Aufbau eines dynamischen Rastersystems für responsive Besprechungskacheln in React

In the era of remote work and virtual meetings, creating a responsive and dynamic grid system for displaying participant video tiles is crucial. Inspired by platforms like Google Meet, I recently developed a flexible grid system in React that adapts seamlessly to varying numbers of participants and different screen sizes. In this blog post, I'll walk you through the implementation, explaining the key components and how they work together to create an efficient and responsive layout.

Table of Contents

1. Introduction
2. Grid Layout Definitions
3. Selecting the Appropriate Grid Layout
4. The useGridLayout Hook
5. Example Usage
6. Styling the Grid
7. Conclusion

Introduction

Creating a dynamic grid system involves adjusting the layout based on the number of items (or "tiles") and the available screen real estate. For video conferencing applications, this ensures that each participant's video feed is displayed optimally, regardless of the number of participants or the device being used.

The solution I developed leverages React hooks and CSS Grid to manage and render the grid layout dynamically. Let's dive into the core components of this system.

Grid Layout Definitions

First, we define the possible grid layouts that our system can use. Each layout specifies the number of columns and rows, as well as constraints on the minimum and maximum number of tiles it can accommodate.

import { useState, useEffect, RefObject } from 'react';

export type GridLayoutDefinition = {
  name: string;
  columns: number;
  rows: number;
  minTiles: number;
  maxTiles: number;
  minWidth: number;
  minHeight: number;
};

export const GRID_LAYOUTS: GridLayoutDefinition[] = [
  { columns: 1, rows: 1, name: '1x1', minTiles: 1, maxTiles: 1, minWidth: 0, minHeight: 0 },
  { columns: 1, rows: 2, name: '1x2', minTiles: 2, maxTiles: 2, minWidth: 0, minHeight: 0 },
  { columns: 2, rows: 1, name: '2x1', minTiles: 2, maxTiles: 2, minWidth: 900, minHeight: 0 },
  { columns: 2, rows: 2, name: '2x2', minTiles: 3, maxTiles: 4, minWidth: 560, minHeight: 0 },
  { columns: 3, rows: 3, name: '3x3', minTiles: 5, maxTiles: 9, minWidth: 700, minHeight: 0 },
  { columns: 4, rows: 4, name: '4x4', minTiles: 10, maxTiles: 16, minWidth: 960, minHeight: 0 },
  { columns: 5, rows: 5, name: '5x5', minTiles: 17, maxTiles: 25, minWidth: 1100, minHeight: 0 },
];

Explanation

• GridLayoutDefinition: A TypeScript type that defines the properties of each grid layout.
• GRID_LAYOUTS: An array of predefined layouts, ordered by complexity. Each layout specifies:
  • columns and rows: The number of columns and rows in the grid.
  • name: A descriptive name for the layout (e.g., '2x2').
  • minTiles and maxTiles: The range of tile counts that the layout can accommodate.
  • minWidth and minHeight: The minimum container dimensions required for the layout.

Selecting the Appropriate Grid Layout

The core logic for selecting the right grid layout based on the number of tiles and container size is encapsulated in the selectGridLayout function.

function selectGridLayout(
  layouts: GridLayoutDefinition[],
  tileCount: number,
  width: number,
  height: number,
): GridLayoutDefinition {
  let currentLayoutIndex = 0;
  let layout = layouts.find((layout_, index, allLayouts) => {
    currentLayoutIndex = index;
    const isBiggerLayoutAvailable = allLayouts.findIndex((l, i) => 
      i > index && l.maxTiles === layout_.maxTiles
    ) !== -1;
    return layout_.maxTiles >= tileCount && !isBiggerLayoutAvailable;
  });

  if (!layout) {
    layout = layouts[layouts.length - 1];
    console.warn(`No layout found for: tileCount: ${tileCount}, width/height: ${width}/${height}. Fallback to biggest available layout (${layout?.name}).`);
  }

  if (layout && (width < layout.minWidth || height < layout.minHeight)) {
    if (currentLayoutIndex > 0) {
      const smallerLayout = layouts[currentLayoutIndex - 1];
      layout = selectGridLayout(
        layouts.slice(0, currentLayoutIndex),
        smallerLayout.maxTiles,
        width,
        height,
      );
    }
  }

  return layout || layouts[0];
}

How It Works

1. Initial Selection: The function iterates through the layouts array to find the first layout where maxTiles is greater than or equal to tileCount and ensures there's no larger layout with the same maxTiles available.

