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‎LICENSE.txt‎

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

‎README.md‎

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

‎composer.json‎

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

‎src/IntegerScaling.php‎

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

‎src/IntegerScaling/Ratios.php‎

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

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