vendor: import KillerPDF 1.7.5 source (GPL-3.0) as the base for MMD PDF

2026-08-27 06:58:22 +02:00
commit 532485a830
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+#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
+
+namespace PdfSharpCore.Drawing
+{
+    // In GDI+ the functions Save/Restore, BeginContainer/EndContainer, Transform, SetClip and ResetClip
+    // can be combined in any order. E.g. you can set a clip region, save the graphics state, empty the
+    // clip region and draw without clipping. Then you can restore to the previous clip region. With PDF
+    // this behavior is hard to implement. To solve this problem I first an automaton that keeps track
+    // of all clipping paths and the current transformation when the clip path was set. The automation
+    // manages a PDF graphics state stack to calculate the desired bahaviour. It also takes into consideration
+    // not to multiply with inverse matrixes when the user sets a new transformation matrix.
+    // After the design works on pager I decided not to implement it because it is much to large-scale.
+    // Instead I lay down some rules how to use the XGraphics class.
+    //
+    // * Before you set a transformation matrix save the graphics state (Save) or begin a new container
+    //   (BeginContainer).
+    // 
+    // * Instead of resetting the transformation matrix, call Restore or EndContainer. If you reset the
+    //   transformation, in PDF must be multiplied with the inverse matrix. That leads to round off errors
+    //   because in PDF file only 3 digits are used and Acrobat internally uses fixed point numbers (until
+    //   versioin 6 or 7 I think).
+    //
+    // * When no clip path is defined, you can set or intersect a new path.
+    //
+    // * When a clip path is already defined, you can always intersect with a new one (wich leads in general
+    //   to a smaller clip region).
+    //
+    // * When a clip path is already defined, you can only reset it to the empty region (ResetClip) when
+    //   the graphics state stack is at the same position as it had when the clip path was defined. Otherwise
+    //   an error occurs.
+    //
+    // Keeping these rules leads to easy to read code and best results in PDF output.
+
+    /// <summary>
+    /// Represents the internal state of an XGraphics object.
+    /// Used when the state is saved and restored.
+    /// </summary>
+    internal class InternalGraphicsState
+    {
+        public InternalGraphicsState(XGraphics gfx)
+        {
+            _gfx = gfx;
+        }
+
+        public InternalGraphicsState(XGraphics gfx, XGraphicsState state)
+        {
+            _gfx = gfx;
+            State = state;
+            State.InternalState = this;
+        }
+
+        public InternalGraphicsState(XGraphics gfx, XGraphicsContainer container)
+        {
+            _gfx = gfx;
+            container.InternalState = this;
+        }
+
+        /// <summary>
+        /// Gets or sets the current transformation matrix.
+        /// </summary>
+        public XMatrix Transform
+        {
+            get { return _transform; }
+            set { _transform = value; }
+        }
+        XMatrix _transform;
+
+        /// <summary>
+        /// Called after this instanced was pushed on the internal graphics stack.
+        /// </summary>
+        public void Pushed()
+        {
+        }
+
+        /// <summary>
+        /// Called after this instanced was popped from the internal graphics stack.
+        /// </summary>
+        public void Popped()
+        {
+            Invalid = true;
+        }
+
+        public bool Invalid;
+
+        readonly XGraphics _gfx;
+
+        internal XGraphicsState State;
+    }
+}