JUCE/modules/juce_graphics/colour/juce_ColourGradient.cpp

/*
  ==============================================================================

   This file is part of the JUCE library.
   Copyright (c) 2017 - ROLI Ltd.

   JUCE is an open source library subject to commercial or open-source
   licensing.

   By using JUCE, you agree to the terms of both the JUCE 5 End-User License
   Agreement and JUCE 5 Privacy Policy (both updated and effective as of the
   27th April 2017).

   End User License Agreement: www.juce.com/juce-5-licence
   Privacy Policy: www.juce.com/juce-5-privacy-policy

   Or: You may also use this code under the terms of the GPL v3 (see
   www.gnu.org/licenses).

   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
   DISCLAIMED.

  ==============================================================================
*/

namespace juce
{

ColourGradient::ColourGradient() noexcept
{
   #if JUCE_DEBUG
    point1.setX (987654.0f);
    #define JUCE_COLOURGRADIENT_CHECK_COORDS_INITIALISED   jassert (point1.x != 987654.0f);
   #else
    #define JUCE_COLOURGRADIENT_CHECK_COORDS_INITIALISED
   #endif
}

ColourGradient::ColourGradient (Colour colour1, float x1, float y1,
                                Colour colour2, float x2, float y2, bool radial)
    : ColourGradient (colour1, Point<float> (x1, y1),
                      colour2, Point<float> (x2, y2), radial)
{
}

ColourGradient::ColourGradient (Colour colour1, Point<float> p1,
                                Colour colour2, Point<float> p2, bool radial)
    : point1 (p1),
      point2 (p2),
      isRadial (radial)
{
    colours.add (ColourPoint (0.0, colour1));
    colours.add (ColourPoint (1.0, colour2));
}

ColourGradient::~ColourGradient()
{
}

bool ColourGradient::operator== (const ColourGradient& other) const noexcept
{
    return point1 == other.point1 && point2 == other.point2
            && isRadial == other.isRadial
            && colours == other.colours;
}

bool ColourGradient::operator!= (const ColourGradient& other) const noexcept
{
    return ! operator== (other);
}

//==============================================================================
void ColourGradient::clearColours()
{
    colours.clear();
}

int ColourGradient::addColour (const double proportionAlongGradient, Colour colour)
{
    // must be within the two end-points
    jassert (proportionAlongGradient >= 0 && proportionAlongGradient <= 1.0);

    if (proportionAlongGradient <= 0)
    {
        colours.set (0, ColourPoint (0.0, colour));
        return 0;
    }

    auto pos = jmin (1.0, proportionAlongGradient);

    int i;
    for (i = 0; i < colours.size(); ++i)
        if (colours.getReference(i).position > pos)
            break;

    colours.insert (i, ColourPoint (pos, colour));
    return i;
}

void ColourGradient::removeColour (int index)
{
    jassert (index > 0 && index < colours.size() - 1);
    colours.remove (index);
}

void ColourGradient::multiplyOpacity (const float multiplier) noexcept
{
    for (auto& c : colours)
        c.colour = c.colour.withMultipliedAlpha (multiplier);
}

//==============================================================================
int ColourGradient::getNumColours() const noexcept
{
    return colours.size();
}

double ColourGradient::getColourPosition (const int index) const noexcept
{
    if (isPositiveAndBelow (index, colours.size()))
        return colours.getReference (index).position;

    return 0;
 }

Colour ColourGradient::getColour (const int index) const noexcept
{
    if (isPositiveAndBelow (index, colours.size()))
        return colours.getReference (index).colour;

    return {};
}

void ColourGradient::setColour (int index, Colour newColour) noexcept
{
    if (isPositiveAndBelow (index, colours.size()))
        colours.getReference (index).colour = newColour;
}

Colour ColourGradient::getColourAtPosition (const double position) const noexcept
{
    jassert (colours.getReference(0).position == 0.0); // the first colour specified has to go at position 0

    if (position <= 0 || colours.size() <= 1)
        return colours.getReference(0).colour;

    int i = colours.size() - 1;
    while (position < colours.getReference(i).position)
        --i;

    auto& p1 = colours.getReference (i);

    if (i >= colours.size() - 1)
        return p1.colour;

    auto& p2 = colours.getReference (i + 1);

    return p1.colour.interpolatedWith (p2.colour, (float) ((position - p1.position) / (p2.position - p1.position)));
}

//==============================================================================
void ColourGradient::createLookupTable (PixelARGB* const lookupTable, const int numEntries) const noexcept
{
    JUCE_COLOURGRADIENT_CHECK_COORDS_INITIALISED // Trying to use this object without setting its coordinates?
    jassert (colours.size() >= 2);
    jassert (numEntries > 0);
    jassert (colours.getReference(0).position == 0.0); // The first colour specified has to go at position 0

    auto pix1 = colours.getReference (0).colour.getPixelARGB();
    int index = 0;

    for (int j = 1; j < colours.size(); ++j)
    {
        auto& p = colours.getReference (j);
        auto numToDo = roundToInt (p.position * (numEntries - 1)) - index;
        auto pix2 = p.colour.getPixelARGB();

        for (int i = 0; i < numToDo; ++i)
        {
            jassert (index >= 0 && index < numEntries);

            lookupTable[index] = pix1;
            lookupTable[index].tween (pix2, (uint32) ((i << 8) / numToDo));
            ++index;
        }

        pix1 = pix2;
    }

    while (index < numEntries)
        lookupTable [index++] = pix1;
}

int ColourGradient::createLookupTable (const AffineTransform& transform, HeapBlock<PixelARGB>& lookupTable) const
{
    JUCE_COLOURGRADIENT_CHECK_COORDS_INITIALISED // Trying to use this object without setting its coordinates?
    jassert (colours.size() >= 2);

    auto numEntries = jlimit (1, jmax (1, (colours.size() - 1) << 8),
                              3 * (int) point1.transformedBy (transform)
                                              .getDistanceFrom (point2.transformedBy (transform)));
    lookupTable.malloc (numEntries);
    createLookupTable (lookupTable, numEntries);
    return numEntries;
}

bool ColourGradient::isOpaque() const noexcept
{
    for (auto& c : colours)
        if (! c.colour.isOpaque())
            return false;

    return true;
}

bool ColourGradient::isInvisible() const noexcept
{
    for (auto& c : colours)
        if (! c.colour.isTransparent())
            return false;

    return true;
}

bool ColourGradient::ColourPoint::operator== (const ColourPoint& other) const noexcept
{
    return position == other.position && colour == other.colour;
}

bool ColourGradient::ColourPoint::operator!= (const ColourPoint& other) const noexcept
{
    return position != other.position || colour != other.colour;
}

} // namespace juce