I am creating a QLineEditor to manually input a color in hex format. I want to set a validator to check if the input color is a pure HUE color.
All hue colors follow this pattern, being X any hex character [from 0-9 or A-F]:
#FF00XX
#00FFXX
#00XXFF
#XX00FF
#XXFF00
#FFXX00
I managed to check for a correct HEX color value: ^#([A-Fa-f0-9]{6})$, but I don't know how to extend the validator to accept only hue colors.
Any ideas?
CodePudding user response：
The pattern you want is ^#(?:00(?:FFXX|XXFF)|FF(?:00XX|XX00)|XX(?:00FF|FF00))$.
If you want XX to be any hex char, replace with [a-fA-F0-9]{2}. Then, the regex will look like
^#(?:00(?:FF[a-fA-F0-9]{2}|[a-fA-F0-9]{2}FF)|FF(?:00[a-fA-F0-9]{2}|[a-fA-F0-9]{2}00)|[a-fA-F0-9]{2}(?:00FF|FF00))$
See the regex demo.
If you do not want XX to match 00 and FF, replace XX with (?![fF]{2}|00)[a-fA-F0-9]{2}. Then, the regex will look like
^#(?:00(?:FF(?![fF]{2}|00)[a-fA-F0-9]{2}|(?![fF]{2}|00)[a-fA-F0-9]{2}FF)|FF(?:00(?![fF]{2}|00)[a-fA-F0-9]{2}|(?![fF]{2}|00)[a-fA-F0-9]{2}00)|(?![fF]{2}|00)[a-fA-F0-9]{2}(?:00FF|FF00))$
See the regex demo.
The (?![fF]{2}|00)[a-fA-F0-9]{2} part matches any two hex chars that are not equal to FF or 00 (case insensitive).
CodePudding user response：
The simplest way is to just use the pipe operator to cover all the six cases:
00[A-Fa-f0-9]{2}FF|00FF[A-Fa-f0-9]{2}|FF00[A-Fa-f0-9]{2}|FF[A-Fa-f0-9]{2}00|[A-Fa-f0-9]{2}00FF|[A-Fa-f0-9]{2}FF00
Obviously the pattern [A-Fa-f0-9]{2} is repeated several times. To remove redundancy, you can save it in a separate variable and use string formatting to substitute it and form the pattern as shown above.
CodePudding user response：
If there are just 6 cases you can write this cases using boolean OR (|)
(?<=#00FF|#FF00)[A-Fa-f0-9]{2}|[A-Fa-f0-9]{2}(?=00FF|FF00)|(?<=#00)[A-Fa-f0-9]{2}(?=FF)|(?<=#FF)[A-Fa-f0-9]{2}(?=00)