File Bubble - CometChat Docs

The File Bubble component renders file attachments within chat messages while maintaining visual consistency with the design system and ensuring full accessibility:

Message Object Processing: Extracts attachments and metadata from CometChat.MediaMessage objects
Single File Display: File icon, name, size, and download action
File Type Icons: Automatic icon mapping based on file extension or MIME type
File Size Formatting: Human-readable size display (B, KB, MB, GB)
Caption Support: Renders captions using TextMessageBubbleComponent
Download Actions: Direct download links for all files
Dual Styling: Supports sender (outgoing) and receiver (incoming) visual variants
Accessibility: Full keyboard navigation and screen reader support

Live Preview — Default file bubble preview. Open in Storybook ↗

Basic Usage

Simple File Message

import { Component } from '@angular/core';
import { CometChat } from '@cometchat/chat-sdk-javascript';
import { CometChatFileBubbleComponent, MessageBubbleAlignment } from '@cometchat/chat-uikit-angular';

@Component({
  selector: 'app-chat-message',
  standalone: true,
  imports: [CometChatFileBubbleComponent],
  template: `
    <cometchat-file-bubble
      [message]="fileMessage"
      [alignment]="MessageBubbleAlignment.left"
    ></cometchat-file-bubble>
  `
})
export class ChatMessageComponent {
  fileMessage!: CometChat.MediaMessage;
  MessageBubbleAlignment = MessageBubbleAlignment;
}

Incoming vs Outgoing Messages

import { Component } from '@angular/core';
import { CometChat } from '@cometchat/chat-sdk-javascript';
import { CometChatFileBubbleComponent, MessageBubbleAlignment } from '@cometchat/chat-uikit-angular';

@Component({
  selector: 'app-message-list',
  standalone: true,
  imports: [CometChatFileBubbleComponent],
  template: `
    <!-- Incoming message (left-aligned) -->
    <cometchat-file-bubble
      [message]="incomingMessage"
      [alignment]="MessageBubbleAlignment.left"
    ></cometchat-file-bubble>

    <!-- Outgoing message (right-aligned) -->
    <cometchat-file-bubble
      [message]="outgoingMessage"
      [alignment]="MessageBubbleAlignment.right"
    ></cometchat-file-bubble>
  `
})
export class MessageListComponent {
  incomingMessage!: CometChat.MediaMessage;
  outgoingMessage!: CometChat.MediaMessage;
  MessageBubbleAlignment = MessageBubbleAlignment;
}

Properties

Property	Type	Default	Description
`message`	`CometChat.MediaMessage`	required	The CometChat.MediaMessage object to render. Contains file attachments, metadata, and sender information
`alignment`	`MessageBubbleAlignment`	`MessageBubbleAlignment.left`	The alignment of the message bubble. `left` for incoming/receiver messages, `right` for outgoing/sender messages

Advanced Usage

Single File Message

The component displays single file messages with file icon, name, size, and download button:

import { Component } from '@angular/core';
import { CometChat } from '@cometchat/chat-sdk-javascript';
import { CometChatFileBubbleComponent } from '@cometchat/chat-uikit-angular';

@Component({
  selector: 'app-single-file',
  standalone: true,
  imports: [CometChatFileBubbleComponent],
  template: `
    <cometchat-file-bubble
      [message]="singleFileMessage"
    ></cometchat-file-bubble>
  `
})
export class SingleFileComponent {
  singleFileMessage!: CometChat.MediaMessage;
}

Single File Features:

File type icon based on extension
File name display
File size in human-readable format
Download button

Files with Captions

The component automatically renders captions using the TextMessageBubbleComponent:

import { Component } from '@angular/core';
import { CometChat } from '@cometchat/chat-sdk-javascript';
import { CometChatFileBubbleComponent } from '@cometchat/chat-uikit-angular';

