NgTextflow

A small angular component to dynamically create a set of fixed size text nodes based on the input content text.

Installation

$ npm install --save ng-textflow

Then we import the module.

import { NgTextflowModule } from 'ng-textflow';

and we can use NodeComponent and CreateFlowService in our code.

import { NodeComponent, CreateFlowService } from 'ng-textflow';

Usage

The component requires a styles object which should define a fixed size container. This style is applied to all of the dynamically create nodes. When the content text will not fit in the defined container, NgTextflow will dynamically create new nodes and continue to fill them with text until all the content is displayed.

The image below shows an example of the generated nodes. The nodes on the left have simple inline styling with fixed width and height. The nodes on the right have the same content, but are overlay on top of each other using the [isOverlaid] input. This can be useful for page-flip applications.

The style object can be passed in, as below, to achieve the appearance of the nodes on the left. The style object must have the three elements, contentStyle, headingStyle, and numberStyle.

private  nodeStyles  = {
	contentStyle: {
		'height':  '9em',
		'width':  '200px',
		'fontFamily':  '"Vollkorn", "serif"',
		'fontSize':  '11px',
		'wordSpacing':  '2px',
		'textAlign':  'justify',
		'color':  '#444',
		'lineHeight':  '1.1em',
		'leftAlignLast':  'justified'
	},
	headingStyle: {
		'fontFamily':  '"Vollkorn", "serif"',
		'padding-bottom':  '2px',
		'font-size':  '14px',
		'height':  '25px'
	},
	numberStyle: {
		'font-size':  '10px',
		'fontFamily':  '"Vollkorn", "serif"',
	}
};

The following example shows the use of the component where style object and text content is passed in.

<ng-textflow
	[nodeStyles]="nodeStyles"
	[content]="content"
	[firstOnTop]="true"
	[showPageNumbers]="true"
	[isOverlaid]="true">
</ng-textflow>

Component Inputs

input	required	type	note
nodeStyles	required	any	See example nodeStyles above.
content	required	string	content: string = "Lot's of text here.."
firstOnTop	optional	boolean	Defines order of nodes by changing z-index of each node as they are generated.
showPageNumbers	optional	boolean	Displays the page number below or above the content area. NodeComponent.pageNumberAtTop is exposed to change the positioning of the number.
isOverlaid	optional	boolean	Changes the css positioning of the nodes so that they overlap over each other.

NodeComponent members

These members are for each generated node. An array of these can be retrieved from the CreateFlowService.nodes: Observable<NodeComponent[]>.

methods

applyStyle(style: any) Used in CreateFlowService to update the styles when generating a new node.

properties

heading: string The actual text of the heading for a specific node. When the headings for all nodes are empty, then the heading is hidden to preserve formating.

index The unique identifier for each node, also serves as the z-index value for when nodes are overlaid.

isOverlaid If true then all the nodes are overlaid on top of each other.

isVisible Hides or shows the particular node.

overflow: Observable<string> The overflow text is streamed here when there is too much text for the last node, here is where the next node generation is initiated.

pageNumber: number The value of the page number displayed below or above the node.

pageNumberAtTop: boolean Defines where the page number is displayed in the node.

showHeading: boolean Defines the visibility of the heading of a particular node.

showPageNumber: boolean Defines the visibility of the page numbers for a particular node.

text: string The actual text content of the node.

width: number The width of the masking element of the node. When this width is changed then the node content, headings, and numbers, are obscured from the left to the right.

How it works

A service is used to create the nodes. The service puts the text into a dummy node. The actual height of the dummy node in the DOM is compared with the height of the node. The node component estimates the amount to trim off, then fine tunes the number of words until the dummy node size matches the node size. An overflow Observable is pushed prompting the service to create the next node. The following animation is a slowed down debug version to show the process steps.