StartDecompress Method (original) (raw)
Summary
Initializes the buffered decompression engine.
Syntax
C#
Objective-C
C++/CLI
Java
Python
- (nullable NSObject *)startDecompress:(LTCodecsStartDecompressOptions *)decompressOptions error:(NSError **)error public Object startDecompress(CodecsStartDecompressOptions options) Parameters
options
Provides input parameters for the decompression process.
Return Value
An object that identifies the decompression process. This same object must be passed to the Decompress and StopDecompress methods.
Example
using Leadtools;
using Leadtools.Codecs;
using Leadtools.ImageProcessing;
using Leadtools.ImageProcessing.Color;
using Leadtools.Svg;
// This sample loads raw data from a PackBits TIF file
// PackBits.tif is a 24-bit tif packbits compressed file
// PackBits.tif has 46 strips of packbits data
// The strip information is obtained by reading the TIF tags TAG_STRIPOFFSETS and TAG_STRIPBYTECOUNTS
// The strips are directly read and fed to the Compress method
void LoadRawPackbitsStrips(string packTifFile)
{
RasterCodecs codecs = new RasterCodecs();
string destFileName = Path.Combine(LEAD_VARS.ImagesDir, "Decompress.bmp");
CodecsImageInfo imageInfo = codecs.GetInformation(packTifFile, false);
// StartDecompress
CodecsStartDecompressOptions options = CodecsStartDecompressOptions.Empty;
options.DataType = CodecsStartDecompressDataType.Strips;
options.Format = RasterImageFormat.RawPackBits;
options.Width = imageInfo.Width;
options.Height = imageInfo.Height;
options.BitsPerPixel = imageInfo.BitsPerPixel;
options.LeastSignificantBitFirst = false;
options.Pad4 = false;
options.PlanarConfiguration = CodecsPlanarConfiguration.PlanarFormat;
options.ViewPerspective = imageInfo.ViewPerspective;
options.RawOrder = imageInfo.Order;
options.LoadOrder = CodecsLoadByteOrder.BgrOrGray;
options.XResolution = imageInfo.XResolution;
options.YResolution = imageInfo.YResolution;
options.TiffPhotometricInterpretation = CodecsTiffPhotometricInterpretation.Rgb;
options.SetColorMask(options.GetColorMask());
options.SetPalette(options.GetPalette());
options.UsePalette = false;
object decompressObject = codecs.StartDecompress(options);
// Decompress
const int TAG_STRIPOFFSETS = 0x111;
const int TAG_STRIPBYTECOUNTS = 0x117;
const int TAG_ROWSPERSTRIP = 0x116;
const int MAX_STRIPS = 1000;
int[] stripOffsets = new int[MAX_STRIPS];
int[] stripSizes = new int[MAX_STRIPS];
int[] rowsPerStripBuffer = new int[1];
int maxIndex = ReadTag(codecs, packTifFile, TAG_STRIPOFFSETS, stripOffsets);
ReadTag(codecs, packTifFile, TAG_STRIPBYTECOUNTS, stripSizes);
ReadTag(codecs, packTifFile, TAG_ROWSPERSTRIP, rowsPerStripBuffer);
int rowsPerStrip = rowsPerStripBuffer[0];
FileStream fs = File.OpenRead(packTifFile);
const int row = 0; // Note: this parameter is ignored for strips
const int column = 0; // Column offset of tile
for (int index = 0; index < maxIndex; index++)
{
// seek to the first strip
fs.Seek(stripOffsets[index], SeekOrigin.Begin);
byte[] buffer = new byte[stripSizes[index]];
fs.Read(buffer, 0, buffer.Length);
// Calculate the height of uncompressed strip/tile
int height = rowsPerStrip;
if (index == (maxIndex - 1))
{
// fewer rows per strip
height = imageInfo.Height - (maxIndex - 1) * rowsPerStrip;
}
codecs.Decompress(
decompressObject,
buffer,
0,
buffer.Length,
imageInfo.Width,
height,
row,
column,
CodecsDecompressDataFlags.Complete);
}
fs.Close();
// StopDecompress
RasterImage image = codecs.StopDecompress(decompressObject);
// 'image' contains the uncompressed image
codecs.Save(image, destFileName, RasterImageFormat.Bmp, 24);
image.Dispose();
// Clean up
codecs.Dispose();
}
// Returns maximum index
int ReadTag(RasterCodecs codecs, string fileName, int tagId, int[] stripArray)
{
RasterTagMetadata tag = codecs.ReadTag(fileName, 1, tagId);
int[] data = tag.ToInt32();
data.CopyTo(stripArray, 0);
return tag.Count;
}
static class LEAD_VARS
{
public const string ImagesDir = @"C:\LEADTOOLS22\Resources\Images";
}
Leadtools.Codecs Assembly
CompactFile(Stream,Stream,int,int,bool,int,int,bool,int,CodecsSavePageMode,bool,bool) Method
CompactFile(Stream,Stream,int,int,bool,long,int,bool,long,CodecsSavePageMode,bool,bool,bool) Method
CompactFile(string,string,int,int,bool,int,int,bool,int,CodecsSavePageMode,bool,bool) Method
CompactFile(string,string,int,int,bool,long,int,bool,long,CodecsSavePageMode,bool,bool,bool) Method