I grab an image from a external camera. The winforms application works so far. Now I need to transfer it to WPF. Therefore I converted the bitmap-image to WPF like this:
GrabHandler frameCallbackDelegate;
void frameCallBack(IntPtr lpUserData, ref VCECLB_FrameInfoEx frameInfo)
{
if (frameInfo.dma_status != 0) return;
// fill image
Rectangle rect = new Rectangle(0, 0, image.Width, image.Height);
BitmapData bmdata = image.LockBits(rect, ImageLockMode.ReadWrite, image.PixelFormat);
UInt32 outputBitDepth;
IntPtr stride = new IntPtr(bmdata.Stride);
VCECLB_Error err = NativeFunctions.VCECLB_UnpackRawPixelsEx(ref pRawPixelInfo, frameInfo.lpRawBuffer, bmdata.Scan0, ref stride, VCECLB_Output_Format.VCECLB_EX_FMT_TopDown | VCECLB_Output_Format.VCECLB_EX_FMT_3Channel, out outputBitDepth);
image.UnlockBits(bmdata);
Dispatcher.Invoke(new Action(() =>
{
// Convert bitmap to WPF-Image
var bmp = new Bitmap(image);
var hBitmap = bmp.GetHbitmap();
ImageSource wpfBitmap = System.Windows.Interop.Imaging.CreateBitmapSourceFromHBitmap(
hBitmap,
IntPtr.Zero,
Int32Rect.Empty,
BitmapSizeOptions.FromEmptyOptions());
image_LowLight.Source = wpfBitmap;
DeleteObject(hBitmap);
image.Dispose();
}));
GC.Collect();
}
private void StartGrab(object sender, RoutedEventArgs e)
{
start_button.IsEnabled = true;
stop_button.IsEnabled = false;
frameCallbackDelegate = new GrabHandler(frameCallBack);
m_ImageAquisition.StartGrab(frameCallbackDelegate);
}
When I enter for the first time the frameCallBack from the StartGrab, the image.Width and image.Height have a valid value (not 0) and it seems correct. When the frameCallBack is entered for the second time all image-data (width and height) are 0 and therefore rect gives an error.
Is there something wrong in the way I am using the Dispatcher.Invoke to get a valid bitmap-image?
Thanks!
Avoid using volatile data in an Action() which gets executed some time later by the Dispatcher.
Refactor your code like this:
GrabHandler frameCallbackDelegate;
void frameCallBack(IntPtr lpUserData, ref VCECLB_FrameInfoEx frameInfo)
{
if (frameInfo.dma_status != 0) return;
// fill image
Rectangle rect = new Rectangle(0, 0, image.Width, image.Height);
BitmapData bmdata = image.LockBits(rect, ImageLockMode.ReadWrite, image.PixelFormat);
UInt32 outputBitDepth;
IntPtr stride = new IntPtr(bmdata.Stride);
VCECLB_Error err = NativeFunctions.VCECLB_UnpackRawPixelsEx(ref pRawPixelInfo, frameInfo.lpRawBuffer, bmdata.Scan0, ref stride, VCECLB_Output_Format.VCECLB_EX_FMT_TopDown | VCECLB_Output_Format.VCECLB_EX_FMT_3Channel, out outputBitDepth);
image.UnlockBits(bmdata);
// Convert bitmap to WPF-Image
var bmp = new Bitmap(image);
var hBitmap = bmp.GetHbitmap();
ImageSource wpfBitmap =
System.Windows.Interop.Imaging.CreateBitmapSourceFromHBitmap(
hBitmap,
IntPtr.Zero,
Int32Rect.Empty,
BitmapSizeOptions.FromEmptyOptions());
DeleteObject(hBitmap);
image.Dispose();
Dispatcher.Invoke(new Action(() =>
{
image_LowLight.Source = wpfBitmap;
}));
GC.Collect();
}
Related
I'm trying to take a screenshot of another window specified by a valid hwnd. The procedure works, however the window flickers when the screenshot is taken.
The first function uses PrintScreen, the second BitBlt. Each is called from a routine that takes a screenshot every 10 seconds.
Is there a way to avoid a flicker when using the PrintScreen or BitBlt functions?
Any help would be appreciated.
