opacity support for create_histogram and helpers

lightweight_charts/abstract.py

@@ -14,7 +14,7 @@ from .topbar import TopBar
 from .util import (
     BulkRunScript, Pane, Events, IDGen, as_enum, jbool, js_json, TIME, NUM, FLOAT,
     LINE_STYLE, MARKER_POSITION, MARKER_SHAPE, CROSSHAIR_MODE, MARKER_TYPE,
-    PRICE_SCALE_MODE, marker_position, marker_shape, js_data, is_vbt_indicator
+    PRICE_SCALE_MODE, marker_position, marker_shape, js_data, is_vbt_indicator, apply_opacity
 )
 
 current_dir = os.path.dirname(os.path.abspath(__file__))
@@ -913,13 +913,15 @@ class AbstractChart(Candlestick, Pane):
     def create_histogram(
             self, name: str = '', color: str = None,
             price_line: bool = False, price_label: bool = True,
-            scale_margin_top: float = 0.0, scale_margin_bottom: float = 0.0
+            scale_margin_top: float = 0.0, scale_margin_bottom: float = 0.0, opacity: float = None,
     ) -> Histogram:
         """
         Creates and returns a Histogram object.
         """
         if color is None:
             color = get_next_color()
+        if opacity is not None:
+            color = apply_opacity(color, opacity)
         return Histogram(
             self, name, color, price_line, price_label,
             scale_margin_top, scale_margin_bottom)

lightweight_charts/helpers.py

@@ -148,13 +148,15 @@ def chart(panes: list[Panel], sync=False, title='', size="m"):
                             active_chart.markers_set(markers)
 
             for tup in pane.histogram:
-                    series, name, color, _, _ = (tup + (None, None, None, None, None))[:5]
+                    series, name, color, opacity, _ = (tup + (None, None, None, None, None))[:5]
                     if series is None:
                             continue
                     #conditionally include color
                     kwargs = {'name': name}
                     if color is not None:
-                            kwargs['color'] = color
+                            kwargs['color'] = color 
+                    if opacity is not None:
+                            kwargs['opacity'] = opacity
                     tmp = active_chart.create_histogram(**kwargs) #green transparent "rgba(53, 94, 59, 0.6)"
                     tmp.set(series)
 

lightweight_charts/util.py

@@ -5,7 +5,43 @@ from random import choices
 from typing import Literal, Union
 from numpy import isin
 import pandas as pd
+import re
+from matplotlib.colors import to_rgba
 
+def apply_opacity(color, opacity):
+    """
+    Converts any color format (named, hex, RGB, or RGBA) to RGBA format and applies a specified opacity.
+
+    Parameters:
+    - color (str): The color in named, hex, RGB, or RGBA format.
+    - opacity (float): The opacity value to apply, ranging from 0.0 to 1.0.
+
+    Returns:
+    - str: The color in 'rgba(r, g, b, opacity)' format with the specified opacity applied.
+
+    Raises:
+    - ValueError: If the opacity is not within the range of 0 to 1.
+    """
+    # Validate the opacity
+    if not (0 <= opacity <= 1):
+        raise ValueError("Opacity must be between 0 and 1")
+
+    # Check if color is already in rgba format
+    rgba_regex = r'rgba?\((\d{1,3}),\s*(\d{1,3}),\s*(\d{1,3})(?:,\s*([0-9\.]+))?\)'
+    match = re.match(rgba_regex, color)
+
+    if match:
+        # Color is in RGB or RGBA format
+        r, g, b = int(match.group(1)), int(match.group(2)), int(match.group(3))
+        current_opacity = float(match.group(4)) if match.group(4) else 1
+        # Apply the new opacity by multiplying with the current opacity if it exists
+        final_opacity = current_opacity * opacity
+    else:
+        # Color is a named color or hex; convert it using matplotlib
+        rgba = to_rgba(color)
+        r, g, b, _ = [int(255 * x) for x in rgba]
+        final_opacity = opacity  # Directly use the given opacity
+    return f"rgba({r}, {g}, {b}, {final_opacity})"
 
 def is_vbt_indicator(variable):
     # Get the module path of the variable's type