[DUG] Image Magick examples

[Todd Martin]

Do you ever get values > 255?

Todd.

On Wednesday 19 Apr 2006 21:42, Phil Middlemiss wrote:
>  Thanks for the example Todd - yeah, that's compiling and seems to be
> running fine. There are no reported memory leaks around the pixel wands
> either.
>
>  One question though: the PixelPacket contains *Word* values for red,
> green, blue, and opacity. How do I interpret values greater than 255?
>
>  Cheers,
>  Phil.
>
>  Todd Martin wrote:
> 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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