XForm.cs

#region PDFsharp - A .NET library for processing PDF
//
// Authors:
//   Stefan Lange
//
// Copyright (c) 2005-2016 empira Software GmbH, Cologne Area (Germany)
//
// http://www.PdfSharp.com
// http://sourceforge.net/projects/pdfsharp
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 
// DEALINGS IN THE SOFTWARE.
#endregion

using System;
using System.Diagnostics;
using PdfSharpCore.Drawing.Pdf;
using PdfSharpCore.Pdf;
using PdfSharpCore.Pdf.Advanced;

namespace PdfSharpCore.Drawing
{
    /// <summary>
    /// Represents a graphical object that can be used to render retained graphics on it.
    /// In GDI+ it is represented by a Metafile, in WPF by a DrawingVisual, and in PDF by a Form XObjects.
    /// </summary>
    public class XForm : XImage, IContentStream
    {
        internal enum FormState
        {
            /// <summary>
            /// The form is an imported PDF page.
            /// </summary>
            NotATemplate,

            /// <summary>
            /// The template is just created.
            /// </summary>
            Created,

            /// <summary>
            /// XGraphics.FromForm() was called.
            /// </summary>
            UnderConstruction,

            /// <summary>
            /// The form was drawn at least once and is 'frozen' now.
            /// </summary>
            Finished,
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="XForm"/> class.
        /// </summary>
        protected XForm()
        { }

        /// <summary>
        /// Initializes a new instance of the <see cref="XForm"/> class that represents a page of a PDF document.
        /// </summary>
        /// <param name="document">The PDF document.</param>
        /// <param name="viewBox">The view box of the page.</param>
        public XForm(PdfDocument document, XRect viewBox)
        {
            if (viewBox.Width < 1 || viewBox.Height < 1)
                throw new ArgumentNullException("viewBox", "The size of the XPdfForm is to small.");
            // I must tie the XPdfForm to a document immediately, because otherwise I would have no place where
            // to store the resources.
            if (document == null)
                throw new ArgumentNullException("document", "An XPdfForm template must be associated with a document at creation time.");

            _formState = FormState.Created;
            _document = document;
            _pdfForm = new PdfFormXObject(document, this);
            //_templateSize = size;
            _viewBox = viewBox;
            PdfRectangle rect = new PdfRectangle(viewBox);
            _pdfForm.Elements.SetRectangle(PdfFormXObject.Keys.BBox, rect);
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="XForm"/> class that represents a page of a PDF document.
        /// </summary>
        /// <param name="document">The PDF document.</param>
        /// <param name="size">The size of the page.</param>
        public XForm(PdfDocument document, XSize size)
            : this(document, new XRect(0, 0, size.Width, size.Height))
        {
            ////if (size.width < 1 || size.height < 1)
            ////  throw new ArgumentNullException("size", "The size of the XPdfForm is to small.");
            ////// I must tie the XPdfForm to a document immediately, because otherwise I would have no place where
            ////// to store the resources.
            ////if (document == null)
            ////  throw new ArgumentNullException("document", "An XPdfForm template must be associated with a document.");

            ////_formState = FormState.Created;
            ////_document = document;
            ////pdfForm = new PdfFormXObject(document, this);
            ////templateSize = size;
            ////PdfRectangle rect = new PdfRectangle(new XPoint(), size);
            ////pdfForm.Elements.SetRectangle(PdfFormXObject.Keys.BBox, rect);
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="XForm"/> class that represents a page of a PDF document.
        /// </summary>
        /// <param name="document">The PDF document.</param>
        /// <param name="width">The width of the page.</param>
        /// <param name="height">The height of the page</param>
        public XForm(PdfDocument document, XUnit width, XUnit height)
            : this(document, new XRect(0, 0, width, height))
        { }

        /// <summary>
        /// This function should be called when drawing the content of this form is finished.
        /// The XGraphics object used for drawing the content is disposed by this function and 
        /// cannot be used for any further drawing operations.
        /// PDFsharp automatically calls this function when this form was used the first time
        /// in a DrawImage function. 
        /// </summary>
        public void DrawingFinished()
        {
            if (_formState == FormState.Finished)
                return;

            if (_formState == FormState.NotATemplate)
                throw new InvalidOperationException("This object is an imported PDF page and you cannot finish drawing on it because you must not draw on it at all.");

