【pdf转换成jpg】pdf转换成jpg示例分享

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pdf转换成jpg示例分享

using System; 
using System.Collections.Generic; 
using System.Text; 
using System.Runtime.InteropServices; 
using System.Collections; 
 
namespace ConvertPDF 
{ 
    /// <summary> 
    ///  
    /// Class to convert a pdf to an image using GhostScript DLL 
    /// Credit for this code go to:Rangel Avulso 
    /// i only fix a little bug and refactor a little 
    /// http://www.hrangel.com.br/index.php/2006/12/04/converter-pdf-para-imagem-jpeg-em-c/ 
    /// </summary> 
    /// <seealso cref="http://www.hrangel.com.br/index.php/2006/12/04/converter-pdf-para-imagem-jpeg-em-c/"/> 
    class PDFConvert 
    { 
        #region GhostScript Import 
        /// <summary>Create a new instance of Ghostscript. This instance is passed to most other gsapi functions. The caller_handle will be provided to callback functions. 
        ///  At this stage, Ghostscript supports only one instance. </summary> 
        /// <param name="pinstance"></param> 
        /// <param name="caller_handle"></param> 
        /// <returns></returns> 
        [DllImport("gsdll32.dll", EntryPoint="gsapi_new_instance")] 
        private static extern int gsapi_new_instance (out IntPtr pinstance, IntPtr caller_handle); 
        /// <summary>This is the important function that will perform the conversion</summary> 
        /// <param name="instance"></param> 
        /// <param name="argc"></param> 
        /// <param name="argv"></param> 
        /// <returns></returns> 
        [DllImport("gsdll32.dll", EntryPoint="gsapi_init_with_args")] 
        private static extern int gsapi_init_with_args (IntPtr instance, int argc, IntPtr argv); 
        /// <summary> 
        /// Exit the interpreter. This must be called on shutdown if gsapi_init_with_args() has been called, and just before gsapi_delete_instance().  
        /// </summary> 
        /// <param name="instance"></param> 
        /// <returns></returns> 
        [DllImport("gsdll32.dll", EntryPoint="gsapi_exit")] 
        private static extern int gsapi_exit (IntPtr instance); 
        /// <summary> 
        /// Destroy an instance of Ghostscript. Before you call this, Ghostscript must have finished. If Ghostscript has been initialised, you must call gsapi_exit before gsapi_delete_instance.  
        /// </summary> 
        /// <param name="instance"></param> 
        [DllImport("gsdll32.dll", EntryPoint="gsapi_delete_instance")] 
        private static extern void gsapi_delete_instance (IntPtr instance); 
        #endregion 
        #region Variables 
        private string _sDeviceFormat; 
        private int _iWidth; 
        private int _iHeight; 
        private int _iResolutionX; 
        private int _iResolutionY; 
        private int _iJPEGQuality; 
        private Boolean _bFitPage; 
        private IntPtr _objHandle; 
        #endregion 
        #region Proprieties 
        public string OutputFormat 
        { 
            get { return _sDeviceFormat; } 
            set { _sDeviceFormat=value; } 
        } 
        public int Width 
        { 
            get { return _iWidth; } 
            set { _iWidth=value; } 
        } 
        public int Height 
        { 
            get { return _iHeight; } 
            set { _iHeight=value; } 
        } 
        public int ResolutionX 
        { 
            get { return _iResolutionX; } 
            set { _iResolutionX=value; } 
        } 
        public int ResolutionY 
        { 
            get { return _iResolutionY; } 
            set { _iResolutionY=value; } 
        } 
        public Boolean FitPage 
        { 
            get { return _bFitPage; } 
            set { _bFitPage=value; } 
        } 
        /// <summary>Quality of compression of JPG</summary> 
        public int JPEGQuality 
        { 
            get { return _iJPEGQuality; } 
            set { _iJPEGQuality=value; } 
        } 
        #endregion 
        #region Init 
        public PDFConvert(IntPtr objHandle) 
        { 
            _objHandle=objHandle; 
        } 
        public PDFConvert() 
        { 
            _objHandle=IntPtr.Zero; 
        } 
        #endregion 
        private byte[] StringToAnsiZ(string str) 
        { 
            //' Convert a Unicode string to a null terminated Ansi string for Ghostscript. 
            //' The result is stored in a byte array. Later you will need to convert 
            //' this byte array to a pointer with GCHandle.Alloc(XXXX, GCHandleType.Pinned) 
            //' and GSHandle.AddrOfPinnedObject() 
            int intElementCount; 
            int intCounter; 
            byte[] aAnsi; 
            byte bChar; 
            intElementCount=str.Length; 
            aAnsi=new byte[intElementCount+1]; 
            for(intCounter=0; intCounter < intElementCount;intCounter++) 
            { 
                bChar=(byte)str[intCounter]; 
                aAnsi[intCounter]=bChar; 
            } 
            aAnsi[intElementCount]=0; 
            return aAnsi; 
        } 
        /// <summary>Convert the file!</summary> 
        public void Convert(string inputFile,string outputFile, 
            int firstPage, int lastPage, string deviceFormat, int width, int height) 
        { 
            //Avoid to work when the file doesn't exist 
            if (!System.IO.File.Exists(inputFile)) 
            { 
                System.Windows.Forms.MessageBox.Show(string.Format("The file :'{0}' doesn't exist",inputFile)); 
                return; 
            } 
            int intReturn; 
            IntPtr intGSInstanceHandle; 
            object[] aAnsiArgs; 
            IntPtr[] aPtrArgs; 
            GCHandle[] aGCHandle; 
            int intCounter; 
            int intElementCount; 
            IntPtr callerHandle; 
            GCHandle gchandleArgs; 
            IntPtr intptrArgs; 
            string[] sArgs=GetGeneratedArgs(inputFile,outputFile, 
                firstPage, lastPage, deviceFormat, width, height); 
            // Convert the Unicode strings to null terminated ANSI byte arrays 
            // then get pointers to the byte arrays. 
            intElementCount=sArgs.Length; 
            aAnsiArgs=new object[intElementCount]; 
            aPtrArgs=new IntPtr[intElementCount]; 
            aGCHandle=new GCHandle[intElementCount]; 
            // Create a handle for each of the arguments after  
            // they've been converted to an ANSI null terminated 
            // string. Then store the pointers for each of the handles 
            for(intCounter=0; intCounter< intElementCount; intCounter++) 
            { 
                aAnsiArgs[intCounter]=StringToAnsiZ(sArgs[intCounter]); 
                aGCHandle[intCounter]=GCHandle.Alloc(aAnsiArgs[intCounter], GCHandleType.Pinned); 
                aPtrArgs[intCounter]=aGCHandle[intCounter].AddrOfPinnedObject(); 
            } 
            // Get a new handle for the array of argument pointers 
            gchandleArgs=GCHandle.Alloc(aPtrArgs, GCHandleType.Pinned); 
            intptrArgs=gchandleArgs.AddrOfPinnedObject(); 
            intReturn=gsapi_new_instance(out intGSInstanceHandle, _objHandle); 
            callerHandle=IntPtr.Zero; 
            try 
            { 
                intReturn=gsapi_init_with_args(intGSInstanceHandle, intElementCount, intptrArgs); 
            } 
            catch (Exception ex) 
            { 
                //System.Windows.Forms.MessageBox.Show(ex.Message); 

