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   1 /**
   2  * Copyright (c) 2010-2022 Contributors to the openHAB project
   3  *
   4  * See the NOTICE file(s) distributed with this work for additional
   5  * information.
   6  *
   7  * This program and the accompanying materials are made available under the
   8  * terms of the Eclipse Public License 2.0 which is available at
   9  * http://www.eclipse.org/legal/epl-2.0
  10  *
  11  * SPDX-License-Identifier: EPL-2.0
  12  */
  13 package org.openhab.binding.nanoleaf.internal.layout.shape;
  14
  15 import java.awt.Color;
  16 import java.awt.Paint;
  17 import java.awt.PaintContext;
  18 import java.awt.Rectangle;
  19 import java.awt.RenderingHints;
  20 import java.awt.geom.AffineTransform;
  21 import java.awt.geom.Rectangle2D;
  22 import java.awt.image.ColorModel;
  23 import java.awt.image.DataBufferInt;
  24 import java.awt.image.PackedColorModel;
  25 import java.awt.image.Raster;
  26 import java.awt.image.WritableRaster;
  27
  28 import org.eclipse.jdt.annotation.NonNullByDefault;
  29 import org.eclipse.jdt.annotation.Nullable;
  30 import org.openhab.binding.nanoleaf.internal.layout.ImagePoint2D;
  31
  32 /**
  33  * Paint for triangles with one color in each corner. Used to make gradients between the colors when
  34  * dividing a hexagon into 6 triangles.
  35  *
  36  * https://codeplea.com/triangular-interpolation is instructive for the math.
  37  *
  38  * Inspired by
  39  * https://github.com/hageldave/JPlotter/blob/9c92731f3b29a2cdb14f3dfdeeed6fffde37eee4/jplotter/src/main/java/hageldave/jplotter/util/BarycentricGradientPaint.java,
  40  * for how to integrate it into Java AWT but kept so simple that I could understand it. It was however far too big to
  41  * use as a dependency.
  42  *
  43  * @author Jørgen Austvik - Initial contribution
  44  */
  45 @NonNullByDefault
  46 public class BarycentricTriangleGradient implements Paint {
  47
  48     private final Color color1;
  49     private final Color color2;
  50     private final Color color3;
  51
  52     private final ImagePoint2D corner1;
  53     private final ImagePoint2D corner2;
  54     private final ImagePoint2D corner3;
  55
  56     public BarycentricTriangleGradient(ImagePoint2D corner1, Color color1, ImagePoint2D corner2, Color color2,
  57             ImagePoint2D corner3, Color color3) {
  58         this.corner1 = corner1;
  59         this.corner2 = corner2;
  60         this.corner3 = corner3;
  61         this.color1 = color1;
  62         this.color2 = color2;
  63         this.color3 = color3;
  64     }
  65
  66     @Override
  67     public @Nullable PaintContext createContext(@Nullable ColorModel cm, @Nullable Rectangle deviceBounds,
  68             @Nullable Rectangle2D userBounds, @Nullable AffineTransform xform, @Nullable RenderingHints hints) {
  69         return new BarycentricTriangleGradientContext(corner1, color1, corner2, color2, corner3, color3);
  70     }
  71
  72     @Override
  73     public int getTransparency() {
  74         return OPAQUE;
  75     }
  76
  77     private class BarycentricTriangleGradientContext implements PaintContext {
  78
  79         private final Color color1;
  80         private final Color color2;
  81         private final Color color3;
  82
  83         private final ImagePoint2D corner1;
  84         private final ImagePoint2D corner2;
  85         private final ImagePoint2D corner3;
  86
  87         private final PackedColorModel colorModel = (PackedColorModel) ColorModel.getRGBdefault();
  88
  89         public BarycentricTriangleGradientContext(ImagePoint2D corner1, Color color1, ImagePoint2D corner2,
  90                 Color color2, ImagePoint2D corner3, Color color3) {
  91             this.corner1 = corner1;
  92             this.corner2 = corner2;
  93             this.corner3 = corner3;
  94             this.color1 = color1;
  95             this.color2 = color2;
  96             this.color3 = color3;
  97         }
  98
  99         @Override
 100         public void dispose() {
 101         }
 102
 103         @Override
 104         public @Nullable ColorModel getColorModel() {
 105             return colorModel;
 106         }
 107
 108         @Override
 109         public Raster getRaster(int x, int y, int w, int h) {
 110             int[] data = new int[h * w];
 111             DataBufferInt buffer = new DataBufferInt(data, w * h);
 112             WritableRaster raster = Raster.createPackedRaster(buffer, w, h, w, colorModel.getMasks(), null);
 113
 114             float denominator = 1f / (((corner2.getY() - corner3.getY()) * (corner1.getX() - corner3.getX()))
 115                     + ((corner3.getX() - corner2.getX()) * (corner1.getY() - corner3.getY())));
 116
 117             for (int yPos = 0; yPos < h; yPos++) {
 118                 int imageY = y + yPos;
 119                 for (int xPos = 0; xPos < w; xPos++) {
 120                     int imageX = xPos + x;
 121
 122                     float weight1 = (((corner2.getY() - corner3.getY()) * (imageX - corner3.getX()))
 123                             + ((corner3.getX() - corner2.getX()) * (imageY - corner3.getY()))) * denominator;
 124                     float weight2 = (((corner3.getY() - corner1.getY()) * (imageX - corner3.getX()))
 125                             + ((corner1.getX() - corner3.getX()) * (imageY - corner3.getY()))) * denominator;
 126                     float weight3 = 1 - weight1 - weight2;
 127
 128                     if (weight1 < 0 || weight2 < 0 || weight3 < 0) {
 129                         // Outside of triangle
 130                         data[yPos * w + xPos] = 0;
 131                     } else {
 132                         Color c = mergeColors(weight1, color1, weight2, color2, weight3, color3);
 133                         data[yPos * w + xPos] = c.getRGB();
 134                     }
 135                 }
 136             }
 137
 138             return raster;
 139         }
 140
 141         private Color mergeColors(float weight1, Color color1, float weight2, Color color2, float weight3,
 142                 Color color3) {
 143             float normalize = 1f / (weight1 + weight2 + weight3);
 144             float r = (color1.getRed() * weight1 + color2.getRed() * weight2 + color3.getRed() * weight3) * normalize;
 145             float g = (color1.getGreen() * weight1 + color2.getGreen() * weight2 + color3.getGreen() * weight3)
 146                     * normalize;
 147             float b = (color1.getBlue() * weight1 + color2.getBlue() * weight2 + color3.getBlue() * weight3)
 148                     * normalize;
 149             return new Color((int) r, (int) g, (int) b);
 150         }
 151     }
 152 }