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/* $Id: DisplayResampleImage.cpp $ */
/** @file
* Image resampling code, used for snapshot thumbnails.
*/
/*
* Copyright (C) 2009-2023 Oracle and/or its affiliates.
*
* This file is part of VirtualBox base platform packages, as
* available from https://www.virtualbox.org.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, in version 3 of the
* License.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <https://www.gnu.org/licenses>.
*
* SPDX-License-Identifier: GPL-3.0-only
*/
#include <iprt/types.h>
DECLINLINE(void) imageSetPixel (uint8_t *im, int x, int y, int color, int w)
{
*(int32_t *)(im + y * w * 4 + x * 4) = color;
}
#define trueColorGetAlpha(c) (((c) & 0x7F000000) >> 24)
#define trueColorGetRed(c) (((c) & 0xFF0000) >> 16)
#define trueColorGetGreen(c) (((c) & 0x00FF00) >> 8)
#define trueColorGetBlue(c) ((c) & 0x0000FF)
/* Fast integer implementation for 32 bpp bitmap scaling.
* Using fixed point values * 16.
*/
typedef int32_t FIXEDPOINT;
#define INT_TO_FIXEDPOINT(i) (FIXEDPOINT)((i) << 4)
#define FIXEDPOINT_TO_INT(v) (int)((v) >> 4)
#define FIXEDPOINT_FLOOR(v) ((v) & ~0xF)
#define FIXEDPOINT_FRACTION(v) ((v) & 0xF)
/* For 32 bit source only. */
void BitmapScale32 (uint8_t *dst,
int dstW, int dstH,
const uint8_t *src,
int iDeltaLine,
int srcW, int srcH)
{
int x, y;
for (y = 0; y < dstH; y++)
{
FIXEDPOINT sy1 = INT_TO_FIXEDPOINT(y * srcH) / dstH;
FIXEDPOINT sy2 = INT_TO_FIXEDPOINT((y + 1) * srcH) / dstH;
for (x = 0; x < dstW; x++)
{
FIXEDPOINT red = 0, green = 0, blue = 0;
FIXEDPOINT sx1 = INT_TO_FIXEDPOINT(x * srcW) / dstW;
FIXEDPOINT sx2 = INT_TO_FIXEDPOINT((x + 1) * srcW) / dstW;
FIXEDPOINT spixels = (sx2 - sx1) * (sy2 - sy1);
FIXEDPOINT sy = sy1;
do
{
FIXEDPOINT yportion;
if (FIXEDPOINT_FLOOR (sy) == FIXEDPOINT_FLOOR (sy1))
{
yportion = INT_TO_FIXEDPOINT(1) - FIXEDPOINT_FRACTION(sy);
if (yportion > sy2 - sy1)
{
yportion = sy2 - sy1;
}
sy = FIXEDPOINT_FLOOR (sy);
}
else if (sy == FIXEDPOINT_FLOOR (sy2))
{
yportion = FIXEDPOINT_FRACTION(sy2);
}
else
{
yportion = INT_TO_FIXEDPOINT(1);
}
const uint8_t *pu8SrcLine = src + iDeltaLine * FIXEDPOINT_TO_INT(sy);
FIXEDPOINT sx = sx1;
do
{
FIXEDPOINT xportion;
FIXEDPOINT pcontribution;
if (FIXEDPOINT_FLOOR (sx) == FIXEDPOINT_FLOOR (sx1))
{
xportion = INT_TO_FIXEDPOINT(1) - FIXEDPOINT_FRACTION(sx);
if (xportion > sx2 - sx1)
{
xportion = sx2 - sx1;
}
pcontribution = xportion * yportion;
sx = FIXEDPOINT_FLOOR (sx);
}
else if (sx == FIXEDPOINT_FLOOR (sx2))
{
xportion = FIXEDPOINT_FRACTION(sx2);
pcontribution = xportion * yportion;
}
else
{
xportion = INT_TO_FIXEDPOINT(1);
pcontribution = xportion * yportion;
}
/* Color depth specific code begin */
int32_t p = *(int32_t *)(pu8SrcLine + FIXEDPOINT_TO_INT(sx) * 4);
/* Color depth specific code end */
red += trueColorGetRed (p) * pcontribution;
green += trueColorGetGreen (p) * pcontribution;
blue += trueColorGetBlue (p) * pcontribution;
sx += INT_TO_FIXEDPOINT(1);
} while (sx < sx2);
sy += INT_TO_FIXEDPOINT(1);
} while (sy < sy2);
if (spixels != 0)
{
red /= spixels;
green /= spixels;
blue /= spixels;
}
/* Clamping to allow for rounding errors above */
if (red > 255)
{
red = 255;
}
if (green > 255)
{
green = 255;
}
if (blue > 255)
{
blue = 255;
}
imageSetPixel (dst,
x, y,
( ((int) red) << 16) + (((int) green) << 8) + ((int) blue),
dstW);
}
}
}
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