@Component({
  selector: 'app-captioned-file',
  standalone: true,
  imports: [CometChatFileBubbleComponent],
  template: `
    <cometchat-file-bubble
      [message]="captionedFileMessage"
    ></cometchat-file-bubble>
  `
})
export class CaptionedFileComponent {
  captionedFileMessage!: CometChat.MediaMessage;
  
  // Message with caption:
  // message.getText() returns "Here are the project documents"
}

Caption Features:

Displays below the file(s)
Supports rich text formatting (bold, italic, etc.)
Supports @mentions with click events
Supports URLs with click events
Supports read more/less for long captions
Inherits alignment from parent bubble

File Type Icons

The component automatically selects appropriate icons based on file type:

import { Component } from '@angular/core';
import { CometChat } from '@cometchat/chat-sdk-javascript';
import { CometChatFileBubbleComponent } from '@cometchat/chat-uikit-angular';

@Component({
  selector: 'app-file-types',
  standalone: true,
  imports: [CometChatFileBubbleComponent],
  template: `
    <!-- PDF document -->
    <cometchat-file-bubble [message]="pdfMessage"></cometchat-file-bubble>
    
    <!-- Excel spreadsheet -->
    <cometchat-file-bubble [message]="excelMessage"></cometchat-file-bubble>
    
    <!-- PowerPoint presentation -->
    <cometchat-file-bubble [message]="pptMessage"></cometchat-file-bubble>
    
    <!-- ZIP archive -->
    <cometchat-file-bubble [message]="zipMessage"></cometchat-file-bubble>
    
    <!-- Unknown file type -->
    <cometchat-file-bubble [message]="unknownMessage"></cometchat-file-bubble>
  `
})
export class FileTypesComponent {
  pdfMessage!: CometChat.MediaMessage;      // Shows PDF icon
  excelMessage!: CometChat.MediaMessage;    // Shows spreadsheet icon
  pptMessage!: CometChat.MediaMessage;      // Shows presentation icon
  zipMessage!: CometChat.MediaMessage;      // Shows archive icon
  unknownMessage!: CometChat.MediaMessage;  // Shows generic file icon
}

Supported File Types:

Documents: PDF, DOC, DOCX, TXT
Spreadsheets: XLS, XLSX, CSV
Presentations: PPT, PPTX
Code Files: JS, TS, HTML, CSS, JSON
Archives: ZIP, RAR, TAR, GZ
Media: JPG, PNG, MP3, MP4, MOV
Unknown: Generic file icon for unsupported types

File Size Formatting

The component automatically formats file sizes in human-readable units:

// File size examples:
// 512 bytes → "512 B"
// 2048 bytes → "2.00 KB"
// 5242880 bytes → "5.00 MB"
// 2147483648 bytes → "2.00 GB"
// null or 0 → "Size unknown"

Size Formatting Rules:

Less than 1024 bytes: Displays in bytes (B)
Less than 1 MB: Displays in kilobytes (KB)
Less than 1 GB: Displays in megabytes (MB)
1 GB or more: Displays in gigabytes (GB)
Always rounds to 2 decimal places
Handles missing size gracefully

Customization

Styling with CSS Variables

The File Bubble component uses CSS variables exclusively for easy customization:

/* Custom file bubble styling */
cometchat-file-bubble {
  /* Spacing */
  --cometchat-spacing-1: 4px;
  --cometchat-spacing-2: 8px;
  --cometchat-spacing-3: 12px;
  --cometchat-spacing-4: 16px;

  /* Typography */
  --cometchat-font-body-medium: 500 14px 'Inter';
  --cometchat-font-caption1-regular: 400 12px 'Inter';
  --cometchat-font-caption1-bold: 600 12px 'Inter';

  /* Colors - Incoming messages */
  --cometchat-background-color-01: #FFFFFF;
  --cometchat-background-color-02: #F5F5F5;
  --cometchat-text-color-primary: #141414;
  --cometchat-text-color-secondary: #666666;

  /* Colors - Outgoing messages */
  --cometchat-primary-button-background: #6852D6;
  --cometchat-primary-button-text: #FFFFFF;

