我尝试使用下面的代码将rtf文件转换为Jpg图像，但它返回的参数无效异常。
byte[] fileBytes = File.ReadAllBytes(filePath + extension);
MemoryStream ms = new MemoryStream(fileBytes);
Image img = Image.FromStream(ms, true, false);
img.Save(filePath + extension);
答案 0 :(得分：0)
您要做的是从文本文件中复制字节并将其插入图像中 你应该做什么，是从文本/ RTF /任何文件中读取字节，然后将转换为图像。
不幸的是，由于richtextbox不支持在内部执行此操作，因此有几种方法可以执行此操作。
方法1：覆盖RichTextBox
您可以覆盖经典的richtextbox，并执行以下操作：
using System;
using System.Drawing;
using System.Runtime.InteropServices;
using System.Windows.Forms;
using System.Drawing.Imaging;
using System.Text;
public static class Graphics_DrawRtfText
{
private static RichTextBoxDrawer rtfDrawer;
public static void DrawRtfText(this Graphics graphics, string rtf, RectangleF layoutArea,float xFactor)
{
if (Graphics_DrawRtfText.rtfDrawer == null)
{
Graphics_DrawRtfText.rtfDrawer = new RichTextBoxDrawer();
}
Graphics_DrawRtfText.rtfDrawer.Rtf = rtf;
Graphics_DrawRtfText.rtfDrawer.Draw(graphics, layoutArea,xFactor);
}
private class RichTextBoxDrawer : RichTextBox
{
//Code converted from code found here: http://support.microsoft.com/kb/812425/en-us
//Convert the unit used by the .NET framework (1/100 inch)
//and the unit used by Win32 API calls (twips 1/1440 inch)
private const double anInch = 14.4;
public void LineSpace()
{
SafeNativeMethods.PARAFORMAT2 fmt = new SafeNativeMethods.PARAFORMAT2();
fmt.cbSize = Marshal.SizeOf(fmt);
fmt.dwMask |= SafeNativeMethods.PFM_LINESPACING | SafeNativeMethods.PFM_SPACEAFTER;
fmt.dyLineSpacing = (int)(22 * this.SelectionFont.SizeInPoints); // in twips
// specify exact line spacing
fmt.bLineSpacingRule = Convert.ToByte(4);
SafeNativeMethods.SendMessage(this.Handle, SafeNativeMethods.EM_SETPARAFORMAT, 0, ref fmt); // 0 - to all text. 1 - only to seleted
}
public void LineSpace(int _linespace)
{
SafeNativeMethods.PARAFORMAT2 fmt = new SafeNativeMethods.PARAFORMAT2();
fmt.cbSize = Marshal.SizeOf(fmt);
fmt.dwMask |= SafeNativeMethods.PFM_LINESPACING | SafeNativeMethods.PFM_SPACEAFTER;
fmt.dyLineSpacing = _linespace; // in twips
// specify exact line spacing
fmt.bLineSpacingRule = Convert.ToByte(4);
SafeNativeMethods.SendMessage(this.Handle, SafeNativeMethods.EM_SETPARAFORMAT, 0, ref fmt); // 0 - to all text. 1 - only to seleted
}
protected override CreateParams CreateParams
{
get
{
CreateParams createParams = base.CreateParams;
if (SafeNativeMethods.LoadLibrary("msftedit.dll") != IntPtr.Zero)
{
createParams.ExStyle |= SafeNativeMethods.WS_EX_TRANSPARENT; // transparent
createParams.ClassName = "RICHEDIT50W";
}
return createParams;
}
}
private void DPToHIMETRIC(Graphics graphics,ref SizeF size)
{
size.Width = (size.Width * 2540.0f) / graphics.DpiX;
size.Height = (size.Height * 2540.0f) / graphics.DpiY;
}
public void Draw(Graphics graphics, RectangleF layoutArea, float xFactor)
{
System.Diagnostics.Debug.WriteLine("LayoutArea " + layoutArea);
SizeF metaSize = layoutArea.Size;
DPToHIMETRIC(graphics, ref metaSize);
System.Diagnostics.Debug.WriteLine("MetaSize " + metaSize);
IntPtr hdc = graphics.GetHdc();
//create a metafile, convert the size to himetrics
Metafile metafile = new Metafile(hdc, new RectangleF(0,0,metaSize.Width,metaSize.Height));
graphics.ReleaseHdc(hdc);
Graphics g = Graphics.FromImage(metafile);
IntPtr hDCEMF = g.GetHdc();
//Calculate the area to render.
