Initial commit.

LICENSE.txt

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+MIT License
+
+Copyright (c) 2020 Marat Tanalin (http://tanalin.com )
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+Calculates integer ratios for pixel-perfect image upscaling with optional aspect-ratio correction.
+
+See the project [webpage](http://tanalin.com/en/projects/integer-scaling/) for details.

composer.json

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+{
+	"name": "marat-tanalin/integer-scaling",
+	"version" : "1.2.1",
+	"type": "library",
+	"description": "Calculates integer ratios for pixel-perfect image upscaling with optional aspect-ratio correction.",
+	"homepage": "http://tanalin.com/en/projects/integer-scaling/",
+	"license": "MIT",
+	"authors": [
+		{
+			"name": "Marat Tanalin",
+			"homepage": "http://tanalin.com"
+		}
+	],
+	"keywords": [
+		"integer-scaling",
+		"pixel-perfect-scaling",
+		"image-scaling",
+		"algorithms",
+		"graphics"
+	],
+	"require": {
+		"php": "^7.2"
+	},
+	"autoload": {
+		"psr-4": {
+			"MaratTanalin\\": "src/"
+		}
+	}
+}

src/IntegerScaling.php

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+<?php
+
+/*! Marat Tanalin | http://tanalin.com */
+
+namespace MaratTanalin;
+
+require_once 'IntegerScaling/Ratios.php';
+
+class IntegerScaling
+{
+	/**
+	 * Calculates an integer scaling ratio common for X/Y axes (square pixels).
+	 * 
+	 * @param int $areaWidth
+	 * @param int $areaHeight
+	 * @param int $imageWidth
+	 * @param int $imageHeight
+	 * @return int;
+	 */
+	public static function calculateRatio(int $areaWidth, int $areaHeight, int $imageWidth, int $imageHeight) {
+		if ($areaHeight * $imageWidth < $areaWidth * $imageHeight) {
+			$areaSize  = $areaHeight;
+			$imageSize = $imageHeight;
+		}
+		else {
+			$areaSize  = $areaWidth;
+			$imageSize = $imageWidth;
+		}
+
+		$ratio = floor($areaSize / $imageSize);
+
+		if ($ratio < 1) {
+			$ratio = 1;
+		}
+
+		return $ratio;
+	}
+
+	/**
+	 * Calculates integer scaling ratios potentially different for X/Y axes
+	 * as a result of aspect-ratio correction (rectangular pixels).
+	 * 
+	 * @param int $areaWidth
+	 * @param int $areaHeight
+	 * @param int $imageWidth
+	 * @param int $imageHeight
+	 * @param float $aspectX
+	 * @param float $aspectY
+	 * @return array(string => int)
+	 */
+	public static function calculateRatios(int $areaWidth, int $areaHeight, int $imageWidth, int $imageHeight, float $aspectX = 0.0, float $aspectY = 0.0) {
+		if ($imageWidth * $aspectY === $imageHeight * $aspectX) {
+			$ratio = self::calculateRatio($areaWidth, $areaHeight, $imageWidth, $imageHeight);
+
+			return new IntegerScaling\Ratios($ratio);
+		}
+
+		$maxRatioX        = floor($areaWidth  / $imageWidth);
+		$maxRatioY        = floor($areaHeight / $imageHeight);
+		$maxWidth         = $imageWidth  * $maxRatioX;
+		$maxHeight        = $imageHeight * $maxRatioY;
+		$maxWidthAspectY  = $maxWidth  * $aspectY;
+		$maxHeightAspectX = $maxHeight * $aspectX;
+
+		if ($maxWidthAspectY === $maxHeightAspectX) {
+			$ratioX = $maxRatioX;
+			$ratioY = $maxRatioY;
+		}
+		else {
+			$maxAspectLessThanTarget = $maxWidthAspectY < $maxHeightAspectX;
+
+			if ($maxAspectLessThanTarget) {
+				$ratioA     = $maxRatioX;
+				$maxSizeA   = $maxWidth;
+				$imageSizeB = $imageHeight;
+				$aspectA    = $aspectX;
+				$aspectB    = $aspectY;
+			}
+			else {
+				$ratioA     = $maxRatioY;
+				$maxSizeA   = $maxHeight;
+				$imageSizeB = $imageWidth;
+				$aspectA    = $aspectY;
+				$aspectB    = $aspectX;
+			}
+
+			$ratioBFract = $maxSizeA * $aspectB / $aspectA / $imageSizeB;
+			$ratioBFloor = floor($ratioBFract);
+			$ratioBCeil  = ceil($ratioBFract);
+			$parFloor    = $ratioBFloor / $ratioA;
+			$parCeil     = $ratioBCeil  / $ratioA;
+
+			if ($maxAspectLessThanTarget) {
+				$parFloor = 1 / $parFloor;
+				$parCeil  = 1 / $parCeil;
+			}
+
+			$commonFactor = $imageWidth * $aspectY / $aspectX / $imageHeight;
+			$errorFloor   = abs(1 - $commonFactor * $parFloor);
+			$errorCeil    = abs(1 - $commonFactor * $parCeil);
+
+			if (abs($errorFloor - $errorCeil) < .001) {
+				$ratioB = abs($ratioA - $ratioBFloor) < abs($ratioA - $ratioBCeil)
+				        ? $ratioBFloor
+				        : $ratioBCeil;
+			}
+			else {
+				$ratioB = $errorFloor < $errorCeil
+				        ? $ratioBFloor
+				        : $ratioBCeil;
+			}
+
+			if ($maxAspectLessThanTarget) {
+				$ratioX = $ratioA;
+				$ratioY = $ratioB;
+			}
+			else {
+				$ratioX = $ratioB;
+				$ratioY = $ratioA;
+			}
+		}
+
+		if ($ratioX < 1) {
+			$ratioX = 1;
+		}
+
+		if ($ratioY < 1) {
+			$ratioY = 1;
+		}
+
+		return new IntegerScaling\Ratios($ratioX, $ratioY);
+	}
+}

src/IntegerScaling/Ratios.php

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+<?php
+
+/*! Marat Tanalin | http://tanalin.com */
+
+namespace MaratTanalin\IntegerScaling;
+
+class Ratios
+{
+	public $x, $y;
+
+	public function __construct(int $x, int $y = 0) {
+		$this->x = $x;
+		$this->y = 0 === $y ? $x : $y;
+	}
+}