///<summary>Fills a memory address to quickly get the point of the char index within the RichTextBox from the Windows API wrapper.
///This is MUCH faster than using RichTextBox.GetPositionFromCharIndex().</summary>
private Point GetPosFromCharIndex(int index)
{
int rawPointSize = Marshal.SizeOf(typeof(Point));
IntPtr wParam = Marshal.AllocHGlobal(rawPointSize);
WindowsApiWrapper.SendMessage(this.Handle, (int)WindowsApiWrapper.EM_Rich.EM_POSFROMCHAR, (int)wParam, index);
Point position = (Point)Marshal.PtrToStructure(wParam, typeof(Point));
Marshal.FreeHGlobal(wParam);
return(position);
}
private void PaintLineNumbers(Graphics g)
{
int lineNumberWidth = LineNumberWidth;
//If the line number width has changed, we need to grow or shrink the left margin and repaint.
if (lineNumberWidth != _lastLineWidth)
{
SetLeftMargin(lineNumberWidth + Margin.Left);
_lastLineWidth = lineNumberWidth;
WindowsApiWrapper.SendMessage(Handle, (int)WindowsApiWrapper.WinMessagesOther.WM_PAINT, 0, 0);
return;
}
//Figure out how many total lines can be shown on the screen.
int visibleLineCount = (int)Math.Ceiling((double)this.Bounds.Height / _lineNumberSize.ToSize().Height);
int minLineCount = Math.Min(visibleLineCount, ListIndicesOfNewLines.Count);
int firstLineNumber = ListIndicesOfNewLines.Count;
int firstCharIndex = this.GetCharIndexFromPosition(new Point(1, 1));
int idx = 0;
foreach (int index in ListIndicesOfNewLines)
{
idx++;
if (firstCharIndex <= index)
{
firstLineNumber = idx;
break;
}
}
using (Bitmap doubleBufferer = new Bitmap(lineNumberWidth, this.Bounds.Height))
using (Graphics gDoubleBuffer = Graphics.FromImage(doubleBufferer))
{
Rectangle rect = new Rectangle(0, 0, lineNumberWidth, this.Bounds.Height);
gDoubleBuffer.FillRectangle(SystemBrushes.ControlLight, rect);
int curNumberWidth = lineNumberWidth;
for (int i = firstLineNumber; i <= ListIndicesOfNewLines.Count; i++)
{
int curPointY = 0;
if (firstLineNumber != 1)
{
//Get the Y position of the character after the new line character of the previous line.
curPointY = GetPosFromCharIndex(ListIndicesOfNewLines[i - 2] + 1).Y; //2 because we want the previous line and the list is 0 based
}
if (this.Bounds.Height <= curPointY)
{
break;
}
Rectangle rectDraw = new Rectangle(0, curPointY, curNumberWidth, _lineNumberSize.ToSize().Height);
gDoubleBuffer.DrawString(firstLineNumber.ToString(), _lineNumberFont, _brushOlive, rectDraw, _stringFormatForDrawingNumbers);
firstLineNumber++;
}
g.DrawImage(doubleBufferer, new Point(0, 0));
}
}
///<summary>Nulls out variables so that the text boxes recalculate their contents on paint.</summary>
private void LineNumberRecalculate()
{
_listIndicesOfNewLines = null;
_lineNumberWidth = -1;
WindowsApiWrapper.SendMessage(this.Handle, (int)WindowsApiWrapper.WinMessagesOther.WM_PAINT, 0, 0);
}
public void SetScroll(int delta)
{
WindowsApiWrapper.SendMessage(this.Handle, (int)WindowsApiWrapper.EM_Rich.EM_LINESCROLL, 0, delta);
}
private void SetLeftMargin(int widthInPixels)
{
WindowsApiWrapper.SendMessage(this.Handle, (int)WindowsApiWrapper.EM_Rich.EM_SETMARGINS, WindowsApiWrapper.EC_LEFTMARGIN,
widthInPixels);
}