fcl-image

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Introduction

FCL-Image started life as "fpimage", pretty much as an attempt to implement a generally portable TImage like class, without the deep win32 and VCL ties.

Current file list

The central units are fpimage and fpcanvas and these are further enhanced by OOP derivation.

• bmpcomn A few structures and constants for the BMP fileformat
• clipping Some utility routines that help with clipping and intersecting of rects.
• ellipses Drawing of ellipses and arcs, and filling ellipses and pies.
  • TEllipseInfo
• extinterpolation interpolation filters for TFPCanvas.StretchDraw (
  • TBlackmanInterpolation
  • TBlackmanSincInterpolation
  • TBlackmanBesselInterpolation
  • TGaussianInterpolation
  • TBoxInterpolation
  • THermiteInterpolation
  • TLanczosInterpolation
  • TQuadraticInterpolation
  • TCubicInterpolation
  • TCatromInterpolation
  • TBilineairInterpolation
  • THanningInterpolation
  • THammingInterpolation
• fpcanvas Generic Canvas classes.
  • TFPCanvasException
  • TFPPenException
  • TFPBrushException
  • TFPFontException
  • TFPCustomCanvas
  • TFPCanvasHelper
  • TFPCustomFont
  • TFPCustomFontClass
  • TFPCustomPen
  • TFPCustomPenClass
  • TFPCustomBrush
  • TFPCustomBrushClass
  • TFPCustomInterpolation
  • TFPBaseInterpolation
  • TMitchelInterpolation
  • TFPCustomCanvas
  • TFPCustomDrawFont
  • TFPEmptyFont
  • TFPCustomDrawPen
  • TFPEmptyPen
  • TFPCustomDrawBrush
  • TFPEmptyBrush
• fpcolhash an implementation of a color hash table.
  • TFPColorHashException
  • TFPColorHashTable
• fpditherer contains classes used to dither images.
  • FPDithererException
  • TFPBaseDitherer
  • TFPFloydSteinbergDitherer
• fpimage fpImage base definitions and classes
  • TFPCustomImageReader
  • TFPCustomImageWriter
  • TFPCustomImage
  • FPImageException
  • TFPPalette
  • TFPCustomImage
  • TFPMemoryImage
  • TFPCustomImageHandler
  • TFPCustomImageReader
  • TFPCustomImageWriter
  • TIHData
  • TImageHandlersManager
• fpimgcanv Image Canvas - canvas which draws on an image.
  • TFPImageCanvas
• fpimgcmn Image Common: small procedural Helpers (swap,crc)
• fppixlcanv
  • TPixelCanvas
• fpquantizer classes used to quantize images.
• freetype Encapsulating classes over freetype
• freetypeh Freetype header translation
• ftfont More freetype related font classes
• pcxcomn PCX fileformat records and types
• pixtools Pixel drawing routines.
• pngcomn PNG fileformat records and types
• pscanvas TPostScriptCanvas implementation.
• targacmn Targa fileformat records and types

Readers and writers for various image formats

• fpreadbmp
• fpreadjpeg
• fpreadpcx
• fpreadpng
• fpreadpnm
• fpreadtga
• fpreadxpm
• fpwritebmp
• fpwritejpeg
• fpwritepcx
• fpwritepng
• fpwritepnm
• fpwritetga
• fpwritexpm

INC files uses in fpcanvas

• fpbrush
• fpcanvas
• fpcdrawh
• fpfont
• fphelper
• fpinterpolation
• fppen

INC files uses in fpmake

• fpcolors
• fpimage
• fphandler
• fpcolcnv
• fppalette

Demoes

• drawing
• imgconv

Known Issues and limitations

• fcl-image is written for maximal portability and maintainability and is quite slow. The main storage type is 16-bit RGBA, storing always 64-bit per pixel, and a function is called to get each pixel.
• pngwriter doesn't implement automatic detection of filters, and thus is always "filter none"

Walk-through

Basic Canvas Setup

You'll need a few things to start up. A canvas, image, and writer. The writer is to write images like PNG. The sample below will give you a 100x100 black png.

{$mode objfpc}{$h+}
program demo;
 
uses classes, sysutils,
     FPImage, FPCanvas, FPImgCanv,
     FPWritePNG;
 
var canvas : TFPCustomCanvas;
    image : TFPCustomImage;
    writer : TFPCustomImageWriter;
begin
  { Create an image 100x100 pixels}
  image := TFPMemoryImage.Create (100,100);
  
  { Attach the image to the canvas }
  Canvas := TFPImageCanvas.Create (image);
  
  { Create the writer }
  Writer := TFPWriterPNG.Create;
  
  { Save to file }
  image.SaveToFile ('DrawTest.png', writer);
  
  { Clean up! }
  Canvas.Free;
  image.Free;
  writer.Free;
end.

