c# - How to read image inside (as a part of) a stream? -

i have files structure

+-------------+-------------+---------------+---------+-------------+ | img1_offset | img1_length |  custom info  | image 1 |   image 2   | +-------------+-------------+---------------+---------+-------------+ 

now want read image 1 image control. 1 possible way open file in stream (filestream), copy image 1 part other stream (i1_stream) read image i1_stream. code i'm using:

using (filestream filestream = new filestream(path, filemode.open, fileaccess.read)) {     using (memorystream i1_stream = new memorystream())     {         filestream.seek(500, seekorigin.begin); // i1_offset         filestream.copyto(i1_stream, 30000); // i1_length          var bitmap = new bitmapimage();         bitmap.begininit();         bitmap.cacheoption = bitmapcacheoption.onload;         bitmap.streamsource = i1_stream;         bitmap.endinit();         return bitmap;     } } 

because need open many file @ 1 time (ie. load 50 images 50 files wrappanel), think better if can read image 1 directly filestream. how can that? thank!

first, should read array of image bytes input stream. copy new bitmap:

var imagewidth = 640; // read value image metadata stream part var imageheight = 480 // same width var bytes = stream.read(..) // array length must width * height  using (var image = new bitmap(imagewidth, imageheight)) {     var bitmapdata = image.lockbits(new rectangle(0, 0, imagewidth, imageheight),         system.drawing.imaging.imagelockmode.readwrite, // r/w memory access         image.pixelformat); // possibly should read stream       // copying     system.runtime.interopservices.marshal.copy(bytes, 0, bitmapdata.scan0, bitmapdata.height * bitmapdata.stride);     image.unlockbits(bitmapdata);      // work bitmap }