Alignment class

A point within a rectangle.

Alignment(0.0, 0.0) represents the center of the rectangle. The distance from -1.0 to +1.0 is the distance from one side of the rectangle to the other side of the rectangle. Therefore, 2.0 units horizontally (or vertically) is equivalent to the width (or height) of the rectangle.

Alignment(-1.0, -1.0) represents the top left of the rectangle.

Alignment(1.0, 1.0) represents the bottom right of the rectangle.

Alignment(0.0, 3.0) represents a point that is horizontally centered with respect to the rectangle and vertically below the bottom of the rectangle by the height of the rectangle.

Alignment(0.0, -0.5) represents a point that is horizontally centered with respect to the rectangle and vertically half way between the top edge and the center.

Alignment(x, y) in a rectangle with height h and width w describes the point (x * w/2 + w/2, y * h/2 + h/2) in the coordinate system of the rectangle.

Alignment uses visual coordinates, which means increasing x moves the point from left to right. To support layouts with a right-to-left TextDirection, consider using AlignmentDirectional, in which the direction the point moves when increasing the horizontal value depends on the TextDirection.

A variety of widgets use Alignment in their configuration, most notably:

• Align positions a child according to an Alignment.

See also:

• AlignmentDirectional, which has a horizontal coordinate orientation that depends on the TextDirection.
• AlignmentGeometry, which is an abstract type that is agnostic as to whether the horizontal direction depends on the TextDirection.