private void CaptureScreenArea(int x, int y, int w, int h, ref HBITMAP hBitmap)
{
hBitmap = NativeMethods.CreateCompatibleBitmap(m_hdcSource, w, h);
m_hBitmapTemp = NativeMethods.SelectObject(m_hdcSrcTemp, hBitmap);
NativeMethods.BitBlt(m_hdcSrcTemp, 0, 0, w, h, m_hdcSource, x, y, SRCCOPY);
hBitmap = NativeMethods.SelectObject(m_hdcSrcTemp, m_hBitmapTemp);
}
private void CloneArea(int x, int y, int w, int h, bool preserveAspectRatio = false)
{
CaptureScreenArea(x, y, w, h, ref m_hBitmapSource);
// Invalidate but don`t erase, it helps to avoid blinks caused by background color. We also set it to null just in case.
NativeMethods.InvalidateRect(m_hwndNotOverlay, IntPtr.Zero, false); // Tells that the window should be repainted
m_hdcDestination = NativeMethods.BeginPaint(m_hwndNotOverlay, out PAINTSTRUCT m_paintStruct);
m_hdcDstTemp = NativeMethods.CreateCompatibleDC(m_hdcDestination);
m_hBitmapTemp = NativeMethods.SelectObject(m_hdcDstTemp, m_hBitmapSource);
// No resizing (ideal when same resolution)
//// NativeMethods.BitBlt(m_hdcDestination, 0, 0, w, h, m_hdcDstTemp, 0, 0, SRCCOPY);
// Resizing (ideal when resolutions are different)
NativeMethods.GetClientRect(m_hwndNotOverlay, ref m_windowSize);
NativeMethods.SetStretchBltMode(m_hdcDestination, (int)Enum.Parse(typeof(StretchBltModes), "COLORONCOLOR")); // Use HALFTONE for better image quality (but slower)
// https://www.experts-exchange.com/questions/24774563/StretchBlt-in-C-Csharp-trying-to-copy-a-bitmap-image-to-screen.html
if (preserveAspectRatio)
{
if (scaleAspectRatio == 0)
{
scaleAspectRatio = Math.Round((double)w / h, 2);
}
int m_windowSizeNewX;
int m_windowSizeNewY;
if (m_windowSize.right > m_windowSize.bottom)
{
m_windowSizeNewY = Math.Min(m_windowSize.bottom, (int)Math.Round(m_windowSize.right / scaleAspectRatio));
m_windowSizeNewX = (int)Math.Round(m_windowSizeNewY * scaleAspectRatio, 2);
}
else
{
m_windowSizeNewX = Math.Min(m_windowSize.right, (int)Math.Round(m_windowSize.bottom * scaleAspectRatio));
m_windowSizeNewY = (int)Math.Round(m_windowSizeNewX / scaleAspectRatio, 2);
}
NativeMethods.StretchBlt(m_hdcDestination, 0, 0, m_windowSizeNewX, m_windowSizeNewY, m_hdcDstTemp, x, y, w, h, SRCCOPY);
}
else
{
NativeMethods.StretchBlt(m_hdcDestination, 0, 0, m_windowSize.right, m_windowSize.bottom, m_hdcDstTemp, x, y, w, h, SRCCOPY);
}
NativeMethods.EndPaint(m_hwndNotOverlay, ref m_paintStruct);
NativeMethods.UpdateWindow(m_hwndNotOverlay); // Force direct repaint window
// Without it memory leak will occurr. C++ version needs this too.
NativeMethods.DeleteObject(m_hBitmapSource);
NativeMethods.DeleteObject(m_hBitmapTemp);
NativeMethods.DeleteDC(m_hdcDstTemp);
}
internal static extern bool DeleteObject(HBITMAP hObject);
internal static extern HBITMAP SelectObject(HDC hdc, HBITMAP hgdiobj);
