function mergeLayers(belowLayer, topLayer) { // Copying the above content on the layerBelow let belowImageData = belowLayer.getImageData(0, 0, canvas.width, canvas.height); let toMergeImageData = topLayer.getImageData(0, 0, canvas.width, canvas.height); for (let i=0; i max || isPixelEmpty(selectedColor) || selectedColor === undefined) { max = layers[i].canvas.style.zIndex; if (!isPixelEmpty(tmpColour)) { selectedColor = tmpColour; } } } if (isPixelEmpty(tmpColour) && selectedColor === undefined) { selectedColor = [0, 0, 0]; } return selectedColor; } function getElementAbsolutePosition(element) { let curleft = curtop = 0; if (element.offsetParent) { do { curleft += element.offsetLeft; curtop += element.offsetTop; } while (element = element.offsetParent); } return [curleft,curtop]; } function nearestNeighbor (src, dst) { let pos = 0 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 } } } function bilinearInterpolation (src, dst) { 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 } } } 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: throw new Error(`Unknown algorithm: ${algorithm}`) } const result = new ImageData(width, height) resize(image, result) return result } 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)]; }