File indexing completed on 2024-05-12 04:44:33

 // SPDX-FileCopyrightText: Lukas Sommer <sommerluk@gmail.com>
 // SPDX-License-Identifier: BSD-2-Clause OR MIT
 
 // Own header
 #include "interlacingpass.h"
 
 #include "helpermath.h"
 #include <qglobal.h>
 #include <qmath.h>
 #include <type_traits>
 
 namespace PerceptualColor
 {
 /** @brief Constructor
  *
  * Constructs an object for a new interlacing cycle.
  *
  * @param passCount Number of passes within this interlacing cycle. This MUST
  * be a positive odd number (otherwise an exception is thrown). Use <tt>7</tt>
  * for <a href="https://en.wikipedia.org/wiki/Adam7_algorithm">Adam7</a>
  * interlacing, or any other positive odd number for
  * <a href="https://en.wikipedia.org/wiki/Adam7_algorithm">Adam7</a>-like
  * interlacing, but with a different number of steps.
  *
  * @exception int Thrown when the parameter is not a positive odd number. */
 InterlacingPass::InterlacingPass(const int passCount)
 {
     if (!isOdd(passCount)) {
         throw 0;
     }
     if (passCount < 1) {
         throw 0;
     }
 
     const int floorOfHalfCoundown = qFloor(passCount / 2.0);
     const int baseSize = qRound(qPow(2, floorOfHalfCoundown));
 
     countdown = passCount;
     rectangleSize.setWidth(baseSize);
     rectangleSize.setHeight(baseSize);
     columnFrequency = baseSize;
     columnOffset = 0;
     lineFrequency = baseSize;
     lineOffset = 0;
 }
 
 /** @brief Switches to the next pass, reducing @ref countdown by 1 and
  * changing all other values accordingly.
  *
  * If @ref countdown ≤ 0 than nothing happens. */
 void InterlacingPass::switchToNextPass()
 {
     if (countdown <= 1) {
         return;
     }
 
     countdown--;
 
     const int floorOfHalfCoundown = qFloor(countdown / 2.0);
     const int baseSize = qRound(qPow(2, floorOfHalfCoundown));
 
     if (isOdd(countdown)) {
         rectangleSize.setWidth(baseSize);
         rectangleSize.setHeight(baseSize);
         columnFrequency = baseSize;
         columnOffset = 0;
         lineFrequency = baseSize * 2;
         lineOffset = baseSize;
     } else {
         const int halfBaseSize = baseSize / 2; // Dividing without rounding
         // problems because baseSize is always an even number (it’s always
         // a power of two and bigger than 2 while countdown is ≥ 1).
         rectangleSize.setWidth(halfBaseSize);
         rectangleSize.setHeight(baseSize);
         columnFrequency = baseSize;
         columnOffset = halfBaseSize;
         lineFrequency = baseSize;
         lineOffset = 0;
     }
 }
 
 static_assert(std::is_trivially_copyable_v<InterlacingPass>);
 
 static_assert(std::is_standard_layout_v<InterlacingPass>);
 
 } // namespace PerceptualColor