RWFlag mode; // file open mode: Read or Write
/// <summary>
/// Create a file given specs
/// </summary>
public ErdasImageFile(string filename,
Dimensions dimensions,
int bandCount,
System.TypeCode bandType,
IMetadata metadata)
{
// set instance variables
this.open = false;
this.mode = RWFlag.Write;
this.dimensions = dimensions;
this.bandType = bandType;
this.bandCount = bandCount;
this.currPixel = 0;
this.totalPixels = dimensions.Rows * dimensions.Columns;
this.metadata = metadata;
// if filename does not end in .gis or .lan throw exception
string extension = Path.GetExtension(filename).ToLower();
if (!(extension.Equals(".gis")) && !(extension.Equals(".lan")))
{
throw new System.ApplicationException("Erdas file must have either GIS or LAN as extension");
}
// if dimensions are messed up throw exception
if ((dimensions.Rows < 1) || (dimensions.Columns < 1))
{
throw new System.ApplicationException("Erdas file given invalid dimensions");
}
// if bandCount messed up throw exception
if ((bandCount < 1) || (bandCount > 0xffff))
{
throw new System.ApplicationException("Erdas file given invalid band count");
}
// more bandCount checking
if (extension.Equals(".gis"))
{
if (bandCount > 1)
{
throw new System.ApplicationException("Erdas GIS files cannot support multiband images");
}
if (bandType != System.TypeCode.Byte)
{
throw new System.ApplicationException("Erdas GIS files only suupport byte for bandtype");
}
}
// if bandType not System.Byte or System.UInt16 throw exception
if (bandType == System.TypeCode.Byte)
{
this.bandSize = 1;
}
else if (bandType == System.TypeCode.UInt16)
{
this.bandSize = 2;
}
else
{
throw new System.ApplicationException("Erdas file given unsupported band type");
}
// open file for writing
this.file = new FileStream(filename, FileMode.OpenOrCreate);
this.fileWriter = new BinaryWriter(this.file);
this.open = true;
// write header (using metadata whenever possible)
try
{
// sentinel
byte[] sentinel = new byte[6];
sentinel[0] = (byte)'H';
sentinel[1] = (byte)'E';
sentinel[2] = (byte)'A';
sentinel[3] = (byte)'D';
sentinel[4] = (byte)'7';
sentinel[5] = (byte)'4';
this.fileWriter.Write(sentinel);
// packing
System.UInt16 ipack;
if (bandType == System.TypeCode.Byte)
{
ipack = 0;
}
else
{
ipack = 2;
}
this.fileWriter.Write(ipack);
// nbands
System.UInt16 nbands = (System.UInt16)bandCount;
this.fileWriter.Write(nbands);
// unused
for (int i = 0; i < 6; i++)
{
this.fileWriter.Write((byte)0);
}
// icols
System.UInt32 icols = (System.UInt32)dimensions.Columns;
this.fileWriter.Write(icols);
// irows
System.UInt32 irows = (System.UInt32)dimensions.Rows;
this.fileWriter.Write(irows);
// xstart
System.Int32 xstart = 0;
if ((metadata != null) &&
(metadata.TryGetValue <System.Int32>(RASTER_ULX, ref xstart)))
{
}
this.fileWriter.Write(xstart);
// ystart
System.Int32 ystart = 0;
if ((metadata != null) &&
(metadata.TryGetValue <System.Int32>(RASTER_ULY, ref ystart)))
{
}
this.fileWriter.Write(ystart);
// unused
for (int i = 0; i < 56; i++)
{
this.fileWriter.Write((byte)0);
}
// maptyp
System.UInt16 maptyp = 99; // 99 means NONE
string projection = null;
if ((metadata != null) &&
(metadata.TryGetValue <string>(PROJECTION, ref projection)))
{
int projNum = Projections.find(projection);
if (projNum != -1)
{
maptyp = (System.UInt16)projNum;
}
}
this.fileWriter.Write(maptyp);
// nclass : calc if needed but never has been in past
System.UInt16 nclass = 0;
this.fileWriter.Write(nclass);
// unused
for (int i = 0; i < 14; i++)
{
this.fileWriter.Write((byte)0);
}
// iautyp : first need xcell and ycell and then acre
System.Single xcell = 0;
if ((metadata != null) &&
(metadata.TryGetValue <System.Single>(X_SCALE, ref xcell)))
{
}
if (maptyp == 99)
{
xcell = 0;
}
System.Single ycell = 0;
if ((metadata != null) &&
(metadata.TryGetValue <System.Single>(Y_SCALE, ref ycell)))
{
}
if (maptyp == 99)
{
ycell = 0;
}
System.UInt16 iautyp = 0;
System.Single acre = 0;
switch (maptyp) // iautyp depends upon maptyp indirectly
{
case 0: // Lat/Long -> dist unit == degrees
iautyp = 0; // default to no area unit
break;
case 2: // State Plane -> dist unit == feet
iautyp = 1; // default to acres
acre = xcell * ycell;
// acre = sq.feet at this pt
// so now convert to acres
acre = (float)((double)acre * 0.0000229568411386593);
break;
default: // dist unit == meters
iautyp = 2; // default to hectares