2. Fallback Mechanism: If no suitable layout is found, it defaults to the largest available layout and logs a warning.

3. Responsive Adjustment: If the selected layout's minWidth or minHeight constraints aren't met by the container dimensions, the function recursively selects a smaller layout that fits within the constraints.

4. Final Return: The selected layout is returned, ensuring that the grid is both adequate for the number of tiles and fits within the container's size.

The useGridLayout Hook

To encapsulate the grid selection logic and make it reusable across components, I created the useGridLayout custom hook.

export function useGridLayout(
  gridRef: RefObject<HTMLElement>,
  tileCount: number
): { layout: GridLayoutDefinition } {
  const [layout, setLayout] = useState<GridLayoutDefinition>(GRID_LAYOUTS[0]);

  useEffect(() => {
    const updateLayout = () => {
      if (gridRef.current) {
        const { width, height } = gridRef.current.getBoundingClientRect();
        const newLayout = selectGridLayout(GRID_LAYOUTS, tileCount, width, height);
        setLayout(newLayout);

        gridRef.current.style.setProperty('--col-count', newLayout.columns.toString());
        gridRef.current.style.setProperty('--row-count', newLayout.rows.toString());
      }
    };

    updateLayout();

    window.addEventListener('resize', updateLayout);
    return () => window.removeEventListener('resize', updateLayout);
  }, [gridRef, tileCount]);

  return { layout };
}

Hook Breakdown

• Parameters:

  • gridRef: A reference to the grid container element.
  • tileCount: The current number of tiles to display.

• State Management: Uses useState to keep track of the current layout, initializing with the first layout in GRID_LAYOUTS.

• Effect Hook:

  • updateLayout Function: Retrieves the container's width and height, selects the appropriate layout using selectGridLayout, and updates the state. It also sets CSS variables --col-count and --row-count on the container for styling.
  • Event Listener: Adds a resize event listener to update the layout whenever the window size changes. Cleans up the listener on component unmount.

• Return Value: Provides the current layout object to the consuming component.

Example Usage

To demonstrate how this dynamic grid system works in practice, here's an example React component that uses the useGridLayout hook.

'use client'

import React, { useState, useRef, useEffect } from 'react'
import { Button } from "@/components/ui/button"
import { useGridLayout, GridLayoutDefinition } from './useGridLayout'

export default function Component() {
  const [tiles, setTiles] = useState<number[]>([1, 2, 3, 4]);
  const [containerWidth, setContainerWidth] = useState(typeof window !== 'undefined' ? window.innerWidth : 1000);
  const gridRef = useRef<HTMLDivElement>(null);

  const { layout } = useGridLayout(gridRef, tiles.length);

  useEffect(() => {
    const handleResize = () => {
      setContainerWidth(window.innerWidth);
    };

    window.addEventListener('resize', handleResize);
    return () => window.removeEventListener('resize', handleResize);
  }, []);

  const addTile = () => setTiles(prev => [...prev, prev.length + 1]);
  const removeTile = () => setTiles(prev => prev.slice(0, -1));

