277 lines
7 KiB
JavaScript
277 lines
7 KiB
JavaScript
/**
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* Command pattern to allow for editing history
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*/
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const _commands_events = new Observer();
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/** CommandNonExistentError */
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class CommandNonExistentError extends Error {}
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/** Global Commands Object */
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const commands = makeReadOnly(
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{
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/** Current History Index Reader */
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get current() {
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return this._current;
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},
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/** Current History Index (private) */
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_current: -1,
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/** Command History (private) */
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_history: [],
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/** The types of commands we can run (private) */
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_types: {},
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/**
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* Undoes the last commands in the history
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*
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* @param {number} n Number of actions to undo
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*/
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undo(n = 1) {
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for (var i = 0; i < n && this.current > -1; i++) {
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this._history[this._current--].undo();
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}
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},
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/**
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* Redoes the next commands in the history
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*
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* @param {number} n Number of actions to redo
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*/
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redo(n = 1) {
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for (var i = 0; i < n && this.current + 1 < this._history.length; i++) {
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this._history[++this._current].redo();
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}
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},
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/**
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* Creates a basic command, that can be done and undone
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*
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* They must contain a 'run' method that performs the action for the first time,
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* a 'undo' method that undoes that action and a 'redo' method that does the
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* action again, but without requiring parameters. 'redo' is by default the
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* same as 'run'.
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*
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* The 'run' and 'redo' functions will receive a 'options' parameter which will be
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* forwarded directly to the operation, and a 'state' parameter that
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* can be used to store state for undoing things.
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*
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* The 'state' object will be passed to the 'undo' function as well.
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*
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* @param {string} name Command identifier (name)
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* @param {(title: string, options: any, state: {[key: string]: any}) => void | Promise<void>} run A method that performs the action for the first time
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* @param {(title: string, state: {[key: string]: any}) => } undo A method that reverses what the run method did
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* @param {(title: string, options: any, state: {[key: string]: any}) => void | Promise<void>} redo A method that redoes the action after undone (default: run)
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* @returns
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*/
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createCommand(name, run, undo, redo = run) {
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const command = async function runWrapper(title, options) {
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// Create copy of options and state object
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const copy = {};
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Object.assign(copy, options);
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const state = {};
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const entry = {
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id: guid(),
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title,
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state,
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};
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// Attempt to run command
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try {
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await run(title, copy, state);
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} catch (e) {
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console.warn(`Error while running command '${name}' with options:`);
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console.warn(copy);
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console.warn(e);
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return;
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}
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const undoWrapper = () => {
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console.debug(`Undoing ${name}, currently ${this._current}`);
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undo(title, state);
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_commands_events.emit({
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id: entry.id,
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name,
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action: "undo",
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state,
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current: this._current,
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});
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};
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const redoWrapper = () => {
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console.debug(`Redoing ${name}, currently ${this._current}`);
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redo(title, copy, state);
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_commands_events.emit({
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id: entry.id,
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name,
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action: "redo",
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state,
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current: this._current,
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});
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};
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// Add to history
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if (commands._history.length > commands._current + 1) {
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commands._history.forEach((entry, index) => {
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if (index >= commands._current + 1)
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_commands_events.emit({
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id: entry.id,
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name,
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action: "deleted",
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state,
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current: this._current,
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});
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});
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commands._history.splice(commands._current + 1);
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}
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commands._history.push(entry);
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commands._current++;
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entry.undo = undoWrapper;
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entry.redo = redoWrapper;
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_commands_events.emit({
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id: entry.id,
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name,
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action: "run",
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state,
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current: commands._current,
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});
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return entry;
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};
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this._types[name] = command;
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return command;
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},
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/**
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* Runs a command
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*
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* @param {string} name The name of the command to run
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* @param {string} title The display name of the command on the history panel view
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* @param {any} options The options to be sent to the command to be run
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*/
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runCommand(name, title, options = null) {
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if (!this._types[name])
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throw CommandNonExistentError(
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`[commands] Command '${name}' does not exist`
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);
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this._types[name](title, options);
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},
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},
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"commands",
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["_current"]
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);
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/**
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* Draw Image Command, used to draw a Image to a context
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*/
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commands.createCommand(
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"drawImage",
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(title, options, state) => {
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if (
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!options ||
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options.image === undefined ||
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options.x === undefined ||
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options.y === undefined
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)
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throw "Command drawImage requires options in the format: {image, x, y, w?, h?, ctx?}";
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// Check if we have state
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if (!state.context) {
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const context = options.ctx || imgCtx;
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state.context = context;
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// Saving what was in the canvas before the command
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const imgData = context.getImageData(
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options.x,
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options.y,
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options.w || options.image.width,
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options.h || options.image.height
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);
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state.box = {
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x: options.x,
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y: options.y,
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w: options.w || options.image.width,
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h: options.h || options.image.height,
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};
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// Create Image
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const cutout = document.createElement("canvas");
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cutout.width = state.box.w;
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cutout.height = state.box.h;
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cutout.getContext("2d").putImageData(imgData, 0, 0);
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state.original = new Image();
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state.original.src = cutout.toDataURL();
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}
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// Apply command
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state.context.drawImage(
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options.image,
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0,
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0,
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options.image.width,
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options.image.height,
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state.box.x,
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state.box.y,
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state.box.w,
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state.box.h
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);
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},
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(title, state) => {
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// Clear destination area
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state.context.clearRect(state.box.x, state.box.y, state.box.w, state.box.h);
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// Undo
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state.context.drawImage(state.original, state.box.x, state.box.y);
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}
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);
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commands.createCommand(
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"eraseImage",
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(title, options, state) => {
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if (
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!options ||
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options.x === undefined ||
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options.y === undefined ||
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options.w === undefined ||
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options.h === undefined
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)
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throw "Command eraseImage requires options in the format: {x, y, w, h, ctx?}";
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// Check if we have state
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if (!state.context) {
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const context = options.ctx || imgCtx;
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state.context = context;
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// Saving what was in the canvas before the command
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const imgData = context.getImageData(
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options.x,
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options.y,
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options.w,
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options.h
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);
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state.box = {
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x: options.x,
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y: options.y,
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w: options.w,
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h: options.h,
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};
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// Create Image
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const cutout = document.createElement("canvas");
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cutout.width = state.box.w;
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cutout.height = state.box.h;
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cutout.getContext("2d").putImageData(imgData, 0, 0);
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state.original = new Image();
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state.original.src = cutout.toDataURL();
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}
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// Apply command
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state.context.clearRect(state.box.x, state.box.y, state.box.w, state.box.h);
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},
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(title, state) => {
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// Clear destination area
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state.context.clearRect(state.box.x, state.box.y, state.box.w, state.box.h);
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// Undo
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state.context.drawImage(state.original, state.box.x, state.box.y);
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}
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);
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