ColorBlock.cpp

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/*
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * 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; either version 2
 * of the License, or (at your option) any later version.
 *
 * 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, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * Contributors: Amorilia (amorilia@users.sourceforge.net)
 *
 * ***** END GPL LICENSE BLOCK *****
 */

/*
 * This file is based on a similar file from the NVIDIA texture tools
 * (http://nvidia-texture-tools.googlecode.com/)
 *
 * Original license from NVIDIA follows.
 */

// This code is in the public domain -- castanyo@yahoo.es

#include <ColorBlock.h>
#include <Image.h>
#include <Common.h>

    // Get approximate luminance.
    inline static uint colorLuminance(Color32 c)
    {
        return c.r + c.g + c.b;
    }
    
    // Get the euclidean distance between the given colors.
    inline static uint colorDistance(Color32 c0, Color32 c1)
    {
        return (c0.r - c1.r) * (c0.r - c1.r) + (c0.g - c1.g) * (c0.g - c1.g) + (c0.b - c1.b) * (c0.b - c1.b);
    }
    

ColorBlock::ColorBlock()
{
}

ColorBlock::ColorBlock(const uint * linearImage)
{
    for(uint i = 0; i < 16; i++) {
        color(i) = Color32(linearImage[i]);
    }
}

ColorBlock::ColorBlock(const ColorBlock & block)
{
    for(uint i = 0; i < 16; i++) {
        color(i) = block.color(i);
    }
}


ColorBlock::ColorBlock(const Image * img, uint x, uint y)
{
    init(img, x, y);
}

void ColorBlock::init(const Image * img, uint x, uint y)
{
    init(img->width(), img->height(), (const uint *)img->pixels(), x, y);
}

void ColorBlock::init(uint w, uint h, const uint * data, uint x, uint y)
{
    const uint bw = min(w - x, 4U);
    const uint bh = min(h - y, 4U);

    // Blocks that are smaller than 4x4 are handled by repeating the pixels.
    // @@ Thats only correct when block size is 1, 2 or 4, but not with 3. :(
    // @@ Ideally we should zero the weights of the pixels out of range.

    for (uint i = 0; i < 4; i++)
    {
        const int by = i % bh;

        for (uint e = 0; e < 4; e++)
        {
            const int bx = e % bw;
            const uint idx = (y + by) * w + x + bx;

            color(e, i).u = data[idx];
        }
    }
}

void ColorBlock::init(uint w, uint h, const float * data, uint x, uint y)
{
    const uint bw = min(w - x, 4U);
    const uint bh = min(h - y, 4U);

    // Blocks that are smaller than 4x4 are handled by repeating the pixels.
    // @@ Thats only correct when block size is 1, 2 or 4, but not with 3. :(
    // @@ Ideally we should zero the weights of the pixels out of range.

    uint srcPlane = w * h;

    for (uint i = 0; i < 4; i++)
    {
        const uint by = i % bh;
        
        for (uint e = 0; e < 4; e++)
        {
            const uint bx = e % bw;
            const uint idx = ((y + by) * w + x + bx);
            
            Color32 & c = color(e, i);
            c.r = uint8(255 * clamp(data[idx + 0 * srcPlane], 0.0f, 1.0f)); // @@ Is this the right way to quantize floats to bytes?
            c.g = uint8(255 * clamp(data[idx + 1 * srcPlane], 0.0f, 1.0f));
            c.b = uint8(255 * clamp(data[idx + 2 * srcPlane], 0.0f, 1.0f));
            c.a = uint8(255 * clamp(data[idx + 3 * srcPlane], 0.0f, 1.0f));
        }
    }
}

static inline uint8 component(Color32 c, uint i)
{
    if (i == 0) return c.r;
    if (i == 1) return c.g;
    if (i == 2) return c.b;
    if (i == 3) return c.a;
    if (i == 4) return 0xFF;
    return 0;
}

void ColorBlock::swizzle(uint x, uint y, uint z, uint w)
{
    for (int i = 0; i < 16; i++)
    {
        Color32 c = m_color[i];
        m_color[i].r = component(c, x);
        m_color[i].g = component(c, y);
        m_color[i].b = component(c, z);
        m_color[i].a = component(c, w);
    }
}


bool ColorBlock::isSingleColor(Color32 mask/*= Color32(0xFF, 0xFF, 0xFF, 0x00)*/) const
{
    uint u = m_color[0].u & mask.u;
    
    for (int i = 1; i < 16; i++)
    {
        if (u != (m_color[i].u & mask.u))
        {
            return false;
        }
    }
    
    return true;
}

/*
bool ColorBlock::isSingleColorNoAlpha() const
{
    Color32 c;
    int i;
    for(i = 0; i < 16; i++)
    {
        if (m_color[i].a != 0) c = m_color[i];
    }

