python/rgb_to_hex.py

@@ -0,0 +1,50 @@
+def rgb_to_hex(r, g, b, a=None, bg=255, prefix="#"):
+    """
+    Convert given RGB color decimals or floats to Hex string.
+
+    Parameters
+    ---
+    r, g, b: float | int
+        Corresponding channel value. Support decimal or float.
+
+    a: float | None, Default: None
+        Alpha value for generate simulated transparent color.
+        If specified, the returned hex color should looks like
+        rendered as `a` alpha value, on the given background `bg`.
+        Default to None, which means disable simuating transparent.
+
+    bg: int, Default: 255
+        If `a` is specified, `bg` will be used as the background
+        for render transparent color.
+        Default to 255, which means 'white' background.
+
+    Examples
+    ---
+    >>> rgb_to_hex(255, 0, 255)
+    '#FF00FF'
+
+    >>> rgb_to_hex(255, 255, 0, a=0.0625, bg=0)
+    '#0F0F00'
+    """
+
+    def to_decimal(v, base=255) -> int:
+        if isinstance(v, float) and v <= 1:
+            v *= base
+        return int(v)
+
+    def patch_alpha(v, alpha, bg=255):
+        return int(v * alpha + bg * (1 - alpha))
+
+    r = to_decimal(r)
+    g = to_decimal(g)
+    b = to_decimal(b)
+
+    if a is not None:
+        r = patch_alpha(r, a, bg)
+        g = patch_alpha(g, a, bg)
+        b = patch_alpha(b, a, bg)
+
+    if prefix is None:
+        prefix = ""
+
+    return f"{prefix}{r:02X}{g:02X}{b:02X}"