get_brightness()

float xtd::drawing::color::get_brightness ( ) const

noexcept

Gets the hue-saturation-brightness (HSB) brightness value for this xtd::drawing::color structure.

Returns

The brightness of this xtd::drawing::color. The lightness ranges from 0.0 through 1.0, where 0.0 represents black and 1.0 represents white.

Examples

The following code example is designed for use with Windows Forms, and it requires xtd::forms::paint_event_args, which is a parameter of the xtd::forms::control::paint event handler. The code performs the following actions:

• Creates an instance of a xtd::drawing::color structure, redShade, to be used for comparisons.
• Iterates through the xtd::drawing::known_color enumeration elements to find all known colors that have the same lightness as redShade. The iterations are terminated when 15 matches are found or the value of the loop counter is greater than the last xtd::drawing::known_color element.
• During each iteration, saves the xtd::drawing::known_color element—if it matches the criteria—in an array.
• Uses a brush to paint rectangles. The first rectangle is painted the color represented by redShade. Each of the other rectangles is painted a xtd::drawing::known_color that matches the hue of the redShade.

  void known_color_brightness_example2(paint_event_args& e) {
    graphics g = e.graphics();
   
    // xtd::drawing::color structures. One is a variable used for temporary storage. The other is a constant used for comparisons.
    xtd::drawing::color some_color = xtd::drawing::color::from_argb(0);
    xtd::drawing::color red_shade = xtd::drawing::color::from_argb(255, 200, 0, 100);
   
    // Array to store xtd::drawing::known_color values that match the hue of the redShade color.
    std::vector<xtd::drawing::known_color> color_matches(15);
   
    // Number of matches found.
    int count = 0;
   
    // Iterate through the xtd::drawing::known_color enums until 15 matches are found.
    for (xtd::drawing::known_color enum_value = 0; enum_value <= xtd::drawing::known_color::yellow_green && count < 15; enum_value = known_color(int(enum_value) + 1)) {
      some_color = xtd::drawing::color::from_known_color(enum_value);
      if (some_color.get_brightness() == red_shade.get_brightness())
        color_matches[count++] = enum_value;
    }
   
    // Display the redShade color and its argb value.
    solid_brush  my_brush1(red_shade);
    font my_font("Arial", 12);
    int x = 20;
    int y = 20;
    some_color = red_shade;
    g.fill_rectangle(my_brush1, x, y, 100, 30);
    g.draw_string(some_color.to_string(), my_font, brushes::black, x + 120, y);
   
    // Iterate through the matches that were found and display each color that corresponds with the enum value in the array. also display the name of the xtd::drawing::known_color.
    for (int i = 0; i < count; i++) {
      y += 40;
      some_color = xtd::drawing::color::from_known_color(color_matches[i]);
      my_brush1.xtd::drawing::color = some_color;
      g.fill_rectangle(my_brush1, x, y, 100, 30);
      g.draw_string(some_color.to_string(), my_font, brushes::black, x + 120, y);
    }
  }