static Color adjustColorForVisibilityOnBackground(Color textColor, Color backgroundColor)
{
int d = differenceSquared(textColor, backgroundColor);
// Semi-arbitrarily chose 65025 (255^2) value here after a few tests.
if (d > 65025)
return textColor;
int distanceFromWhite = differenceSquared(textColor, Color::white);
int distanceFromBlack = differenceSquared(textColor, Color::black);
if (distanceFromWhite < distanceFromBlack)
return textColor.dark();
return textColor.light();
}
static Color disabledTextColor(const Color& textColor, const Color& backgroundColor)
{
// The explicit check for black is an optimization for the 99% case (black on white).
// This also means that black on black will turn into grey on black when disabled.
Color disabledColor;
if (textColor.rgb() == Color::black || differenceSquared(textColor, Color::white) > differenceSquared(backgroundColor, Color::white))
disabledColor = textColor.light();
else
disabledColor = textColor.dark();
// If there's not very much contrast between the disabled color and the background color,
// just leave the text color alone. We don't want to change a good contrast color scheme so that it has really bad contrast.
// If the the contrast was already poor, then it doesn't do any good to change it to a different poor contrast color scheme.
if (differenceSquared(disabledColor, backgroundColor) < minColorContrastValue)
return textColor;
return disabledColor;
}
Color correctedTextColor(Color textColor, Color backgroundColor)
{
// Adjust the text color if it is too close to the background color,
// by darkening or lightening it to move it further away.
int d = differenceSquared(textColor, backgroundColor);
// semi-arbitrarily chose 65025 (255^2) value here after a few tests;
if (d > 65025) {
return textColor;
}
int distanceFromWhite = differenceSquared(textColor, Color::white);
int distanceFromBlack = differenceSquared(textColor, Color::black);
if (distanceFromWhite < distanceFromBlack) {
return textColor.dark();
}
return textColor.light();
}
Color TextPainter::textColorForWhiteBackground(Color textColor) {
int distanceFromWhite = differenceSquared(textColor, Color::white);
// semi-arbitrarily chose 65025 (255^2) value here after a few tests;
return distanceFromWhite > 65025 ? textColor : textColor.dark();
}