acre = xcell * ycell;
// acre = sq.meters at this pt
// so now convert to hectares
acre *= 0.0001f;
break;
}
this.fileWriter.Write(iautyp);
// acre
this.fileWriter.Write(acre);
// xmap
System.Single xmap = 0;
if ((metadata != null) &&
(metadata.TryGetValue <System.Single>(WORLD_ULX, ref xmap)))
{
}
this.fileWriter.Write(xmap);
// ymap
System.Single ymap = 0;
if ((metadata != null) &&
(metadata.TryGetValue <System.Single>(WORLD_ULY, ref ymap)))
{
}
this.fileWriter.Write(ymap);
// xcell
this.fileWriter.Write(xcell);
// ycell
this.fileWriter.Write(ycell);
// now create pixel data as zeroes for now
// many nested for loops avoids index calc overflows
for (int row = 0; row < dimensions.Rows; row++)
{
for (int bandNum = 0; bandNum < this.bandCount; bandNum++)
{
for (int col = 0; col < dimensions.Columns; col++)
{
for (int byteNum = 0; byteNum < this.bandSize; byteNum++)
{
this.fileWriter.Write((byte)0);
}
}
}
}
}
catch (System.Exception)
{
Close();
throw;
}
}
/// <summary>
/// Open an existing file
/// </summary>
public ErdasImageFile(string filename, RWFlag mode)
{
this.open = false;
this.mode = mode;
// if filename does not end in .gis or .lan throw exception
string extension = Path.GetExtension(filename).ToLower();
if (!(extension.Equals(".gis")) && !(extension.Equals(".lan")))
{
throw new System.ApplicationException("Erdas file must have either GIS or LAN as extension");
}
// open file
this.file = new FileStream(filename, FileMode.Open);
this.fileReader = new BinaryReader(this.file);
this.open = true;
try
{
// prepare to build metadata while reading
Metadata metadata = new Metadata();
// Read Header
// if not start with "HEAD74" throw exception
byte[] sentinel = fileReader.ReadBytes(6);
if ((sentinel[0] != (byte)'H') ||
(sentinel[1] != (byte)'E') ||
(sentinel[2] != (byte)'A') ||
(sentinel[3] != (byte)'D') ||
(sentinel[4] != (byte)'7') ||
(sentinel[5] != (byte)'4'))
{
throw new System.ApplicationException(filename + " is not an ERDAS 7.4 compatible image file");
}
// packing
System.UInt16 ipack = this.fileReader.ReadUInt16();
if ((ipack != 0) && (ipack != 2))
{
throw new System.ApplicationException("Only 8 and 16 bit bands are supported by Erdas reader");
}
// nbands
System.UInt16 nbands = this.fileReader.ReadUInt16();
// unused
byte[] unused = this.fileReader.ReadBytes(6);
// icols
System.UInt32 icols = this.fileReader.ReadUInt32();
// irows
System.UInt32 irows = this.fileReader.ReadUInt32();
// xstart
System.Int32 xstart = this.fileReader.ReadInt32();
metadata[RASTER_ULX] = xstart;
// ystart
System.Int32 ystart = this.fileReader.ReadInt32();
metadata[RASTER_ULY] = ystart;
// unused
unused = this.fileReader.ReadBytes(56);
// maptyp
System.UInt16 maptyp = this.fileReader.ReadUInt16();
string projection = Projections.find(maptyp);
if (projection != null)
{
metadata[PROJECTION] = projection;
}
if (maptyp == 0)
{
metadata[SCALE_UNITS] = "degrees";
}
else if (maptyp == 2)
{
metadata[SCALE_UNITS] = "feet";
}
else
{
metadata[SCALE_UNITS] = "meters";
}
// nclass : calc if needed but never has been in past
System.UInt16 nclass = this.fileReader.ReadUInt16();
// unused
unused = this.fileReader.ReadBytes(14);
// iautyp
System.UInt16 iautyp = this.fileReader.ReadUInt16();
// acre
System.Single acre = this.fileReader.ReadSingle();
// xmap
System.Single xmap = this.fileReader.ReadSingle();
metadata[WORLD_ULX] = xmap;
// ymap
System.Single ymap = this.fileReader.ReadSingle();
metadata[WORLD_ULY] = ymap;
// xcell
System.Single xcell = this.fileReader.ReadSingle();
metadata[X_SCALE] = xcell;
// ycell
System.Single ycell = this.fileReader.ReadSingle();
metadata[Y_SCALE] = ycell;
// construct instance variables based upon hedaer info
this.dimensions = new Dimensions((int)irows, (int)icols);
if (ipack == 0)
{
this.bandType = System.TypeCode.Byte;
this.bandSize = 1;
}
else // ipack == 2 due to earlier screening
{
this.bandType = System.TypeCode.UInt16;
this.bandSize = 2;
}
this.bandCount = nbands;
this.currPixel = 0;
this.totalPixels = (int)irows * (int)icols;
this.metadata = metadata;
if (mode == RWFlag.Write)
{
this.fileReader.Close();
this.fileReader = null;
// need to reopen stream - fileReader.Close() shuts it
this.file = new FileStream(filename, FileMode.Open);
this.fileWriter = new BinaryWriter(this.file);
}
}
catch (System.Exception)
{
Close();
throw;
}
}