public int evaluate(float fraction, int startValue, int endValue) { int startInt = (Integer) startValue; float startA = ((startInt >> 24) & 0xff) / 255.0f; float startR = ((startInt >> 16) & 0xff) / 255.0f; float startG = ((startInt >> 8) & 0xff) / 255.0f; float startB = ( startInt & 0xff) / 255.0f; int endInt = (Integer) endValue; float endA = ((endInt >> 24) & 0xff) / 255.0f; float endR = ((endInt >> 16) & 0xff) / 255.0f; float endG = ((endInt >> 8) & 0xff) / 255.0f; float endB = ( endInt & 0xff) / 255.0f; // convert from sRGB to linear startR = (float) Math.pow(startR, 2.2); startG = (float) Math.pow(startG, 2.2); startB = (float) Math.pow(startB, 2.2); endR = (float) Math.pow(endR, 2.2); endG = (float) Math.pow(endG, 2.2); endB = (float) Math.pow(endB, 2.2); // compute the interpolated color in linear space float a = startA + fraction * (endA - startA); float r = startR + fraction * (endR - startR); float g = startG + fraction * (endG - startG); float b = startB + fraction * (endB - startB); // convert back to sRGB in the [0..255] range a = a * 255.0f; r = (float) Math.pow(r, 1.0 / 2.2) * 255.0f; g = (float) Math.pow(g, 1.0 / 2.2) * 255.0f; b = (float) Math.pow(b, 1.0 / 2.2) * 255.0f; return Math.round(a) << 24 | Math.round(r) << 16 | Math.round(g) << 8 | Math.round(b); }
不错啊,总结得