Source code for schrodinger.ui.qt.standard.colors

# defined by WCAG 2.0
# https://www.w3.org/TR/UNDERSTANDING-WCAG20/visual-audio-contrast-contrast.html
CONTRAST_THRESHOLD = 4.5


class NativeColors:
    BLACK = '#000000'
    GRAY = '#808080'
    GREEN = '#00ff00'
    ORANGE = '#ffa500'
    RED = '#ff0000'
    WHITE = '#ffffff'


class LightModeColors(NativeColors):
    INVALID_STATE_BORDER = NativeColors.RED
    STANDARD_BACKGROUND = NativeColors.WHITE
    STANDARD_BORDER = NativeColors.WHITE

    LINK = '#2e9cdc'
    LINK_HOVERED = '#34b0f8'
    LINK_DISABLED = '#acb8bf'
    LINK_PRESSED = '#2e9cdc'

    EMPHASIZED_TEXT = '#555555'
    ERROR_TEXT = '#cc0000'
    HEADER_TEXT = '#666666'
    GOOD_TEXT = '#336622'
    INFORMATIONAL_TEXT = '#666666'
    LONG_ERROR_TEXT = '#990000'
    STANDARD_TEXT = NativeColors.BLACK
    SUCCESS_TEXT = '#006633'
    WARNING_TEXT = '#c87c00'

    DISABLED_BUTTON_BACKGROUND = '#cccccc'
    DISABLED_BUTTON_COLOR = '#eeeeee'
    DISABLED_BUTTON_BORDER = '#cccccc'

    HIGHLIGHTED_BUTTON_BACKGROUND = 'qlineargradient(x1:0, y1:0, x2:0, y2:1, stop:0 #96b260, stop:1 #87a056)'
    HIGHLIGHTED_BUTTON_BORDER_DISABLED = '#bbbbbb'
    HIGHLIGHTED_BUTTON_BORDER_ENABLED = '#989898'
    HIGHLIGHTED_BUTTON_COLOR = NativeColors.WHITE
    HIGHLIGHTED_PRESSED_BUTTON_BACKGROUND_COLOR = '#87a056'

    STANDARD_BUTTON_BACKGROUND = 'qlineargradient(x1:0, y1:0, x2:0, y2:1, stop:0 #dddddd, stop:1 #cccccc)'
    STANDARD_BUTTON_BORDER_DISABLED = '#bbbbbb'
    STANDARD_BUTTON_BORDER_ENABLED = '#989898'
    STANDARD_BUTTON_COLOR = NativeColors.BLACK
    STANDARD_PRESSED_BUTTON_BACKGROUND_COLOR = '#aaaaaa'

    PRESSED_BUTTON_COLOR = NativeColors.WHITE


class DarkModeColors(NativeColors):
    LINK = '#34b0f8'
    LINK_HOVERED = '#2e9cdc'
    LINK_DISABLED = '#798084'
    LINK_PRESSED = '#34b0f8'


def _convert_color_comp(color_comp):
    color_comp /= 255
    if color_comp < 0.03928:
        return color_comp / 12.92
    return ((color_comp + 0.055) / 1.055)**2.4


def get_luma(rgb):
    """
    Return the WCAG2 luma value of the given color.

    See
    https://www.w3.org/TR/2008/REC-WCAG20-20081211/#relativeluminancedef
    for additional information.

    :param rgb: Red, green, blue values (range 0-255). Rgba values are allowed
        but alpha is ignored.
    :type rgb: tuple[int] or QtGui.QColor

    :return: Luma value (range 0.0 - 1.0)
    :rtype: float
    """
    try:
        rgb = rgb.getRgb()
    except AttributeError:
        pass
    rgb = rgb[:3]  # allow rgba 4-tuple
    r, g, b = (_convert_color_comp(c) for c in rgb)

    return r * 0.2126 + g * 0.7152 + b * 0.0722


def get_contrast(rgb1, rgb2):
    """
    Return the contrast ratio for the given colors.

    See
    https://www.w3.org/TR/UNDERSTANDING-WCAG20/visual-audio-contrast-contrast.html#contrast-ratiodef
    for additional information.

    :return: Contrast ratio (range 1.0 - 21.0)
    :rtype: float
    """
    epsilon = 0.05
    contrast = (get_luma(rgb1) + epsilon) / (get_luma(rgb2) + epsilon)
    if contrast < 1:
        contrast = 1 / contrast
    return contrast


def get_contrasting_color(set_rgb, contrast=CONTRAST_THRESHOLD, options=None):
    """
    :param set_rgb: Red, green, blue values (range 0-255). Rgba values are allowed
        but alpha is ignored.
    :type set_rgb: tuple[int] or QtGui.QColor

    :param contrast: Contrast ratio (range 1.0 - 21.0)
    :type contrast: float

    :param options: Possible colors to contrast with `set_rgb`
    :type options: iterable(tuple[int] or QtGui.QColor)
    """
    try:
        set_rgb = set_rgb.getRgb()
    except AttributeError:
        pass
    if options:
        # Check whether any option has sufficient contrast
        contrasts = [get_contrast(rgb, set_rgb) for rgb in options]
        best_contrast = max(contrasts)
        if best_contrast >= contrast:
            idx = contrasts.index(best_contrast)
            return options[idx]

    # Otherwise, return most contrasting default color
    default_options = [(0, 0, 0), (255, 255, 255)]
    contrasts = [get_contrast(rgb, set_rgb) for rgb in default_options]
    best_contrast = max(contrasts)
    idx = contrasts.index(best_contrast)
    return default_options[idx]


def is_color_dark(rgb):
    """
    For a given color, return whether it is dark. If a background color is
    dark, it should have a light foreground color and vice versa.

    :note: This is determined using the luma value of the given color. The
        function returns True if the luma is less than 50% (i.e. closer to
        black than white) and False if the luma is greater than 50% (i.e.
        closer to white than black).

    :param rgb: Red, green, blue values (range 0-255). Rgba values are allowed
        but alpha is ignored.
    :type rgb: tuple[int]

    :return: Whether the color is dark
    :rtype: bool
    """
    return get_luma(rgb) < 0.5