juce_EdgeTable.h

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/*
  ==============================================================================
 
   This file is part of the JUCE library.
   Copyright (c) 2022 - Raw Material Software Limited
 
   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 7 End-User License
   Agreement and JUCE Privacy Policy.
 
   End User License Agreement: www.juce.com/juce-7-licence
   Privacy Policy: www.juce.com/juce-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
{
 
//==============================================================================
class JUCE_API  EdgeTable
{
public:
    //==============================================================================
    EdgeTable (Rectangle<int> clipLimits,
               const Path& pathToAdd,
               const AffineTransform& transform);

    explicit EdgeTable (Rectangle<int> rectangleToAdd);

    explicit EdgeTable (Rectangle<float> rectangleToAdd);

    explicit EdgeTable (const RectangleList<int>& rectanglesToAdd);

    explicit EdgeTable (const RectangleList<float>& rectanglesToAdd);

    EdgeTable (const EdgeTable&);

    EdgeTable& operator= (const EdgeTable&);

    ~EdgeTable();
 
    //==============================================================================
    void clipToRectangle (Rectangle<int> r);
    void excludeRectangle (Rectangle<int> r);
    void clipToEdgeTable (const EdgeTable&);
    void clipLineToMask (int x, int y, const uint8* mask, int maskStride, int numPixels);
    bool isEmpty() noexcept;
    const Rectangle<int>& getMaximumBounds() const noexcept      { return bounds; }
    void translate (float dx, int dy) noexcept;

    void multiplyLevels (float factor);

    void optimiseTable();
 
 
    //==============================================================================
    template <class EdgeTableIterationCallback>
    void iterate (EdgeTableIterationCallback& iterationCallback) const noexcept
    {
        const int* lineStart = table;
 
        for (int y = 0; y < bounds.getHeight(); ++y)
        {
            const int* line = lineStart;
            lineStart += lineStrideElements;
            int numPoints = line[0];
 
            if (--numPoints > 0)
            {
                int x = *++line;
                jassert ((x / scale) >= bounds.getX() && (x / scale) < bounds.getRight());
                int levelAccumulator = 0;
 
                iterationCallback.setEdgeTableYPos (bounds.getY() + y);
 
                while (--numPoints >= 0)
                {
                    const int level = *++line;
                    jassert (isPositiveAndBelow (level, scale));
                    const int endX = *++line;
                    jassert (endX >= x);
                    const int endOfRun = (endX / scale);
 
                    if (endOfRun == (x / scale))
                    {
                        // small segment within the same pixel, so just save it for the next
                        // time round..
                        levelAccumulator += (endX - x) * level;
                    }
                    else
                    {
                        // plot the fist pixel of this segment, including any accumulated
                        // levels from smaller segments that haven't been drawn yet
                        levelAccumulator += (0x100 - (x & 0xff)) * level;
                        levelAccumulator /= scale;
                        x /= scale;
 
                        if (levelAccumulator > 0)
                        {
                            if (levelAccumulator >= 255)
                                iterationCallback.handleEdgeTablePixelFull (x);
                            else
                                iterationCallback.handleEdgeTablePixel (x, levelAccumulator);
                        }
 
                        // if there's a run of similar pixels, do it all in one go..
                        if (level > 0)
                        {
                            jassert (endOfRun <= bounds.getRight());
                            const int numPix = endOfRun - ++x;
 
                            if (numPix > 0)
                                iterationCallback.handleEdgeTableLine (x, numPix, level);
                        }
 
                        // save the bit at the end to be drawn next time round the loop.
                        levelAccumulator = (endX & 0xff) * level;
                    }
 
                    x = endX;
                }
 
                levelAccumulator /= scale;
 
                if (levelAccumulator > 0)
                {
                    x /= scale;
                    jassert (x >= bounds.getX() && x < bounds.getRight());
 
                    if (levelAccumulator >= 255)
                        iterationCallback.handleEdgeTablePixelFull (x);
                    else
                        iterationCallback.handleEdgeTablePixel (x, levelAccumulator);
                }
            }
        }
    }
 
private:
    //==============================================================================
    static constexpr auto defaultEdgesPerLine = 32;
    static constexpr auto scale = 256;
 
    //==============================================================================
    // table line format: number of points; point0 x, point0 levelDelta, point1 x, point1 levelDelta, etc
    struct LineItem
    {
        int x, level;
 
        bool operator< (const LineItem& other) const noexcept   { return x < other.x; }
    };
 
    HeapBlock<int> table;
    Rectangle<int> bounds;
    int maxEdgesPerLine, lineStrideElements;
    bool needToCheckEmptiness = true;
 
    void allocate();
    void clearLineSizes() noexcept;
    void addEdgePoint (int x, int y, int winding);
    void addEdgePointPair (int x1, int x2, int y, int winding);
    void remapTableForNumEdges (int newNumEdgesPerLine);
    void remapWithExtraSpace (int numPointsNeeded);
    void intersectWithEdgeTableLine (int y, const int* otherLine);
    void clipEdgeTableLineToRange (int* line, int x1, int x2) noexcept;
    void sanitiseLevels (bool useNonZeroWinding) noexcept;
    static void copyEdgeTableData (int* dest, int destLineStride, const int* src, int srcLineStride, int numLines) noexcept;
 
    JUCE_LEAK_DETECTOR (EdgeTable)
};
 
} // namespace juce