UI-library

A collection of tools for common UI requirements for Decentraland scenes.

To use any of the helpers provided by the UI utils library:

1. Install the library as an npm package. Run this command in your scene's project folder:

npm install decentraland-ui-utils

2. Import the library into the scene's script. Add this line at the start of your game.ts file, or any other TypeScript files that require it:

import * as ui from '../node_modules/decentraland-ui-utils/index'

3. In your TypeScript file, write ui. and let the suggestions of your IDE show the available helpers.

Text Announcement

To display a text announcement on the center of the screen for a specified amount of time, use the displayAnnouncement function.

ui.displayAnnouncement('Hello world')

This function can take the following parameters:

• value: String to display
• duration: Time to keep the text visible (in seconds). Default: 3 seconds. If set to -1, the announcement will remain on screen till it's hidden.
• silent: By default the displayAnnouncement function plays a notification sound when the text appears. If this flag is true, the sound is avoided.
• color: Text color, as a Color4, default: yellow.
• size: Font size, default: 50
• bordersOff: The text has a thin black margin unless this field is set to true.

ui.displayAnnouncement('Ouch!', 5, true, Color4.Red(), 50, true)

To hide any open announcements, you can call hideAnnouncements().

ui.hideAnnouncements()

Counter

To display a number on a corner of the screen that can be easily updated, you can create a Counter.

let ammo = new ui.UICounter(30)

When instancing a new counter you can pass the following parameters:

• value: Starting value
• xOffset: Offset on X away from the bottom-left corner
• yOffset: Offset on Y away from the bottom-left corner
• color: Text color, white by default
• size: Text size, 25 by default
• bordersOff: The text has a thin black margin unless this field is set to true.

let ammo = new ui.UICounter(30, 0, 60, Color4.Yellow(), 30, true)

Once a UICounter object is instanced, you can call the following functions on it:

• read: Returns the current value of the counter
• increase: Increases the number by a given amount. If no parameters are passed, it raises the value by 1.
• decrease: Decreases the number by a given amount. If no parameters are passed, it lowers the value by 1.
• set: Sets the number to a given amount, no matter what the previous value was.

myEntiy.addComponent(new OnPointerDown(e => {
  if (ammo.read() <= 0) return
  ammo.decrease()
})

Corner Labels

To display text on the bottom-left corner of the screen, you can create a CornerLabel.

let healthLabel = new ui.CornerLabel('Health:')

When instancing a new corner label you can pass the following parameters:

• value: Text to show.
• xOffset: Offset on X, relative to the bottom-right corner.
• yOffset: Offset on Y, relative to the bottom-right corner.
• color: Text color, white by default
• size: Text size, 25 by default
• bordersOff: The text has a thin black margin unless this field is set to true.

Bar

To display a bar that can be updated to increase or shorten in length, similar to a typical health bar in games, you can create a UIBar.

let health = new ui.UIBar(0.8)

When instancing a new bar you can pass the following parameters:

• value: Starting value of the bar, from 0 to 1. With 1 the bar is full, with 0 it's empty.
• xOffset: Offset on X away from the bottom-left corner
• yOffset: Offset on Y away from the bottom-left corner
• fillColor: Color of the bar filling, red by default
• style: Margin style of the bar, from a list of different predetermined options in different colors and shapes. It takes a value from the BarStyles enum.
• scale: Multiplier to alter the size of the bar proportionally. A scale of 1 = 128 x 32 pixels

let health = new ui.UIBar(1, -30, 130, Color4.Red(), BarStyles.ROUNDSILVER, 1)

Once a UIBar object is instanced, you can call the following functions on it:

• read: Returns the current value of the counter
• increase: Increases the number by a given amount. If no parameters are passed, it raises the value by 0.1.
• decrease: Secreases the number by a given amount. If no parameters are passed, it lowers the value by 0.1.
• set: Sets the bar to a given value, no matter what the previous value was.

myEntiy.addComponent(new OnPointerDown(e => {
	health.decrease(0.1)
	if (health.read() <= 0) {
		// die
	}
})

Corner Icons

To display an icon of on the bottom-left corner of the screen you can create one of the following:

• SmallIcon: by default 32x32 pixels in size
• MediumIcon: by default 64x64 pixels in size
• LargeIcon: by default 128x128 pixels in size

let healthIcon = new ui.MediumIcon('images/heart64.png')

When instancing a new icon you can pass the following parameters:

• image: Path to the image file
• xOffset: Offset on X, relative to the bottom-right corner
• yOffset: Offset on Y, relative to the bottom-right corner
• width: Image width on screen in pixels
• height: Image height on screen in pixels
• section: Use only a section of the image file, useful when arranging multiple icons into an image atlas. This field takes an ImageSection object, specifying sourceWidth and sourceHeight, and optionally also sourceLeft and sourceTop.

