pixel-editor/js/_pixelEditorUtility.js
2021-09-16 07:30:10 +01:00

270 lines
8.5 KiB
JavaScript

/***********MISCELLANEOUS UTILITY FUNCTIONS**************/
/** Merges topLayer onto belowLayer
*
* @param {*} belowLayer The layer on the bottom of the layer stack
* @param {*} topLayer The layer on the top of the layer stack
*/
function mergeLayers(belowLayer, topLayer) {
// Copying the above content on the layerBelow
let belowImageData = belowLayer.getImageData(0, 0, belowLayer.canvas.width, belowLayer.canvas.height);
let toMergeImageData = topLayer.getImageData(0, 0, topLayer.canvas.width, topLayer.canvas.height);
for (let i=0; i<belowImageData.data.length; i+=4) {
let currentMovePixel = [
toMergeImageData.data[i], toMergeImageData.data[i+1],
toMergeImageData.data[i+2], toMergeImageData.data[i+3]
];
let currentUnderlyingPixel = [
belowImageData.data[i], belowImageData.data[i+1],
belowImageData.data[i+2], belowImageData.data[i+3]
];
if (isPixelEmpty(currentMovePixel)) {
if (!isPixelEmpty(belowImageData)) {
toMergeImageData.data[i] = currentUnderlyingPixel[0];
toMergeImageData.data[i+1] = currentUnderlyingPixel[1];
toMergeImageData.data[i+2] = currentUnderlyingPixel[2];
toMergeImageData.data[i+3] = currentUnderlyingPixel[3];
}
}
}
// Putting the top data into the belowdata
belowLayer.putImageData(toMergeImageData, 0, 0);
}
/** Used to programmatically create an input event
*
* @param {*} keyCode KeyCode of the key to press
* @param {*} ctrl Is ctrl pressed?
* @param {*} alt Is alt pressed?
* @param {*} shift Is shift pressed?
*/
function simulateInput(keyCode, ctrl, alt, shift) {
// I just copy pasted this from stack overflow lol please have mercy
let keyboardEvent = document.createEvent("KeyboardEvent");
let initMethod = typeof keyboardEvent.initKeyboardEvent !== 'undefined' ? "initKeyboardEvent" : "initKeyEvent";
keyboardEvent[initMethod](
"keydown", // event type: keydown, keyup, keypress
true, // bubbles
true, // cancelable
window, // view: should be window
ctrl, // ctrlKey
alt, // altKey
shift, // shiftKey
false, // metaKey
keyCode, // keyCode: unsigned long - the virtual key code, else 0
keyCode // charCode: unsigned long - the Unicode character associated with the depressed key, else 0
);
document.dispatchEvent(keyboardEvent);
}
/** Tells if a pixel is empty (has alpha = 0)
*
* @param {*} pixel
*/
function 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
*/
function 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;
}
/** Gets the eyedropped colour (the colour of the pixel pointed by the cursor when the user is using the eyedropper).
* It takes the colour of the canvas with the biggest z-index, basically the one the user can see, since it doesn't
* make much sense to sample a colour which is hidden behind a different layer
*
* @param {*} cursorLocation The position of the cursor
*/
function getEyedropperColor(cursorLocation) {
// Making sure max will take some kind of value
let max = -1;
// Using tmpColour to sample the sprite
let tmpColour;
// Returned colour
let selectedColor;
for (let i=1; i<layers.length; i++) {
// Getting the colour of the pixel in the cursorLocation
tmpColour = layers[i].context.getImageData(Math.floor(cursorLocation[0]/zoom),Math.floor(cursorLocation[1]/zoom),1,1).data;
// If it's not empty, I check if it's on the top of the previous colour
if (layers[i].canvas.style.zIndex > max || isPixelEmpty(selectedColor) || selectedColor === undefined) {
max = layers[i].canvas.style.zIndex;
if (!isPixelEmpty(tmpColour)) {
selectedColor = tmpColour;
}
}
}
// If the final colour was empty, I return black
if (isPixelEmpty(tmpColour) && selectedColor === undefined) {
selectedColor = [0, 0, 0];
}
return selectedColor;
}
/** Gets the absolute position of the element (position on the screen)
