Hex transparency in colors

Question

I m working on implementing a widget transparency option for my app widget although I m having some trouble getting the hex color values right  Being completely new to hex color transparency I searched around a bit although I couldn t find a specific answer to my question    I want to set transparency by hex color so let s say my hex color id   33b5e5  and I want it to be 50  transparent  Then I ll use   8033b5e5  because 80 is 50     I found a useful chart here  http   www dtp-aus com hexadeci htm   With this data I managed to come up with this   0     00 10     16 20     32 30     48 40     64 50     80 60     96 70     112 80     128 90     144   Now the issues start appearing when I get higher than 100 in hex  Hex color codes can only be 8 symbols long right  For example  11233b5e5  80   crashes   What can I do to enable me to use the higher numbers aswell

User · Answer

I built this small helper method for an android app  may come of use            param originalColor color  without alpha     param alpha         from 0 0 to 1 0     return     public static String addAlpha String originalColor  double alpha        long alphaFixed   Math round alpha   255       String alphaHex   Long toHexString alphaFixed       if  alphaHex length      1            alphaHex    0    alphaHex            originalColor   originalColor replace            alphaHex         return originalColor

User · Answer

Short answer   You can see the full table of percentages to hex values and run the code in this playground in https   play golang org p l1JaPYFzDkI    Short explanation in pseudocode   Percentage to hex values   decimal   percentage   255   100   ex   decimal    50 255 100   127 5 convert decimal to hexadecimal value   ex  127 5 in decimal   7 16  1   15   7F in hexadecimal    Hex values to percentage   convert the hexaxdecimal value to decimal  ex  D6   13 16  1   6   214 percentage    value in decimal     100   255  ex   214  100 255   84    More infos for the conversion decimal  lt    hexadecimal   Long answer  how to calculate in your head   The problem can be solved generically by a cross multiplication    We have a percentage  ranging from 0 to 100   and another number  ranging from 0 to 255  then converted to hexadecimal    100  lt     255  FF in hexadecimal  0   lt     0  00 in hexadecimal    For 1     1   255   100   2 5 2 5 in hexa is 2 if you round it down    For 2     2   255   100   5 5 in hexa is 5      The table in the best answer gives the percentage by step of 5    How to calculate the numbers between in your head   Due to the 2 5 increment  add 2 to the first and 3 to the next   95      F2     start 96      F4     add 2 to F2 97      F7     add 3    Or F2   5   F7 98      F9     add 2 99      FC     add 3  9   3   12 in hexa   C   100      FF     add 2     I prefer to teach how to find the solution rather than showing an answer table you don t know where the results come from      Give a man a fish and you feed him for a day  teach a man to fish and   you feed him for a lifetime

User · Answer

This might be very late answer  But this chart kills it    All percentage values are mapped to the hexadecimal values   http   online sfsu edu chrism hexval html

User · Answer

That chart is not showing percents    90  is not  90    That chart shows the hexadecimal to decimal conversion  The hex number 90  typically represented as 0x90  is equivalent to the decimal number 144   Hexadecimal numbers are base-16  so each digit is a value between 0 and F  The maximum value for a two byte hex value  such as the transparency of a color  is 0xFF  or 255 in decimal  Thus 100  is 0xFF

User · Answer

I always keep coming here to check for int hex alpha value  So  end up creating a simple method in my java utils class  This method will convert the percentage to hex value and append to the color code string value    public static String setColorAlpha int percentage  String colorCode       double decValue     double percentage   100    255      String rawHexColor   colorCode replace              StringBuilder str   new StringBuilder rawHexColor        if Integer toHexString  int decValue  length      1          str insert 0    0    Integer toHexString  int decValue        else         str insert 0        Integer toHexString  int decValue        return str toString        So  Utils setColorAlpha 30    000000   will give you  4c000000

User · Answer

Here s a correct table of percentages to hex values  E g  for 50  white you d use  80FFFFFF    100      FF 95      F2 90      E6 85      D9 80      CC 75      BF 70      B3 65      A6 60      99 55      8C 50      80 45      73 40      66 35      59 30      4D 25      40 20      33 15      26 10      1A 5      0D 0      00    source

User · Answer

Using python to calculate this  for example written in python 3   50  transparency    hex round 256 0 50

User · Answer

Color hexadecimal notation is like following   AARRGGBB    A   alpha   R   red G   green B   blue   You should first look at how hexadecimal works  You can write at most FF

User · Answer

try this on google search  or click here   255    2 to hex  it will generate 0x33 as a result   However  google does not round off values so you can only use 1-digit multipliers  if you want to use say  85  you have to get the rounded-off value of 255    85 first  then type  rounded-value here  to hex in google search

User · Answer

I realize this is an old question  but I came across it when doing something similar    Using SASS  you have a very elegant way to convert RGBA to hex ARGB  ie-hex-str  I ve used it here in a mixin     mixin ie8-rgba   r   g   b   a        rgba  rgba  r   g   b   a        ie8-rgba  ie-hex-str  rgba        lt-ie9  amp         background-color  transparent        filter progid DXImageTransform Microsoft gradient GradientType 0 startColorstr     ie8-rgba    endColorstr     ie8-rgba             transparent       include ie8-rgba 88 153 131  8       background-color  rgba 88 153 131  8       outputs    x000D   x000D   transparent   x000D    background-color  rgba 88  153  131  0 8   x000D    x000D   lt-ie9  transparent   x000D    background-color  transparent  x000D    filter  progid DXImageTransform Microsoft gradient GradientType 0 startColorstr   CC589983   endColorstr   CC589983    x000D    zoom  1  x000D    x000D   x000D   x000D

[android] Hex transparency in colors

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