Create a gradient fill style for an element.
create_gradient_fill(direction, start_color, end_color)A gradient fill style object.
The direction of the gradient (e.g., left-to-right, right-to-left, bottom-to-top, top-to-bottom).
Taking the example of bottom-to-top, this means that the start color is at the bottom of the paint pattern and the end color is at the top, with a gradient between them.
The starting color of the gradient. It can be any HTML color name or HEX code, as well as special keywords such as inherit, none, swimlane.
The ending color of the gradient. It can be any HTML color name or HEX code, as well as special keywords such as inherit, none, swimlane.