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-/****************************************************************************
-**
-** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
-** All rights reserved.
-** Contact: Nokia Corporation (qt-info@nokia.com)
-**
-** This file is part of the plugins of the Qt Toolkit.
-**
-** $QT_BEGIN_LICENSE:LGPL$
-** GNU Lesser General Public License Usage
-** This file may be used under the terms of the GNU Lesser General Public
-** License version 2.1 as published by the Free Software Foundation and
-** appearing in the file LICENSE.LGPL included in the packaging of this
-** file. Please review the following information to ensure the GNU Lesser
-** General Public License version 2.1 requirements will be met:
-** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
-**
-** In addition, as a special exception, Nokia gives you certain additional
-** rights. These rights are described in the Nokia Qt LGPL Exception
-** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
-**
-** GNU General Public License Usage
-** Alternatively, this file may be used under the terms of the GNU General
-** Public License version 3.0 as published by the Free Software Foundation
-** and appearing in the file LICENSE.GPL included in the packaging of this
-** file. Please review the following information to ensure the GNU General
-** Public License version 3.0 requirements will be met:
-** http://www.gnu.org/copyleft/gpl.html.
-**
-** Other Usage
-** Alternatively, this file may be used in accordance with the terms and
-** conditions contained in a signed written agreement between you and Nokia.
-**
-**
-**
-**
-**
-** $QT_END_LICENSE$
-**
-****************************************************************************/
-
-// Implements two dithering methods:
-//
-// * convertRGBA32_to_RGB565
-//
-// This is implemented using Ordered Bayer Dithering. The code has been adapted
-// from QX11PixmapData::fromImage. This method was originally implemented using
-// Floyd-Steinberg dithering but was later changed to Ordered Dithering because
-// of the better quality of the results.
-//
-// * convertRGBA32_to_RGBA4444
-//
-// This is implemented using Floyd-Steinberg dithering.
-//
-// The alghorithm used here is not the fastest possible but it's prolly fast enough:
-// uses look-up tables, integer-only arthmetics and works in one pass on two lines
-// at a time. It's a high-quality dithering using 1/8 diffusion precission.
-// Each channel (RGBA) is diffused independently and alpha is dithered too.
-
-#include <string.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <math.h>
-#include <QVarLengthArray>
-
-// Gets a component (red = 1, green = 2...) from a RGBA data structure.
-// data is unsigned char. stride is the number of bytes per line.
-#define GET_RGBA_COMPONENT(data, x, y, stride, c) (data[(y * stride) + (x << 2) + c])
-
-// Writes a new pixel with r, g, b to data in 565 16bit format. Data is a short.
-#define PUT_565(data, x, y, width, r, g, b) (data[(y * width) + x] = (r << 11) | (g << 5) | b)
-
-// Writes a new pixel with r, g, b, a to data in 4444 RGBA 16bit format. Data is a short.
-#define PUT_4444(data, x, y, width, r, g, b, a) (data[(y * width) + x] = (r << 12) | (g << 8) | (b << 4) | a)
-
-// Writes(ads) a new value to the diffusion accumulator. accumulator is a short.
-// x, y is a position in the accumulation buffer. y can be 0 or 1 -- we operate on two lines at time.
-#define ACCUMULATE(accumulator, x, y, width, v) if (x < width && x >= 0) accumulator[(y * width) + x] += v
-
-// Clamps a value to be in 0..255 range.
-#define CLAMP_256(v) if (v > 255) v = 255; if (v < 0) v = 0;
-
-// Converts incoming RGB32 (QImage::Format_RGB32) to RGB565. Returns the newly allocated data.
-unsigned short* convertRGB32_to_RGB565(const unsigned char *in, int width, int height, int stride)
-{
- static bool thresholdMapInitialized = false;
- static int thresholdMap[16][16];
-
- if (!thresholdMapInitialized) {
- int i;
- int j;
- int n;
-
- thresholdMap[0][0] = 0;
- thresholdMap[1][0] = 2;
- thresholdMap[0][1] = 3;
- thresholdMap[1][1] = 1;
-
- for (n=2; n<16; n*=2) {
- for (i=0; i<n; i++) {
- for (j=0; j<n; j++) {
- thresholdMap[i][j] *= 4;
- thresholdMap[i+n][j] = thresholdMap[i][j] + 2;
- thresholdMap[i][j+n] = thresholdMap[i][j] + 3;
- thresholdMap[i+n][j+n] = thresholdMap[i][j] + 1;
- }
- }
- }
-
- thresholdMapInitialized = true;
- }
-
- // Output line stride. Aligned to 4 bytes.
- int alignedWidth = width;
- if (alignedWidth % 2 > 0)
- alignedWidth++;
-
- // Will store output
- unsigned short *out = (unsigned short *)malloc (alignedWidth * height * 2);
-
- int x;
- int y;
- int threshold;
-
- // For each line...
- for (y = 0; y < height; y++) {
-
- // For each column....
- for (x = 0; x < width; x++) {
-
- int r = GET_RGBA_COMPONENT(in, x, y, stride, 0);
- int g = GET_RGBA_COMPONENT(in, x, y, stride, 1);
- int b = GET_RGBA_COMPONENT(in, x, y, stride, 2);
-
- threshold = thresholdMap[x%16][y%16];
-
- if (r <= (255-(1<<3)) && ((r<<5) & 255) > threshold) r += (1<<3);
- if (g <= (255-(1<<2)) && ((g<<6) & 255) > threshold) g += (1<<2);
- if (b <= (255-(1<<3)) && ((b<<5) & 255) > threshold) b += (1<<3);
-
- // Write the newly produced pixel
- PUT_565(out, x, y, alignedWidth, ((b >> 3) & 0x1f), ((g >> 2) & 0x3f), ((r >> 3) & 0x1f));
- }
- }
-
- return out;
-}
-
-// Converts incoming RGBA32 (QImage::Format_ARGB32_Premultiplied) to RGB565. Returns the newly allocated data.
