Query pixel bounds of text layer

Posted by Mo Dejong on October 17, 2008 at 9:58 pm

{

// Round down to the nearest integer value

function round_down(n) {
  var floor = Math.floor(n);
  if (n == floor) {
    return n; // already rounded down
  }
  var window = 0.01;
  if (Math.abs(n - floor) < window) {
    return floor; // very close to floor
  }
  var ceil = Math.ceil(n);
  if (Math.abs(ceil - n) < window) {
    return ceil; // very close to ceil
  }
  return floor;
}

// Round up to the nearest integer value

function round_up(n) {
  var ceil = Math.ceil(n);
  if (n == ceil) {
    return n; // already rounded up
  }
  var window = 0.01;
  if (Math.abs(ceil - n) < window) {
    return ceil; // very close to ceil
  }
  var floor = Math.floor(n);
  if (Math.abs(n - floor) < window) {
    return floor; // very close to floor
  }
  return ceil;
}

// Given a layer, return an array contiaing the [x, y, width, height]
// coordinates of the bounding box for the layer. The coord values
// are rounded to whole pixels and are in terms of the comp coordinates.
// For a text layer, return the actual coordinates of the rendered text.

function layer_bbox(thisLayer, time) {
  var rect = thisLayer.sourceRectAtTime(time, true);

  // The left value indicates an offset from the layer position
  // to the left most position where the layer is rendered.
  // The width value indicates an offset from the left position
  // to the right most rendered position.

  var left = round_down(rect.left);
  var right = round_up(rect.left + rect.width);
  var width = right - left;

  // The top value is the pixel height above the layer position,
  // rounded down to the nearest pixel.

  var top = round_down(rect.top);
  var bottom = round_up(rect.top + rect.height);
  var height = bottom - top;

  // Convert offsets from layer origin to offsets in terms
  // of comp coordinates.

  var pos = chordLayer.transform.position.value;
  var anchor = chordLayer.transform.anchorPoint.value;  

  var origin_x = Math.round(pos[0] - anchor[0]) + left;
  var origin_y = Math.round(pos[1] - anchor[1]) + top;

  return [origin_x, origin_y, width, height];
}




thisComp = app.project.activeItem;
if (thisComp == null) {
  alertStr = "No active comp found";
  alert(alertStr);
} else {
//  alertStr = "thisComp.name is \\"" + thisComp.name + "\\"";
//  alert(alertStr);

  chordLayer = thisComp.layer("Chord");

  var bbox = layer_bbox(chordLayer, 0.0) ;

  var origin_x = bbox[0];
  var origin_y = bbox[1];
  var width = bbox[2];
  var height = bbox[3];

  alertStr = "bbox x,y = " + origin_x + "," + origin_y + "  WxH = " + width + "x" + height;
  alert(alertStr);

}

} // end of file scope

Hello all

I recently tried to figure out how to get the bounding box of a text layer, that is the
X,Y and WIDTH and HEIGHT, so that I could put a box around the text. I found the
Layer.sourceRectAtTime() API, but it took a little code to turn its results into something
I could use to create a box. The trick was that I wanted X,Y values in terms of pixels in
the comp, so a little rounding of the coord values was required. I am posting this script
in case it is helpful to others.

cheers
Mo DeJong

Dennis Cheung replied 14 years, 1 month ago 2 Members · 1 Reply

1 Reply

Dennis Cheung
April 4, 2012 at 8:58 pm

Hi

I was digging around for a script like this. Can you or anyone tell me how and where to apply this? It’s a little advanced for me.

Thanks

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Query pixel bounds of text layer

Dennis Cheung