// Demonstrates bug in text placement. This sketch should draw some text and 
// a rectangle at the same location on screen. The draw() method moves the 
// drawing location left and right accross the screen. If text placement was
// working correctly, the rectangle should surround the text.
//
// The bug appears to be due to the the text location being rounded before it
// it scaled by the scaling factor. The larger the scaling, the coarser the
// text placement. Note also, that even without scaling (set scaling=1), there
// is some minor rounding of text position. Related to this is that the offset
// implied by textAlign() is also rounded, so any values other than 
// textAlign(LEFT, BOTTOM) result in incorrect positioning.

PFont font;
float pos=0;
float inc = 0.005;
float w,h;

float scaling = 50;    // Change the value between 1 and 100 to see rounding effect.

void setup()
{
  size(400, 200);  // Problem only occurs with default renderer.
  frameRate(10);
  font = createFont("GillSans",12);
  textFont(font, width/20);
  textAlign(LEFT,TOP); 
  w = textWidth("Test");
  h = textAscent();
}


void draw()
{
  background(200,180,180);
  textFont(font, width/(20*scaling));
 
  strokeWeight(1/scaling);
  float x = lerp(0,(width-w)/scaling,pos);
  
  scale(scaling);
  
  // Draw rectangle and text at the same location.
  fill(255);
  rect(x,height/(2*scaling),w/scaling,h/scaling);
  fill(0);
  text("Test",x,height/(2*scaling));
 
  
  // Move label a little to the left or right.
  pos += inc;
  if (pos >=1) inc = -0.005;
  if (pos <=0) inc = 0.005;
}