*
* @param {*} element The element of which we have to get the position
*/
function getElementAbsolutePosition(element) {
// Probably copy pasted this from stack overflow too, if not I don't recall how it works
let curleft = curtop = 0;
if (element.offsetParent) {
do {
curleft += element.offsetLeft;
curtop += element.offsetTop;
} while (element = element.offsetParent);
}
return [curleft,curtop];
}
/** Nearest neighbor algorithm to scale a sprite
*
* @param {*} src The source imageData
* @param {*} dst The destination imageData
*/
function nearestNeighbor (src, dst) {
let pos = 0
// Just applying the nearest neighbor algorithm
for (let y = 0; y < dst.height; y++) {
for (let x = 0; x < dst.width; x++) {
const srcX = Math.floor(x * src.width / dst.width)
const srcY = Math.floor(y * src.height / dst.height)
let srcPos = ((srcY * src.width) + srcX) * 4
dst.data[pos++] = src.data[srcPos++] // R
dst.data[pos++] = src.data[srcPos++] // G
dst.data[pos++] = src.data[srcPos++] // B
dst.data[pos++] = src.data[srcPos++] // A
}
}
}
/** Bilinear interpolation used to scale a sprite
*
* @param {*} src The source imageData
* @param {*} dst The destination imageData
*/
function bilinearInterpolation (src, dst) {
// Applying the bilinear interpolation algorithm
function interpolate (k, kMin, kMax, vMin, vMax) {
return Math.round((k - kMin) * vMax + (kMax - k) * vMin)
}
function interpolateHorizontal (offset, x, y, xMin, xMax) {
const vMin = src.data[((y * src.width + xMin) * 4) + offset]
if (xMin === xMax) return vMin
const vMax = src.data[((y * src.width + xMax) * 4) + offset]
return interpolate(x, xMin, xMax, vMin, vMax)
}
function interpolateVertical (offset, x, xMin, xMax, y, yMin, yMax) {
const vMin = interpolateHorizontal(offset, x, yMin, xMin, xMax)
if (yMin === yMax) return vMin
const vMax = interpolateHorizontal(offset, x, yMax, xMin, xMax)
return interpolate(y, yMin, yMax, vMin, vMax)
}
let pos = 0
for (let y = 0; y < dst.height; y++) {
for (let x = 0; x < dst.width; x++) {
const srcX = x * src.width / dst.width
const srcY = y * src.height / dst.height
const xMin = Math.floor(srcX)
const yMin = Math.floor(srcY)
const xMax = Math.min(Math.ceil(srcX), src.width - 1)
const yMax = Math.min(Math.ceil(srcY), src.height - 1)
dst.data[pos++] = interpolateVertical(0, srcX, xMin, xMax, srcY, yMin, yMax) // R
dst.data[pos++] = interpolateVertical(1, srcX, xMin, xMax, srcY, yMin, yMax) // G
dst.data[pos++] = interpolateVertical(2, srcX, xMin, xMax, srcY, yMin, yMax) // B
dst.data[pos++] = interpolateVertical(3, srcX, xMin, xMax, srcY, yMin, yMax) // A
}
}
}
/** Resizes an imageData depending on the algorithm and on the new width and height
*
* @param {*} image The imageData to scale
* @param {*} width The new width of the imageData
* @param {*} height The new height of the imageData
* @param {*} algorithm Scaling algorithm chosen by the user in the dialogue
*/
function resizeImageData (image, width, height, algorithm) {
algorithm = algorithm || 'bilinear-interpolation'
let resize;
switch (algorithm) {
case 'nearest-neighbor': resize = nearestNeighbor; break
case 'bilinear-interpolation': resize = bilinearInterpolation; break
default: return image;
}
const result = new ImageData(width, height)
resize(image, result)
return result
}
/** Gets the position in (x, y) format of the pixel with index "index"
*
* @param {*} index The index of the pixel of which we need the (x, y) position
*/
function getPixelPosition(index) {
let linearIndex = index / 4;
let x = linearIndex % layers[0].canvasSize[0];
let y = Math.floor(linearIndex / layers[0].canvasSize[0]);
return [Math.ceil(x), Math.ceil(y)];
}
/** Sets isDragging to false, used when the user interacts with sortable lists
*
*/
function makeIsDraggingFalse(event) {
dragging = false;
}