50 lines
1.4 KiB
JavaScript
50 lines
1.4 KiB
JavaScript
import { Rectangle } from '../../maths/shapes/Rectangle.mjs';
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"use strict";
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function checkRow(data, width, y) {
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for (let x = 0, index = 4 * y * width; x < width; ++x, index += 4) {
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if (data[index + 3] !== 0)
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return false;
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}
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return true;
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}
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function checkColumn(data, width, x, top, bottom) {
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const stride = 4 * width;
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for (let y = top, index = top * stride + 4 * x; y <= bottom; ++y, index += stride) {
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if (data[index + 3] !== 0)
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return false;
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}
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return true;
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}
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function getCanvasBoundingBox(canvas, resolution = 1) {
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const { width, height } = canvas;
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const context = canvas.getContext("2d", {
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willReadFrequently: true
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});
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if (context === null) {
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throw new TypeError("Failed to get canvas 2D context");
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}
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const imageData = context.getImageData(0, 0, width, height);
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const data = imageData.data;
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let left = 0;
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let top = 0;
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let right = width - 1;
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let bottom = height - 1;
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while (top < height && checkRow(data, width, top))
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++top;
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if (top === height)
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return Rectangle.EMPTY;
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while (checkRow(data, width, bottom))
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--bottom;
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while (checkColumn(data, width, left, top, bottom))
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++left;
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while (checkColumn(data, width, right, top, bottom))
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--right;
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++right;
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++bottom;
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return new Rectangle(left / resolution, top / resolution, (right - left) / resolution, (bottom - top) / resolution);
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}
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export { getCanvasBoundingBox };
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//# sourceMappingURL=getCanvasBoundingBox.mjs.map
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