  /* Border radius */
  --cometchat-radius-2: 8px;
  --cometchat-radius-max: 1000px;

  /* Border colors */
  --cometchat-border-color-light: #E0E0E0;
}

Available CSS Variables

Variable	Purpose	Default
`--cometchat-spacing-1` to `--cometchat-spacing-4`	Padding, margin, gap	`4px` to `16px`
`--cometchat-font-body-medium`	File name font	`500 14px Roboto`
`--cometchat-font-caption1-regular`	File size font	`400 12px Roboto`
`--cometchat-font-caption1-bold`	Expand indicator font	`600 12px Roboto`
`--cometchat-background-color-01`	Incoming bubble background	`#FFFFFF`
`--cometchat-background-color-02`	Incoming file item background	`#F5F5F5`
`--cometchat-text-color-primary`	File name color	`#141414`
`--cometchat-text-color-secondary`	File size color	`#666666`
`--cometchat-primary-button-background`	Outgoing bubble background	`#6852D6`
`--cometchat-primary-button-text`	Outgoing text color	`#FFFFFF`
`--cometchat-primary-color`	Expand indicator background	`#6852D6`
`--cometchat-radius-2`	Border radius	`8px`
`--cometchat-radius-max`	Expand indicator radius	`1000px` (circular)
`--cometchat-border-color-light`	Border color	`#E0E0E0`

Custom Color Schemes

/* Blue theme for incoming messages */
.theme-blue cometchat-file-bubble {
  --cometchat-background-color-02: #E3F2FD;
  --cometchat-border-color-light: #90CAF9;
}

/* Green theme for outgoing messages */
.theme-green cometchat-file-bubble {
  --cometchat-primary-button-background: #4CAF50;
  --cometchat-primary-color: #4CAF50;
}

/* Dark theme */
[data-theme="dark"] cometchat-file-bubble {
  --cometchat-background-color-01: #1E1E1E;
  --cometchat-background-color-02: #2C2C2C;
  --cometchat-text-color-primary: #FFFFFF;
  --cometchat-text-color-secondary: #B0B0B0;
  --cometchat-border-color-light: #404040;
}

Custom Expand Indicator Styling

/* Custom expand indicator button */
::ng-deep .cometchat-file-bubble__expand-indicator {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  padding: 6px 12px;
  border-radius: 16px;
  font-weight: 700;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
  transition: transform 0.2s, box-shadow 0.2s;
}

::ng-deep .cometchat-file-bubble__expand-indicator:hover {
  transform: translateY(-1px);
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.15);
}

Custom File Item Styling

/* Custom file item styling */
::ng-deep .cometchat-file-bubble__file-item {
  background: #FAFAFA;
  border: 1px solid #E0E0E0;
  border-radius: 8px;
  padding: 12px;
  transition: background-color 0.2s;
}

::ng-deep .cometchat-file-bubble__file-item:hover {
  background: #F5F5F5;
}

::ng-deep .cometchat-file-bubble__filename {
  font-weight: 600;
  color: #141414;
}

::ng-deep .cometchat-file-bubble__filesize {
  font-size: 11px;
  color: #999999;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

Accessibility

The File Bubble component is fully accessible and follows WCAG 2.1 Level AA guidelines.

WCAG 2.1 Compliance

The component meets the following WCAG 2.1 Level AA success criteria:

✅ 1.1.1 Non-text Content (Level A): All file icons have descriptive text alternatives
✅ 1.3.1 Info and Relationships (Level A): Proper semantic structure with buttons and links
✅ 2.1.1 Keyboard (Level A): All functionality available via keyboard
✅ 2.4.7 Focus Visible (Level AA): Clear focus indicators on all interactive elements
✅ 4.1.2 Name, Role, Value (Level A): All elements have accessible names and roles

Keyboard Support

Key	Action	Context
`Tab`	Navigate to download links	When files are displayed

ARIA Attributes

The component automatically applies appropriate ARIA attributes:

Attribute	Element	Value	Purpose
`aria-label`	Download links	`"Download [filename]"`	Describes download action for each file

Screen readers announce the file bubble with:

Single file: “File, [filename], [size], Download button”
Download links: “Link, Download [filename]“

Accessibility Best Practices

The component automatically handles all accessibility requirements. No additional ARIA attributes or keyboard handling is needed.