            } 
            finally 
            { 
                for (intCounter=0; intCounter < intReturn; intCounter++) 
                { 
                    aGCHandle[intCounter].Free(); 
                } 
                gchandleArgs.Free(); 
                gsapi_exit(intGSInstanceHandle); 
                gsapi_delete_instance(intGSInstanceHandle); 
            } 
        } 
        private string[] GetGeneratedArgs(string inputFile, string outputFile, 
            int firstPage, int lastPage, string deviceFormat, int width, int height) 
        { 
            this._sDeviceFormat=deviceFormat; 
            this._iResolutionX=width; 
            this._iResolutionY=height; 
            // Count how many extra args are need - HRangel - 11/29/2006, 3:13:43 PM 
            ArrayList lstExtraArgs=new ArrayList(); 
            if ( _sDeviceFormat=="jpg" && _iJPEGQuality > 0 && _iJPEGQuality < 101) 
                lstExtraArgs.Add("-dJPEGQ=" + _iJPEGQuality); 
            if (_iWidth > 0 && _iHeight > 0) 
                lstExtraArgs.Add("-g" + _iWidth + "x" + _iHeight); 
            if (_bFitPage) 
                lstExtraArgs.Add("-dPDFFitPage"); 
            if (_iResolutionX > 0) 
            { 
                if (_iResolutionY > 0) 
                    lstExtraArgs.Add("-r" + _iResolutionX + "x" + _iResolutionY); 
                else 
                    lstExtraArgs.Add("-r" + _iResolutionX); 
            } 
            // Load Fixed Args - HRangel - 11/29/2006, 3:34:02 PM 
            int iFixedCount=17; 
            int iExtraArgsCount=lstExtraArgs.Count; 
            string[] args=new string[iFixedCount + lstExtraArgs.Count]; 
             
            args[0]="pdf2img";//this parameter have little real use 
            args[1]="-dNOPAUSE";//I don't want interruptions 
            args[2]="-dBATCH";//stop after 
            //args[3]="-dSAFER"; 
            args[3]="-dPARANOIDSAFER"; 
            args[4]="-sDEVICE="+_sDeviceFormat;//what kind of export format i should provide 
            args[5]="-q"; 
            args[6]="-dQUIET"; 
            args[7]="-dNOPROMPT"; 
            args[8]="-dMaxBitmap=500000000"; 
            args[9]=String.Format("-dFirstPage={0}", firstPage); 
            args[10]=String.Format("-dLastPage={0}", lastPage); 
            args[11]="-dAlignToPixels=0"; 
            args[12]="-dGridFitTT=0"; 
            args[13]="-dTextAlphaBits=4"; 
            args[14]="-dGraphicsAlphaBits=4"; 
            //For a complete list watch here: 
            //http://pages.cs.wisc.edu/~ghost/doc/cvs/Devices.htm 
            //Fill the remaining parameters 
            for (int i=0; i < iExtraArgsCount; i++) 
            { 
                args[15+i]=(string) lstExtraArgs[i]; 
            } 
            //Fill outputfile and inputfile 
            args[15 + iExtraArgsCount]=string.Format("-sOutputFile={0}",outputFile); 
            args[16 + iExtraArgsCount]=string.Format("{0}",inputFile); 
            return args; 
        } 
        public void pdf2jpgTest() 
        {             
            this.Convert(@"C://tmp//pdfimg//test1.pdf",@"C://tmp//pdfimg//out.jpg",1,1,"jpeg",100,100); 
            //this.Convert(@"C://tmp//pdfimg//test.pdf", @"C://tmp//pdfimg//out2.jpg", 291, 291, "jpeg", 800, 800); 
        } 
    } 
} 

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