SvgVisualElement.cs

using System;
using System.Drawing;
using System.Drawing.Drawing2D;

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, ISvgBoundable, 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(SvgRenderer renderer);

        PointF ISvgBoundable.Location
        {
            get
            {
                return Bounds.Location;
            }
        }

        SizeF ISvgBoundable.Size
        {
            get
            {
                return Bounds.Size;
            }
        }

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

        protected virtual bool Renderable { get { return true; } }

        /// <summary>
        /// Renders the <see cref="SvgElement"/> and contents to the specified <see cref="Graphics"/> object.
        /// </summary>
        /// <param name="renderer">The <see cref="SvgRenderer"/> object to render to.</param>
        protected override void Render(SvgRenderer renderer)
        {
            this.Render(renderer, true);
        }

        private void Render(SvgRenderer renderer, bool renderFilter)
        {
            if (this.Visible && this.Displayable && this.PushTransforms(renderer) &&
                (!Renderable || this.Path(renderer) != null))
            {
                bool renderNormal = true;

                if (renderFilter && this.Filter != null)
                {
                    var filter = this.OwnerDocument.IdManager.GetElementById(this.Filter) as FilterEffects.SvgFilter;
                    if (filter != null)
                    {
                        this.PopTransforms(renderer);
                        filter.ApplyFilter(this, renderer, (r) => this.Render(r, false));
                        renderNormal = false;
                    }
                }


                if (renderNormal)
                {
                    this.SetClip(renderer);

                    if (Renderable)
                    {
                        // 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;
                        }
                    }
                    else
                    {
                        base.RenderChildren(renderer);
                    }

                    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, renderer, Math.Min(Math.Max(this.FillOpacity * this.Opacity, 0), 1)))
                {
                    if (brush != null)
                    {
                        this.Path(renderer).FillMode = this.FillRule == SvgFillRule.NonZero ? FillMode.Winding : FillMode.Alternate;
                        renderer.FillPath(brush, this.Path(renderer));
                    }
                }
            }
        }

        /// <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(renderer, UnitRenderingType.Other, this);
                using (var pen = new Pen(this.Stroke.GetBrush(this, renderer, Math.Min(Math.Max(this.StrokeOpacity * this.Opacity, 0), 1)), 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 <= 0) ? 1 : u.Value) / ((strokeWidth <= 0) ? 1 : strokeWidth)).ToArray();
                    }

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

        /// <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.AddClip(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);
        }

        public override SvgElement DeepCopy<T>()
        {
            var newObj = base.DeepCopy<T>() as SvgVisualElement;
            newObj.ClipPath = this.ClipPath;
            newObj.ClipRule = this.ClipRule;
            newObj.Filter = this.Filter;

            newObj.Visible = this.Visible;
            if (this.Fill != null)
                newObj.Fill = this.Fill;
            if (this.Stroke != null)
                newObj.Stroke = this.Stroke;
            newObj.FillRule = this.FillRule;
            newObj.FillOpacity = this.FillOpacity;
            newObj.StrokeWidth = this.StrokeWidth;
            newObj.StrokeLineCap = this.StrokeLineCap;
            newObj.StrokeLineJoin = this.StrokeLineJoin;
            newObj.StrokeMiterLimit = this.StrokeMiterLimit;
            newObj.StrokeDashArray = this.StrokeDashArray;
            newObj.StrokeDashOffset = this.StrokeDashOffset;
            newObj.StrokeOpacity = this.StrokeOpacity;
            newObj.Opacity = this.Opacity;

            return newObj;
        }

    }
}