LinearGradientBrush Problem

[paulushub]

I am trying to open the following SVG file after downloading from: http://upload.wikimedia.org/wikipedia/commons/1/15/Boiling_water_reactor_english.svg

The "GdiTestSvgViewer" reports incorrectly the LinearGradientBrush, if it is 'vertical'. However the 'horizontal' LGB is ok.

Also the 'arrow-head' is incorrectly rendered.

I have downloaded the the change-set 19058.

Attached is the rendered image.

Attachments

boiler.jpg

This work item was migrated from CodePlex

CodePlex work item ID: '1438'
Vote count: '2'

[paulushub]

[tanveerakl@2013/03/01]
Following Code change seems to render the LinearGradient Properly.

But still the "pipe4.svg" in Issue: 434, radial parts is not getting rendered. Also, this should work with fractional angles of linear gradient.

Also the http://en.wikipedia.org/wiki/File:COGAS_diagram.svg does not render the gradient properly, because there seems to be no provision for "pad" spreadmethod in GDI+. Or am I missing something?

    private LinearGradientBrush GetLinearGradientBrush(SvgLinearGradientElement res, RectangleF bounds)
    {
        float fLeft = (float)res.X1.AnimVal.Value;
        float fRight = (float)res.X2.AnimVal.Value;
        float fTop = (float)res.Y1.AnimVal.Value;
        float fBottom = (float)res.Y2.AnimVal.Value;

        #region code by tanveerakl

        PointF[] pa = new PointF[] { new PointF(fLeft, fTop), new PointF(fRight, fBottom) };

        Matrix m = GetTransformMatrix(res);
        m.TransformPoints(pa);

        LinearGradientBrush brush = new LinearGradientBrush(pa[0], pa[1], Color.White, Color.White);

        #endregion

        bool bForceUserSpaceOnUse = (fLeft > 1 || fRight > 1 || fTop > 1 || fBottom > 1);

        //float fEffectiveLeft = fLeft;
        //float fEffectiveRight = fRight;
        //float fEffectiveTop = fTop;
        //float fEffectiveBottom = fBottom;

        //if (res.GradientUnits.AnimVal.Equals((ushort)SvgUnitType.ObjectBoundingBox) && !bForceUserSpaceOnUse)
        //{
        //    if (res.SpreadMethod.AnimVal.Equals((ushort)SvgSpreadMethod.Pad))
        //    {
        //        fEffectiveRight = bounds.Right;
        //        fEffectiveLeft = bounds.Left;
        //    }
        //    else
        //    {
        //        fEffectiveLeft = bounds.Left + fLeft * (bounds.Width);
        //        fEffectiveRight = bounds.Left + fRight * (bounds.Width);
        //    }

        //    fEffectiveTop = bounds.Top + fTop * (bounds.Height);
        //    fEffectiveBottom = bounds.Top + fBottom * (bounds.Height);
        //}

        //LinearGradientMode mode = LinearGradientMode.Horizontal;

        //if (fTop == fBottom)
        //{
        //    mode = LinearGradientMode.Horizontal;
        //}
        //else
        //{
        //    if (fLeft == fRight)
        //    {
        //        mode = LinearGradientMode.Vertical;
        //    }
        //    else
        //    {
        //        if (fLeft < fRight)
        //            mode = LinearGradientMode.ForwardDiagonal;
        //        else
        //            mode = LinearGradientMode.BackwardDiagonal;
        //    }
        //}

        //float fEffectiveWidth = fEffectiveRight - fEffectiveLeft;

        //if (fEffectiveWidth <= 0)
        //    fEffectiveWidth = bounds.Width;

        //float fEffectiveHeight = fEffectiveBottom - fEffectiveTop;

        //if (fEffectiveHeight <= 0)
        //    fEffectiveHeight = bounds.Height;

        //LinearGradientBrush brush = new LinearGradientBrush(new RectangleF(fEffectiveLeft - 1,
        //    fEffectiveTop - 1, fEffectiveWidth + 2, fEffectiveHeight + 2),
        //    Color.White, Color.White, mode);

        XmlNodeList stops = res.Stops;

        ColorBlend cb = new ColorBlend();

        List<Color> adjcolors = new List<Color>();
        List<float> adjpositions = new List<float>();
        GetColorsAndPositions(stops, adjpositions, adjcolors);

        if (res.GradientUnits.AnimVal.Equals((ushort)SvgUnitType.ObjectBoundingBox) && !bForceUserSpaceOnUse)
        {
            if (res.SpreadMethod.AnimVal.Equals((ushort)SvgSpreadMethod.Pad))
            {
                for (int i = 0; i < adjpositions.Count; i++)
                {
                    if (fLeft == fRight)
                        adjpositions[i] = fTop + adjpositions[i] * (fBottom - fTop);
                    else
                        adjpositions[i] = fLeft + adjpositions[i] * (fRight - fLeft);
                }

                // this code corrects the values again... fix
                int nSize = adjcolors.Count;

                if (adjpositions[0] > 0.0)
                    ++nSize;

                if (adjpositions[adjcolors.Count - 1] < 1)
                    ++nSize;

                Color[] readjcolors = new Color[nSize];
                float[] readjpositions = new float[nSize];

                if (adjpositions[0] > 0.0)
                {
                    adjpositions.CopyTo(readjpositions, 1);
                    adjcolors.CopyTo(readjcolors, 1);

                    readjcolors[0] = readjcolors[1];
                    readjpositions[0] = 0;
                }
                else
                {
                    adjpositions.CopyTo(readjpositions, 0);
                    adjcolors.CopyTo(readjcolors, 0);
                }

                if (adjpositions[adjcolors.Count - 1] < 1)
                {
                    readjcolors[nSize - 1] = readjcolors[nSize - 2];
                    readjpositions[nSize - 1] = 1;
                }

                cb.Colors = readjcolors;
                cb.Positions = readjpositions;
            }
            else
            {
                cb.Colors = adjcolors.ToArray();
                cb.Positions = adjpositions.ToArray();
            }
        }
        else
        {
            cb.Colors = adjcolors.ToArray();
            cb.Positions = adjpositions.ToArray();
        }

        brush.InterpolationColors = cb;

        brush.WrapMode = WrapMode.TileFlipXY;


        if (res.SpreadMethod.AnimVal.Equals((ushort)SvgSpreadMethod.Reflect))
        {
            brush.WrapMode = WrapMode.TileFlipXY;
        }
        else if (res.SpreadMethod.AnimVal.Equals((ushort)SvgSpreadMethod.Repeat))
        {
            brush.WrapMode = WrapMode.Tile;
        }
        else if (res.SpreadMethod.AnimVal.Equals((ushort)SvgSpreadMethod.Pad))
        {
            brush.WrapMode = WrapMode.Tile;
        }

       // brush.Transform = GetTransformMatrix(res);

        if (res.GetPropertyValue("color-interpolation") == "linearRGB")
        {
            brush.GammaCorrection = true;
        }
        else
        {
            brush.GammaCorrection = false;
        }

        return brush;
    }

[paulushub]

[UnknownUser@2013/03/09]

[MikeGratsas]

I found another issue rendering SVG file with linear gradient using GDI+. As I understand the code stop colors and positions correction is not performed always. Therefore, an exception can be thrown on the line

brush.InterpolationColors = cb;

I attached sample file to demonstrate this issue.
YouTube_logo.zip