Pixel-Editor

Browser based Pixel Editor for creating pixel assets or fonts.

• Editor
  • Self contained React drawing canvas.
• Application
  • Work in Progress Features
    • Eraser (pen erasers work on tablets)
    • Shapes (Line, Rect, Circle)
    • Cache state to localStorage to persist changes

Editor Canvas

Majority of the functionality lives in the Editor component.

Any contributions or updates to the Editor component must be self contained.

Props

• width - Image width
• height - Image height
• size - Grid size
• onChange - Get the path data on change.

Note: onChange criteria for triggering:

• 1 second after any concurrent drawing.
• Instantly after undo/redo actions.

Methods

• getJson: (includeHistory: Boolean) => string
• setJson: () => void
• getVersion: () => number
• addColor: (color: EditorColor) => void
• updateColor: (index: number, color: EditorColor) => void
• removeColor: (index: number, mergeIntoIndex: number) => void
• moveColor: (fromIndex: number, toIndex: number) => void
• getColors: () => EditorColor[]
• clear: () => void
• clearHistory: () => void
• getHistory: () => []
• setMeta: (property: string, value: string | number | Boolean ) => void
• getMeta: (property: string) => string | number | Boolean
• getMetaProperties: () => Object
• applyTemplate: (data: number[][]) => void
• flipHorizontal: () => void
• flipVertical: () => void
• translate: (x: number, y: number) => void
• rotate: (counterClockwise?: boolean) => void
• invert: () => void
• undo: () => void
• redo: () => void
• hasUndo: () => boolean
• hasRedo: () => boolean
• inputModePixel: () => void
• inputModeLine: () => void
• inputModeRectangle: () => void
• inputModeRectangleOutline: () => void
• inputModeEllipse: () => void
• inputModeEllipseOutline: () => void

Usage

import Editor, { EditorRef } from '@pictogrammers/editor';

function App() {
  const editorRef = useRef<EditorRef>(null);
  const width = 22;
  const height = 22;
  const size = 10; // Grid size

  function handleChange(path: string) {
    console.log('Path:', path);
  }

  function handleClear() {
    editorRef.current?.clear();
  }

  return (
    <Editor ref={editorRef}
            width={width}
            height={height}
            size={size}
            onChange={handleChange}></Editor>
    <button onClick={handleClear}>Clear</button>
  );
}

export default App;

Managing Data

The data grid stores each pixel as a reference to the colors array. A diagonal line in a 3x3 canvas would look like below.

data = [
  [0, 0, 1],
  [0, 1, 0],
  [1, 0, 0]
]

See the helper methods above for all the quick operations for modify the data grid.

Managing Colors

The data grid stores each pixel as a reference to the colors array. For example 1 in the data grid would be the 2nd item in the colors array. The color object looks like below:

type Color = {
  r: number;    // Red 0 to255
  g: number;    // Green 0 to 255
  b: number;    // Blue 0 to 255
  a: number;    // Alpha 0 to 1
  name: string; // Friendly name
}

The default colors array then looks like below:

colors = [
  { r: 0, g: 0, b: 0, a: 0, name: 'transparent' },
  { r: 0, g: 0, b: 0, a: 1, name: 'Black' }
]

To ensure the indexes in the data grid stays in sync with the colors array the helper methods below are provided.

• getColors: ()
  • Get an array of colors
• addColor: (color: EditorColor)
  • Add a new color to the end of the array.
• updateColor: (index: number, color: EditorColor)
  • Update the color value.
• removeColor: (index: number, mergeIntoIndex: number)
  • Removing a color requires selecting an existing color.
  • This operation throws an error for less than 2 colors.
• moveColor: (fromIndex: number, toIndex: number)
  • Swap the position of 2 colors.
• mergeColor: (fromIndex: number, toIndex: number)
  • Merge one color into another. This is only supported with more than 2 colors.

Note: All color operations are added to the canvas history.

Managing History

All operations that change the canvas or meta data create change records in the history.

• Pixel - Single color change on the canvas.
  • After 1 second or any other canvas operation is called.
  • { type: 'pixel', value: [] }
• Undo - { type: 'undo', value: 2 }
• Redo
  • Decreases the Undo value by 1 if it is the last history value.
• Clear
  • { type: 'clear', value: { data: [] } }
• Width / Height
  • { type: 'width', value: { from: 22, to: 24, data: [] } }
  • { type: 'height', value: { from: 22, to: 24, data: [] } }
  • Note: Resizing canvas takes a snapshot of the canvas prior to resize
• Color
  • { type: 'addColor', value: EditorColor }
  • { type: 'removeColor', value: index }
  • { type: 'updateColor', value: EditorColor }
  • { type: 'moveColor', value: EditorColor }
  • { type: 'mergeColor', value: { from: 2, to: 1 } }
• Meta - Any change that impacts meta data.
  • { type: 'meta', value: { name: 'Foo', _name: 'Bar' }}

The application can modify the history log through the helper methods:

• undo() - Undo
• redo() - Redo
• hasUndo() - Has at least 1 item in the history
• hasRedo() - Last history record is type: 'undo'
• setMeta(property, value) - Only supports adding meta data.
  • { type: 'meta', value: { property: value, _property: value } }
  • The _property is the previous value or null
  • Setting a null value removes the property.
• getMeta(property)
• getMetaProperties() - Properties object.
• getHistory() - Retrieves entire history log.
• clearHistory() - Clears the history