public Bitmap GetScreenshot(IntPtr ihandle)
{
IntPtr hwnd = ihandle;//handle here
RECT rc;
FocusWindow(ihandle);
GetWindowRect(hwnd, out rc);
Bitmap bmp = new Bitmap(rc.Right - rc.Left, rc.Bottom - rc.Top, PixelFormat.Format32bppArgb);
Graphics gfxBmp = Graphics.FromImage(bmp);
IntPtr hdcBitmap;
try
{
hdcBitmap = gfxBmp.GetHdc();
}
catch
{
return null;
}
bool succeeded = PrintWindow(hwnd, hdcBitmap, 0);
gfxBmp.ReleaseHdc(hdcBitmap);
if (!succeeded)
{
gfxBmp.FillRectangle(new SolidBrush(Color.Gray), new Rectangle(Point.Empty, bmp.Size));
}
IntPtr hRgn = CreateRectRgn(0, 0, 0, 0);
GetWindowRgn(hwnd, hRgn);
Region region = Region.FromHrgn(hRgn);//err here once
if (!region.IsEmpty(gfxBmp))
{
gfxBmp.ExcludeClip(region);
gfxBmp.Clear(Color.Transparent);
}
gfxBmp.Dispose();
return bmp;
}
public Bitmap CaptureWindowImage(IntPtr hWnd) //, System.Drawing.Rectangle wndRect)
{
IntPtr hWndDc = GetDC(hWnd);
IntPtr hMemDc = CreateCompatibleDC(hWndDc);
RECT rc;
GetWindowRect(hWnd, out rc);
IntPtr hBitmap = CreateCompatibleBitmap(hWndDc, rc.Width, rc.Height);
SelectObject(hMemDc, hBitmap);
BitBlt(hMemDc, 0, 0, rc.Width, rc.Height, hWndDc, 0, 0, TernaryRasterOperations.SRCCOPY);
Bitmap bitmap = Bitmap.FromHbitmap(hBitmap);
DeleteObject(hBitmap);
ReleaseDC(hWnd, hWndDc);
ReleaseDC(IntPtr.Zero, hMemDc);
DeleteDC(hMemDc);
return bitmap;
}
I'm building a small video recording of a specific Windows but I just noticied it will not work when the Window is minimized, it take screenshot only the application's window superior bar. Is possible to workaround it?
Here's my current code:
public Bitmap GetScreenshot(IntPtr hwnd)
{
RECT rc;
if (!GetWindowRect(hwnd, out rc))
throw new Win32Exception(Marshal.GetLastWin32Error());
Bitmap bmp = new Bitmap(rc.right - rc.left, rc.bottom - rc.top, PixelFormat.Format32bppArgb);
using (var gfxBmp = Graphics.FromImage(bmp))
{
IntPtr hdcBitmap = gfxBmp.GetHdc();
bool succeeded = PrintWindow(hwnd, hdcBitmap, 0);
gfxBmp.ReleaseHdc(hdcBitmap);
if (!succeeded)
{
gfxBmp.FillRectangle(new SolidBrush(Color.Gray), new Rectangle(Point.Empty, bmp.Size));
}
IntPtr hRgn = CreateRectRgn(0, 0, 0, 0);
GetWindowRgn(hwnd, hRgn);
Region region = Region.FromHrgn(hRgn);
if (!region.IsEmpty(gfxBmp))
{
gfxBmp.ExcludeClip(region);
gfxBmp.Clear(Color.Transparent);
}
return bmp;
}
}
I have a problem, and i don't know how resolved.. I'm using the drive twain to do scanner some documents, and i don't get create a new BitMap when i'm scanning a big number of the files.. So.. i need help to solution this.. my code is:
public static Bitmap FromHDib(IntPtr dibPtrArg, out ServiceError error)
{
error = null;
try
{
Win32.BITMAPINFOHEADER bmi;
IntPtr pixptr;
var ptr = Win32.GlobalLock(dibPtrArg);
GetPixelInfo(ptr, out pixptr, out bmi);
Bitmap bitMap = new Bitmap(bmi.biWidth, bmi.biHeight);
Graphics scannedImageGraphics = Graphics.FromImage(bitMap);
**IntPtr hdc = scannedImageGraphics.GetHdc();** //parameter is not valid
SetDIBitsToDevice(
hdc,
0, // XDest
0, // YDest
bmi.biWidth,
bmi.biHeight,
0, // XSrc
0, // YSrc
0, // uStartScan
bmi.biHeight, // cScanLines
pixptr, // lpvBits
ptr, // lpbmi
0); // 0 = literal RGB values rather than palette
scannedImageGraphics.ReleaseHdc(hdc);
const float inchPerMeter = 39.3700787F;
bitMap.SetResolution(bmi.biXPelsPerMeter / inchPerMeter, bmi.biYPelsPerMeter / inchPerMeter);
Win32.GlobalUnlock(dibPtrArg);
Win32.GlobalFree(dibPtrArg);
Win32.DeleteDC(hdc);
bitMap.Dispose();
return bitMap;
}
catch (OutOfMemoryException memoryEx)
{
return new Bitmap(0, 0);
}
catch (ArgumentException argEx)
{
return new Bitmap(0, 0);
}
}
I am using kinect!!I get a frame and then I convert it to bitmap in order to use Emgucv to convert frame in grayscale then convert bitmap to bitmpa source in order to show in window!I am usign C# visual studio WPF!But my program consume much CPU usage and in case the video is frozen for seconds!!I guess that is the conversion bitmpa source to bitmap and viceverse
byte[] colorData = null;
WriteableBitmap colorImageBitmap = null;
void myKinect_ColorFrameReady(object sender, ColorImageFrameReadyEventArgs e)
