Draw overlapping lines with same transparency












2















I have roughly this logic:



Bitmap bmp = ....
Pen pen = new Pen(Color.FromArgb(125, 0, 0, 255), 15);
var graphics = Graphics.FromImage(bmp);
graphics.DrawLines(pen, points1);
graphics.DrawLines(pen, points2);


The problem is, that points1 and points2 contain some line segments that are overlaping.



If I draw this lines, the overlapping part have a different color then the rest, due to the blending of the same segments (first, 1 with background and later 2 with already blended 1 with background). Is there a way, how to achieve the effect, that the overlapping parts have the same color as a single non-overlapping segmens?










share|improve this question





























    2















    I have roughly this logic:



    Bitmap bmp = ....
    Pen pen = new Pen(Color.FromArgb(125, 0, 0, 255), 15);
    var graphics = Graphics.FromImage(bmp);
    graphics.DrawLines(pen, points1);
    graphics.DrawLines(pen, points2);


    The problem is, that points1 and points2 contain some line segments that are overlaping.



    If I draw this lines, the overlapping part have a different color then the rest, due to the blending of the same segments (first, 1 with background and later 2 with already blended 1 with background). Is there a way, how to achieve the effect, that the overlapping parts have the same color as a single non-overlapping segmens?










    share|improve this question



























      2












      2








      2


      1






      I have roughly this logic:



      Bitmap bmp = ....
      Pen pen = new Pen(Color.FromArgb(125, 0, 0, 255), 15);
      var graphics = Graphics.FromImage(bmp);
      graphics.DrawLines(pen, points1);
      graphics.DrawLines(pen, points2);


      The problem is, that points1 and points2 contain some line segments that are overlaping.



      If I draw this lines, the overlapping part have a different color then the rest, due to the blending of the same segments (first, 1 with background and later 2 with already blended 1 with background). Is there a way, how to achieve the effect, that the overlapping parts have the same color as a single non-overlapping segmens?










      share|improve this question
















      I have roughly this logic:



      Bitmap bmp = ....
      Pen pen = new Pen(Color.FromArgb(125, 0, 0, 255), 15);
      var graphics = Graphics.FromImage(bmp);
      graphics.DrawLines(pen, points1);
      graphics.DrawLines(pen, points2);


      The problem is, that points1 and points2 contain some line segments that are overlaping.



      If I draw this lines, the overlapping part have a different color then the rest, due to the blending of the same segments (first, 1 with background and later 2 with already blended 1 with background). Is there a way, how to achieve the effect, that the overlapping parts have the same color as a single non-overlapping segmens?







      c# graphics gdi+






      share|improve this question















      share|improve this question













      share|improve this question




      share|improve this question








      edited Feb 2 at 17:59









      Uwe Keim

      27.6k32132213




      27.6k32132213










      asked Jan 2 at 12:22









      Martin PerryMartin Perry

      5,14933165




      5,14933165
























          1 Answer
          1






          active

          oldest

          votes


















          4














          DrawLines will not work in this case as it will only draw connected lines in one go.



          You need to add the line sets to one GraphicsPath using StartFigure to separate the two sets.



          Example, Drawline to the left, DrawPath to the right:



          enter image description here



          Here is the code for both:



          using System.Drawing.Imaging;
          using System.Drawing.Drawing2D;
          ..
          Pen pen = new Pen(Color.FromArgb(125, 0, 0, 255), 15)
          { LineJoin = LineJoin.Round };
          var graphics = Graphics.FromImage(bmp);
          graphics.Clear(Color.White);
          graphics.DrawLines(pen, points1);
          graphics.DrawLines(pen, points2);
          bmp.Save("D:\__x19DL", ImageFormat.Png);

          graphics.Clear(Color.White);
          using (GraphicsPath gp = new GraphicsPath())
          {
          gp.AddLines(points1);
          gp.StartFigure();
          gp.AddLines(points2);
          graphics.DrawPath(pen, gp);
          bmp.Save("D:\__x19GP", ImageFormat.Png);
          }


          Don't forget to Dispose of the Pen and the Graphics object, or, better, put them in using clauses!






          share|improve this answer

























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            1 Answer
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            active

            oldest

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            1 Answer
            1






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes









            4














            DrawLines will not work in this case as it will only draw connected lines in one go.



            You need to add the line sets to one GraphicsPath using StartFigure to separate the two sets.



