[DUG] Stringgrid

Fri Apr 21 16:17:38 NZST 2006

Its close to the truncation value from int64 to int32 that we see sometimes

From:	"John Bird" <johnkbird at paradise.net.nz>
To:	"'NZ Borland Developers Group - Delphi List'" <delphi at ns3.123.co.nz>
Subject:	[DUG] Stringgrid
Date sent:	Fri, 21 Apr 2006 15:27:17 +1200
Organization:	John Bird Consulting
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4661289

Anyone recognise that number? I am getting that when I pass a StringGrid 
to a utility routine as the value of the rowcount.
It should be zero or 1 in the example I am running.
Not surprisingly causes an access violation....

procedure xcClearGrid(PGrid:TStringGrid);
var
i,maxclear:integer;
begin
 maxclear:=PGrid.FixedRows;
 if Pgrid.rowcount>0 then maxclear:=PGrid.rowcount-
1;<======here
 for I := PGrid.FixedRows to maxclear do
 PGrid.Rows[i].Clear();
 PGrid.RowCount:=PGrid.FixedRows; //can only clearfrom there
end;

John Bird
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-----Original Message-----
From: delphi-bounces at ns3.123.co.nz [mailto:delphi-
bounces at ns3.123.co.nz] On Behalf Of Phil Middlemiss
Sent: Friday, 21 April 2006 8:37 a.m.
To: NZ Borland Developers Group - Delphi List
Subject: Re: [DUG] Image Magick examples

It's OK, I've worked it out. There is another set of routines to retrieve 
normalised colour values (0..1) and they match up with dividing the 
Word values by 65535 so I'm guessing it's to support graphic formats 
that have ability to store a 2bytes per pixel colour depth. Anyway, I'm 
using the normalised values now and it's all good.

The ImageMagick libraries seem very good at handling large graphic 
files without being processor intensive (although you need a lot of 
hard drive space). I'm adapting a TGraphic descendant that 
someone wrote a few years ago for an earlier version, to work with 
the latest version of ImageMagick (seems they reworked their 
architecture somewhat). If anyone else is interested then let me know 
and I'll make the code available when it's polished off.

Phil.

Paul A Norman wrote: 
Shouldn't, but is there a setting for the Colour Gamut?

On 21/04/06, Todd Martin <toddm at kol.co.nz> wrote: 
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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> Delphi at ns3.123.co.nz
> http://ns3.123.co.nz/mailman/listinfo/delphi
>
>
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