C / C++ / MFC

#define WS_OVERLAPPEDWINDOW (WS_OVERLAPPED     | \
                             WS_CAPTION        | \
                             WS_SYSMENU        | \
                             WS_THICKFRAME     | \
                             WS_MINIMIZEBOX    | \
                             WS_MAXIMIZEBOX)

newRed = ( baseAlpha * baseRed + paintAlpha * paintRed ) / (baseAlpha + paintAlpha);
newGreen = ...
newBlue = ...
newAlpha = 1 - (1-baseAlpha)*(1-paintAlpha);

afterRed = topAlpha * topRed + (1-topAlpha) * bottomRed;

public override ColorBgra Apply(ColorBgra color)
{
    int a = blendColor.A;
    int invA = 255 - a;

    int r = ((color.R * invA) + (blendColor.R * a)) / 256;
    int g = ((color.G * invA) + (blendColor.G * a)) / 256;
    int b = ((color.B * invA) + (blendColor.B * a)) / 256;
    byte a2 = ComputeAlpha(color.A, blendColor.A);

    return ColorBgra.FromBgra((byte)b, (byte)g, (byte)r, a2);
}

public static ColorBgra Blend(ColorBgra ca, ColorBgra cb, byte cbAlpha)
{
    uint caA = (uint)Utility.FastScaleByteByByte((byte)(255 - cbAlpha), ca.A);
    uint cbA = (uint)Utility.FastScaleByteByByte(cbAlpha, cb.A);
    uint cbAT = caA + cbA;

    uint r;
    uint g;
    uint b;

    if (cbAT == 0)
    {
        r = 0;
        g = 0;
        b = 0;
    }
    else
    {
        r = ((ca.R * caA) + (cb.R * cbA)) / cbAT;
        g = ((ca.G * caA) + (cb.G * cbA)) / cbAT;
        b = ((ca.B * caA) + (cb.B * cbA)) / cbAT;
    }

    return ColorBgra.FromBgra((byte)b, (byte)g, (byte)r, (byte)cbAT);
}

public static int FastScaleByteByByte(byte a, byte b)
{
    int r1 = a * b + 0x80;
    int r2 = ((r1 >> 8) + r1) >> 8;
    return (byte)r2;
}

public static int FastScaleByteByByte(byte a, byte b)
{
   int r1 = a * b + 0x80;
   int r2 = ((r1 >> 8) + r1) >> 8;
   return (byte)r2;
}

public static int FastScaleByteByByte(byte a, byte b)
{
   int r1 = a * b + 128;  // 128 is half if 256, and is the equivalent of adding 0.5 before rounding a number to
   int r2 = ((r1 / 256) + r1) / 256;
   return (byte)r2;
}

Iain Clarke wrote:

You can peek at their math... and then prove me correct, obviously!

Rajesh R Subramanian wrote:

the tiff compression itself uses the LZW algorithm

double d = 12.3;<br />
CString cs;<br />
cs.Format("%f", d);<br />

narayanagvs wrote:

1)I would like to know what it does internally? Where does it store the GUID for comparing?

narayanagvs wrote:

2)I would like to know where else can we save strings in windows other than files and registries.