Drawing Waveform ?

[Danesvar Neelamagam]

Hello everyone. For the app i'm developing i need to draw the waveform. I have done a project that needed to draw a wave form using arduino processing. heres the code:

// DRAW THE PULSE WAVEFORM

  // prepare pulse data points    

  RawY[RawY.length-1] = (1023 - Sensor) - 212;   // place the new raw datapoint at the end of the array

  zoom = scaleBar.getPos();                      // get current waveform scale value

  offset = map(zoom,0.5,1,150,0);                // calculate the offset needed at this scale

  for (int i = 0; i < RawY.length-1; i++) {      // move the pulse waveform by

    RawY[i] = RawY[i+1];                         // shifting all raw datapoints one pixel left

    float dummy = RawY[i] * zoom + offset;       // adjust the raw data to the selected scale

    ScaledY[i] = constrain(int(dummy),44,556);   // transfer the raw data array to the scaled array

  }

  stroke(250,0,0);                               // red

  noFill();

  beginShape();                                  // using beginShape() renders fast

  for (int x = 1; x < ScaledY.length-1; x++) {    

    vertex(x+10, ScaledY[x]);                    //draw a line connecting the data points

  }

  endShape();

How do i do this with app inventor?

[SteveJG]

This will will get you a graph on the AI2 Canvas.

Canvas Graph…an expert AI2 tutorial

You save the curve information  (data points x,y) in a csv file  and plot as shown in one of the examples

or

use the Acellerometer real time example to plot the data in real time.

The code you provided draws a graph using a different language ... there is a scaling routine shown showing how to move from World coordinates (your data set) to Screen coordinates (the x,y coordinates of the Canvas).

Regards,

Steve