether 8-bit or 24-bit color.

    [download]
    Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
    "Science is about questioning the status quo. Questioning authority".
    In the absence of evidence, opinion is indistinguishable from prejudice.
[reply]
[d/l]
      Oh dear!
      Thanks

      Now the image is created and the error is gone, but the GD image stays black.
      use Win32::API;
use Win32::GUI::DIBitmap;
use GD;

$GetDC                 = new Win32::API('user32','GetDC',['N'],'N');

my $dc      = $GetDC->Call(0);
my $dib     = newFromDC Win32::GUI::DIBitmap ($dc);

$dib->SaveToFile("DIBitmap.png");

my $width   = $dib->GetWidth() ;
my $height  = $dib->GetHeight() ;
my $GDimage = new GD::Image($width,$height,1);
$dib->CopyToGD($GDimage,1) ;

#do something with the gd object 
#....

open (DISPLAY, ">GD.png");
binmode DISPLAY;
print DISPLAY $GDimage->png;
close (DISPLAY);

      [download]


      Thanks again
[reply]
[d/l]

        That seems to be a bug in the CopyToGD() method.

        It can load the png you write to disk without error.

        It can also successfully create a GD image from the data returned by the SaveToData() method: 

        use Win32::API;
use Win32::GUI::DIBitmap;
use GD;

$GetDC      = new Win32::API('user32','GetDC',['N'],'N');

my $dc      = $GetDC->Call(0);
my $dib     = newFromDC Win32::GUI::DIBitmap ($dc);

$dib->SaveToFile("DIBitmap.png");

#my $GDimage = GD::Image->newFromPng( "DIBitmap.png", 1 );

my $mem = $dib->SaveToData( Win32::GUI::DIBitmap::GetFIFFromFormat( 'P
+NG' ) );
my $GDimage = GD::Image->newFromPngData( $mem, 1 );

open (DISPLAY, ">GD.png");
binmode DISPLAY;
print DISPLAY $GDimage->png;
close (DISPLAY);

        [download]

        You should raise a bug report with the author.

        The problem probably stems from the mismatch between the version of the GDImageStruct used by DIBitmap & the version used by the latest GD incarnations: 

        Compare: (<)C:\test\GDstruct.gd (3146 bytes)
   with: (>)C:\test\GDstruct.dib (3124 bytes)

63,67c63
<     /* There should NEVER BE ACCESSOR MACROS FOR ITEMS BELOW HERE, s
+o this
<        part of the structure can be safely changed in new releases. 
+*/
< 
<     /* 2.0.12: anti-aliased globals. 2.0.26: just a few vestiges aft
+er
<       switching to the fast, memory-cheap implementation from PHP-gd
+. */
---
>     /* 2.0.12: anti-aliased globals */
71a67,78
>     unsigned char **AA_opacity;
>     int AA_polygon;
>     /* Stored and pre-computed variables for determining the perpend
+icular
>        distance from a point to the anti-aliased line being drawn: *
+/
>     int AAL_x1;
>     int AAL_y1;
>     int AAL_x2;
>     int AAL_y2;
>     int AAL_Bx_Ax;
>     int AAL_By_Ay;
>     int AAL_LAB_2;
>     float AAL_LAB;
79,82d87
< 
<     /* 2.1.0: allows to specify resolution in dpi */
<     unsigned int res_x;
<     unsigned int res_y;
84,85d88
<   
<

        [download]
        Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
        "Science is about questioning the status quo. Questioning authority".
        In the absence of evidence, opinion is indistinguishable from prejudice.
[reply]
[d/l]
[select]

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