/// <summary>
/// Get the color from the pixel on the screen at "x,y"
/// </summary>
/// <param name="screenCoordinates">Point with the coordinates</param>
/// <returns>Color at the specified screenCoordinates</returns>
static private Color GetPixelColor(Point screenCoordinates)
{
using (SafeWindowDCHandle screenDC = SafeWindowDCHandle.fromDesktop()) {
try {
uint pixel = GDI32.GetPixel(screenDC, screenCoordinates.X, screenCoordinates.Y);
Color color = Color.FromArgb(255, (int)(pixel & 0xFF), (int)(pixel & 0xFF00) >> 8, (int)(pixel & 0xFF0000) >> 16);
return(color);
} catch (Exception) {
return(Color.Empty);
}
}
}
/// <summary>
/// This method will use User32 code to capture the specified captureBounds from the screen
/// </summary>
/// <param name="captureBounds">Rectangle with the bounds to capture</param>
/// <returns>Bitmap which is captured from the screen at the location specified by the captureBounds</returns>
public static Bitmap CaptureRectangle(Rectangle captureBounds)
{
Bitmap returnBitmap = null;
if (captureBounds.Height <= 0 || captureBounds.Width <= 0)
{
LOG.Warn("Nothing to capture, ignoring!");
return(null);
}
LOG.Debug("CaptureRectangle Called!");
// .NET GDI+ Solution, according to some post this has a GDI+ leak...
// See http://connect.microsoft.com/VisualStudio/feedback/details/344752/gdi-object-leak-when-calling-graphics-copyfromscreen
// Bitmap capturedBitmap = new Bitmap(captureBounds.Width, captureBounds.Height);
// using (Graphics graphics = Graphics.FromImage(capturedBitmap)) {
// graphics.CopyFromScreen(captureBounds.Location, Point.Empty, captureBounds.Size, CopyPixelOperation.CaptureBlt);
// }
// capture.Image = capturedBitmap;
// capture.Location = captureBounds.Location;
using (SafeWindowDCHandle desktopDCHandle = SafeWindowDCHandle.fromDesktop()) {
if (desktopDCHandle.IsInvalid)
{
// Get Exception before the error is lost
Exception exceptionToThrow = CreateCaptureException("desktopDCHandle", captureBounds);
// throw exception
throw exceptionToThrow;
}
// create a device context we can copy to
using (SafeCompatibleDCHandle safeCompatibleDCHandle = GDI32.CreateCompatibleDC(desktopDCHandle)) {
// Check if the device context is there, if not throw an error with as much info as possible!
if (safeCompatibleDCHandle.IsInvalid)
{
// Get Exception before the error is lost
Exception exceptionToThrow = CreateCaptureException("CreateCompatibleDC", captureBounds);
// throw exception
throw exceptionToThrow;
}
// Create BITMAPINFOHEADER for CreateDIBSection
BITMAPINFOHEADER bmi = new BITMAPINFOHEADER(captureBounds.Width, captureBounds.Height, 24);
// Make sure the last error is set to 0
Win32.SetLastError(0);
// create a bitmap we can copy it to, using GetDeviceCaps to get the width/height
IntPtr bits0; // not used for our purposes. It returns a pointer to the raw bits that make up the bitmap.
using (SafeDibSectionHandle safeDibSectionHandle = GDI32.CreateDIBSection(desktopDCHandle, ref bmi, BITMAPINFOHEADER.DIB_RGB_COLORS, out bits0, IntPtr.Zero, 0)) {
if (safeDibSectionHandle.IsInvalid)
{
// Get Exception before the error is lost
Exception exceptionToThrow = CreateCaptureException("CreateDIBSection", captureBounds);
exceptionToThrow.Data.Add("hdcDest", safeCompatibleDCHandle.DangerousGetHandle().ToInt32());
exceptionToThrow.Data.Add("hdcSrc", desktopDCHandle.DangerousGetHandle().ToInt32());
// Throw so people can report the problem
throw exceptionToThrow;
}
// select the bitmap object and store the old handle
using (safeCompatibleDCHandle.SelectObject(safeDibSectionHandle)) {
// bitblt over (make copy)
GDI32.BitBlt(safeCompatibleDCHandle, 0, 0, captureBounds.Width, captureBounds.Height, desktopDCHandle, captureBounds.X, captureBounds.Y, CopyPixelOperation.SourceCopy | CopyPixelOperation.CaptureBlt);
}
// get a .NET image object for it
// A suggestion for the "A generic error occurred in GDI+." E_FAIL/0×80004005 error is to re-try...
bool success = false;
ExternalException exception = null;
for (int i = 0; i < 3; i++)
{
try {
// Collect all screens inside this capture
List <Screen> screensInsideCapture = new List <Screen>();
foreach (Screen screen in Screen.AllScreens)
{
if (screen.Bounds.IntersectsWith(captureBounds))
{
screensInsideCapture.Add(screen);
}
}
// Check all all screens are of an equal size
bool offscreenContent;
using (Region captureRegion = new Region(captureBounds)) {
// Exclude every visible part
foreach (Screen screen in screensInsideCapture)
{
captureRegion.Exclude(screen.Bounds);
}
// If the region is not empty, we have "offscreenContent"
using (Graphics screenGraphics = Graphics.FromHwnd(User32.GetDesktopWindow())) {
offscreenContent = !captureRegion.IsEmpty(screenGraphics);
}
}
// Check if we need to have a transparent background, needed for offscreen content
if (offscreenContent)
{
using (Bitmap tmpBitmap = Image.FromHbitmap(safeDibSectionHandle.DangerousGetHandle())) {
// Create a new bitmap which has a transparent background
returnBitmap = ImageHelper.CreateEmpty(tmpBitmap.Width, tmpBitmap.Height, PixelFormat.Format32bppArgb, Color.Transparent, tmpBitmap.HorizontalResolution, tmpBitmap.VerticalResolution);
// Content will be copied here
using (Graphics graphics = Graphics.FromImage(returnBitmap)) {
// For all screens copy the content to the new bitmap
foreach (Screen screen in Screen.AllScreens)
{
Rectangle screenBounds = screen.Bounds;
// Make sure the bounds are offsetted to the capture bounds
screenBounds.Offset(-captureBounds.X, -captureBounds.Y);
graphics.DrawImage(tmpBitmap, screenBounds, screenBounds.X, screenBounds.Y, screenBounds.Width, screenBounds.Height, GraphicsUnit.Pixel);
}
}
}
}
else
{
// All screens, which are inside the capture, are of equal size
// assign image to Capture, the image will be disposed there..
returnBitmap = Image.FromHbitmap(safeDibSectionHandle.DangerousGetHandle());
}
// We got through the capture without exception
success = true;
break;
} catch (ExternalException ee) {
LOG.Warn("Problem getting bitmap at try " + i + " : ", ee);
exception = ee;
}
}
if (!success)
{
LOG.Error("Still couldn't create Bitmap!");
if (exception != null)
{
throw exception;
}
}
}
}
}
return(returnBitmap);
}
