Use the mouseMoved method. Compute dist(pmouseX, pmouseY, mouseX, mouseY) to get the distance of move in pixels. Translate to meters. Cumulate in a variable and check the current value.

thanks for the information - i'am not good in programming at all.
I took the example file from processing and added dist(mouseX, mouseY, pmouseX, pmouseY)

void setup() {
  size(640, 200);
  background(102);
}

void draw() {
  stroke(255);
  if(mousePressed) {
    line(mouseX, mouseY, pmouseX, pmouseY);//this is drawing the line
    dist(mouseX, mouseY, pmouseX, pmouseY); //this should mesure the distance, right?
  }
}

but how do I get the information, what he mesured?
so how can I do this? "Cumulate in a variable and check the current value." I need to write the mesured distance down somehow. but I have no idea how.
can you help me again?

float totalDistance; // Before setup

totalDistance += dist( ... );

like this?

float totalDistance; // Before setup

void setup() {
  size(640, 200);
  background(102);
}

void draw() {
  stroke(255);
  if(mousePressed) {
    line(mouseX, mouseY, pmouseX, pmouseY);
    totalDistance += dist(mouseX, mouseY, pmouseX, pmouseY); 
  }
}

it still looks the same as before? where do I make a mistake?

hi


the "translation to meters" I need in the real world, which means printed - not on the monitor.

your instruction:
..."Now, you can use the variable to display the total distance, to stop drawing when reaching a given value, etc."

my problem is, that I have no idea, how I have to do this. how can I display it?

You can look at the text() function, as a starter.

ok the totalDistance is written into the text() field or however it is called. the problem is, that it is overwriting itself as soon as I move the mouse. it is unreadable. below is the code...

float totalDistance; // Before setup

void setup() {
  size(640, 200);
  background(102);
}

void draw() {
  stroke(255);
  if(mousePressed) {
    line(mouseX, mouseY, pmouseX, pmouseY);
    totalDistance += dist(mouseX, mouseY, pmouseX, pmouseY); 
  }
 
PFont font;
font = loadFont("SansSerif-48.vlw");
textFont(font);
text("word", 15, 30);
fill(0, 102, 153);
text(totalDistance, 15, 60);
fill(0, 102, 153, 51);
}

That's because you are not clearing the background... see line 12.

Jesse is right, move the font loading to setup(), otherwise you load it in each frame!
Alternatively, you can erase only the text area:

1. float totalDistance; // Before setup
2. 
   
3. void setup() {
4.   size(640, 200);
5.   background(102);
6. }
7. 
   
8. void draw() {
9.   stroke(255);
10.   if (mousePressed) {
11.     line(mouseX, mouseY, pmouseX, pmouseY);
12.     totalDistance += dist(mouseX, mouseY, pmouseX, pmouseY);
13.   }
14. 
    
15.   fill(180);
16.   rect(0, 0, 80, 70);
17.   fill(0, 102, 153);
18.   text("word", 15, 30);
19.   fill(0, 102, 153, 51);
20.   text(totalDistance, 15, 60);
21. }

Here, I just used the default font of Processing, for simplicity sake.

hey thank you both for your help.

with the script of phi.Iho there is a error message : use textFont() before text()   ???

jesse - yes! my next question is exactly the one, ...why my line only shows up when I press the mouse now...
I tried to solve the problem like this:
I also placed a smooth() for a better quality of line. it is funny, when I press and move the mouse, the numbers are smooth. If I stop and don't press the mouse, the numbers are pixelated - why?
and - is there another and more elegant way to solve the problem with overwriting the numbers and see the line at the same time, without repeating the background() or the overwriting function?

1.    float totalDistance;
      PFont font; // Note that you can declare your font once before setup, not every frame within draw()
    
      void setup() {
        size(640, 200);
        background(102);
        smooth();
        font = loadFont("SansSerif-48.vlw");  // again, declare what your font is, not every frame
        textFont(font);  // ditto
      }
    
     void overwritetext(){
     fill(255);
     noStroke();
     rect(10,20,268,50);
   }
    
      void draw() {
        //background(102); // Calling the background everyframe will clear your text
        stroke(255);
       
        if(mousePressed) {
          line(mouseX, mouseY, pmouseX, pmouseY);
          totalDistance += dist(mouseX, mouseY, pmouseX, pmouseY);
          overwritetext();
        }
      
       
        fill(0, 102, 153);
        text(totalDistance, 15, 60);
       
      }
   

You are using an old version of Processing, are you?

processing 1.0.1
is there a newer version?

why do it simple if one can do it complicated too
I just got version 1.5.1 - now it works perfect!!!! thank you a lot!
I changed it a bit yet (just for the optical effect)

and I need the pixels converted in cm - and it works too

and now I need to save it as picture - I use
saveFrame("drawing.jpg");
is there a possibility to save it as vectorfile like vgs ?

