SvgVisualElement.cs

using System;
using System.Collections.Generic;
using System.Text;
using System.Xml;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Xml.Serialization;
using System.ComponentModel;
using System.Diagnostics;

namespace Svg
{
    /// <summary>
    /// The class that all SVG elements should derive from when they are to be rendered.
    /// </summary>
    public abstract partial class SvgVisualElement : SvgElement, ISvgStylable, ISvgClipable
    {
        private bool _dirty;
        private bool _requiresSmoothRendering;
        private Region _previousClip;

        /// <summary>
        /// Gets the <see cref="GraphicsPath"/> for this element.
        /// </summary>
        public abstract GraphicsPath Path { get; }
        /// <summary>
        /// Gets the bounds of the element.
        /// </summary>
        /// <value>The bounds.</value>
        public abstract RectangleF Bounds { get; }

        /// <summary>
        /// Gets or sets a value indicating whether this element's <see cref="Path"/> is dirty.
        /// </summary>
        /// <value>
        /// 	<c>true</c> if the path is dirty; otherwise, <c>false</c>.
        /// </value>
        protected virtual bool IsPathDirty
        {
            get { return this._dirty; }
            set { this._dirty = value; }
        }

        /// <summary>
        /// Gets the associated <see cref="SvgClipPath"/> if one has been specified.
        /// </summary>
        [SvgAttribute("clip-path")]
        public virtual Uri ClipPath
        {
            get { return this.Attributes.GetAttribute<Uri>("clip-path"); }
            set { this.Attributes["clip-path"] = value; }
        }

        /// <summary>
        /// Gets or sets the algorithm which is to be used to determine the clipping region.
        /// </summary>
        [SvgAttribute("clip-rule")]
        public SvgClipRule ClipRule
        {
            get { return this.Attributes.GetAttribute<SvgClipRule>("clip-rule", SvgClipRule.NonZero); }
            set { this.Attributes["clip-rule"] = value; }
        }

        /// <summary>
        /// Gets or sets a value to determine if anti-aliasing should occur when the element is being rendered.
        /// </summary>
        protected virtual bool RequiresSmoothRendering
        {
            get { return this._requiresSmoothRendering; }
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="SvgGraphicsElement"/> class.
        /// </summary>
        public SvgVisualElement()
        {
            this._dirty = true;
            this._requiresSmoothRendering = false;
            this.Fill = new SvgColourServer(); //in case fill attribute is not set by xml, default fill is black
        }

        /// <summary>
        /// Renders the <see cref="SvgElement"/> and contents to the specified <see cref="Graphics"/> object.
        /// </summary>
        /// <param name="graphics">The <see cref="SvgRenderer"/> object to render to.</param>
        protected override void Render(SvgRenderer renderer)
        {
            if (this.Path != null && this.Visible)
            {
                this.PushTransforms(renderer);
                this.SetClip(renderer);

                // If this element needs smoothing enabled turn anti-aliasing on
                if (this.RequiresSmoothRendering)
                {
                    renderer.SmoothingMode = SmoothingMode.AntiAlias;
                }

                this.RenderFill(renderer);
                this.RenderStroke(renderer);

                // Reset the smoothing mode
                if (this.RequiresSmoothRendering && renderer.SmoothingMode == SmoothingMode.AntiAlias)
                {
                    renderer.SmoothingMode = SmoothingMode.Default;
                }

                this.ResetClip(renderer);
                this.PopTransforms(renderer);
            }
        }

        /// <summary>
        /// Renders the fill of the <see cref="SvgVisualElement"/> to the specified <see cref="SvgRenderer"/>
        /// </summary>
        /// <param name="renderer">The <see cref="SvgRenderer"/> object to render to.</param>
        protected internal virtual void RenderFill(SvgRenderer renderer)
        {
            if (this.Fill != null)
            {
                using (Brush brush = this.Fill.GetBrush(this, this.FillOpacity))
                {
                    if (brush != null)
                    {
                    	this.Path.FillMode = this.FillRule == SvgFillRule.NonZero ? FillMode.Winding : FillMode.Alternate;
                        renderer.FillPath(brush, this.Path);
                    }
                }
            }
        }

        /// <summary>
        /// Renders the stroke of the <see cref="SvgVisualElement"/> to the specified <see cref="SvgRenderer"/>
        /// </summary>
        /// <param name="renderer">The <see cref="SvgRenderer"/> object to render to.</param>
        protected internal virtual void RenderStroke(SvgRenderer renderer)
        {
            if (this.Stroke != null)
            {
                float strokeWidth = this.StrokeWidth.ToDeviceValue(this);
                using (var pen = new Pen(this.Stroke.GetBrush(this, this.StrokeOpacity), strokeWidth))
                {
                    if (this.StrokeDashArray != null && this.StrokeDashArray.Count > 0)
                    {
                        /* divide by stroke width - GDI behaviour that I don't quite understand yet.*/
                        pen.DashPattern = this.StrokeDashArray.ConvertAll(u => u.Value/((strokeWidth <= 0) ? 1 : strokeWidth)).ToArray();
                    }

                    renderer.DrawPath(pen, this.Path);
                }
            }
        }

        /// <summary>
        /// Sets the clipping region of the specified <see cref="SvgRenderer"/>.
        /// </summary>
        /// <param name="renderer">The <see cref="SvgRenderer"/> to have its clipping region set.</param>
        protected internal virtual void SetClip(SvgRenderer renderer)
        {
            if (this.ClipPath != null)
            {
                SvgClipPath clipPath = this.OwnerDocument.GetElementById<SvgClipPath>(this.ClipPath.ToString());
                this._previousClip = renderer.Clip;

                if (clipPath != null)
                {
                    renderer.Clip = clipPath.GetClipRegion(this);
                }
            }
        }

        /// <summary>
        /// Resets the clipping region of the specified <see cref="SvgRenderer"/> back to where it was before the <see cref="SetClip"/> method was called.
        /// </summary>
        /// <param name="renderer">The <see cref="SvgRenderer"/> to have its clipping region reset.</param>
        protected internal virtual void ResetClip(SvgRenderer renderer)
        {
            if (this._previousClip != null)
            {
                renderer.Clip = this._previousClip;
                this._previousClip = null;
            }
        }

        /// <summary>
        /// Sets the clipping region of the specified <see cref="SvgRenderer"/>.
        /// </summary>
        /// <param name="renderer">The <see cref="SvgRenderer"/> to have its clipping region set.</param>
        void ISvgClipable.SetClip(SvgRenderer renderer)
        {
            this.SetClip(renderer);
        }

        /// <summary>
        /// Resets the clipping region of the specified <see cref="SvgRenderer"/> back to where it was before the <see cref="SetClip"/> method was called.
        /// </summary>
        /// <param name="renderer">The <see cref="SvgRenderer"/> to have its clipping region reset.</param>
        void ISvgClipable.ResetClip(SvgRenderer renderer)
        {
            this.ResetClip(renderer);
        }
    }
}