Ensure file names are descriptive for screen reader users. Avoid cryptic filenames like “IMG_1234.jpg”.

All interactive elements (expand indicator, collapse button, download links) are keyboard accessible and have visible focus indicators.

Best Practices

Always provide the complete CometChat.MediaMessage object to ensure all features (attachments, captions, metadata) work correctly.

The component expects file attachments with valid URLs. Ensure your message objects have properly formatted attachment data.

Use the alignment property to distinguish between incoming and outgoing messages for proper visual styling.

File names should be descriptive and include file extensions for better user experience and accessibility.

The component does NOT open a modal or fullscreen view. Expansion happens inline within the message bubble.

The component handles missing or invalid data gracefully, displaying “Size unknown” for missing file sizes and generic icons for unknown file types.

CometChatTextBubble: Used for rendering captions in file messages
CometChatImageBubble: Displays image messages with grid layouts and gallery
CometChatVideoBubble: Displays video messages with thumbnails and player
CometChatMessageBubble: Uses File Bubble as the content view for file messages
CometChatMessageList: Displays lists of messages including file bubbles

Technical Details

Standalone Component: Can be imported and used independently
Change Detection: Uses OnPush change detection strategy for optimal performance
Dependencies:
- Angular CommonModule
- CometChat SDK for message types
- TranslatePipe for localization
- CometChatTextBubbleComponent for captions
Bundle Size: Minimal footprint (~8KB)
BEM CSS: Follows Block Element Modifier naming convention
Accessibility: WCAG 2.1 Level AA compliant

Performance Considerations

Optimization Strategies

Change Detection:

Uses OnPush strategy to minimize unnecessary re-renders
Only updates when inputs change or events are emitted

State Management:

Minimal internal state (only UI state for expand/collapse)
All data derived from message input
No SDK calls or service dependencies

Layout Determination:

Attachments extracted once during message processing
File type and size formatting cached
Avoids repeated calculations during rendering

Expand/Collapse Animation:

Uses CSS transitions for smooth animations
Efficient height animation without JavaScript
Focus management optimized with setTimeout

Best Practices for Performance

The component uses OnPush change detection. Ensure message objects are immutable for optimal performance.

The component does not make any SDK calls or service calls. All data is derived from the input message object.

Avoid frequently changing the message input. Each change triggers re-processing of attachments and metadata.

For troubleshooting tips, see the Troubleshooting Guide.

​Basic Usage

​Simple File Message

​Incoming vs Outgoing Messages

​Properties

​Advanced Usage

​Single File Message

​Files with Captions

​File Type Icons

​File Size Formatting

​Customization

​Styling with CSS Variables

​Available CSS Variables

​Custom Color Schemes

​Custom Expand Indicator Styling

​Custom File Item Styling

​Accessibility

​WCAG 2.1 Compliance

​Keyboard Support

​ARIA Attributes

​Screen Reader Behavior

​Accessibility Best Practices

​Best Practices

​Related Components

​Technical Details

​Performance Considerations

​Optimization Strategies

​Best Practices for Performance

Basic Usage

Simple File Message

Incoming vs Outgoing Messages

Properties

Advanced Usage

Single File Message

Files with Captions

File Type Icons

File Size Formatting

Customization

Styling with CSS Variables

Available CSS Variables

Custom Color Schemes

Custom Expand Indicator Styling

Custom File Item Styling

Accessibility

WCAG 2.1 Compliance

Keyboard Support

ARIA Attributes

Screen Reader Behavior

Accessibility Best Practices

Best Practices

Related Components

Technical Details

Performance Considerations

Optimization Strategies

Best Practices for Performance