            Finish();
        }

        /// <summary>
        /// Called from XGraphics constructor that creates an instance that work on this form.
        /// </summary>
        internal void AssociateGraphics(XGraphics gfx)
        {
            if (_formState == FormState.NotATemplate)
                throw new NotImplementedException("The current version of PDFsharp cannot draw on an imported page.");

            if (_formState == FormState.UnderConstruction)
                throw new InvalidOperationException("An XGraphics object already exists for this form.");

            if (_formState == FormState.Finished)
                throw new InvalidOperationException("After drawing a form it cannot be modified anymore.");

            Debug.Assert(_formState == FormState.Created);
            _formState = FormState.UnderConstruction;
            Gfx = gfx;
        }
        internal XGraphics Gfx;

        /// <summary>
        /// Disposes this instance.
        /// </summary>
        protected override void Dispose(bool disposing)
        {
            base.Dispose(disposing);
        }

        /// <summary>
        /// Sets the form in the state FormState.Finished.
        /// </summary>
        internal virtual void Finish()
        {
            if (_formState == FormState.NotATemplate || _formState == FormState.Finished)
                return;

            if (!(_formState == FormState.Created || _formState == FormState.UnderConstruction))
            {
                throw new InvalidOperationException("Expected the form to be Created or UnderConstruction");
            }

            _formState = FormState.Finished;
            Gfx.Dispose();
            Gfx = null;

            if (PdfRenderer != null)
            {
                //pdfForm.CreateStream(PdfEncoders.RawEncoding.GetBytes(PdfRenderer.GetContent()));
                PdfRenderer.Close();

                if (_document.Options.CompressContentStreams)
                {
                    _pdfForm.Stream.Value = Filtering.FlateDecode.Encode(_pdfForm.Stream.Value, _document.Options.FlateEncodeMode);
                    _pdfForm.Elements["/Filter"] = new PdfName("/FlateDecode");
                }
                int length = _pdfForm.Stream.Length;
                _pdfForm.Elements.SetInteger("/Length", length);
            }
        }

        /// <summary>
        /// Gets the owning document.
        /// </summary>
        internal PdfDocument Owner
        {
            get { return _document; }
        }
        PdfDocument _document;

        /// <summary>
        /// Gets the color model used in the underlying PDF document.
        /// </summary>
        internal PdfColorMode ColorMode
        {
            get
            {
                if (_document == null)
                    return PdfColorMode.Undefined;
                return _document.Options.ColorMode;
            }
        }

        /// <summary>
        /// Gets a value indicating whether this instance is a template.
        /// </summary>
        internal bool IsTemplate
        {
            get { return _formState != FormState.NotATemplate; }
        }
        internal FormState _formState;

        /// <summary>
        /// Get the width in point of this image.
        /// </summary>
        public override double PointWidth
        {
            //get { return templateSize.width; }
            get { return _viewBox.Width; }
        }

        /// <summary>
        /// Get the height in point of this image.
        /// </summary>
        public override double PointHeight
        {
            //get { return templateSize.height; }
            get { return _viewBox.Height; }
        }

        /// <summary>
        /// Get the width of the page identified by the property PageNumber.
        /// </summary>
        public override int PixelWidth
        {
            //get { return (int)templateSize.width; }
            get { return (int)_viewBox.Width; }
        }

        /// <summary>
        /// Get the height of the page identified by the property PageNumber.
        /// </summary>
        public override int PixelHeight
        {
            //get { return (int)templateSize.height; }
            get { return (int)_viewBox.Height; }
        }

        /// <summary>
        /// Get the size of the page identified by the property PageNumber.
        /// </summary>
        public override XSize Size
        {
            //get { return templateSize; }
            get { return _viewBox.Size; }
        }
        //XSize templateSize;

        /// <summary>
        /// Gets the view box of the form.
        /// </summary>
        public XRect ViewBox
        {
            get { return _viewBox; }
        }
        XRect _viewBox;

        /// <summary>
        /// Gets 72, the horizontal resolution by design of a form object.
        /// </summary>
        public override double HorizontalResolution
        {
            get { return 72; }
        }

        /// <summary>
        /// Gets 72 always, the vertical resolution by design of a form object.
        /// </summary>
        public override double VerticalResolution
        {
            get { return 72; }
        }

        /// <summary>
        /// Gets or sets the bounding box.
        /// </summary>
        public XRect BoundingBox
        {
            get { return _boundingBox; }
            set { _boundingBox = value; }  // TODO: pdfForm = null
        }
        XRect _boundingBox;

