internal static int GetBaselineOffsetAtCharIndex(TextBoxBase tb, int index)
{
if (!(tb is RichTextBox rtb) || !EnvUtils.RunningOnWindows())
{
return(tb.Font.Height);
}
var lineNumber = rtb.GetLineFromCharIndex(index);
var lineIndex = NativeMethods.SendMessageInt(rtb.Handle, NativeMethods.EM_LINEINDEX, new IntPtr(lineNumber), IntPtr.Zero).ToInt32();
var lineLength = NativeMethods.SendMessageInt(rtb.Handle, NativeMethods.EM_LINELENGTH, new IntPtr(lineNumber), IntPtr.Zero).ToInt32();
var charRange = new NativeMethods.CHARRANGE
{
cpMin = lineIndex,
cpMax = lineIndex + lineLength
};
var rect = new NativeMethods.RECT
{
Top = 0,
Bottom = (int)AnInch,
Left = 0,
Right = 10000000 ////(int)(rtb.Width * anInch + 20);
};
var rectPage = new NativeMethods.RECT
{
Top = 0,
Bottom = (int)AnInch,
Left = 0,
Right = 10000000 ////(int)(rtb.Width * anInch + 20);
};
var canvas = Graphics.FromHwnd(rtb.Handle);
var canvasHdc = canvas.GetHdc();
var formatRange = new NativeMethods.FORMATRANGE
{
chrg = charRange,
hdc = canvasHdc,
hdcTarget = canvasHdc,
rc = rect,
rcPage = rectPage
};
NativeMethods.SendMessage(rtb.Handle, NativeMethods.EM_FORMATRANGE, IntPtr.Zero, ref formatRange);
canvas.ReleaseHdc(canvasHdc);
canvas.Dispose();
return((int)((formatRange.rc.Bottom - formatRange.rc.Top) / AnInch));
}
private static Image RenderImage(string rtfContent, SizeF sizeInInches, Func <IntPtr, Size, Image> createImage)
{
using (var richText = new RichTextBox())
{
richText.SetRtfOrText(rtfContent);
richText.CreateControl();
using (var g = richText.CreateGraphics())
{
var dpiX = g.DpiX;
var dpiY = g.DpiY;
richText.Width = (int)(sizeInInches.Width * dpiX);
richText.Height = (int)(sizeInInches.Height * dpiY);
var hdc = g.GetHdc();
var image = createImage(hdc, new Size(richText.Width, richText.Height));
using (var imageG = Graphics.FromImage(image))
{
var formatRange = new NativeMethods.FORMATRANGE();
formatRange.hdc = formatRange.hdcTarget = imageG.GetHdc();
formatRange.rc.right = formatRange.rcPage.right = (int)Math.Ceiling(sizeInInches.Width * 1440);
formatRange.rc.bottom = formatRange.rcPage.bottom = (int)Math.Ceiling(sizeInInches.Height * 1440);
formatRange.chrg.cpMin = 0;
formatRange.chrg.cpMax = -1;
var lParam = Marshal.AllocCoTaskMem(Marshal.SizeOf(formatRange));
Marshal.StructureToPtr(formatRange, lParam, false);
NativeMethods.SendMessage(richText.Handle, NativeMethods.EM_FORMATRANGE, 1, lParam);
Marshal.FreeCoTaskMem(lParam);
imageG.ReleaseHdc(formatRange.hdc);
}
g.ReleaseHdc(hdc);
return(image);
}
}
}