public void BlendHL(int x1, int y, int x2, ColorRGBA sourceColor, byte cover)
        {
            if (sourceColor.alpha == 0)
            {
                return;
            }
            //-------------------------------------------------

            int len = x2 - x1 + 1;

            byte[] buffer       = GetBuffer();
            int    bufferOffset = GetBufferOffsetXY(x1, y);
            int    alpha        = (((int)(sourceColor.alpha) * (cover + 1)) >> 8);

            if (alpha == BASE_MASK)
            {
                //full
                recieveBlender.CopyPixels(buffer, bufferOffset, sourceColor, len);
            }
            else
            {
                ColorRGBA c2 = new ColorRGBA(sourceColor, alpha);
                do
                {
                    //copy pixel-by-pixel
                    recieveBlender.BlendPixel(buffer, bufferOffset, c2);
                    bufferOffset += m_DistanceInBytesBetweenPixelsInclusive;
                }while (--len != 0);
            }
        }
        static void CopyOrBlend_BasedOnAlpha(IPixelBlender recieveBlender, byte[] destBuffer, int bufferOffset, ColorRGBA sourceColor)
        {
            //if (sourceColor.m_A != 0)
            {
#if false // we blend regardless of the alpha so that we can get Light Opacity working (used this way we have addative and faster blending in one blender) LBB
                if (sourceColor.m_A == base_mask)
                {
                    Blender.CopyPixel(pDestBuffer, sourceColor);
                }
                else
#endif
                {
                    recieveBlender.BlendPixel(destBuffer, bufferOffset, sourceColor);
                }
            }
        }
        static void CopyOrBlend_BasedOnAlphaAndCover(IPixelBlender recieveBlender, byte[] destBuffer, int bufferOffset, Color sourceColor, int cover)
        {
            if (cover == 255)
            {
                CopyOrBlend_BasedOnAlpha(recieveBlender, destBuffer, bufferOffset, sourceColor);
            }
            else
            {
                //if (sourceColor.m_A != 0)
                {
                    sourceColor.alpha = (byte)((sourceColor.alpha * (cover + 1)) >> 8);
#if false // we blend regardless of the alpha so that we can get Light Opacity working (used this way we have addative and faster blending in one blender) LBB
                    if (sourceColor.m_A == base_mask)
                    {
                        Blender.CopyPixel(pDestBuffer, sourceColor);
                    }
                    else
#endif
                    {
                        recieveBlender.BlendPixel(destBuffer, bufferOffset, sourceColor);
                    }
                }
            }
        }
        void SubPixRender(IImageReaderWriter dest, Scanline scanline, ColorRGBA color)
        {
            byte[] covers    = scanline.GetCovers();
            int    num_spans = scanline.SpanCount;
            int    y         = scanline.Y;

            byte[]        buffer       = dest.GetBuffer();
            IPixelBlender blender      = dest.GetRecieveBlender();
            int           last_x       = int.MinValue;
            int           prev_cover   = 0;
            int           bufferOffset = 0;
            ColorRGBA     prevColor    = ColorRGBA.White;

            for (int i = 1; i <= num_spans; ++i)
            {
                //render span by span

                ScanlineSpan span = scanline.GetSpan(i);
                if (span.x != last_x + 1)
                {
                    bufferOffset = dest.GetBufferOffsetXY(span.x, y);
                    //when skip  then reset
                    prev_cover = 0;
                    prevColor  = ColorRGBA.White;
                }

