Immortal Nephi <Immortal_Ne...@hotmail.com> writes:
On Jun 11, 5:45??am, Paul Bibbings <paul.bibbi...@gmail.com> wrote:
Before you decide on using `bidirectional communication', consider
something like the following, which uses a `traits' type. Note that I
have changed some of the names to match what it is that I think you are
trying to do.
#include <iostream>
#include <new>
enum bits { rgb3 = 3, rgb6 = 6, rgb8 = 8 };
template<bits>
struct color_traits;
template<>
struct color_traits<rgb3> { /* ... */ };
template<>
struct color_traits<rgb6> { /* ... */ };
template<>
struct color_traits<rgb8>
{
// ...
static const int RedBits = 0x03;
static const int GreenBits = 0x07;
static const int BlueBits = 0x07;
static const int ShiftRed = 6;
static const int ShiftGreen = 3;
static const unsigned char ClearRedMask = 0x3F;
static const unsigned char ClearGreenMask = 0xC7;
static const unsigned char ClearBlueMask = 0xF8;
};
template<
bits Bits,
typename Tr = color_traits<Bits>
class Color {
public:
Color(unsigned char& col)
: m_col(col)
{ }
~Color() { }
Color(const Color& other)
: m_col(other.m_col)
{ }
Color& operator=(const Color& other)
{
if (this != &other)
{
this->~Color();
new (this) Color(other);
}
return *this;
}
Color& operator=(unsigned char new_col) // Set_Color
{
m_col = new_col;
return *this;
}
Color& Set_Red(unsigned char red)
{
m_col &= Tr::ClearRedMask;
unsigned char temp = red << Tr::ShiftRed;
m_col |= temp;
return *this;
}
Color& Set_Green(unsigned char green)
{
m_col &= Tr::ClearGreenMask;
unsigned char temp = green << Tr::ShiftGreen;
m_col |= temp;
return *this;
}
Color& Set_Blue(unsigned char blue)
{
m_col &= Tr::ClearBlueMask;
m_col |= blue;
return *this;
}
operator unsigned char&() { return m_col; } // Get_Color
operator unsigned char() const { return m_col; } // Get_Color
unsigned char Get_Red() const
{
return (m_col >> Tr::ShiftRed) & Tr::RedBits;
}
unsigned char Get_Green() const
{
return (m_col >> Tr::ShiftGreen) & Tr::GreenBits;
}
unsigned char Get_Blue() const
{
return m_col & Tr::BlueBits;
}
private:
unsigned char& m_col;
};
template<bits Bits>
class ColorArray {
public:
ColorArray(int size)
: pData(new unsigned char[size])
{ }
~ColorArray() { delete [] pData; }
Color<Bits> operator[](int index)
{
return pData[index];
}
const Color<Bits> operator[](int index) const
{
return pData[index];
}
private:
unsigned char *pData;
};
typedef ColorArray<rgb3> RGB3;
typedef ColorArray<rgb6> RGB6;
typedef ColorArray<rgb8> RGB8;
int main()
{
RGB8 col_array8(4);
col_array8[0].Set_Red(0x01).Set_Green(0x07).Set_Blue(0x05);
col_array8[1].Set_Red(col_array8[0].Get_Red() + 1)
.Set_Green(col_array8[0].Get_Green() - 3)
.Set_Blue(col_array8[0].Get_Blue() - 2);
std::cout << "red : " << int(col_array8[1].Get_Red()) << '\n';
std::cout << "green: " << int(col_array8[1].Get_Green()) << '\n';
std::cout << "blue : " << int(col_array8[1].Get_Blue()) << '\n';
}
/**
* Output:
* red : 2
* green: 4
* blue : 3
*/
I do not say that this is the right way to do it, and it may not work
for you for other reasons. However, it is an idea, at least.
Wow! Your suggestion is excellent. I must consider either enum /
template or bidirectional communication.
If RGB has more than 8 bits such as R4G4B4 or R5G6B5 or R8G8B8 or
higher, they will need to use separate data type unsigned short,
unsigned long, and unsigned long long.
In which case, all you would have to do is add a typedef to your
specializations of the color_traits class, so (for example):
template<>
struct color_traits<rgb8>
{
// ...
typedef unsigned char color_type;
};
template<>
struct color_traits<r5g6b4>
{
// ...
typedef unsigned short color_type; // for 16 bit short
};
and adjust the masks for the same type. Then, for the Color type above,
add a typedef:
typedef typename Tr::color_type color_type;
Then, you can replace *all* cases of `unsigned char' in the Color type
with `color_type', and do the same for your ColorArray, either:
1. replacing all cases of `unsigned char' with
typename color_traits<Bits>::color_type; or
2. adding the typedef:
typedef typename color_traits<Bits>::color_type color_type
and then doing the same that you did for the Color type, replacing
`unsigned char' with `color_type'
In this way you will be able to use whatever underlying type seems most
appropriate for *all* your r#g#b# types by merely specializing
color_traits and adding the appropriate typedef for `color_type'. All
the rest of the code is then completely generic, which feels like quite
a gain over what you were starting with, because you cannot change the
underlying type for your original non-template Array class.
You bet. What if I add two colors, four colors, and sixteen colors?
Two colors are monochrome and eight pixels per byte. Four colors are
four pixels per byte. Also, sixteen colors are two pixels per byte.
All three modes don???t use RGB format to hold raw data in memory. They
store into memory.