多显示器屏幕截图-定位鼠标光标 [英] Multi-monitor screenshot - positioning mouse cursor

问题描述

我有一个过程，该过程获取监视器的屏幕截图，并且可以选择将鼠标光标包含在快照中。原始功能仅适用于一台显示器。绘制鼠标光标时，它当前仅在主监视器上正确显示。但是，我不知道如何将其放置在其他任何显示器上。

I have a procedure which takes a screenshot of a monitor and optionally includes the mouse cursor in the snapshot. The original function was only for one monitor. When drawing the mouse cursor, it currently shows properly only on the Main Monitor. But, I can't figure out how to position it on any other monitor. See the comments towards the end of this procedure.

procedure ScreenShot(var Bitmap: TBitmap; const MonitorNum: Integer;
  const DrawCursor: Boolean; const Quality: TPixelFormat);
var
  DC: HDC;
  C: TCanvas;
  R: TRect;
  CursorInfo: TCursorInfo;
  Icon: TIcon;
  IconInfo: TIconInfo;
  M: TMonitor;
  CP: TPoint;
begin
  M:= Screen.Monitors[MonitorNum];
  DC:= GetDC(GetDesktopWindow);
  try
    C:= TCanvas.Create;
    try
      C.Handle:= DC;
      R:= M.BoundsRect;
      Bitmap.Width:= R.Width;
      Bitmap.Height:= R.Height;
      Bitmap.PixelFormat:= Quality;
      Bitmap.Canvas.CopyRect(Rect(0,0,R.Width,R.Height), C, R);
    finally
      C.Free;
    end;
  finally
    ReleaseDC(GetDesktopWindow, DC);
  end;
  if DrawCursor then begin
    R:= Bitmap.Canvas.ClipRect;
    Icon:= TIcon.Create;
    try
      CursorInfo.cbSize:= SizeOf(CursorInfo);
      if GetCursorInfo(CursorInfo) then
      if CursorInfo.Flags = CURSOR_SHOWING then
      begin
        Icon.Handle:= CopyIcon(CursorInfo.hCursor);
        if GetIconInfo(Icon.Handle, IconInfo) then
        begin
          CP:= CursorInfo.ptScreenPos;

          //Transition mouse position...?
          CP.X:= CP.X + M.Left;
          CP.Y:= CP.Y + M.Top;  //No difference?

          Bitmap.Canvas.Draw(
            CP.X - Integer(IconInfo.xHotspot) - R.Left,
            CP.Y - Integer(IconInfo.yHotspot) - R.Top,
            Icon);
        end;
      end;
    finally
      Icon.Free;
    end;
  end;
end;

如何根据正在使用的显示器适当地转换鼠标位置？

How do I transition the mouse position properly depending on which monitor I'm using?

推荐答案

您正在将屏幕坐标 MonitorRect.Left 映射到位图坐标 0 。同样， MonitorRect.Top 到 0 。因此，如果光标的屏幕位置是 CursorPos ，则将其映射到 CursorPos.X-MonitorRect.Left 和 CursorPos.Y-MonitorRect.Top 。然后，您还需要考虑热点问题，但是您似乎已经知道该怎么做。

You are mapping screen coord MonitorRect.Left to bitmap coord 0. And likewise, MonitorRect.Top to 0. So, if the cursor's screen position is CursorPos then you map that to CursorPos.X - MonitorRect.Left and CursorPos.Y - MonitorRect.Top. And then you also need to account for the hot spot, but you already seem to know how to do that.

上面的映射同样适用于所有监视器。

The mapping above applies equally to all monitors.

请注意，我使用了自己的符号，因为我发现您的单个字母变量会引起误解。更不用说这些变量的含义在函数运行过程中发生变化的事实。我看着你， R 。

Note that I used my own notation because I found your single letter variables mis-leading. Not to mention that fact that the meaning of these variables changes during the function. I'm look at you, R. That's always a recipe for pain.

此外，您不需要删除调用 GetIconInfo <时传递给您的位图句柄吗？ / code>？而且有些错误检查也不会出错。

Also, don't you need to delete the bitmap handles that are handed to you when you call GetIconInfo? And some error checking wouldn't go amiss.

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