55 lines
2.0 KiB
JavaScript
55 lines
2.0 KiB
JavaScript
function cropX(imageData, { left = 0, right = 0 }) {
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const { data, width, height } = imageData;
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const dataLength = data.length;
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const newWidth = width - left - right;
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const rowLength = width * 4;
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const newRowLength = newWidth * 4;
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const leftCrop = left * 4;
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const newData = [];
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// loop through each row
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for (let x = 0; x < dataLength; x += rowLength) {
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const newRowStart = x + leftCrop;
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const newRowEnd = newRowStart + newRowLength;
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for (let i = newRowStart; i < newRowEnd; i += 4) {
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newData.push(data[i], data[i + 1], data[i + 2], data[i + 3]);
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}
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}
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return { data: newData, height, width: newWidth };
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}
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function cropY(imageData, { top = 0, bottom = 0 }) {
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const { data, width, height } = imageData;
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const rowLength = width * 4;
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const topIndex = top * rowLength;
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const bottomIndex = bottom * rowLength;
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const newHeight = height - top - bottom;
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const newDataEnd = data.length - bottomIndex;
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const newData = [];
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// save each index within the cropped area (avoid .slice() for performance)
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for (let i = topIndex; i < newDataEnd; i++) {
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newData.push(data[i]);
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}
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return { data: newData, height: newHeight, width };
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}
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function toNumber(options) {
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return Object.fromEntries(Object.entries(options).map(([key, value]) => [key, Number(value || 0)]));
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}
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export default function cropImageData(imageData, cropOptions) {
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const { top, right, bottom, left } = toNumber(cropOptions);
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if (imageData.height < top + bottom || imageData.width < left + right) {
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return new ImageData(1, 1);
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}
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let newImageData = {
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data: imageData.data,
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width: imageData.width,
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height: imageData.height,
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};
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if (top || bottom) {
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newImageData = cropY(newImageData, { top, bottom });
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}
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if (left || right) {
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newImageData = cropX(newImageData, { left, right });
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}
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const { data, height, width } = newImageData;
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return new ImageData(Uint8ClampedArray.from(data), width, height);
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}
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