let ammoIcon = new ui.SmallIcon('images/ammo32.png', -70, 70)
let healthIcon = new ui.MediumIcon('images/heart64.png', -170, 120)

Loading icon

To display a loading icon on the center of the screen for a specified amount of time, create a LoadingIcon.

loading = new ui.LoadingIcon(3)

When instancing a new loading icon, you can pass the following parameters:

• duration: seconds to display the image onscreen. If not set, or set to 0, it keeps the icon on till you hide it.
• xOffset: Offset on X, relative to the center of the screen
• yOffset: Offset on Y, relative to the center of the screen
• scale: Multiplier to alter the size of the icon proportionally. A scale of 1 = 48 x 64 pixels

loading = new ui.LoadingIcon(3, 0, 40, 0.5)

Once a LoadingIcon object is instanced, you can call the hide() function to remove it.

Full screen image

To display a large image on the center of the screen for a spefified amount of time, create a CenterImage. By default images must be 512 x 512 pixels, unless specified.

let largeImage = new ui.CenterImage('images/Burn.png')

When instancing a new large image, you can pass the following parameters:

• image: Path to image file
• duration: Seconds to display the image onscreen, 3 seconds by default. -1 keeps it on till you hide it.
• startHidden: If true, the image starts invisible till you run its show() function. Large images may flash white for a second if created and shown at the same time. By deferring the creation you avoid this artifact.
• xOffset: Offset on X, relative to the center of the screen
• yOffset: Offset on Y, relative to the center of the screen

• width: Image width on screen in pixels, 512 by default
• height: Image height on screen in pixels, 512 by default
• section: Use only a section of the image file, useful when arranging multiple images into an image atlas. This field takes an ImageSection object, specifying sourceWidth and sourceHeight, and optionally also sourceLeft and sourceTop.

let gameOver = new ui.CenterImage('images/Burn.png', 3, true, 0, 0, 512, 512, {
  sourceHeight: 512,
  sourceWidth: 512,
  sourceLeft: 0,
  sourceTop: 0
})
gameOver.show()

Once a CenterImage object is instanced, you can call the following functions on it:

• show: Shows the image
• hide: Hides the image

Predefined prompt windows

The UI Utils library includes various common prompt windows to display messages and ask players to take action.

Ok Prompt

Displays a prompt window with a custom message and an OK button. The Ok button can either be clicked or triggered by pressing the E key.

When instancing a new Ok Prompt, you can pass the following parameters:

• instructions: Message string.
• onAccept: Function that gets executed if player clicks the button or presses E.
• acceptLabel: Label to go in the accept button, "Ok" by default.
• useDarkTheme: Switch the style of the window to the dark theme.

let prompt = new ui.OkPrompt(
  'This is an Ok Prompt',
  () => {
    log(`accepted`)
  },
  'Ok',
  true
)

Note: If the player closes the window with the close icon, the related function isn't called.

Option Prompt

Displays a prompt window with a custom message, a title, and two buttons that perform separate actions. The buttons can be clicked or triggered by the E and F keys.

When instancing a new Option Prompt, you can pass the following parameters:

• title: Header in bold letters at the top of the window
• instructions: Smaller print instructions
• onAccept: Function that gets executed if player clicks accept
• onReject: Function that gets executed if player clicks reject
• acceptLabel: String to go in the accept button
• rejectLabel: String to go in the reject button
• useDarkTheme: Switch the style of the window to the dark theme.

let prompt = new ui.OptionPrompt(
  'Pick an option!',
  'What will you choose?',
  () => {
    log(`picked option A`)
  },
  () => {
    log(`picked option B`)
  },
  'Pick A',
  'Pick B'
)

Note: If the player closes the window with the close icon, neither of the functions are called.

Fill in Prompt

Displays a prompt window with a header, a text field to fill in and a submit button. The value filled into the text box can be used as a parameter in the submit function.

When instancing a new Fill-in Prompt, you can pass the following parameters:

• title: Header in bold letters at the top of the window.
• onAccept: Function that gets executed when player clicks button of presses the E key.
• acceptLabel: String to use as label on the submit button. "Submit" by default.
• placeholder: Text to display as placeholder in the text box.
• useDarkTheme: Switch the style of the window to the dark theme.

let prompt = new ui.FillInPrompt(
  'What are you thinking?',
  (e: string) => {
    log(e)
  },
  'Submit!',
  'Text goes here'
)

Note: If the player closes the window with the close icon, the related function isn't called.

Custom Prompt Windows

Custom prompt windows let you arrange as many elements as you want into a window, including buttons, text, checkboxes, switches, textboxes and icons.

