彩虹色多色阶热力图温度映射

convert.java

private float a, b, c, d;
private int red, green, blue;

private static final float minTemp = 20.0f;
private static final float maxTemp = 40.0f;
private void setAbcd() {
    a = minTemp + (maxTemp - minTemp) * 0.2121f;
    b = minTemp + (maxTemp - minTemp) * 0.3182f;
    c = minTemp + (maxTemp - minTemp) * 0.4242f;
    d = minTemp + (maxTemp - minTemp) * 0.8182f;
}


private int constrain(double amt, int low, int high) {
    return (amt) < (low) ? (low) : (int) ((amt) > (high) ? (high) : (amt));
}

private int getColor565(int red, int green, int blue) {
    return ((red & 0xF8) << 8) | ((green & 0xFC) << 3) | ((blue & 0xFF) >> 3);
}


private int TempToColor(double val) {
    red = constrain(255.0f / (c - b) * val - ((b * 255.0f) / (c - b)), 0, 255);

    if ((val > minTemp) & (val < a)) {
        green = constrain(255.0f / (a - minTemp) * val - (255.0f * minTemp) / (a - minTemp), 0, 255);
    } else if ((val >= a) & (val <= c)) {
        green = 255;
    } else if (val > c) {
        green = constrain(255.0f / (c - d) * val - (d * 255.0f) / (c - d), 0, 255);
    } else if ((val > d) | (val < a)) {
        green = 0;
    }

    if (val <= b) {
        blue = constrain(255.0f / (a - b) * val - (255.0f * b) / (a - b), 0, 255);
    } else if ((val > b) & (val <= d)) {
        blue = 0;
    } else if (val > d) {
        blue = constrain(240.0f / (maxTemp - d) * val - (d * 240.0f) / (maxTemp - d), 0, 240);
    }

    //Log.i(TAG, "red= " + red + ", green = " + green + ", blue = " + blue);
    // use the displays color mapping function to get 5-6-5 color palet (R=5 bits, G=6 bits, B-5 bits)
    int color = getColor565(red, green, blue);
    return RGB565ToARGB(color);
}

private int RGB565ToARGB(int aPixel) {
    int r = ((aPixel & 0xF800) >>> 8) & 0xFF;
    int g = ((aPixel & 0x07E0) >>> 3) & 0xFF;
    int b = ((aPixel & 0x001F) << 3) & 0xFF;

    return 0xff000000 | (r << 16) | (g << 8) | b;
}