1.    float totalDistance; // Before setup
      float cmDistance;
      void setup() {
        size(361, 461);
        background(255);
        smooth();
        textSize(9);
        rect(0,100,360,360);//border of canvas
        line(0,100,740,100);//line above canvas
            
      }
    
      void draw() {
        stroke(0);
        if (mousePressed) {
          line(mouseX, mouseY, pmouseX, pmouseY);
          totalDistance += dist(mouseX, mouseY, pmouseX, pmouseY);
          cmDistance = totalDistance * 0.035277;
        }
    
        fill(255);
        rect(16, 5, 72, 72);//square for text
      
        fill(0, 0, 0);//font color
        text(" it's picture 1", 18, 15);
        text("dist in px", 18, 41);
        text("72dpi=2.54cm", 18, 28);
         fill(255, 0, 0);//font color
        text(totalDistance, 15, 60);
        text("px", 73, 60);
        text(cmDistance, 15, 73);
        text("cm", 73, 73);
   
      }
   

Out of the box, the only vector output format is PDF.

I took the example from the library page
there comes an error:
isRecording(), or this particular variation of it, is not available with this renderer
what does that mean exactly?

1. import processing.pdf.*;
   
   void setup() {
     size(400, 400);
     noLoop();
     beginRecord(PDF, "filename.pdf");
   }
   
   void draw() {
     // Draw something good here
     line(0, 0, 200, 200);
     rect(10,10,100,100);
   
     endRecord();
   }
   

I get the same error, it can be a bug in 1.5.1. But the file is there, so it is only a warning.

yes the file is here.
now I have a new problem. I would like to draw a while and when I'm done, I would like to make a pdf.
If I want to save a picture, I can do this with the function mouseClicked() at the end of the script

1. void mouseClicked() {
          saveFrame("zeichnung.jpg");
         
        }

If I want to save a pdf with the function mouseClicked() it saves a pdf - but it is empty
I guess it is because the endRecord(); is within void draw() ?
and the size of the text is bigger than in the original file... ?

1. void mouseClicked() {
          beginRecord(PDF, "zeichnung.pdf");
         
        }

where do I have to start with recording the pdf? I do not want to make a pdf of every change. only the endpicture needs to be saved... otherwise my computer would possibly explode

As the name implies, beginRecord marks where the recording begins: Processing has to keep track of your drawing actions to be able to record them. That's the idea of vector drawing; every change is recorded in the form of a vector.

ups - that's not good for my old computer - I need to draw 36090 pixels (or 12,732 meters) - it will explode!

when a picture is saved, there is some "noise" around the letters and the lines.
is there a possiblity to change the resolution? maybe to 200 dpi? only for the print-quality?

I did try it out again with a reduction of the amount of the recording pictures - the pdf is still somehow empty. all the parts, that are "static" are visible, but in the wrong size (text).
the moving of the mouse - the line that I am drawing - is not visible. do you have any idea why?

" when a picture is saved, there is some "noise" around the letters and the lines."
You probably save in Jpeg. Save in PNG instead.

" I need to draw 36090 pixels (or 12,732 meters)"
That's not that much, probably less than a MB. Beside, you don't save pixels, in PDF, but lines. Each line includes lot of pixels...

" do you have any idea why?"
No. Not without seeing your sketch.

hey it works much better with png! no more noise! super! thank's

because pdf troubles - here is my script

1.   import processing.pdf.*;
   
      float totalDistance; //zahlenvariable für distanz in pixeln
      float cmDistance;//zahlenvariable für cm-umrechnung
    
        
      void setup() {
        size(361, 461);
        background(255);
        smooth();
        textSize(9);
        rect(0,100,360,360);//bilderrand resp. zeichenfläche
        line(0,100,740,100);//abgrenzung zu zeichenfläche
    
   
2.  beginRecord(PDF, "zeichnung.pdf");
       
      }
    
      void draw() {
       
        stroke(0);
        if (mousePressed) {
          line(mouseX, mouseY, pmouseX, pmouseY);
          totalDistance += dist(mouseX, mouseY, pmouseX, pmouseY);
          cmDistance = totalDistance * 0.035277;
    
        }
    
        fill(255);
        rect(16, 5, 72, 72);//referenzquadrat und texthalter
      
        fill(0, 0, 0);//schriftfarbe
        text("das ist bild 1", 18, 15);
        text("strecke in px", 18, 41);
        text("72dpi=2.54cm", 18, 28);
         fill(255, 0, 0);//schriftfarbe
        text(totalDistance, 15, 60);
        text("px", 73, 60);
        text(cmDistance, 15, 73);
        text("cm", 73, 73);
           
          endRecord();
         
      }
     
      void mouseClicked() {
          saveFrame("zeichnung.png");
        }