33 lines
931 B
TypeScript
33 lines
931 B
TypeScript
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import { GribMessage } from '../../interfaces/interfaces'
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import { CropBounds } from './drawGrib'
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export function extractFromBounds(
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grib: GribMessage,
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source: Uint8Array,
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cropBounds: CropBounds,
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): Uint8Array {
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const { grid, bitsPerDataPoint } = grib
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const bytesPerPoint = bitsPerDataPoint / 8
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const { x, y, width, height } = cropBounds
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if (
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x < 0
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|| y < 0
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|| x + width > grid.cols-1
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|| y + height > grid.rows-1
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) {
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throw new Error('Extract bbox out of grid bounds')
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}
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const output = new Uint8Array(width*height*bytesPerPoint)
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for (let row=y, i=0; row < y+height; row++) {
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const inputOffset = (row*grid.cols + x)*bytesPerPoint
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const readBytes = width*bytesPerPoint
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const inputBuffer = source.slice(inputOffset, inputOffset+readBytes)
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output.set(inputBuffer, i)
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i += readBytes
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}
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return output
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}
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