pixel-editor/js/Util.js

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JavaScript
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// Acts as a public static class
class Util {
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/** Pastes the source image data on the destination image data, keeping the pixels where the
* source image data is transparent
*
* @param {*} source
* @param {*} destination
*/
static pasteData(underlyingImageData, pasteData, finalContext) {
for (let i=0; i<underlyingImageData.data.length; i+=4) {
let currentMovePixel = [
pasteData.data[i], pasteData.data[i+1], pasteData.data[i+2], pasteData.data[i+3]
];
let currentUnderlyingPixel = [
underlyingImageData.data[i], underlyingImageData.data[i+1],
underlyingImageData.data[i+2], underlyingImageData.data[i+3]
];
// If the pixel of the clipboard is empty, but the one below it isn't, I use the pixel below
if (Util.isPixelEmpty(currentMovePixel)) {
if (!Util.isPixelEmpty(currentUnderlyingPixel)) {
pasteData.data[i] = currentUnderlyingPixel[0];
pasteData.data[i+1] = currentUnderlyingPixel[1];
pasteData.data[i+2] = currentUnderlyingPixel[2];
pasteData.data[i+3] = currentUnderlyingPixel[3];
}
}
}
finalContext.putImageData(pasteData, 0, 0);
}
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/** Tells if a pixel is empty (has alpha = 0)
*
* @param {*} pixel
*/
static isPixelEmpty(pixel) {
if (pixel == null || pixel === undefined) {
return false;
}
// If the alpha channel is 0, the current pixel is empty
if (pixel[3] == 0) {
return true;
}
return false;
}
/** Tells if element is a child of an element with class className
*
* @param {*} element
* @param {*} className
*/
static isChildOfByClass(element, className) {
// Getting the element with class className
while (element != null && element.classList != null && !element.classList.contains(className)) {
element = element.parentElement;
}
// If that element exists and its class is the correct one
if (element != null && element.classList != null && element.classList.contains(className)) {
// Then element is a chld of an element with class className
return true;
}
return false;
}
/** Returns elementOrElementId if the argument is already an element, otherwise it finds
* the element by its ID (given by the argument) and returns it
*
* @param {*} elementOrElementId The element to return, or the ID of the element to return
* @returns The desired element
*/
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static getElement(elementOrElementId) {
if (typeof(elementOrElementId) == "object") {
return elementOrElementId;
}
else if (typeof(elementOrElementId) == "string") {
return document.getElementById(elementOrElementId);
}
else {
console.log("Type not supported: " + typeof(elementOrElementId));
}
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}
// Returns the text content of the element with ID elementId
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static getText(elementId) {
return Util.getElement(elementId).textContent;
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}
// Sets the text content of the element with ID elementId
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static setText(elementId, text) {
Util.getElement(elementId).textContent = text;
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}
// Gets the value of the element with ID elementId
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static getValue(elementId) {
return Util.getElement(elementId).value;
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}
// Sets the value of the element with ID elementId
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static setValue(elementId, value) {
Util.getElement(elementId).value = value;
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}
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//add class .selected to specified element
static select(elementId) {
Util.getElement(elementId).classList.add('selected');
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}
//remove .selected class from specified element
static deselect(elementId) {
Util.getElement(elementId).classList.remove('selected');
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}
//toggle the status of the .selected class on the specified element
static toggle(elementId) {
Util.getElement(elementId).classList.toggle('selected');
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}
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static getPixelColor(data, x, y, dataWidth) {
let pos = (y * dataWidth + x) * 4;
return [data[pos], data[pos+1], data[pos+2], data[pos + 3]];
}
static isPixelTransparent(data, x, y, dataWidth) {
return this.getPixelColor(data, x, y, dataWidth)[3] == 255;
}
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static cursorInCanvas(canvasSize, mousePos) {
return mousePos[0] >= 0 && mousePos[1] >= 0 && canvasSize[0] > mousePos[0] && canvasSize[1] > mousePos[1];
}
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}