【转】【WPF】WriteableBitmap应用及图片数据格式转换

. public void WritePixels(Int32Rect sourceRect, Array pixels, int stride, int offset);
. public void WritePixels(Int32Rect sourceRect, IntPtr buffer, int bufferSize, int stride);
. public void WritePixels(Int32Rect sourceRect, Array sourceBuffer, int sourceBufferStride,
int destinationX, int destinationY);
. public void WritePixels(Int32Rect sourceRect, IntPtr sourceBuffer, int sourceBufferSize,
int sourceBufferStride, int destinationX, int destinationY);

WriteableBitmap bitmap = new WriteableBitmap(, , , , PixelFormats.Bgr24, null);
Byte[] buffer = new Byte[bitmap.BackBufferStride * bitmap.PixelHeight];
for (byte i = ; i < buffer.Length; i++)
{
buffer[i] = i;
}
bitmap.WritePixels(new Int32Rect(, , , ), buffer, bitmap.BackBufferStride, );Marshal.Copy(bitmap.BackBuffer, buffer, , buffer.Length);

unsafe
{
var bytes = (byte*)m_Bitmap.BackBuffer.ToPointer();
m_Bitmap.Lock();
for (int i = ; i < m_Bitmap.BackBufferStride * m_Bitmap.PixelHeight; i++)
{
bytes[i] = (byte)(-bytes[i]);
}
m_Bitmap.AddDirtyRect(new Int32Rect(, , m_Bitmap.PixelWidth, m_Bitmap.PixelHeight));
m_Bitmap.Unlock();
}

m_Bitmap.AddDirtyRect(new Int32Rect(, , , ));
m_Bitmap.AddDirtyRect(new Int32Rect(, , , ));
m_Bitmap.AddDirtyRect(new Int32Rect(, , , ));

FileStream fs = new FileStream(filepath, FileMode.Open, FileAccess.Read);
byte[] desBytes = new byte[fs.Length];
fs.Read(desBytes, , desBytes.Length);
fs.Close();

public static BitmapImage ByteArrayToBitmapImage(byte[] byteArray)
{
BitmapImage bmp = null;
try
{
bmp = new BitmapImage();
bmp.BeginInit();
bmp.StreamSource = new MemoryStream(byteArray);
bmp.EndInit();
}
catch
{
bmp = null;
}
return bmp;
}

public static byte[] BitmapImageToByteArray(BitmapImage bmp)
{
byte[] byteArray = null;
try
{
Stream sMarket = bmp.StreamSource;
if (sMarket != null && sMarket.Length > )
{
//很重要，因为Position经常位于Stream的末尾，导致下面读取到的长度为0。
sMarket.Position = ; using (BinaryReader br = new BinaryReader(sMarket))
{
byteArray = br.ReadBytes((int)sMarket.Length);
}
}
}
catch
{
//other exception handling
}
return byteArray;
}

WriteableBitmap wb = new WriteableBitmap(img.Source as BitmapSource);//将Image对象转换为WriteableBitmap
byte[] b = Convert.FromBase64String(GetBase64Image(wb));//得到byte数组

var bi= new BitmapImage();
bi.SetSource(wb.ToImage().ToStream()); //其中wb是WriteableBitmap对象。

WriteableBitmap wb = new WriteableBitmap(bi.Source as BitmapSource);

byte[] b = Convert.FromBase64String(GetBase64Image(wb));
//这里通过base64间接处理，效率不是很高。

MemoryStream ms = new MemoryStream(b); // b为byte[]
using (var stream = new MemoryStream(data))// data为byte[]
{
var bitmap = new BitmapImage();
bitmap.BeginInit();
bitmap.StreamSource = stream;
bitmap.CacheOption = BitmapCacheOption.OnLoad;
bitmap.EndInit();
bitmap.Freeze();
}
//以下方法为Stream转BitmapFrame
using (var stream = new MemoryStream(data))
{
var bi = BitmapFrame.Create(stream , BitmapCreateOptions.IgnoreImageCache, BitmapCacheOption.OnLoad);
}

[DllImport("gdi32.dll", SetLastError = true)]
private static extern bool DeleteObject(IntPtr hObject); IntPtr hBitmap = bitmap.GetHbitmap();
ImageSource wpfBitmap = System.Windows.Interop.Imaging.CreateBitmapSourceFromHBitmap
(
hBitmap,
IntPtr.Zero,
Int32Rect.Empty,
BitmapSizeOptions.FromEmptyOptions()
);
DeleteObject(hBitmap);

WriteableBitmap wtbBmp;//Image对象
RenderTargetBitmap rtbitmap = new RenderTargetBitmap(wtbBmp.PixelWidth, wtbBmp.PixelHeight, wtbBmp.DpiX, wtbBmp.DpiY, PixelFormats.Default);
DrawingVisual drawingVisual = new DrawingVisual();
using (DrawingContext context = drawingVisual.RenderOpen())
{
context.DrawImage(wtbBmp, new Rect(, , wtbBmp.Width, wtbBmp.Height));
}
rtbitmap.Render(drawingVisual);
JpegBitmapEncoder bitmapEncoder = new JpegBitmapEncoder();
bitmapEncoder.Frames.Add(BitmapFrame.Create(rtbitmap));
using (System.IO.FileStream fs = new System.IO.FileStream("D:\\mq.jpg", System.IO.FileMode.Create))
jpeg.Save(fs);

private unsafe void DrawBitmap(WriteableBitmap dst, Bitmap src, System.Drawing.Rectangle rect)
{
int srcw = src.Width;
int srch = src.Height;
int left = rect.Left < ? : rect.Left;
int top = rect.Top < ? : rect.Top;
int right = rect.Right > srcw ? srcw : rect.Right;
int bottom = rect.Bottom > srch ? srch : rect.Bottom;
if (left >= right || top >= bottom) return;
BitmapData srcdata = src.LockBits(new System.Drawing.Rectangle(, , srcw, srch), ImageLockMode.ReadOnly, System.Drawing.Imaging.PixelFormat.Format32bppArgb);
dst.Lock();
var srcints = (int*)srcdata.Scan0;
var dstints = (int*)dst.BackBuffer.ToPointer();
for (int j = top; j < bottom; ++j)
{
int y = j * srcw;
for (int i = left; i < right; ++i)
{
int index = y + i;
dstints[index] = srcints[index];
}
}
dst.AddDirtyRect(new Int32Rect(left, top, right - left, bottom - top));
src.UnlockBits(srcdata);
dst.Unlock();
}

private unsafe void DrawWriteableBitmap(Bitmap dst, WriteableBitmap src, System.Drawing.Rectangle rect)
{
int dstw = dst.Width;
int dsth = dst.Height;
int left = rect.Left < ? : rect.Left;
int top = rect.Top < ? : rect.Top;
int right = rect.Right > dstw ? dstw : rect.Right;
int bottom = rect.Bottom > dsth ? dsth : rect.Bottom;
if (left >= right || top >= bottom) return;
BitmapData dstdata = dst.LockBits(new System.Drawing.Rectangle(, , dstw, dsth), ImageLockMode.WriteOnly, System.Drawing.Imaging.PixelFormat.Format32bppArgb);
var dstints = (int*)dstdata.Scan0;
var srcints = (int*)src.BackBuffer.ToPointer();
for (int j = top; j < bottom; ++j)
{
int y = j * dstw;
for (int i = left; i < right; ++i)
{
int index = y + i;
dstints[index] = srcints[index];
}
}
dst.UnlockBits(dstdata);
}