public static VirtualRasterHeader Create(CoordEnvelope coordEnvelope, float resolutionX, float resolutionY)
{
VirtualRasterHeader vr = new VirtualRasterHeader();
vr.CoordEnvelope = coordEnvelope;
vr.ResolutionX = resolutionX;
vr.ResolutionY = resolutionY;
vr.Width = RasterRectOffset.GetInteger(coordEnvelope.Width / resolutionX);
vr.Height = RasterRectOffset.GetInteger(coordEnvelope.Height / resolutionY);
return(vr);
}
/// <summary>
/// 修改日期2013年1月3日
/// 修改内容：
/// 取相交区域，
/// if (tWidth == intInSrc.Width && intInSrc.Height == tHeight)即分辨率一致时候，后面的读取参数偏移量应当使用前面修正后的toffsetx, toffsety
/// 应为toffsetx, toffsety可能和intInSrc.X，intInSrc.Y 有偏差（由于浮点运算的缘故）。
/// 读取数据
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="bandNo"></param>
/// <param name="vOffsetX"></param>
/// <param name="vOffsetY"></param>
/// <param name="vSizex"></param>
/// <param name="vSizey"></param>
/// <param name="nullValue">非相交区域数据填充值（默认为default(T)）</param>
/// <returns></returns>
public T[] ReadData <T>(int bandNo, int vOffsetX, int vOffsetY, int vSizex, int vSizey, T nullValue)
{
if (_bandMaps != null)
{
bandNo = _bandMaps[bandNo - 1];
}
if (vOffsetX < 0 || vOffsetY < 0 || vSizex > _vHeader.Width || vSizey > _vHeader.Height)
{
return(null);
}
GCHandle buffer = new GCHandle();
IntPtr bufferPtr;
try
{
T df = default(T);
Type type = df.GetType();
enumDataType dataType = GetDataTypeFrom(type);// _raster.DataType;
int dataTypeSize = Marshal.SizeOf(type);
T[] vBufferData = null;
//计算当前分块的位置
RasterRectOffset offset = _inOffset.Offset(vOffsetX, vOffsetY, vSizex, vSizey);
Rectangle rectDst = offset.rectDst;
Rectangle srcInDst = offset.srcInDst;
Rectangle intInSrc = offset.intInSrc;
Rectangle intInDst = offset.intInDst;
vBufferData = new T[intInDst.Width * intInDst.Height];
buffer = GetHandles(vBufferData);
bufferPtr = buffer.AddrOfPinnedObject();
//获取相交区域的数据
int toffsetx = RasterRectOffset.GetInteger(intInSrc.X / offset.ResolutionXScale);
int toffsety = RasterRectOffset.GetInteger(intInSrc.Y / offset.ResolutionYScale);
#region by chennan 20140812 分辨率不同，切块剩余行数小于分辨率放大倍数时，误判断为不相交
if (intInSrc.Width == 0 || intInSrc.Height == 0)//当前分块不相交，造成无数据
{
return(null);
}
int tWidth = RasterRectOffset.GetWHInteger(intInSrc.Width / offset.ResolutionXScale);
int tHeight = RasterRectOffset.GetWHInteger(intInSrc.Height / offset.ResolutionYScale);
//int tWidth = RasterRectOffset.GetInteger(intInSrc.Width / offset.ResolutionXScale);
//int tHeight = RasterRectOffset.GetInteger(intInSrc.Height / offset.ResolutionYScale);
//if (tWidth == 0 || tHeight == 0)//当前分块不相交，造成无数据
// return null;
#endregion
if (tWidth + toffsetx > _raster.Width)
{
tWidth = _raster.Width - toffsetx;
}
if (tHeight + toffsety > _raster.Height)
{
tHeight = _raster.Height - toffsety;
}
_raster.GetRasterBand(bandNo).Read(toffsetx, toffsety, tWidth, tHeight, bufferPtr, dataType, intInSrc.Width, intInSrc.Height);
//如果相交区域即是目标区域
if (intInDst == rectDst)
{
return(vBufferData);
}
else//按行列填充目标区域
{
int readH = intInDst.Height;
int readW = intInDst.Width;
int padLeft = intInDst.Left;
int padRight = (vSizey + vOffsetY) - intInDst.Right;
int topOffset = intInDst.Top - rectDst.Top;
T[] tdata = new T[vSizex * vSizey];
if (!nullValue.Equals(df))
{
for (int i = 0; i < vSizex * vSizey; i++)
{
tdata[i] = nullValue;
}
}
for (int readLine = 0; readLine < readH; readLine++)//按行拷贝
{
int srcOffset = readLine * readW;
int dstOffset = (topOffset + readLine) * vSizex + padLeft;
Array.Copy(vBufferData, srcOffset, tdata, dstOffset, readW);
}
return(tdata);
}
}
finally
{
if (buffer.IsAllocated)
{
buffer.Free();
}
}
}
