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Forums Adobe After Effects Expressions SOURCERECTATTIME FOR STRING



  • Mackie john

    March 9, 2022 at 5:43 pm

    I need to use sourcerectattime().width for only a particular string in a layer source text.

    E.g. if the text is Thisismytext**Here you go. So i want to be able measure the width of “Thisismytext” and “Here you go” separately within the same source text. How can i achieve this.

  • Tomas Bumbulevičius

    March 9, 2022 at 8:26 pm

    Only possible if you put that XXX phrase in a temporary text layer and get the width from there. Side note – font family & style must be identical.

  • Mackie john

    March 10, 2022 at 4:46 am

    Many thanks for your response Tomas. That is not an option for me. Is there any alternative to sourcerectattime. I want be able to acheive with expressions within the same layer

  • Andrei Popa

    March 10, 2022 at 7:29 am


    I think this could work. You still need to do some testing.

    Add a scale animator to your text. Set units to index, set mode to subtract and scale to 0.

    Then on start and end add these expressions.

    txt = text.sourceText.replace(/\r/g,"");
    var parts = ["testing", "is a text"];
    val = txt.indexOf(parts[-Math.ceil(time+1)]);
    val = value}

    txt = text.sourceText.replace(/\r/g,"");
    var parts = ["testing", "is a text"];
    val = text.animator("Animator 1").selector("Range Selector 1").start+parts[-Math.ceil(time+1)].length;
    val = txt.length}

    And when you want to see the text width for some specific word, run:

    thisComp.layer("Text Layer").sourceRectAtTime(-1,false).width

    -1 means the first word from the array, -2 means the second and so on.

  • Filip Vandueren

    March 10, 2022 at 8:40 am

    I have made an animation preset which helps with the process Andrei showcases.

    Also working on a second version which is even compatible with text-animators.

    here’s V1:

    demo of what v2 can do:

    explanation of subSourceRect animation preset

  • Tomas Bumbulevičius

    March 10, 2022 at 3:08 pm

    This looks amazing Filip, well done!!! And the good thing about it is that you made it as a preset – definitely something a lot easier for others to apply than understanding all the tiny pieces in a whole picture (less prone to errors when using – thus, less questions caused!)

  • René Pedersen

    December 14, 2022 at 10:25 am

    Amazing preset. I was told again and again it was impossible to get the size of individual lines in a text box since sourceRectAtTime uses the boundary of the entire text box.

    I am having problems utilizing the full potential though since I cant figure out what the Left – Top value is relative to.

    I am trying to create a coloured box for just one of the lines in a text box that automatically resizes when I change the text. Therefore I changed the sourceSubRect Helper to be based on Lines instead of characters.

    And I have added a shape layer with a path (and a fill) and added this code from the mask path that the preset generates to the path.

    pos=thisComp.layer("Text").effect("Left - Top")("Point"); //I have pickwhipped the effect to the text-layer.

    dim=thisComp.layer("Text").effect("Width - Height")("Point");








    It creates a perfect sized box for my line, but I cant really figure out how to position it.

    When I have marked the Text layer I can see that the mask created is positioned correct, but if I try to use the points from “Left – Top” in the position of the TextBox/Shape Layer it is placed outside of the comps boundaries.

    My text layer is positioned at x = 0 and y = 0 and the anchor point on both my Text layer and Shape layer is placed top left with this expression

    sourceSize = thisLayer.sourceRectAtTime(time, false);

    T =;

    L = sourceSize.left;

    [L , T]

    The left value always ends up around -515 and -519 (depending on the text) but I have no idea how to use these values.

  • Filip Vandueren

    December 19, 2022 at 9:13 am

    Hi René,

    The coordinates are relative to the anchorPoint of the text-layer.

    If the text is right- or center-aligned, it makes sense that some of the coordinates will be negative (to the left of the anchorPoint).

    The easiest way to implement it in a shape, is to parent the shape to your text-layer, and make sure all positions/anchorpoints of the shape layer and its groups are at [0,0].

    If you now use the coordinates in a createPath() the vertices should line up.

    if you don’t want to parent, you need to use (pseudocode:)

    shapeLayer.fromComp(textLayer.toComp( vertex ))

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