  return (
    <div className="flex flex-col items-center gap-4 p-4 w-full">
      <div className="flex flex-wrap justify-center gap-2 mb-4">
        <Button onClick={addTile}>Add Tile</Button>
        <Button onClick={removeTile}>Remove Tile</Button>
      </div>
      <div className="w-full border border-gray-300 p-4">
        <div 
          ref={gridRef} 
          className="grid gap-4"
          style={{
            gridTemplateColumns: `repeat(var(--col-count), 1fr)`,
            gridTemplateRows: `repeat(var(--row-count), 1fr)`,
          }}
        >
          {tiles.slice(0, layout.maxTiles).map((tile) => (
            <div key={tile} className="bg-primary text-primary-foreground p-4 rounded flex items-center justify-center">
              Tile {tile}
            </div>
          ))}
        </div>
      </div>
      <div className="text-center mt-4">
        <p>Current Layout: {layout.name} ({layout.columns}x{layout.rows})</p>
        <p>Container Width: {containerWidth}px</p>
        <p>Visible Tiles: {Math.min(tiles.length, layout.maxTiles)} / Total Tiles: {tiles.length}</p>
      </div>
    </div>
  )
}

Component Breakdown

1. State Management:

   • tiles: An array representing the current tiles. Initially contains four tiles.
   • containerWidth: Tracks the container's width, updating on window resize.

2. Refs:

   • gridRef: A reference to the grid container, passed to the useGridLayout hook.

3. Using the Hook:

   • Destructures the layout object from the useGridLayout hook, which determines the current grid layout based on the number of tiles and container size.

4. Event Handling:

   • Add Tile: Adds a new tile to the grid.
   • Remove Tile: Removes the last tile from the grid.
   • Resize Listener: Updates containerWidth on window resize.

5. Rendering:

   • Controls: Buttons to add or remove tiles.
   • Grid Container:
     • Uses CSS Grid with dynamic gridTemplateColumns and gridTemplateRows based on CSS variables set by the hook.
     • Renders tiles up to the layout.maxTiles limit.
   • Info Section: Displays the current layout, container width, and the number of visible versus total tiles.

What Happens in Action

• Adding Tiles: As you add more tiles, the useGridLayout hook recalculates the appropriate grid layout to accommodate the new number of tiles while respecting the container's size.
• Removing Tiles: Removing tiles triggers a layout recalculation to potentially use a smaller grid layout, optimizing space.
• Resizing: Changing the window size dynamically adjusts the grid layout to ensure that the tiles remain appropriately sized and positioned.

Styling the Grid

The grid's responsiveness is primarily handled via CSS Grid properties and dynamically set CSS variables. Here's a brief overview of how the styling works:

/* Example Tailwind CSS classes used in the component */
/* The actual styles are managed via Tailwind, but the key dynamic properties are set inline */

.grid {
  display: grid;
  gap: 1rem; /* Adjust as needed */
}

.grid > div {
  /* Example styles for tiles */
  background-color: var(--color-primary, #3490dc);
  color: var(--color-primary-foreground, #ffffff);
  padding: 1rem;
  border-radius: 0.5rem;
  display: flex;
  align-items: center;
  justify-content: center;
}

Dynamic CSS Variables

In the useGridLayout hook, the following CSS variables are set based on the selected layout:

• --col-count: Number of columns in the grid.
• --row-count: Number of rows in the grid.

These variables are used to define the gridTemplateColumns and gridTemplateRows properties inline:

style={{
  gridTemplateColumns: `repeat(var(--col-count), 1fr)`,
  gridTemplateRows: `repeat(var(--row-count), 1fr)`,
}}

This approach ensures that the grid layout adapts seamlessly without the need for extensive CSS media queries.

Conclusion

Building a dynamic grid system for applications like video conferencing requires careful consideration of both the number of elements and the available display space. By defining a set of responsive grid layouts and implementing a custom React hook to manage layout selection, we can create a flexible and efficient system that adapts in real-time to user interactions and screen size changes.

This approach not only enhances the user experience by providing an optimal viewing arrangement but also simplifies the development process by encapsulating the layout logic within reusable components. Whether you're building a video conferencing tool, a dashboard, or any application that requires dynamic content arrangement, this grid system can be a valuable addition to your toolkit.

Feel free to customize and extend this system to suit your specific needs. Happy coding!

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