    Color32 mask(0xFF, 0xFF, 0xFF, 0x00);
    uint u = c.u & mask.u;

    for(; i < 16; i++)
    {
        if (u != (m_color[i].u & mask.u))
        {
            return false;
        }
    }
    
    return true;
}
*/

/*uint ColorBlock::countUniqueColors() const
{
    uint count = 0;

    // @@ This does not have to be o(n^2)
    for(int i = 0; i < 16; i++)
    {
        bool unique = true;
        for(int j = 0; j < i; j++) {
            if( m_color[i] != m_color[j] ) {
                unique = false;
            }
        }
        
        if( unique ) {
            count++;
        }
    }
    
    return count;
}*/

/*/// Get average color of the block.
Color32 ColorBlock::averageColor() const
{
    uint r, g, b, a;
    r = g = b = a = 0;

    for(uint i = 0; i < 16; i++) {
        r += m_color[i].r;
        g += m_color[i].g;
        b += m_color[i].b;
        a += m_color[i].a;
    }
    
    return Color32(uint8(r / 16), uint8(g / 16), uint8(b / 16), uint8(a / 16));
}*/

bool ColorBlock::hasAlpha() const
{
    for (uint i = 0; i < 16; i++)
    {
        if (m_color[i].a != 255) return true;
    }
    return false;
}

#if 0

void ColorBlock::diameterRange(Color32 * start, Color32 * end) const
{
    Color32 c0, c1;
    uint best_dist = 0;
    
    for(int i = 0; i < 16; i++) {
        for (int j = i+1; j < 16; j++) {
            uint dist = colorDistance(m_color[i], m_color[j]);
            if( dist > best_dist ) {
                best_dist = dist;
                c0 = m_color[i];
                c1 = m_color[j];
            }
        }
    }
    
    *start = c0;
    *end = c1;
}

void ColorBlock::luminanceRange(Color32 * start, Color32 * end) const
{
    Color32 minColor, maxColor;
    uint minLuminance, maxLuminance;
    
    maxLuminance = minLuminance = colorLuminance(m_color[0]);
    
    for(uint i = 1; i < 16; i++)
    {
        uint luminance = colorLuminance(m_color[i]);
        
        if (luminance > maxLuminance) {
            maxLuminance = luminance;
            maxColor = m_color[i];
        }
        else if (luminance < minLuminance) {
            minLuminance = luminance;
            minColor = m_color[i];
        }
    }

    *start = minColor;
    *end = maxColor;
}

void ColorBlock::boundsRange(Color32 * start, Color32 * end) const
{
    Color32 minColor(255, 255, 255);
    Color32 maxColor(0, 0, 0);

    for(uint i = 0; i < 16; i++)
    {
        if (m_color[i].r < minColor.r) { minColor.r = m_color[i].r; }
        if (m_color[i].g < minColor.g) { minColor.g = m_color[i].g; }
        if (m_color[i].b < minColor.b) { minColor.b = m_color[i].b; }
        if (m_color[i].r > maxColor.r) { maxColor.r = m_color[i].r; }
        if (m_color[i].g > maxColor.g) { maxColor.g = m_color[i].g; }
        if (m_color[i].b > maxColor.b) { maxColor.b = m_color[i].b; }
    }

    // Offset range by 1/16 of the extents
    Color32 inset;
    inset.r = (maxColor.r - minColor.r) >> 4;
    inset.g = (maxColor.g - minColor.g) >> 4;
    inset.b = (maxColor.b - minColor.b) >> 4;

    minColor.r = (minColor.r + inset.r <= 255) ? minColor.r + inset.r : 255;
    minColor.g = (minColor.g + inset.g <= 255) ? minColor.g + inset.g : 255;
    minColor.b = (minColor.b + inset.b <= 255) ? minColor.b + inset.b : 255;

    maxColor.r = (maxColor.r >= inset.r) ? maxColor.r - inset.r : 0;
    maxColor.g = (maxColor.g >= inset.g) ? maxColor.g - inset.g : 0;
    maxColor.b = (maxColor.b >= inset.b) ? maxColor.b - inset.b : 0;