{
using (ColorImageFrame colorFrame = e.OpenColorImageFrame())
{
if (colorFrame == null) return;
if (colorData == null)
colorData = new byte[colorFrame.PixelDataLength];
colorFrame.CopyPixelDataTo(colorData);
if (colorImageBitmap == null)
{
this.colorImageBitmap = new WriteableBitmap(
colorFrame.Width,
colorFrame.Height,
96, // DpiX
96, // DpiY
PixelFormats.Bgr32,
null);
}
this.colorImageBitmap.WritePixels(
new Int32Rect(0, 0, colorFrame.Width, colorFrame.Height),
colorData, // video data
colorFrame.Width * colorFrame.BytesPerPixel, // stride,
0 // offset into the array - start at 0
);
Image<Gray, Byte> My_Image = new Image<Gray, byte>(BitmapFromSource(colorImageBitmap));
kinectVideo.Source = ToBitmapSource(My_Image);
}
}
private System.Drawing.Bitmap BitmapFromSource(BitmapSource bitmapsource)
{
System.Drawing.Bitmap bitmap;
using (MemoryStream outStream = new MemoryStream())
{
BitmapEncoder enc = new BmpBitmapEncoder();
enc.Frames.Add(BitmapFrame.Create(bitmapsource));
enc.Save(outStream);
bitmap = new System.Drawing.Bitmap(outStream);
}
return bitmap;
}
[DllImport("gdi32")]
private static extern int DeleteObject(IntPtr o);
public static BitmapSource ToBitmapSource(IImage image)
{
using (System.Drawing.Bitmap source = image.Bitmap)
{
IntPtr ptr = source.GetHbitmap(); //obtain the Hbitmap
BitmapSource bs = System.Windows.Interop.Imaging.CreateBitmapSourceFromHBitmap(
ptr,
IntPtr.Zero,
Int32Rect.Empty,
System.Windows.Media.Imaging.BitmapSizeOptions.FromEmptyOptions());
DeleteObject(ptr); //release the HBitmap
return bs;
}
}
}
Instead of using Emgucv to do the greyscaling...which means you have to create a GDI+ Bitmap (System.Drawing.Bitmap) pass it to Emgucv, then convert it back from the GDI+ Bitmap to a BitmapSource, you could use FormatConvertedBitmap to keep it in the WPF world.
void myKinect_ColorFrameReady(object sender, ColorImageFrameReadyEventArgs e)
{
using (ColorImageFrame colorFrame = e.OpenColorImageFrame())
{
if (colorFrame == null) return;
if (colorData == null)
colorData = new byte[colorFrame.PixelDataLength];
colorFrame.CopyPixelDataTo(colorData);
if (colorImageBitmap == null)
{
this.colorImageBitmap = new WriteableBitmap(
colorFrame.Width,
colorFrame.Height,
96, // DpiX
96, // DpiY
PixelFormats.Bgr32,
null);
}
this.colorImageBitmap.WritePixels(
new Int32Rect(0, 0, colorFrame.Width, colorFrame.Height),
colorData, // video data
colorFrame.Width * colorFrame.BytesPerPixel, // stride,
0 // offset into the array - start at 0
);
kinectVideo.Source = new FormatConvertedBitmap(colorImageBitmap, PixelFormats.Gray32Float, null, 0);
}
}
http://www.shujaat.net/2010/08/wpf-image-format-conversion-including.html
Another option is to use a pixel shader that applies a greyscale effect on your "kinectVideo" element (which is presumably an Image element to display the frame).
http://bursjootech.blogspot.co.uk/2008/06/grayscale-effect-pixel-shader-effect-in.html
I´m using Kinect (Microsoft SDK) with XNA. I want to use GRATF for marker-recognition
How to convert the data of a Kinect ColorImageFrame to a System.Drawing.Bitmap or AForge.Imaging.UnmanagedImage that I can process them with GRATF?
void kinectSensor_ColorFrameReady(object sender, ColorImageFrameReadyEventArgs e)
{
Bitmap bitmap = null;
ColorImageFrame frame = e.OpenColorImageFrame();
byte[] buffer = new byte[frame.PixelDataLength];
frame.CopyPixelData(buffer);
// how to convert the data in buffer to a bitmap?
var glyphs = recognizer.FindGlyphs(bitmap);
...
}
You can find the answer in this article.
To summarize it, this method should do the trick:
Bitmap ImageToBitmap(ColorImageFrame img)
{
byte[] pixeldata = new byte[img.PixelDataLength];
img.CopyPixelDataTo(pixeldata);
Bitmap bmap = new Bitmap(img.Width, img.Height, PixelFormat.Format32bppRgb);
BitmapData bmapdata = bmap.LockBits(
new Rectangle(0, 0, img.Width, img.Height),
ImageLockMode.WriteOnly,
bmap.PixelFormat);
IntPtr ptr = bmapdata.Scan0;
Marshal.Copy(pixeldata, 0, ptr, img.PixelDataLength);
bmap.UnlockBits(bmapdata);
return bmap;
}