Auto resizing shape layer

I thought the idea of sizing a background shape layer to fit over two horizontally spaced text layers would make a good animation preset, so I spent a few minutes this afternoon creating one. Here's the basic code before I added the Expression Controls for padding and animation. 

Create two text layers. name one Left and the other Right, and make sure they are lined up horizontally.

Add a shape layer below the text layers by double-clicking the Rectangle tool. Spin down the properties until you get to Contents/Rectangle 1/Rectangle Path 1/Size and add this expression.

// two text layers stacked horizontally
// Left side
L = thisComp.layer("Left");
lBox = L.sourceRectAtTime();
lLeft = -lBox.left;
lCenter = lBox.width/2;
// Left width add 
if (lLeft < 2){
	lx = 0;
	}
if (lLeft < lCenter + 10 && lLeft > lCenter - 10){
	lx = lCenter;
}
if (lLeft > lBox.width - 20){
	lx = lBox.width;
}

// Right Side
R = thisComp.layer("Right");
rBox = R.sourceRectAtTime();
rLeft = -rBox.left;
rCenter = rBox.width/2;
// Right width add 
if (rLeft < 2){
	rx = rBox.width;
	}
if (rLeft < rCenter + 10 && rLeft > rCenter - 10){
	rx = rCenter;
}
if (rLeft > rBox.width - 20){
	rx = 0;
}
// Gap Calculations

rhPos = R.position[0];
lhPos = L.position[0];
hGap = rhPos - lhPos;

// Calculate Width 

x = hGap + rx + lx;

// Calculate height
if (lBox.height > rBox.height){
	y = lBox.height;
}
else{
	y = rBox.height
}

[x, y]

Add the following expression to the Shape Layer/Contents/Rectangle1/Rectangle Path 1/Position:

ref = thisComp.layer("Left");
refBox = ref.sourceRectAtTime();
xOfst = refBox.width + refBox.left;
box = sourceRectAtTime();
l = box.left;
w = box.width;
[l + w + xOfst - refBox.width , refBox.height/2 + refBox.top]

The last step is to reveal the Left Text layers' position and the shape layers' position and use the pickwhip to tie them together. You'll get this:

thisComp.layer("Left").transform.position

Feel free to use this expression and modify it as you like to add padding, turn on or off a layer, or compensate for the baseline shift on both text layers in the Rectangle Path 1/Position expression.

The last expression you will need is applied to the Right layer's Transform Position Property to keep it lined up vertically with the Left layer. It looks like this:

x = value[0];
y = thisComp.layer("Left").transform.position[1];
[x, y]

The expressions I shared let you reposition everything by moving the Left layer, the Right layer follows, and Paragraph Justification is taken into account.

You will also have to compensate for the distance between the Date and Month layers. This expression will do that for layer size:

xPad = 100; //set horizontal padding
yPad = 80; // set vertical padding
refMonth = thisComp.layer("Month");
refDate = thisComp.layer("Date");
mPos = refMonth.position;
dPos = refDate.position;
mSize = refMonth.sourceRectAtTime();
dSize = refDate.sourceRectAtTime();
tWidth = dPos[0] - mPos[0] + mSize.width/2 + dSize.width/2;
// Controls
lyrOff = thisComp.layer("Date Controls").effect("Month On/Off")("Checkbox");

if (lyrOff == 1){
	totX = tWidth + xPad;
}
else{
	totX = dSize.width + xPad;
}

[totX, mSize.height + yPad]

You can use sourceRectAtTime().left and top to get the actual position of the text layers and link that to the shape layer position so that the Rectangle is always centered over the text layers. Paragraph justification and Baseline shift can also be adjusted if you add in those parameters, and the Rectangle will always be centered over the text layers.

Let us know if you also want help centering the shape layer over the text.

Try layA.width and layA.height instead.

Mylenium

Sure. You just need to sample the two layers and then add their values.

layA=thisComp.layer("Month").sourceRectAtTime();
layB=thisComp.layer("Date").sourceRectAtTime();

//padding
padX=20;
padY=20;

laySwitch=thisComp.layer("Null").effect("Checkbox")("Checkbox");

if (laySwitch == 1)
{layW=layA[0]+layB[0]}
else
{layW=layA[0]};

X=layW+padX;
Y=layA[1];

[X,Y]

Mylenium