SafeNativeMethods.RECT rectLayoutArea;
rectLayoutArea.Left = 0;
rectLayoutArea.Top = 0;
rectLayoutArea.Right = (int)((1440 * metaSize.Width + 2540 / 2) / 2540);
rectLayoutArea.Bottom = (int)((1440 * metaSize.Height + 2540 / 2) / 2540);
System.Diagnostics.Debug.WriteLine(String.Format("RectLayoutArea ({0},{1})",rectLayoutArea.Right,rectLayoutArea.Bottom));
SafeNativeMethods.FORMATRANGE fmtRange;
fmtRange.chrg.cpMax = -1; //Indicate character from to character to
fmtRange.chrg.cpMin = 0;
fmtRange.hdc = hDCEMF; //Use the same DC for measuring and rendering
fmtRange.hdcTarget = hDCEMF; //Point at printer hDC
fmtRange.rc = rectLayoutArea; //Indicate the area on page to print
fmtRange.rcPage = rectLayoutArea; //Indicate size of page
IntPtr wParam = IntPtr.Zero;
wParam = new IntPtr(1);
//Get the pointer to the FORMATRANGE structure in memory
IntPtr lParam = IntPtr.Zero;
lParam = Marshal.AllocCoTaskMem(Marshal.SizeOf(fmtRange));
Marshal.StructureToPtr(fmtRange, lParam, false);
SafeNativeMethods.SendMessage(this.Handle, SafeNativeMethods.EM_FORMATRANGE, wParam, lParam);
SafeNativeMethods.SendMessage(this.Handle, SafeNativeMethods.EM_FORMATRANGE, wParam, IntPtr.Zero);
//Free the block of memory allocated
Marshal.FreeCoTaskMem(lParam);
//Release the device context handle obtained by a previous call
g.ReleaseHdc(hDCEMF);
g.Dispose();
hdc = graphics.GetHdc();
int nHorzSize = SafeNativeMethods.GetDeviceCaps(hdc, SafeNativeMethods.DeviceCap.HORZSIZE);
int nVertSize = SafeNativeMethods.GetDeviceCaps(hdc, SafeNativeMethods.DeviceCap.VERTSIZE);
int nHorzRes = SafeNativeMethods.GetDeviceCaps(hdc, SafeNativeMethods.DeviceCap.HORZRES);
int nVertRes = SafeNativeMethods.GetDeviceCaps(hdc, SafeNativeMethods.DeviceCap.VERTRES);
int nLogPixelsX = SafeNativeMethods.GetDeviceCaps(hdc, SafeNativeMethods.DeviceCap.LOGPIXELSX);
int nLogPixelsY = SafeNativeMethods.GetDeviceCaps(hdc, SafeNativeMethods.DeviceCap.LOGPIXELSY);
graphics.ReleaseHdc(hdc);
float fHorzSizeInches = nHorzSize / 25.4f;
float fVertSizeInches = nVertSize / 25.4f;
float fHorzFudgeFactor = (nHorzRes / fHorzSizeInches) / nLogPixelsX;
float fVertFudgeFactor = (nVertRes / fVertSizeInches) / nLogPixelsY;
System.Diagnostics.Debug.WriteLine("Fudge Factor " + fHorzFudgeFactor.ToString() + " " + fVertFudgeFactor.ToString() + " XFactor " + xFactor.ToString());
Pen RedPen = new Pen(Color.Red);
graphics.DrawRectangle(RedPen, layoutArea.X * xFactor, layoutArea.Y * xFactor, layoutArea.Width * xFactor, layoutArea.Height * xFactor);
float Left = layoutArea.Left;
float Top = layoutArea.Top;
//layoutArea.X = layoutArea.Y = 0;
layoutArea.Offset(-Left, -Top);
layoutArea.Offset(Left / fHorzFudgeFactor, Top / fVertFudgeFactor);
System.Drawing.Drawing2D.GraphicsState state = graphics.Save();
graphics.ScaleTransform(fHorzFudgeFactor * xFactor, fVertFudgeFactor * xFactor);
