我需要在 WPF 控件上显示实时图像。我正在寻找使用 WPF 执行此操作的最快方法。
我正在使用其 dll API ( AVT ) 从相机捕获图像。
图像由 dll 写入,相机使用 IntPtr 向名为tFrame的 Image 结构发起回调(如下所述)。像素数据存储在 ImageBuffer 属性中,是一个字节数组的 InPtr。
我知道如何从像素字节数组创建位图,但不知道位图图像。因此可以创建一个 Bitmap,然后从中创建一个 BitmapImagem。 这里有一种方法可以从内存上的 Bitmap 创建 BitmapImage。但我想直接从数据源(tFrame)创建BitmapImage 。我怎样才能做到这一点?
我知道 BitmapImage 有一个 CopyPixels 方法,但它缺少一个 SetPixels。
public struct tFrame
{
public IntPtr AncillaryBuffer;
public uint AncillaryBufferSize;
public uint AncillarySize;
public tBayerPattern BayerPattern;
public uint BitDepth;
public tFrameCtx Context;
public tImageFormat Format;
public uint FrameCount;
public uint Height;
public IntPtr ImageBuffer;
public uint ImageBufferSize;
public uint ImageSize;
public uint RegionX;
public uint RegionY;
public tErr Status;
public uint TimestampHi;
public uint TimestampLo;
public uint Width;
}
这是我从像素字节数组创建位图的方法。这用于该软件的 WinForm 版本。
private void CreateBitmap(tFrame frame)
{
//This sample is for a 8bpp captured image
PixelFormat pxFormat = PixelFormat.Format8bppIndexed;
//STRIDE
//[https://stackoverflow.com/questions/1983781/why-does-bitmapsource-create-throw-an-argumentexception/1983886#1983886][3]
//float bitsPerPixel = System.Drawing.Image.GetPixelFormatSize(format);
int bitsPerPixel = ((int)pxFormat >> 8) & 0xFF;
//Number of bits used to store the image data per line (only the valid data)
int validBitsPerLine = ((int)frame.Width) * bitsPerPixel;
//4 bytes for every int32 (32 bits)
int stride = ((validBitsPerLine + 31) / 32) * 4;
Bitmap bmp = new Bitmap((int)frame.Width, (int)frame.Height, stride, pxFormat, frame.ImageBuffer);
}
编辑1:
感谢 dr.mo,现在我能够以约 3% 的 CPU 使用率显示 60 FPS 1024x1024 图像!我正在做的是:
//@ UI Thread
public WriteableBitmap wbm = new WriteableBitmap(1024, 1024, (double)96, (double)96, System.Windows.Media.PixelFormats.Gray8, null);
this.wbBackBuffer = this.wbm.BackBuffer;
//This can be called by a timer in the UI thread or at the grab Thread for every image, the CPU usage is almost the same.
void UpdateDisplayImage()
{
wbm.Lock();
wbm.AddDirtyRect(new Int32Rect(0, 0, wbm.PixelWidth, wbm.PixelHeight));
wbm.Unlock();
}
//@ Grab Thread
//Update the backbuffer with new camera image data.
UpdateBackBuffer(...);
/// <summary>
/// [http://msdn.microsoft.com/en-us/library/system.windows.media.imaging.writeablebitmap.aspx]
/// </summary>
public void UpdateBackBuffer(IntPtr pData, int w, int h, int ch)
{
//Can not acess wbm from outside UI thread
//CopyMemory(wbm.BackBuffer, pData, (uint)(w * h * ch));
//I dont know if it is safe to write to it buffer like this:
CopyMemory(this.wbBackBuffer, pData, (uint)(w * h * ch));
}