Drawing a Circle

Drawing a circle requires a bit more then just giving a width. You'll need to setup the pen style, mode, width, and color to do this. FCL-Image comes with a few pen modes and styles, it will really be up to you to decide which you'll need. Its best for now to try with a few modes and styles to get a better understanding of what FCL-Image can do.

{$mode objfpc}{$h+}
program demo;
 
uses classes, sysutils,
     FPImage, FPCanvas, FPImgCanv,
     FPWritePNG;
 
var canvas : TFPcustomCanvas;
    image : TFPCustomImage;
    writer : TFPCustomImageWriter;
    { 
      Colors range from 0 to 65535 in each primary color. 
      They can also show as hexideciaml:
      $FFFF = 65535, $0000 = 0 
    }
    passionRed: TFPColor = (Red: 65535; Green: 0; Blue: 0; Alpha: 65535);
begin
  image := TFPMemoryImage.Create (100,100);
  Canvas := TFPImageCanvas.Create (image);
  Writer := TFPWriterPNG.Create;

  { Set the pen styles }
  with canvas do
  begin
    pen.mode    := pmCopy;
    pen.style   := psSolid;
    pen.width   := 1;
    pen.FPColor := passionRed;
  end;

  { Draw a circle }
  canvas.Ellipse (10,10, 90,90);
  
  { Save to file }
  image.SaveToFile ('DrawTest.png', writer);
  
  { Clean up! }
  Canvas.Free;
  image.Free;
  writer.Free;
end.

Pen Modes

The pen mode is how the pixel drawn will react to the pixels beneath it. So if its a white pixel and you draw a red pixel over it with the mode of pmXor then you'll get a vibrate blue pixel.

• pmBlack
• pmWhite
• pmNop
• pmNot
• pmCopy
• pmNotCopy
• pmMergePenNot
• pmMaskPenNot
• pmMergeNotPen
• pmMaskNotPen
• pmMerge
• pmNotMerge
• pmMask
• pmNotMask
• pmXor
• pmNotXor

Pen Styles

• psSolid
• psDash
• psDot
• psDashDot
• psDashDotDot
• psinsideFrame
• psPattern
• psClear

Drawing text

Here is an example, how to create a 200x100 image, painting a white background and some text and saving it as .png: <Delphi> program fontdraw;

{$mode objfpc}{$H+}

uses

 Classes, SysUtils, FPimage, FPImgCanv, ftfont, FPWritePNG, FPCanvas;

procedure TestFPImgFont; var

 Img: TFPMemoryImage;
 Writer: TFPWriterPNG;
 ms: TMemoryStream;
 ImgCanvas: TFPImageCanvas;
 fs: TFileStream;
 AFont: TFreeTypeFont;

begin

 Img:=nil;
 ImgCanvas:=nil;
 Writer:=nil;
 ms:=nil;
 fs:=nil;
 AFont:=nil;
 try
   // initialize free type font manager
   ftfont.InitEngine;
   FontMgr.SearchPath:='/usr/share/fonts/truetype/ttf-dejavu/';
   AFont:=TFreeTypeFont.Create;

   // create an image of width 200, height 100
   Img:=TFPMemoryImage.Create(200,100);
   Img.UsePalette:=false;
   // create the canvas with the drawing operations
   ImgCanvas:=TFPImageCanvas.create(Img);

   // paint white background
   ImgCanvas.Brush.FPColor:=colWhite;
   ImgCanvas.Brush.Style:=bsSolid;
   ImgCanvas.Rectangle(0,0,Img.Width,Img.Height);

   // paint text
   ImgCanvas.Font:=AFont;
   ImgCanvas.Font.Name:='DejaVuSans';
   ImgCanvas.Font.Size:=20;
   ImgCanvas.TextOut(10,30,'Test');

   // write image as png to memory stream
   Writer:=TFPWriterPNG.create;
   ms:=TMemoryStream.Create;
   writer.ImageWrite(ms,Img);
   // write memory stream to file
   ms.Position:=0;
   fs:=TFileStream.Create('testfont.png',fmCreate);
   fs.CopyFrom(ms,ms.Size);
 finally
   AFont.Free;
   ms.Free;
   Writer.Free;
   ImgCanvas.Free;
   Img.Free;
   fs.Free;
 end;

end;

begin

 TestFPImgFont;

end. </Delphi>

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