graphics.DrawImage(metafile, layoutArea);
graphics.Restore(state);
System.Diagnostics.Debug.WriteLine("Layout Aread : "+layoutArea);
}
#region SafeNativeMethods
private static class SafeNativeMethods
{
[DllImport("USER32.dll")]
public static extern IntPtr SendMessage(IntPtr hWnd, int msg, IntPtr wp, IntPtr lp);
[DllImport("kernel32.dll", CharSet = CharSet.Auto)]
public static extern IntPtr LoadLibrary(string lpFileName);
[DllImport("gdi32.dll")]
public static extern int GetDeviceCaps(IntPtr hdc, DeviceCap nIndex);
[DllImport("user32.dll", EntryPoint = "SendMessage", CharSet = CharSet.Auto)]
public static extern int SendMessage(IntPtr hWnd, int msg, int wParam, ref PARAFORMAT2 lParam);
[StructLayout(LayoutKind.Sequential)]
public struct RECT
{
public int Left;
public int Top;
public int Right;
public int Bottom;
}
[StructLayout(LayoutKind.Sequential)]
public struct CHARRANGE
{
public int cpMin; //First character of range (0 for start of doc)
public int cpMax; //Last character of range (-1 for end of doc)
}
[StructLayout(LayoutKind.Sequential)]
public struct FORMATRANGE
{
public IntPtr hdc; //Actual DC to draw on
public IntPtr hdcTarget; //Target DC for determining text formatting
public RECT rc; //Region of the DC to draw to (in twips)
public RECT rcPage; //Region of the whole DC (page size) (in twips)
public CHARRANGE chrg; //Range of text to draw (see earlier declaration)
}
public enum DeviceCap : int
{
/// <summary>
/// Device driver version
/// </summary>
DRIVERVERSION = 0,
/// <summary>
/// Device classification
/// </summary>
TECHNOLOGY = 2,
/// <summary>
/// Horizontal size in millimeters
/// </summary>
HORZSIZE = 4,
/// <summary>
/// Vertical size in millimeters
/// </summary>
VERTSIZE = 6,
/// <summary>
/// Horizontal width in pixels
/// </summary>
HORZRES = 8,
/// <summary>
/// Vertical height in pixels
/// </summary>
VERTRES = 10,
/// <summary>
/// Number of bits per pixel
/// </summary>
BITSPIXEL = 12,
/// <summary>
/// Number of planes
/// </summary>
PLANES = 14,
/// <summary>
/// Number of brushes the device has
/// </summary>
NUMBRUSHES = 16,
/// <summary>
/// Number of pens the device has
/// </summary>
NUMPENS = 18,
/// <summary>
/// Number of markers the device has
/// </summary>
NUMMARKERS = 20,
/// <summary>
/// Number of fonts the device has
/// </summary>
NUMFONTS = 22,
/// <summary>
/// Number of colors the device supports
/// </summary>
NUMCOLORS = 24,
/// <summary>
/// Size required for device descriptor
/// </summary>
PDEVICESIZE = 26,
/// <summary>
/// Curve capabilities
/// </summary>
CURVECAPS = 28,
/// <summary>
/// Line capabilities
/// </summary>
LINECAPS = 30,
/// <summary>
/// Polygonal capabilities
/// </summary>
POLYGONALCAPS = 32,
/// <summary>
/// Text capabilities
/// </summary>
TEXTCAPS = 34,
/// <summary>
/// Clipping capabilities
