Scale a Quad from center in all directions

[AnweshGangula]

I'm searching for text in a pdf and extracting a quad and adding a polygon_annot around it.
But I would like to scale the polygon_annot. How can I do that?

Below is my code:

    for inst in text_instances:
        inst =  inst.transform(fitz.Matrix(2, 2))
        print(inst)
        print(inst.rect)
        # re-ordering the points in list counter-clockwise
        inst[2], inst[3] = inst[3], inst[2]
        highlight = page.add_polygon_annot(inst)

i'm currently scaling it with inst.transform(fitz.Matrix(2, 2)), but this is to simply multiply the values. How do I scale the values frfom the center of the quad?

[JorjMcKie]

You can simply first add the annot.
Then enlarge its rect by the desired factor using annot.set_rect(new_rect). There is no need to use a matrix here.
You can either ue a constant value of say 5 pixels in each direction: new_rect = annot.rect + (-5, -5, 5, 5) or use a factor, e.g. 2:
new_rect = annot.rect + (-annot.rect.width/2, -annot.rect.height/2, annot.rect.width/2, annot.rect.height/2).

[AnweshGangula]

I tried this, but I also have text which are rotated ((not horizontal or vertical). For these instances, the rectangle that I'm getting is the smallest containing rectangle, but I want a rectangle that is aligned to text's rotation. That's why I'm using add_polygon_annot.

How can I extract the rotation of a search_text?

[JorjMcKie]

Manipulating the annot's rect also needs no use of annot.update()

[JorjMcKie]

How can I extract the rotation of a search_text?

When you do page.search_for(text, quads=True)`` you get a list of quads. A quad with points ``(ul, ur, ll, lr)`` carries the text rotation information in those points. If you use page.add_highlight_annot(quad)`, then you will already get a rectangle-like background coloring.
Suppose you have this:

and search like this:

rl = page.search_for("pymupdf", quads=True)
# you will get a quad
>>> quad=rl[0]
>>> page.add_highlight_annot(quad)
'Highlight' annotation on page 0 of x.pdf
>>> doc.ez_save("y.pdf")

which results in this:

You can no problem enlarge this annotation in the way discussed:

If you happen to dislike highlight annotations, you can do the same thing with a polygon annot created like this:
annot=page.add_polygon_annot((quad.ul, quad.ur,quad.lr, quad.ll)).

If you really need the text rotation angle for whatever reason, you can compute the matrix which maps the line from quad.ul to quad.ur to the x-axis:

>>> mat = fitz.planish_line(quad.ul, quad.ur)
>>> mat
Matrix(0.8660264015197754, 0.4999982416629791, -0.4999982416629791,
0.8660264015197754, 20.10912322998047, -236.43589782714844)
>>>

And as you know that a rotation matrix has the form `Matrix(cos, sin, -sin, cos, 0, 0)``, you can easily compute the rotation angle.

[JorjMcKie]

Compare that matrix with this one: fitz.Matrix(30)!

[AnweshGangula]

Thank you for your response @JorjMcKie. But I found that you can use morph to scale the quad

Below is the function that i'm using to scale the morph by its center:

def getPolygon(inst, scale=1):
    [sumX, sumY] = [0, 0]
    for point in inst:
        sumX += point[0]
        sumY += point[1]
    avgX = sumX/4
    avgY = sumY/4

    # Scale the rectange using Quad.morph(): https://pymupdf.readthedocs.io/en/latest/quad.html#Quad.morph
    inst = inst.morph(fitz.Point(avgX,  avgY), fitz.Matrix(scale, scale))
    # re-ordering the points in list counter-clockwise
    inst[2], inst[3] = inst[3], inst[2]
    return inst