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85 lines
2.3 KiB
ObjectPascal
85 lines
2.3 KiB
ObjectPascal
{
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Demonstration program for the ImageMagick Library
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Usage: Just execute the program. It will change all black pixels
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in the image.png image on it's directory to be transparent
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and then it will save it as image2.png
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The idea is to demonstrate pixel access using MagickWand.
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}
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program wandpixelaccess;
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{$mode objfpc}{$H+}
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uses SysUtils, magick_wand, ImageMagick, ctypes;
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procedure ThrowWandException(wand: PMagickWand);
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var
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description: PChar;
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severity: ExceptionType;
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begin
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description := MagickGetException(wand, @severity);
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WriteLn(Format('An error ocurred. Description: %s', [description]));
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description := MagickRelinquishMemory(description);
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Abort;
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end;
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var
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status: MagickBooleanType;
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wand: PMagickWand = nil;
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pixel: MagickPixelPacket;
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iterator: PPixelIterator;
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pixels: PPPixelWand = nil;
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x, y: Integer;
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width: culong;
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begin
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{ Read an image. }
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MagickWandGenesis;
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wand := NewMagickWand();
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try
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status := MagickReadImage(wand, 'image.png');
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if (status = MagickFalse) then ThrowWandException(wand);
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iterator := NewPixelIterator(wand);
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if (iterator = nil) then ThrowWandException(wand);
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for y := 0 to MagickGetImageHeight(wand) - 1 do
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begin
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// WriteLn(' Line ', y, ' from ', MagickGetImageHeight(wand) - 1);
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pixels := PixelGetNextIteratorRow(iterator, width);
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if (pixels = nil) then Break;
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for x := 0 to width - 1 do
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begin
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// WriteLn(Format(' x %d y %d r %f g %f b %f o %f',
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// [x, y, pixel.red, pixel.green, pixel.blue, pixel.opacity]));
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PixelGetMagickColor(pixels[x], @pixel);
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if (pixel.red = 0.0) and
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(pixel.green = 0.0) and
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(pixel.blue = 0.0) then
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begin
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pixel.opacity := QuantumRange;
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pixel.matte := QuantumRange; // matte=alpha
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end;
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PixelSetMagickColor(pixels[x], @pixel);
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end;
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PixelSyncIterator(iterator);
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end;
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// if y < MagickGetImageHeight(wand) then ThrowWandException(wand);
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iterator := DestroyPixelIterator(iterator);
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{ Write the image }
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status := MagickWriteImage(wand, 'image2.png');
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if (status = MagickFalse) then ThrowWandException(wand);
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finally
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{ Clean-up }
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if wand <> nil then wand := DestroyMagickWand(wand);
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MagickWandTerminus;
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end;
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end.
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