-// This function is similar (yet different) to the _565 variant but it makes sense to duplicate it here for simplicity.
-// The output has each scan line aligned to 4 bytes (as expected by GL by default).
-unsigned short* convertARGB32_to_RGBA4444(const unsigned char *in, int width, int height, int stride)
-{
- // Output line stride. Aligned to 4 bytes.
- int alignedWidth = width;
- if (alignedWidth % 2 > 0)
- alignedWidth++;
-
- // Will store output
- unsigned short *out = (unsigned short *) malloc(alignedWidth * 2 * height);
-
- // Lookup tables for the 8bit => 4bit conversion
- unsigned char lookup_8bit_to_4bit[256];
- short lookup_8bit_to_4bit_diff[256];
-
- // Macros for the conversion using the lookup table.
- #define CONVERT_8BIT_TO_4BIT(v) (lookup_8bit_to_4bit[v])
- #define DIFF_8BIT_TO_4BIT(v) (lookup_8bit_to_4bit_diff[v])
-
- int i;
- int x, y, c; // Pixel we're processing. c is component number (0, 1, 2, 3 for r, b, b, a)
- short component[4]; // Stores the new components (r, g, b, a) for pixel produced during conversion
- short diff; // The difference between the converted value and the original one. To be accumulated.
- QVarLengthArray <short> accumulatorData(4 * width * 2); // Data for three acumulators for r, g, b. Each accumulator is two lines.
- short *accumulator[4]; // Helper for accessing the accumulator on a per-channel basis more easily.
- accumulator[0] = accumulatorData.data();
- accumulator[1] = accumulatorData.data() + width;
- accumulator[2] = accumulatorData.data() + (width * 2);
- accumulator[3] = accumulatorData.data() + (width * 3);
-
- // Produce the conversion lookup tables.
- for (i = 0; i < 256; i++) {
- lookup_8bit_to_4bit[i] = round(i / 16.0);
- // Before bitshifts: (i * 8) - (... * 16 * 8)
- lookup_8bit_to_4bit_diff[i] = (i << 3) - (lookup_8bit_to_4bit[i] << 7);
-
- if (lookup_8bit_to_4bit[i] > 15)
- lookup_8bit_to_4bit[i] = 15;
- }
-
- // Clear the accumulators
- memset(accumulator[0], 0, width * 4);
- memset(accumulator[1], 0, width * 4);
- memset(accumulator[2], 0, width * 4);
- memset(accumulator[3], 0, width * 4);
-
- // For each line...
- for (y = 0; y < height; y++) {
-
- // For each component (r, g, b, a)...
- memcpy(accumulator[0], accumulator[0] + width, width * 2);
- memset(accumulator[0] + width, 0, width * 2);
-
- memcpy(accumulator[1], accumulator[1] + width, width * 2);
- memset(accumulator[1] + width, 0, width * 2);
-
- memcpy(accumulator[2], accumulator[2] + width, width * 2);
- memset(accumulator[2] + width, 0, width * 2);
-
- memcpy(accumulator[3], accumulator[3] + width, width * 2);
- memset(accumulator[3] + width, 0, width * 2);
-
- // For each column....
- for (x = 0; x < width; x++) {
-
- // For each component (r, g, b, a)...
- for (c = 0; c < 4; c++) {
-
- // Get the 8bit value from the original image
- component[c] = GET_RGBA_COMPONENT(in, x, y, stride, c);
-
- // Add the diffusion for this pixel we stored in the accumulator.
- // >> 7 because the values in accumulator are stored * 128
- component[c] += accumulator[c][x] >> 7;
-
- // Make sure we're not over the boundaries.
- CLAMP_256(component[c]);
-
- // Store the difference from converting 8bit => 4bit and the orig pixel.
- // Convert 8bit => 4bit.
- diff = DIFF_8BIT_TO_4BIT(component[c]);
- component[c] = CONVERT_8BIT_TO_4BIT(component[c]);
-
- // Distribute the difference according to the matrix in the
- // accumulation bufffer.
- ACCUMULATE(accumulator[c], x + 1, 0, width, diff * 7);
- ACCUMULATE(accumulator[c], x - 1, 1, width, diff * 3);
- ACCUMULATE(accumulator[c], x, 1, width, diff * 5);
- ACCUMULATE(accumulator[c], x + 1, 1, width, diff * 1);
- }
-
- // Write the newly produced pixel
- PUT_4444(out, x, y, alignedWidth, component[0], component[1], component[2], component[3]);
- }
- }
-
- return out;
-}
-
-unsigned char* convertBGRA32_to_RGBA32(const unsigned char *in, int width, int height, int stride)
-{
- unsigned char *out = (unsigned char *) malloc(stride * height);
-
- // For each line...
- for (int y = 0; y < height; y++) {
- // For each column
- for (int x = 0; x < width; x++) {
- out[(stride * y) + (x * 4) + 0] = in[(stride * y) + (x * 4) + 2];
- out[(stride * y) + (x * 4) + 1] = in[(stride * y) + (x * 4) + 1];
- out[(stride * y) + (x * 4) + 2] = in[(stride * y) + (x * 4) + 0];
- out[(stride * y) + (x * 4) + 3] = in[(stride * y) + (x * 4) + 3];
- }
- }
-
- return out;
-}
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