        /// <summary>
        /// Gets or sets the transformation matrix.
        /// </summary>
        public virtual XMatrix Transform
        {
            get { return _transform; }
            set
            {
                if (_formState == FormState.Finished)
                    throw new InvalidOperationException("After a XPdfForm was once drawn it must not be modified.");
                _transform = value;
            }
        }
        internal XMatrix _transform;

        internal PdfResources Resources
        {
            get
            {
                Debug.Assert(IsTemplate, "This function is for form templates only.");
                return PdfForm.Resources;
                //if (resources == null)
                //  resources = (PdfResources)pdfForm.Elements.GetValue(PdfFormXObject.Keys.Resources, VCF.Create); // VCF.CreateIndirect
                //return resources;
            }
        }
        //PdfResources resources;

        /// <summary>
        /// Implements the interface because the primary function is internal.
        /// </summary>
        PdfResources IContentStream.Resources
        {
            get { return Resources; }
        }

        /// <summary>
        /// Gets the resource name of the specified font within this form.
        /// </summary>
        internal string GetFontName(XFont font, out PdfFont pdfFont)
        {
            Debug.Assert(IsTemplate, "This function is for form templates only.");
            pdfFont = _document.FontTable.GetFont(font);
            Debug.Assert(pdfFont != null);
            string name = Resources.AddFont(pdfFont);
            return name;
        }

        string IContentStream.GetFontName(XFont font, out PdfFont pdfFont)
        {
            return GetFontName(font, out pdfFont);
        }

        /// <summary>
        /// Tries to get the resource name of the specified font data within this form.
        /// Returns null if no such font exists.
        /// </summary>
        internal string TryGetFontName(string idName, out PdfFont pdfFont)
        {
            Debug.Assert(IsTemplate, "This function is for form templates only.");
            pdfFont = _document.FontTable.TryGetFont(idName);
            string name = null;
            if (pdfFont != null)
                name = Resources.AddFont(pdfFont);
            return name;
        }

        /// <summary>
        /// Gets the resource name of the specified font data within this form.
        /// </summary>
        internal string GetFontName(string idName, byte[] fontData, out PdfFont pdfFont)
        {
            Debug.Assert(IsTemplate, "This function is for form templates only.");
            pdfFont = _document.FontTable.GetFont(idName, fontData);
            //pdfFont = new PdfType0Font(Owner, idName, fontData);
            //pdfFont.Document = _document;
            Debug.Assert(pdfFont != null);
            string name = Resources.AddFont(pdfFont);
            return name;
        }

        string IContentStream.GetFontName(string idName, byte[] fontData, out PdfFont pdfFont)
        {
            return GetFontName(idName, fontData, out pdfFont);
        }

        /// <summary>
        /// Gets the resource name of the specified image within this form.
        /// </summary>
        internal string GetImageName(XImage image)
        {
            Debug.Assert(IsTemplate, "This function is for form templates only.");
            PdfImage pdfImage = _document.ImageTable.GetImage(image);
            Debug.Assert(pdfImage != null);
            string name = Resources.AddImage(pdfImage);
            return name;
        }

        /// <summary>
        /// Implements the interface because the primary function is internal.
        /// </summary>
        string IContentStream.GetImageName(XImage image)
        {
            return GetImageName(image);
        }

        internal PdfFormXObject PdfForm
        {
            get
            {
                Debug.Assert(IsTemplate, "This function is for form templates only.");
                if (_pdfForm.Reference == null)
                    _document._irefTable.Add(_pdfForm);
                return _pdfForm;
            }
        }

        /// <summary>
        /// Gets the resource name of the specified form within this form.
        /// </summary>
        internal string GetFormName(XForm form)
        {
            Debug.Assert(IsTemplate, "This function is for form templates only.");
            PdfFormXObject pdfForm = _document.FormTable.GetForm(form);
            Debug.Assert(pdfForm != null);
            string name = Resources.AddForm(pdfForm);
            return name;
        }

        /// <summary>
        /// Implements the interface because the primary function is internal.
        /// </summary>
        string IContentStream.GetFormName(XForm form)
        {
            return GetFormName(form);
        }

        /// <summary>
        /// The PdfFormXObject gets invalid when PageNumber or transform changed. This is because a modification
        /// of an XPdfForm must not change objects that are already been drawn.
        /// </summary>
        internal PdfFormXObject _pdfForm;  // TODO: make private

        internal XGraphicsPdfRenderer PdfRenderer;

    }
}