[DUG] Image Magick examples

[Todd Martin]

Hi Phil

I've only just started looking at Image Magic myself. 
Try this :) 
You'll need to add a correction and a function declaration to 
"pixel_iterator.inc" as outlined below.

uses
  magick_wand, ImageMagick;

procedure DrawDiagonalLine(AInputFileName, AOutputFileName : AnsiString);
var
  Iterator : PPixelIterator;
  PixelWands : PPPixelWand;
  ImageWand : PMagickWand;
  Status : MagickBooleanType;
  RowIndex, WandCount : Cardinal;
begin
  Iterator := nil;
  ImageWand := nil;
  try
    ImageWand := NewMagickWand;
    status := MagickReadImage(ImageWand,PChar(AInputFileName));
    if (status = MagickTrue) then
    begin
      //use a pixel iterator to draw a diagonal line
      Iterator:=NewPixelIterator(ImageWand);
      if assigned(Iterator) then
      begin
        //return the next row as an array of pixel wands
        PixelWands:=PixelGetNextIteratorRow(Iterator,WandCount);
        RowIndex := 0;
        while assigned(PixelWands) do
        begin
          inc(PixelWands,RowIndex); //move to the pixel wand at column=row
          PixelSetColor(PixelWands^,'#224466');
          PixelSyncIterator(Iterator);
          PixelWands:=PixelGetNextIteratorRow(Iterator,WandCount);
          inc(RowIndex);
        end;
      end;

      MagickWriteImage(ImageWand,PChar(AOutputFileName));
    end;
  finally
    DestroyPixelIterator(Iterator);
    DestroyMagickWand(ImageWand);
  end;
end;

initialization
  MagickWandGenesis;

finalization
  MagickWandTerminus;


....and put the following in pixel_iterator.inc

//****correction*****
function NewPixelIterator(wand: PMagickWand): PPixelIterator; cdecl; external 
WandExport;

//****extra declaration****
function PixelGetNextIteratorRow(iterator: PPixeliterator; var columnCount : 
Cardinal) : PPPixelWand; cdecl; external WandExport;

I compiled this in Kylix. Let me know if you have any problems. 
Todd.

On Wednesday 19 Apr 2006 03:54, Phil Middlemiss wrote:
>  Yeah, I've got the source and looked through the API.
>
>  >From what I can see of the API though, it jumps straight down into the
>  > fine details of documenting each method and doesn't have anything that
>  > tells you "This is the general approach to use".
>
>  For example, I see that there is a routine called MagickSetFirstIterator
> (among other iteration routines) but nowhere does it describe the way to
> set up an iteration, or even what you are iterating. There is a pixel wand
> too (and a pixel iterator), but I can't find anything that describes the
> overall method of using them.
>
>  Have you got any examples (I don't care if they are not documented) that I
> could look at?
>
>  Cheers,
>  Phil.
>
>  Todd Martin wrote:
> Hi Phil
>
> Have you looked at the API documents?
> {myInstallDirectoryForImageMagic}/share/doc/ImageMagick-6.2.6/www/api
>
> Are you running Windows or Linux? Do you have the ImageMagic source or just
> a binary download?
>
> Todd.
>
> On Wednesday 19 Apr 2006 02:39, Phil Middlemiss wrote:
>
>
> Hi all,
>
> I'm trying to understand Image Magick - I have got the Lazerus headers
> and compiled and run the sample app listed on the wiki page for it. All
> fine.
>
> Now when it comes to actually working out how to use the thing I'm not
> sure how to go about it. The documentation is a little different from
> the actual Lazerus files, and even if it were the same it is lacking the
> whole "This is the overview/paradigm" section.
>
> What I really need is a good example that does more than just read in an
> image and save it to another format. Does anyone has some
> examples/documentation that they are willing to share?
>
> Cheers,
> Phil.
>
>
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