            Example, Drawline to the left, DrawPath to the right:



            enter image description here



            Here is the code for both:



            using System.Drawing.Imaging;
            using System.Drawing.Drawing2D;
            ..
            Pen pen = new Pen(Color.FromArgb(125, 0, 0, 255), 15)
            { LineJoin = LineJoin.Round };
            var graphics = Graphics.FromImage(bmp);
            graphics.Clear(Color.White);
            graphics.DrawLines(pen, points1);
            graphics.DrawLines(pen, points2);
            bmp.Save("D:\__x19DL", ImageFormat.Png);

            graphics.Clear(Color.White);
            using (GraphicsPath gp = new GraphicsPath())
            {
            gp.AddLines(points1);
            gp.StartFigure();
            gp.AddLines(points2);
            graphics.DrawPath(pen, gp);
            bmp.Save("D:\__x19GP", ImageFormat.Png);
            }


            Don't forget to Dispose of the Pen and the Graphics object, or, better, put them in using clauses!






            share|improve this answer






























              4














              DrawLines will not work in this case as it will only draw connected lines in one go.



              You need to add the line sets to one GraphicsPath using StartFigure to separate the two sets.



              Example, Drawline to the left, DrawPath to the right:



              enter image description here



              Here is the code for both:



              using System.Drawing.Imaging;
              using System.Drawing.Drawing2D;
              ..
              Pen pen = new Pen(Color.FromArgb(125, 0, 0, 255), 15)
              { LineJoin = LineJoin.Round };
              var graphics = Graphics.FromImage(bmp);
              graphics.Clear(Color.White);
              graphics.DrawLines(pen, points1);
              graphics.DrawLines(pen, points2);
              bmp.Save("D:\__x19DL", ImageFormat.Png);

              graphics.Clear(Color.White);
              using (GraphicsPath gp = new GraphicsPath())
              {
              gp.AddLines(points1);
              gp.StartFigure();
              gp.AddLines(points2);
              graphics.DrawPath(pen, gp);
              bmp.Save("D:\__x19GP", ImageFormat.Png);
              }


              Don't forget to Dispose of the Pen and the Graphics object, or, better, put them in using clauses!






              share|improve this answer




























                4












                4








                4







                DrawLines will not work in this case as it will only draw connected lines in one go.



                You need to add the line sets to one GraphicsPath using StartFigure to separate the two sets.



                Example, Drawline to the left, DrawPath to the right:



                enter image description here



                Here is the code for both:



                using System.Drawing.Imaging;
                using System.Drawing.Drawing2D;
                ..
                Pen pen = new Pen(Color.FromArgb(125, 0, 0, 255), 15)
                { LineJoin = LineJoin.Round };
                var graphics = Graphics.FromImage(bmp);
                graphics.Clear(Color.White);
                graphics.DrawLines(pen, points1);
                graphics.DrawLines(pen, points2);
                bmp.Save("D:\__x19DL", ImageFormat.Png);

                graphics.Clear(Color.White);
                using (GraphicsPath gp = new GraphicsPath())
                {
                gp.AddLines(points1);
                gp.StartFigure();
                gp.AddLines(points2);
                graphics.DrawPath(pen, gp);
                bmp.Save("D:\__x19GP", ImageFormat.Png);
                }


                Don't forget to Dispose of the Pen and the Graphics object, or, better, put them in using clauses!






                share|improve this answer















                DrawLines will not work in this case as it will only draw connected lines in one go.



                You need to add the line sets to one GraphicsPath using StartFigure to separate the two sets.



                Example, Drawline to the left, DrawPath to the right:



                enter image description here



                Here is the code for both:



                using System.Drawing.Imaging;
                using System.Drawing.Drawing2D;
                ..
                Pen pen = new Pen(Color.FromArgb(125, 0, 0, 255), 15)
                { LineJoin = LineJoin.Round };
                var graphics = Graphics.FromImage(bmp);
                graphics.Clear(Color.White);
                graphics.DrawLines(pen, points1);
                graphics.DrawLines(pen, points2);
                bmp.Save("D:\__x19DL", ImageFormat.Png);

                graphics.Clear(Color.White);
                using (GraphicsPath gp = new GraphicsPath())
                {
                gp.AddLines(points1);
                gp.StartFigure();
                gp.AddLines(points2);
                graphics.DrawPath(pen, gp);
                bmp.Save("D:\__x19GP", ImageFormat.Png);
                }


                Don't forget to Dispose of the Pen and the Graphics object, or, better, put them in using clauses!







                share|improve this answer














                share|improve this answer



                share|improve this answer








                edited Jan 2 at 18:17

























                answered Jan 2 at 15:39









                TaWTaW

                41.7k62866




                41.7k62866
































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