ImageResizer.Plugins.AnimatedGifs.GifCreator Class Reference

Provides methods for creating application and graphics blocks needed to write a animated Gif. More...

Static Public Member Functions
static void	CreateAnimatedGif (List< string > gifFiles, int delay, string outputFile)
static byte[]	CreateGraphicControlExtensionBlock (int delay)
	Written before each frame - specifies the frame's delay and the index of the transparent color (0) More...
static byte[]	CreateGraphicControlExtensionBlock (int delay, byte transparentColorIndex)
	Written before each frame - specifies the frame's delay and the index of the transparent color More...
static byte[]	CreateLoopBlock ()
	Creates a Loop Block (Netscape appliation extension) for infinite looping. Written after the last frame's image data More...
static byte[]	CreateLoopBlock (int numberOfRepeatings)
	Creates a Loop block for the specified number of repeats. Written after the last frame's image data. Do NOT call this if numberOfRepeatings=1. IE and FF < 3 (incorrectly) loop infinitely when loops=1. Simply omit the extension in that case. More...

Detailed Description

Provides methods for creating application and graphics blocks needed to write a animated Gif.

Definition at line 22 of file GifCreator.cs.

Member Function Documentation

static byte [] ImageResizer.Plugins.AnimatedGifs.GifCreator.CreateGraphicControlExtensionBlock ( int  delay )

inlinestatic

Written before each frame - specifies the frame's delay and the index of the transparent color (0)

Parameters

delay

Returns

Definition at line 49 of file GifCreator.cs.

        {
            return CreateGraphicControlExtensionBlock(delay, 0);
        }

static byte [] ImageResizer.Plugins.AnimatedGifs.GifCreator.CreateGraphicControlExtensionBlock ( int  delay, byte  transparentColorIndex  )

inlinestatic

Written before each frame - specifies the frame's delay and the index of the transparent color

Parameters

delay
transparentColorIndex

Returns

Definition at line 59 of file GifCreator.cs.

        {
            /*320:   21 F9 04                Graphic Control Extension frame #1
            323:   08                       - no transparency
            324:   09 00                    - 0.09 sec duration
            325:   00                       - no transparent color
            327:   00                       - end
            */
            byte[] result = new byte[8];
          
    
            result[0] = (byte)0x21; // Start ExtensionBlock
            result[1] = (byte)0xF9; // GraphicControlExtension
            result[2] = (byte)0x04; // Size of DataBlock (4)
            // 1 enables transparency
            // 8 clears to bgcolor after each frame.
            // 25 (8 + 16) = restore to previous data (doesn't work in FF)
            result[3] = 9; //Tansparent, clear to bgcolor (works good for transparent animaions

            // Split the delay into high- and lowbyte
            result[4] = (byte)(delay % 256); //Duration - lsb
            result[5] = (byte)(delay / 256); //msb
            result[6] = transparentColorIndex; //Transparent color - only if transparency bit set.
            result[7] = (byte)0x00; //end
            return result;
        }

static byte [] ImageResizer.Plugins.AnimatedGifs.GifCreator.CreateLoopBlock ( )

inlinestatic

Creates a Loop Block (Netscape appliation extension) for infinite looping. Written after the last frame's image data

Returns

Definition at line 89 of file GifCreator.cs.

        { return CreateLoopBlock(0); }

static byte [] ImageResizer.Plugins.AnimatedGifs.GifCreator.CreateLoopBlock ( int  numberOfRepeatings )

inlinestatic

Creates a Loop block for the specified number of repeats. Written after the last frame's image data. Do NOT call this if numberOfRepeatings=1. IE and FF < 3 (incorrectly) loop infinitely when loops=1. Simply omit the extension in that case.

Parameters

numberOfRepeatings

Returns

Definition at line 97 of file GifCreator.cs.

        {
            //http://www.let.rug.nl/kleiweg/gif/netscape.html
            /*30D:   21 FF 0B                Application Extension
            310:   4E 45 54
                   53 43 41
                   50 45 32
                   2E 30        NETSCAPE2.0
            31B:   03 01                    - data follows
            31D:   FF FF                    - loop animation
            31F:   00                       - end
            */
            byte rep1 = (byte)(numberOfRepeatings % 256);
            byte rep2 = (byte)(numberOfRepeatings / 256);
            byte[] result = new byte[19];
            result[0] = (byte)0x21; // Start ExtensionBlock
            result[1] = (byte)0xFF; // ApplicationExtension
            result[2] = (byte)0x0B; // Size of DataBlock (11) for NETSCAPE2.0)
            result[3] = (byte)'N';
            result[4] = (byte)'E';
            result[5] = (byte)'T';
            result[6] = (byte)'S';
            result[7] = (byte)'C';
            result[8] = (byte)'A';
            result[9] = (byte)'P';
            result[10] = (byte)'E';
            result[11] = (byte)'2';
            result[12] = (byte)'.';
            result[13] = (byte)'0';
            result[14] = (byte)0x03; // Size of Loop Block
            result[15] = (byte)0x01; // Loop Indicator
            result[16] = (byte)rep1; // Number of repetitions
            result[17] = (byte)rep2; // 0 for endless loop
            result[18] = (byte)0x00;
            return result;
        }

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The documentation for this class was generated from the following file:

• C:/Users/nathanael/Documents/resizer/Plugins/AnimatedGifs/GifCreator.cs