/// <summary>
/// Sets the scoll position of the text box.
/// </summary>
/// <remarks>This code compensates for the EM_GETSCROLLPOS message limitations.</remarks>
/// <param name="value">The new scroll position.</param>
protected void SetScrollPos(Point value)
{
// Save the original value
EnhTextBoxAPIFunctions.POINTAPI lpOriginal = (EnhTextBoxAPIFunctions.POINTAPI)value;
if (lpOriginal.Y < 0)
{
lpOriginal.Y = 0;
}
if (lpOriginal.X < 0)
{
lpOriginal.X = 0;
}
// Default factored value to original value with Y Factor compensation
EnhTextBoxAPIFunctions.POINTAPI lpFactored = (EnhTextBoxAPIFunctions.POINTAPI)value;
lpFactored.Y = (int)((double)lpOriginal.Y * mdScrollPosYfactor);
// Current result
EnhTextBoxAPIFunctions.POINTAPI lpResult = (EnhTextBoxAPIFunctions.POINTAPI)value;
EnhTextBoxAPIFunctions.SendMessagePoint(this.Handle, EnhTextBoxAPIFunctions.Messages.EM_SETSCROLLPOS, 0, ref lpFactored);
EnhTextBoxAPIFunctions.SendMessagePoint(this.Handle, EnhTextBoxAPIFunctions.Messages.EM_GETSCROLLPOS, 0, ref lpResult);
int liLoopCount = 0;
int liMaxLoop = 100;
while (lpResult.Y != lpOriginal.Y)
{
// Adjust the input.
if (lpResult.Y > lpOriginal.Y)
{
lpFactored.Y -= (lpResult.Y - lpOriginal.Y) / 2 - 1;
}
else
if (lpResult.Y < lpOriginal.Y)
{
lpFactored.Y += (lpOriginal.Y - lpResult.Y) / 2 + 1;
}
// test the new input.
EnhTextBoxAPIFunctions.SendMessagePoint(this.Handle, EnhTextBoxAPIFunctions.Messages.EM_SETSCROLLPOS, 0, ref lpFactored);
EnhTextBoxAPIFunctions.SendMessagePoint(this.Handle, EnhTextBoxAPIFunctions.Messages.EM_GETSCROLLPOS, 0, ref lpResult);
// save new factor, test for exit.
liLoopCount++;
if (liLoopCount >= liMaxLoop || lpResult.Y == lpOriginal.Y)
{
mdScrollPosYfactor = (double)lpFactored.Y / (double)lpOriginal.Y;
break;
}
}
}
/// <summary>
/// Gets the scroll position of the text box.
/// </summary>
/// <returns>The point denoting the scroll position.</returns>
protected Point GetScrollPos()
{
EnhTextBoxAPIFunctions.POINTAPI lpScrollPoint = new EnhTextBoxAPIFunctions.POINTAPI();
EnhTextBoxAPIFunctions.SendMessagePoint(this.Handle, EnhTextBoxAPIFunctions.Messages.EM_GETSCROLLPOS, 0, ref lpScrollPoint);
return(new Point(lpScrollPoint.X, lpScrollPoint.Y));
}