Codelab Help for a n00b

[Arbruteblade]

I'm trying to make a plugin which makes a rainbow gradient going from left to right, the top line works well, but everything else becomes black, what do I do, or what am I missing about codelab or about Paint.NET? Will I have to make the rest of the plugin in a c# writing program? The version of paint.NET is 3.5.2.

Here's the code.

#region UICode
int Amount1 = 0; // [0,5430] Offset
#endregion

byte nextred = 255;
byte nextgreen = 0;
byte nextblue = 0;
int width = 0;
int number = 0;

void progress()
{
   if (nextred == 255)
       {
           if (nextblue == 0 && nextgreen < 255)
           nextgreen++;
           if (nextblue > 0)
           nextblue--;
       }
       if (nextgreen == 255)
       {
           if (nextred == 0 && nextblue < 255)
           nextblue++;
           if (nextred > 0)
           nextred--;
       }
       if (nextblue == 255)
       {
           if (nextgreen == 0 && nextred < 255)
           nextred--;
           if (nextgreen > 0)
           nextgreen--;
       }
}

void Render(Surface dst, Surface src, Rectangle rect)
{
   int offset = Amount1;
   ColorBgra[] GradientStore = new ColorBgra[5430];
   while (offset > 0)
   {
       progress();
       offset--;
   }
   while (number < 5430)
   {
       GradientStore[number].R = nextred;
       GradientStore[number].G = nextgreen;
       GradientStore[number].B = nextblue;
       progress();
       number++;
   }
   ColorBgra CurrentPixel;
   int x = rect.Left;
   int y;
   while (x < rect.Right)
   {
       y = rect.Top;
       while (y < rect.Bottom)
       {
           CurrentPixel = GradientStore[x];
           CurrentPixel.A = src[x,y].A;
           dst[x,y] = CurrentPixel;
           y++;
       }
       x++;
   }
}

Also, am I in the right forum, any mods please move this if it isn't in the right forum.

[Simon Brown]

You don't need calculate the RGB value by hand, Paint.NET provides a HsvColor class to convert between colour spaces.

[Arbruteblade]

You don't need calculate the RGB value by hand, Paint.NET provides a HsvColor class to convert between colour spaces.

My method creates about 1530 colors, using Hsv only creates 360 colors.

[Rick Brewster]

Then try HsvColorF (new for 3.5.2).

[Arbruteblade]

I already have the gradient working, my problem is that it only writes to the top line of the picture and makes the rest black.

[Arbruteblade]

I got it working, it overall taught me more about codelab's limitations, but I got it working by basing it slightly more on the template (CurrentPixel = src[x,y]), figuring out which variables should be global, etc.

I also managed to improve the algorithm while editing, and I also had to handle, "What if it goes out of the array?"

#region UICode
int Amount1 = 0; // [0,1530] Offset
#endregion

byte nextred = 255;
byte nextgreen = 0;
byte nextblue = 0;
int width = 0;
int number = 0;
int changecheck;
bool done;
bool done2;
ColorBgra[] GradientStore = new ColorBgra[1530];

void progress()
{
   if (nextred == 255 && done == false)
   {
       if (nextblue == 0 && nextgreen < 255)
       {
           nextgreen++;
           done = true;
       }
       if (nextblue > 0)
       {
           nextblue--;
           done = true;
       }
   }
   if (nextgreen == 255 && done == false)
   {
       if (nextred == 0 && nextblue < 255)
       nextblue++;
       if (nextred > 0)
       nextred--;
   }
   if (nextblue == 255 && done == false)
   {
       if (nextgreen == 0 && nextred < 255)
       {
           nextred++;
           done = true;
       }
       if (nextgreen > 0)
       {
           nextgreen--;
           done = true;
       }
   }
   done = false;
}

void Render(Surface dst, Surface src, Rectangle rect)
{
   int offset = Amount1;
   if (offset != changecheck || done2 == false)
   {
       changecheck = Amount1;
       while (offset > 0)
       {
           progress();
           offset--;
       }
       while (number < 1530)
       {
           GradientStore[number].R = nextred;
           GradientStore[number].G = nextgreen;
           GradientStore[number].B = nextblue;
           progress();
           number++;
       }
       done2 = true;
   }
   number = 0;
   nextred = 255;
   nextgreen = 0;
   nextblue = 0;
   int position;
   ColorBgra CurrentPixel;
   int x = rect.Left;
   int y;
   while (x < rect.Right)
   {
       y = rect.Top;
       position = x;
       if (position >= 1529)
           position = position - 1529;
       while (y < rect.Bottom)
       {
           CurrentPixel = src[x,y];
           CurrentPixel.R = GradientStore[position].R;
           CurrentPixel.G = GradientStore[position].G;
           CurrentPixel.B = GradientStore[position].B;
           dst[x,y] = CurrentPixel;
           y++;
       }
       x++;
   }