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    9.2 Color Functions
     
    
      A color is represented by a CLX color object, in which each of the red, 
      green, and blue values is specified by an rgb-val -- a floating 
      point number between 0.0 and 1.0. (see paragraph 1.6, Data Types). The 
      value 0.0 represents the minimum intensity, while 1.0 represents the 
      maximum intensity. CLX automatically converts rgb-val values into 
      16-bit integers when sending colors to an X server. The X server, in 
      turn, scales 16-bit color values to match the actual intensity range 
      supported by the screen.
    
      Colors used on :gray-scale screens must have the same value for 
      each of red, green, and blue. Only one of these values is used by 
      screen hardware to determine intensity; however, CLX does not define 
      which of red, green, or blue is actually used.
    
      The following paragraphs describe the CLX functions used to create, 
      access, and modify colors.
    
      
      
      
        
          | make-color | &key (:blue 
            1.0) (:green 1.0) (:red 1.0) &allow-other-keys | Function | 
      
        
          |  | 
              
                :blue, :green, :red
              
                rgb-val 
                values that specify the saturation for each primary.
             
              Creates, initializes, and returns a new color object with 
              the specified values for red, green, and blue.
             
              
                color
              
                Type color.
             | 
     
     
    
      
      
      
        
          | color-blue | color | Function | 
      
        
          |  | 
              
                color
              
                A color object.
             
              Returns and (with setf) sets the value for blue in the color.
             
              
                blue-intensity
              
                Type rgb-val.
             | 
     
     
    
      
      
      
        
          | color-green | color | Function | 
      
        
          |  | 
              
                color
              
                A color object.
             
              Returns and (with setf) sets the value for green in the 
              color.
             
              
                green-intensity
              
                Type rgb-val.
             | 
     
     
    
      
      
      
      
        
          |  | 
              Returns non-nil if the argument is a color object and nil otherwise.
             
              
                color-p
              
                Type boolean.
             | 
     
     
    
      
      
      
      
        
          |  | 
              
                color
              
                A color object.
             
              Returns and (with setf) sets the value for red in the 
              color.
             
              
                red-intensity
              
                Type rgb-val.
             | 
     
     
    
      
      
      
      
        
          |  | 
              
                color
              
                A color object.
             
              Returns the values for red, green, and blue in the color.
             
              
                red, green, blue
              
                Type rgb-val.
             | 
     
     
    
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