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os: add Color::print, enhance ascii_to<Color>

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This patch adds a 'Color::print' method as counterpart to the 'ascii_to'
function. If the color is opaque (alpha is 255), its output has the form
"#rrggbb". If the color has a distinct alpha value, the output has the
form "#rrggbbaa". The new version of the 'ascii_to' overload for 'Color'
is able to deal with both forms.
This commit is contained in:
Norman Feske 2017-11-15 17:14:17 +01:00 committed by Christian Helmuth
parent 0a5dcc86ed
commit 40c9226bb9
1 changed files with 27 additions and 7 deletions

34
repos/os/include/util/color.h

@ -46,13 +46,26 @@ struct Genode::Color
bool operator != (Color const &other) const {
return !operator == (other); }
void print(Output &output) const
{
using Genode::print;
print(output, Char('#'));
print(output, Hex((unsigned char)r, Hex::OMIT_PREFIX, Hex::PAD));
print(output, Hex((unsigned char)g, Hex::OMIT_PREFIX, Hex::PAD));
print(output, Hex((unsigned char)b, Hex::OMIT_PREFIX, Hex::PAD));
if (a != 255)
print(output, Hex((unsigned char)a, Hex::OMIT_PREFIX, Hex::PAD));
}
};
/**
* Convert ASCII string to Color
*
* The ASCII string must have the format '#rrggbb'
* The ASCII string must have the format '#rrggbb' or '#rrggbbaa'.
*
* \return number of consumed characters, or 0 if the string contains
* no valid color
@ -60,19 +73,26 @@ struct Genode::Color
inline Genode::size_t Genode::ascii_to(const char *s, Genode::Color &result)
{
/* validate string */
if (strlen(s) < 7 || *s != '#') return 0;
Genode::size_t const len = strlen(s);
if (len < 7 || *s != '#') return 0;
enum { HEX = true };
for (unsigned i = 0; i < 6; i++)
if (!is_digit(s[i + 1], HEX)) return 0;
int red = 16*digit(s[1], HEX) + digit(s[2], HEX),
green = 16*digit(s[3], HEX) + digit(s[4], HEX),
blue = 16*digit(s[5], HEX) + digit(s[6], HEX);
int const red = 16*digit(s[1], HEX) + digit(s[2], HEX),
green = 16*digit(s[3], HEX) + digit(s[4], HEX),
blue = 16*digit(s[5], HEX) + digit(s[6], HEX);
result = Color(red, green, blue);
return 7;
bool const has_alpha = (len >= 9) && is_digit(s[7], HEX) && is_digit(s[8], HEX);
int const alpha = has_alpha ? 16*digit(s[7], HEX) + digit(s[8], HEX) : 255;
result = Color(red, green, blue, alpha);
return has_alpha ? 9 : 7;
}
#endif /* _INCLUDE__UTIL__COLOR_H_ */