/*
    File                 : ImageTools.cpp
    Project              : LabPlot
    Description          : Collection of different image processing algorithms
    --------------------------------------------------------------------
    SPDX-FileCopyrightText: 2017 Alexander Semke <alexander.semke@web.de>
    SPDX-License-Identifier: GPL-2.0-or-later
*/

#include "ImageTools.h"

/*!
	\class ImageToools
	\brief Provides static functions implementing different image processing algorithms.
	\ingroup tools
*/
QImage ImageTools::blurred(const QImage& image, QRect rect, int radius, bool alphaOnly) {
	int tab[] = { 14, 10, 8, 6, 5, 5, 4, 3, 3, 3, 3, 2, 2, 2, 2, 2, 2 };
	int alpha = (radius < 1)  ? 16 : (radius > 17) ? 1 : tab[radius-1];

	QImage result = image.convertToFormat(QImage::Format_ARGB32_Premultiplied);
	int r1 = rect.top();
	int r2 = rect.bottom();
	int c1 = rect.left();
	int c2 = rect.right();

	int bpl = result.bytesPerLine();
	int rgba[4];
	unsigned char* p;

	int i1 = 0;
	int i2 = 3;

	if (alphaOnly)
		i1 = i2 = (QSysInfo::ByteOrder == QSysInfo::LittleEndian)*3;

	for (int col = c1; col <= c2; col++) {
		p = result.scanLine(r1) + col * 4;
		for (int i = i1; i <= i2; i++)
			rgba[i] = p[i] << 4;

		p += bpl;
		for (int j = r1; j < r2; j++, p += bpl)
			for (int i = i1; i <= i2; i++)
				p[i] = (rgba[i] += ((p[i] << 4) - rgba[i]) * alpha / 16) >> 4;
	}

	for (int row = r1; row <= r2; row++) {
		p = result.scanLine(row) + c1 * 4;
		for (int i = i1; i <= i2; i++)
			rgba[i] = p[i] << 4;

		p += 4;
		for (int j = c1; j < c2; j++, p += 4)
			for (int i = i1; i <= i2; i++)
				p[i] = (rgba[i] += ((p[i] << 4) - rgba[i]) * alpha / 16) >> 4;
	}

	for (int col = c1; col <= c2; col++) {
		p = result.scanLine(r2) + col * 4;
		for (int i = i1; i <= i2; i++)
			rgba[i] = p[i] << 4;

		p -= bpl;
		for (int j = r1; j < r2; j++, p -= bpl)
			for (int i = i1; i <= i2; i++)
				p[i] = (rgba[i] += ((p[i] << 4) - rgba[i]) * alpha / 16) >> 4;
	}

	for (int row = r1; row <= r2; row++) {
		p = result.scanLine(row) + c2 * 4;
		for (int i = i1; i <= i2; i++)
			rgba[i] = p[i] << 4;

		p -= 4;
		for (int j = c1; j < c2; j++, p -= 4)
			for (int i = i1; i <= i2; i++)
				p[i] = (rgba[i] += ((p[i] << 4) - rgba[i]) * alpha / 16) >> 4;
	}

	return result;
}
