how to construct quad with 4 points?

[nissansz]

                # 构造 quads
                quad = fitz.Quad(fitz.Point(x1, y1), fitz.Point(x2, y2), fitz.Point(x4, y4), fitz.Point(x3, y3))
                quads = [quad]

                # 添加高亮注释
                highlight = page.add_highlight_annot(quads)

No color is displayed

[JorjMcKie]

Make sure to specify the 4 points in zigzag sequence: ul, ur, ll, lr.

[nissansz]

How to compute morph=(point,matrix) for a cerntain angle?
point = upper left coordinates x1, y1?

[JorjMcKie]

No, point is (one of) the fixpoint of the morphing. The angle is defined by the matrix. If a rotation matrix, the rotation happens around that point. If mirroring, fixpoint is one of the points of the line around which this happens, etc.
If a tilting matrix (i.e. either matrix.b or matrix.c is non-zero), then that value is the arctan of the angle.

[nissansz]

For example. tilted area upper left (x1,y1), upper right (x2,y2)
lower right (x3,y3), lower left(x4,y4)

How can I compute fit font size?
Which point should I use to rotate morph? Center point?

[JorjMcKie]

If the quad is rectangular, its height is like if it were a true rectangle height = abs(ul - ll) = abs(ur - lr).
From that compute the font size as usual.
Which point to choose as fixpoint? This is completely up to you: what do you want to do: have a quad and want to morph it again?
Or compute the corresponding rectangle? ...

[nissansz]

I imagine to insert text from x1, y1, then rotate from x1,y1

[nissansz]

It seems working now, page.insert_text((x4 * ratio - padding, y4 * ratio - padding),