Masonry

Primitives for creating a reactive masonry layout.

• createMasonry - Creates a reactive masonry layout data from a reactive source array.

#createMasonry

Calculates reactive masonry layout data from a reactive source array.

It splits the items into columns and calculates the order based on the height of each item.

The masonary is expected to be rendered in a flex container with flex-direction: column, flex-wrap: wrap and limited height to force the items to wrap.

#How to use it

createMasonry requires an options object with the following properties:

• source - Accessor returning the source array of items to be mapped.

  When updating the array, the masonry will be recalculated. The items are compared by reference.

• columns - The number of columns to split the items into.

  This can be an accessor to provide a reactive number of columns.

• mapHeight - A function that maps the source item to a numeric height value.

  This function is not reactive, it will be called only once for each item. The value may relate to any unit of your choosing. To provede a reactice height, return an accessor.

• mapElement - A function that maps the source item to an element to render.

  This function is not reactive, it will be called only once for each item.

  This param is not required. If not provided, the source items with layout data will be returned.

import { createMasonry } from "@solid-primitives/masonry";

const [source, setSource] = createSignal([1, 2, 3, 4, 5, 6, 7, 8, 9, 10]);

const masonry = createMasonry({
  source,
  mapHeight: n => n * 100,
  columns: 3,
  mapElement: data => (
    <div
      style={{
        // data.height is the value returned by `mapHeight`
        // Height of the element should always match that value.
        height: `${data.height()}px`,
        // The flex order of the item in the masonry
        order: data.order(),
        // The space needed to be filled to prevent the next item from switching columns.
        // "margin-bottom" is just an example, you could also add this to the element's height.
        "margin-bottom": `${data.margin()}px`,
      }}
    >
      {/* a reference to the source item. (1, 2, 3, ...) */}
      Item: {data.source} <br />
      {/* The column the item falls into. The first column is 0. */}
      Column: {data.column()}
    </div>
  ),
});

return (
  <div
    style={{
      // The masonry should be rendered in a flex container with the following styles:
      display: "flex",
      "flex-direction": "column",
      "flex-wrap": "wrap",
      // align-items: stretch; is not required, but it will make items fill the full width of the container.
      "align-items": "stretch",
      // The height of the container should be limited to force the items to wrap.
      height: masonry.height(),
    }}
  >
    {/* The masonry is a reactive array of items returned from `mapElement()` */}
    {masonry()}
  </div>
);

#Mapping the elements in JSX

If a mapElement option is not provided, the source items with layout data will be returned. Those items cannot be rendered directly in JSX, but they can be mapped to elements with Solid's <For> component.

const masonry = createMasonry({
  source,
  mapHeight: getItemHeight,
  columns: 3,
});

return (
  <div
    style={{
      display: "flex",
      "flex-direction": "column",
      "flex-wrap": "wrap",
      "align-items": "stretch",
      height: masonry.height(),
    }}
  >
    <For each={masonry()}>
      {item => (
        <div
          style={{
            height: `${item.height()}px`,
            order: item.order(),
            "margin-bottom": `${item.margin()}px`,
          }}
        >
          {item.source}
        </div>
      )}
    </For>
  </div>
);

#Reactive columns

The number of columns can be provided as an accessor to provide a reactive number of columns.

This is useful when the number of columns should change based on the width of the container, size of the items, or a media query.

For example, it can be used with createBreakpoints from @solid-primitives/media to change the number of columns based on the screen size.

import { createBreakpoints } from "@solid-primitives/media";

const br = createBreakpoints({
  sm: "640px",
  md: "768px",
  lg: "1024px",
  xl: "1280px",
});

const masonry = createMasonry({
  columns() {
    if (br.xl) return 6;
    if (br.lg) return 4;
    if (br.md) return 3;
    if (br.sm) return 2;
    return 1;
  },
  // ...
});

#Grid gap

You can freely add a gap between the items using the gap property or a margin on the items.

But that space needs to be accounted for in the height of the items. Otherwise, the layout will be broken.

const gap = 10;

const masonry = createMasonry({
  mapHeight(item) {
    return getItemHeight(item) + gap;
  },
  // ...
});

return (
  <div
    style={{
      display: "flex",
      "flex-direction": "column",
      "flex-wrap": "wrap",
      gap: `${gap}px`,
      // Exclude the size of the gap from the height of the container
      // to remove the bottom margin created by the last row.
      height: masonry.height() - gap,
    }}
  >
    {masonry()}
  </div>
);

#Observing item's height

The mapHeight function is not reactive, it will be called only once for each item. But it can be used to return an accessor to provide a reactive height. The layout will be recalculated when the height changes.

For example, it can be used with createElementSize from @solid-primitives/resize-observer to observe the height of the elements.

import { createElementSize } from "@solid-primitives/resize-observer";

const masonry = createMasonry({
  // the source should be an array of html elements
  source,
  mapHeight(item) {
    // observe the height of the element
    const size = createElementSize(item);
    // return the accessor of the height of the element
    return () => size.height ?? 100;
  },
});

#Demo

Live Site

[Deployed example](https://primitives.solidjs.community | Source code

#Changelog

See CHANGELOG.md