Create a custom prompt

First create a new CustomPrompt object.

let prompt = new ui.CustomPrompt(PromptStyles.DARKSLANTED)

When instancing a new loading icon, you can pass the following parameters:

• useDarkTheme: Switch the style of the window to the dark theme.

• width: Background width on screen in pixels. The default size depends on the theme used.
• height: Background height on screen in pixels. The default size depends on the theme used.

Note: Stretching the background images away from their default values may lead to blurry corners.

Once you instanced a CustomPrompt object, you can add elements to it by calling its various functions.

You can also call the following functions on it:

• close: Hides the window
• reopen: Shows the window if previously closed

Add Text

To add text to a custom prompt, use the addText function.

prompt.addText('Hello World', 0, 100)

The addText() function can take the following parameters:

• value: Text to show
• posX: Offset on X from the center of the window.
• posY: Offset on Y from the center of the window.
• color: Text color.
• size: Text size.

The addText() function returns a CustomPromptText object, that you can then reference to change its values. This object also has the following functions that can be called any time:

• hide
• show

Add a button

To add a button to a custom prompt, use the addButton function.

prompt.addButton(
  'Yes',
  0,
  -30,
  () => {
    log('Yes')
    prompt.close()
  },
  ButtonStyles.E
)

The addButton function can take the following parameters:

• label: Label to show on the button.
• posX: Offset on X from the center of the window.
• posY: Offset on Y from the center of the window.
• onClick: Function to execute when the button is clicked.
• style: Choose out of several predefined style options, with different colors and rounded or square corners.

Note: If you pick the E or F style, the buttons will also be triggered when pressing the E or F keys respectively.

The addButton() function returns a CustomPromptButton object, that you can then reference to change its values. This object also has the following functions that can be called any time:

• hide
• show
• grayOut: Sets the text to gray and makes it unclickable.
• enable: Sets the text to white and makes it clickable again.

Add a Checkbox

To add a checkbox to a custom prompt, use the addCheckbox function.

prompt.addCheckbox(
  "Don't show again",
  -80,
  50,
  () => {
    log('checkbox ticked')
  },
  () => {
    log('checkbox unticked')
  }
)

The addCheckbox function can take the following parameters:

• label: Label to show next to the checkbox.
• posX: Offset on X from the center of the window.
• posY: Offset on Y from the center of the window.
• onCheck: Function to execute when the box is checked.
• onUncheck: Function to execute when the box is unchecked.
• large: The default size of the checkbox is 24 x 24 pixels, checking this box sets the size to 32 x 32.
• startChecked: If true, the box starts checked by default.

The addCheckbox() function returns a CustomPromptCheckbox object, that you can then reference to change and read its values. This object also has the following functions that can be called any time:

• hide
• show
• check: Sets the element to checked, without performing the associated function.
• uncheck: Sets the element to checked, without performing the associated function.

You can also read the returned object's checked property at any time to find its current state.

Add a Switch

To add a switch to a custom prompt, use the addSwitch function.

prompt.addSwitch(
  'Turn on',
  -80,
  50,
  () => {
    log('switch activated')
  },
  () => {
    log('switch deactivated')
  }
)

The addSwitch function can take the following parameters:

• label: Label to show next to the switch.
• posX: Offset on X from the center of the window.
• posY: Offset on Y from the center of the window.
• onCheck: Function to execute when the switch is activated.
• onUncheck: Function to execute when the switch is deactivated.
• style: Pick between several sizes, with different colors and rounded or square corners. The value must be from the SwitchStyles enum.
• startChecked: If true, the switch starts activated by default.

The addSwitch() function returns a CustomPromptSwitch object, that you can then reference to change and read its values. This object also has the following functions that can be called any time:

• hide
• show
• check: Sets the element to checked, without performing the associated function.
• uncheck: Sets the element to checked, without performing the associated function.

You can also read the returned object's checked property at any time to find its current state.

Add an icon

To add an icon to a custom prompt, use the addIcon function.

prompt.addIcon(`images/icon.png`, -50, 0, 64, 64)

The addIcon function can take the following parameters:

• image: Path to the image file
• xOffset: Offset on X, relative to the window's center
• yOffset: Offset on Y, relative to the window's center
• width: Image width on screen in pixels
• height: Image height on screen in pixels
• section: Use only a section of the image file, useful when arranging multiple icons into an image atlas. This field takes an ImageSection object, specifying sourceWidth and sourceHeight, and optionally also sourceLeft and sourceTop.

The addIcon() function returns a CustomPromptIcon object, that you can then reference to change its values. This object also has the following functions that can be called any time:

• hide
• show

Add an input box

To add an input box to a custom prompt, use the addTextBox function.

prompt.addTextBox(`images/icon.png`, 0, 30)

The addTextBox function can take the following parameters:

• posX: Offset on X, relative to the window's center
• posY: Offset on Y, relative to the window's center
• placeholder: Text to display in the input box before the player interacts with it.
• onChange: Function that gets executed every time the player edits the content on the input box, once for each character changed.