    *start = minColor;
    *end = maxColor;
}

void ColorBlock::boundsRangeAlpha(Color32 * start, Color32 * end) const
{
    Color32 minColor(255, 255, 255, 255);
    Color32 maxColor(0, 0, 0, 0);

    for(uint i = 0; i < 16; i++)
    {
        if (m_color[i].r < minColor.r) { minColor.r = m_color[i].r; }
        if (m_color[i].g < minColor.g) { minColor.g = m_color[i].g; }
        if (m_color[i].b < minColor.b) { minColor.b = m_color[i].b; }
        if (m_color[i].a < minColor.a) { minColor.a = m_color[i].a; }
        if (m_color[i].r > maxColor.r) { maxColor.r = m_color[i].r; }
        if (m_color[i].g > maxColor.g) { maxColor.g = m_color[i].g; }
        if (m_color[i].b > maxColor.b) { maxColor.b = m_color[i].b; }
        if (m_color[i].a > maxColor.a) { maxColor.a = m_color[i].a; }
    }

    // Offset range by 1/16 of the extents
    Color32 inset;
    inset.r = (maxColor.r - minColor.r) >> 4;
    inset.g = (maxColor.g - minColor.g) >> 4;
    inset.b = (maxColor.b - minColor.b) >> 4;
    inset.a = (maxColor.a - minColor.a) >> 4;

    minColor.r = (minColor.r + inset.r <= 255) ? minColor.r + inset.r : 255;
    minColor.g = (minColor.g + inset.g <= 255) ? minColor.g + inset.g : 255;
    minColor.b = (minColor.b + inset.b <= 255) ? minColor.b + inset.b : 255;
    minColor.a = (minColor.a + inset.a <= 255) ? minColor.a + inset.a : 255;

    maxColor.r = (maxColor.r >= inset.r) ? maxColor.r - inset.r : 0;
    maxColor.g = (maxColor.g >= inset.g) ? maxColor.g - inset.g : 0;
    maxColor.b = (maxColor.b >= inset.b) ? maxColor.b - inset.b : 0;
    maxColor.a = (maxColor.a >= inset.a) ? maxColor.a - inset.a : 0;
    
    *start = minColor;
    *end = maxColor;
}
#endif

/*/// Sort colors by abosolute value in their 16 bit representation.
void ColorBlock::sortColorsByAbsoluteValue()
{
    // Dummy selection sort.
    for( uint a = 0; a < 16; a++ ) {
        uint max = a;
        Color16 cmax(m_color[a]);
        
        for( uint b = a+1; b < 16; b++ ) {
            Color16 cb(m_color[b]);
            
            if( cb.u > cmax.u ) {
                max = b;
                cmax = cb;
            }
        }
        swap( m_color[a], m_color[max] );
    }
}*/


/*/// Find extreme colors in the given axis.
void ColorBlock::computeRange(Vector3::Arg axis, Color32 * start, Color32 * end) const
{
    
    int mini, maxi;
    mini = maxi = 0;
    
    float min, max; 
    min = max = dot(Vector3(m_color[0].r, m_color[0].g, m_color[0].b), axis);

    for(uint i = 1; i < 16; i++)
    {
        const Vector3 vec(m_color[i].r, m_color[i].g, m_color[i].b);
        
        float val = dot(vec, axis);
        if( val < min ) {
            mini = i;
            min = val;
        }
        else if( val > max ) {
            maxi = i;
            max = val;
        }
    }
    
    *start = m_color[mini];
    *end = m_color[maxi];
}*/


/*/// Sort colors in the given axis.
void ColorBlock::sortColors(const Vector3 & axis)
{
    float luma_array[16];
    
    for(uint i = 0; i < 16; i++) {
        const Vector3 vec(m_color[i].r, m_color[i].g, m_color[i].b);
        luma_array[i] = dot(vec, axis);
    }
    
    // Dummy selection sort.
    for( uint a = 0; a < 16; a++ ) {
        uint min = a;
        for( uint b = a+1; b < 16; b++ ) {
            if( luma_array[b] < luma_array[min] ) {
                min = b;
            }
        }
        swap( luma_array[a], luma_array[min] );
        swap( m_color[a], m_color[min] );
    }
}*/


/*/// Get the volume of the color block.
float ColorBlock::volume() const
{
    Box bounds;
    bounds.clearBounds();
    
    for(int i = 0; i < 16; i++) {
        const Vector3 point(m_color[i].r, m_color[i].g, m_color[i].b);
        bounds.addPointToBounds(point);
    }
    
    return bounds.volume();
}
*/