                last_x = span.x;
                int num_pix = span.len;
                if (num_pix < 0)
                {
                    //special encode***
                    num_pix = -num_pix; //make it positive value
                    last_x += (num_pix - 1);
                    //long span with coverage
                    int coverageValue = covers[span.cover_index];
                    //-------------------------------------------
                    if (coverageValue >= 255)
                    {
                        //100% cover
                        int       a           = ((coverageValue + 1) * color.Alpha0To255) >> 8;
                        ColorRGBA newc        = prevColor = new ColorRGBA(color.red, color.green, color.blue);
                        ColorRGBA todrawColor = new ColorRGBA(newc, a);
                        prev_cover = 255;//full
                        while (num_pix > 0)
                        {
                            blender.BlendPixel(buffer, bufferOffset, todrawColor);
                            bufferOffset += 4; //1 pixel 4 bytes
                            --num_pix;
                        }
                    }
                    else
                    {
                        prev_cover = coverageValue;
                        int       a           = ((coverageValue + 1) * color.Alpha0To255) >> 8;
                        ColorRGBA newc        = prevColor = new ColorRGBA(color.red, color.green, color.blue);
                        ColorRGBA todrawColor = new ColorRGBA(newc, a);
                        while (num_pix > 0)
                        {
                            blender.BlendPixel(buffer, bufferOffset, todrawColor);
                            bufferOffset += 4; //1 pixel 4 bytes
                            --num_pix;
                        }
                    }
                }
                else
                {
                    int coverIndex = span.cover_index;
                    last_x += (num_pix - 1);
                    while (num_pix > 0)
                    {
                        int coverageValue = covers[coverIndex++];
                        if (coverageValue >= 255)
                        {
                            //100% cover
                            ColorRGBA newc = new ColorRGBA(color.red, color.green, color.blue);
                            prevColor = newc;
                            int a = ((coverageValue + 1) * color.Alpha0To255) >> 8;
                            blender.BlendPixel(buffer, bufferOffset, new ColorRGBA(newc, a));
                            prev_cover = 255;//full
                        }
                        else
                        {
                            //check direction :


                            bool isLeftToRight = coverageValue >= prev_cover;
                            prev_cover = coverageValue;
                            byte  c_r, c_g, c_b;
                            float subpix_percent = ((float)(coverageValue) / 256f);
                            if (coverageValue < cover_1_3)
                            {
                                if (isLeftToRight)
                                {
                                    c_r = 255;
                                    c_g = 255;
                                    c_b = (byte)(255 - (255f * (subpix_percent)));
                                }
                                else
                                {
                                    c_r = (byte)(255 - (255f * (subpix_percent)));
                                    c_g = 255;
                                    c_b = 255;
                                }

                                ColorRGBA newc = prevColor = new ColorRGBA(c_r, c_g, c_b);
                                int       a    = ((coverageValue + 1) * color.Alpha0To255) >> 8;
                                blender.BlendPixel(buffer, bufferOffset, new ColorRGBA(newc, a));
                            }
                            else if (coverageValue < cover_2_3)
                            {
                                if (isLeftToRight)
                                {
                                    c_r = prevColor.blue;
                                    c_g = (byte)(255 - (255f * (subpix_percent)));
                                    c_b = color.blue;
                                }
                                else
                                {
                                    c_r = color.blue;
                                    c_g = (byte)(255 - (255f * (subpix_percent)));
                                    c_b = 255;
                                }
                                ColorRGBA newc = prevColor = new ColorRGBA(c_r, c_g, c_b);
                                int       a    = ((coverageValue + 1) * color.Alpha0To255) >> 8;
                                blender.BlendPixel(buffer, bufferOffset, new ColorRGBA(newc, a));
                            }
                            else
                            {
                                //cover > 2/3 but not full
                                if (isLeftToRight)
                                {
                                    c_r = (byte)(255 - (255f * (subpix_percent)));
                                    c_g = color.green;
                                    c_b = color.blue;
                                }
                                else
                                {
                                    c_r = prevColor.green;
                                    c_g = prevColor.blue;
                                    c_b = (byte)(255 - (255f * (subpix_percent)));
                                }

                                ColorRGBA newc = prevColor = new ColorRGBA(c_r, c_g, c_b);
                                int       a    = ((coverageValue + 1) * color.Alpha0To255) >> 8;
                                blender.BlendPixel(buffer, bufferOffset, new ColorRGBA(newc, a));
                            }
                        }
                        bufferOffset += 4; //1 pixel 4 bits
                        --num_pix;
                    }
                }
            }
        }
        static void CopyOrBlend_BasedOnAlphaAndCover(IPixelBlender recieveBlender, byte[] destBuffer, int bufferOffset, Color sourceColor, int cover)
        {
            if (cover == 255)
            {
                CopyOrBlend_BasedOnAlpha(recieveBlender, destBuffer, bufferOffset, sourceColor);
            }
            else
            {
                //if (sourceColor.m_A != 0)
                {
                    sourceColor.alpha = (byte)((sourceColor.alpha * (cover + 1)) >> 8);
#if false // we blend regardless of the alpha so that we can get Light Opacity working (used this way we have addative and faster blending in one blender) LBB
                    if (sourceColor.m_A == base_mask)
                    {
                        Blender.CopyPixel(pDestBuffer, sourceColor);
                    }
                    else
#endif
                    {
                        recieveBlender.BlendPixel(destBuffer, bufferOffset, sourceColor);
                    }
                }
            }
        }