The addTextBox() function returns a CustomPromptTextBox object, that you can then reference to change and read its values. This object also has the following functions that can be called any time:

• hide
• show

You can access the last edited value on the textbox by fetching the currentText value of the returned object.

Full Custom UI example

Here's a full example of a custom UI:

let prompt = new ui.CustomPrompt(PromptStyles.DARKSLANTED)
prompt.addText('What will you do?', 0, 130, Color4.Red(), 30)
prompt.addText("It's an important decision", 0, 100)

let checkBox = prompt.addCheckbox("Don't show again", -80, 50)

prompt.addButton(
  'Yeah',
  0,
  -30,
  () => {
    log('Yes')
    prompt.close()
  },
  ButtonStyles.E
)

prompt.addButton(
  'Nope',
  0,
  -90,
  () => {
    log('No')
    prompt.close()
  },
  ButtonStyles.F
)

NPC Dialog Window

You can display an interactive dialog window to simulate a conversation with a non-player character (NPC).

The conversation is based on a script in JSON format. The script can include questions that can take you forward or backward, or end the conversation.

The Dialog window

To create a new dialog window, create a new DialogWindow object. This will instantiate the window but keep it hidden until you open it.

let dialogWindow = new ui.DialogWindow()

When instantiating a new DialogWindow, you can pass the following parameters:

• defaultPortrait: Sets a default portrait image to use on the left of all dialogs that don't specify an image. If a dialog has no image and no default is provided, no image is shown. This field expects a Portrait object, that may include the following fields: - path: Path to the image file - xOffset: Offset on X, relative to the normal position of the portrait. - yOffset: Offset on Y, relative to the normal position of the portrait. - section: Use only a section of the image file, useful when arranging multiple icons into an image atlas. This field takes an ImageSection object, specifying sourceWidth and sourceHeight, and optionally also sourceLeft and sourceTop.
• useDarkTheme: Switch the style of the window to the dark theme.

Once a DialogWindow object is instanced, you can open a dialog window with the openDialogWindow() function.

dialogWindow.openDialogWindow(NPCTalk, 0)

When calling this function, you must specify:

• NPCScript: A JSON object that includes all the dialog tree.
• textId: The index of the entry to show first from the script. The first entry is 0.

You can close a dialog window at any time by calling the closeDialogWindow() function.

dialogWindow.closeDialogWindow()

The NPC script

Each entry on the script must include at least a text field, but can include several more fields to further customize it.

Below is a minimal dialog.

export let NPCTalk: Dialog[] = [
  {
    text: 'Hi there'
  },
  {
    text: 'It sure is nice talking to you'
  },
  {
    text: 'I must go, my planet needs me',
    isEndOfDialog: true
  }
]

The player advances through each entry by clicking the mouse button. Once the last is reached, clicking again closes the window, as it's marked as isEndOfDialog.

The script must adhere to the following schema:

export class Dialog {
  text: string
  fontSize?: number
  offsetY?: number
  portrait?: Portrait
  isEndOfDialog?: boolean = false
  isQuestion?: boolean = false
  labelE?: {
    label: string
    fontSize?: number
    offsetX?: number
    offsetY?: number
  }
  ifPressE?: number
  triggeredByE?: () => void
  labelF?: {
    label: string
    fontSize?: number
    offsetX?: number
    offset?: number
  }
  ifPressF?: number
  triggeredByF?: () => void
}

You can set the following fields to change the appearance of a dialog:

• text: The dialog text
• fontSize: Size of the text
• offsetY: Offset of the text on the Y axis, relative to its normal position. This is especially useful to align longer multi-line strings.
• portrait: Sets the portrait image to use on the left. This field expects a Portrait object, that may include the following fields: - path: Path to the image file. - xOffset: Offset on X, relative to the normal position of the portrait. - yOffset: Offset on Y, relative to the normal position of the portrait. - section: Use only a section of the image file, useful when arranging multiple icons into an image atlas. This field takes an ImageSection object, specifying sourceWidth and sourceHeight, and optionally also sourceLeft and sourceTop.

Questions and conversation trees

The script can include questions that prompt the player to pick between two options. These questions can branch the conversation out and trigger other actions in the scene.

To make an entry a question, set the isQuestion field to true. This displays two buttons rather than the click icon. It also disables the click to advance to the next entry.

When on a question entry, you can customize the following:

• Set the label of either of the buttons, including text, size and alignment.
• With the ifPressE and ifPressE you specify the index of the next dialog entry to display.
• With triggeredByE and triggeredByF you can provide an additional function that gets run whenever the option is picked.