/// </summary>
CLIPCAPS = 36,
/// <summary>
/// Bitblt capabilities
/// </summary>
RASTERCAPS = 38,
/// <summary>
/// Length of the X leg
/// </summary>
ASPECTX = 40,
/// <summary>
/// Length of the Y leg
/// </summary>
ASPECTY = 42,
/// <summary>
/// Length of the hypotenuse
/// </summary>
ASPECTXY = 44,
/// <summary>
/// Shading and Blending caps
/// </summary>
SHADEBLENDCAPS = 45,
/// <summary>
/// Logical pixels inch in X
/// </summary>
LOGPIXELSX = 88,
/// <summary>
/// Logical pixels inch in Y
/// </summary>
LOGPIXELSY = 90,
/// <summary>
/// Number of entries in physical palette
/// </summary>
SIZEPALETTE = 104,
/// <summary>
/// Number of reserved entries in palette
/// </summary>
NUMRESERVED = 106,
/// <summary>
/// Actual color resolution
/// </summary>
COLORRES = 108,
// Printing related DeviceCaps. These replace the appropriate Escapes
/// <summary>
/// Physical Width in device units
/// </summary>
PHYSICALWIDTH = 110,
/// <summary>
/// Physical Height in device units
/// </summary>
PHYSICALHEIGHT = 111,
/// <summary>
/// Physical Printable Area x margin
/// </summary>
PHYSICALOFFSETX = 112,
/// <summary>
/// Physical Printable Area y margin
/// </summary>
PHYSICALOFFSETY = 113,
/// <summary>
/// Scaling factor x
/// </summary>
SCALINGFACTORX = 114,
/// <summary>
/// Scaling factor y
/// </summary>
SCALINGFACTORY = 115,
/// <summary>
/// Current vertical refresh rate of the display device (for displays only) in Hz
/// </summary>
VREFRESH = 116,
/// <summary>
/// Horizontal width of entire desktop in pixels
/// </summary>
DESKTOPVERTRES = 117,
/// <summary>
/// Vertical height of entire desktop in pixels
/// </summary>
DESKTOPHORZRES = 118,
/// <summary>
/// Preferred blt alignment
/// </summary>
BLTALIGNMENT = 119
}
public struct PARAFORMAT2
{
public int cbSize;
public uint dwMask;
public short wNumbering;
public short wReserved;
public int dxStartIndent;
public int dxRightIndent;
public int dxOffset;
public short wAlignment;
public short cTabCount;
[MarshalAs(UnmanagedType.ByValArray, SizeConst = 32)]
public int[] rgxTabs;
// PARAFORMAT2 from here onwards.
public int dySpaceBefore;
public int dySpaceAfter;
public int dyLineSpacing;
public short sStyle;
public byte bLineSpacingRule;
public byte bOutlineLevel;
public short wShadingWeight;
public short wShadingStyle;
public short wNumberingStart;
public short wNumberingStyle;
public short wNumberingTab;
public short wBorderSpace;
public short wBorderWidth;
public short wBorders;
}
public const int EM_FORMATRANGE = WM_USER + 57;
public const int PFM_SPACEAFTER = 128;
public const int PFM_LINESPACING = 256;
public const int EM_SETPARAFORMAT = 1095;
public const int WM_USER = 0x0400;
public const int WS_EX_TRANSPARENT = 0x20;
}
#endregion
}
}
方法2：将控件中的纯文本转换为图像
这是一篇精彩的文章，可以帮助您自己实现整个事情：CodeProject Article