private void createShapes() {

		int displayHeight = canvas.getHeight();
		int displayWidth = canvas.getWidth();// - FlowArrowPlugin.LEFT_OFFSET;
		int lineWidth = calculateLineWidth(displayWidth);

		arrowBody = FlowArrowShapeFactory.createArrowBody(plugin, this, displayWidth, displayHeight,
			lineWidth);

		arrowHead = FlowArrowShapeFactory.createArrowHead(plugin, this, displayWidth, displayHeight,
			lineWidth);
	}
Call when the screen moves so that the shape can be updated
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/flowarrow/FlowArrow.java