From af75d1bf5c244939a989c6b31b710c7b632f832b Mon Sep 17 00:00:00 2001
From: Dorival Pedroso <dorival.pedroso@gmail.com>
Date: Sun, 18 Jan 2026 07:16:22 +1000
Subject: [PATCH 1/2] Improve fill_alpha and line_alpha in Contour

---
 src/contour.rs        | 33 +++++++++++++++++++++++----------
 tests/test_contour.rs |  2 ++
 2 files changed, 25 insertions(+), 10 deletions(-)

diff --git a/src/contour.rs b/src/contour.rs
index f4e7ea2..d803fe6 100644
--- a/src/contour.rs
+++ b/src/contour.rs
@@ -48,7 +48,6 @@ use std::fmt::Write;
 ///
 /// ![integ_contour.svg](https://raw.githubusercontent.com/cpmech/plotpy/main/figures/integ_contour.svg)
 pub struct Contour {
-    alpha: f64,                   // Alpha (transparacy) of the plot
     colors: Vec<String>,          // Colors to be used instead of colormap
     levels: Vec<f64>,             // Pre-defined levels
     colormap_name: String,        // Colormap name
@@ -62,6 +61,8 @@ pub struct Contour {
     colorbar_location: String,    // Colorbar location
     colorbar_extra: String,       // Extra options for the colorbar
     number_format_cb: String,     // Number format for the labels in lines contour
+    fill_alpha: Option<f64>,      // Transparency of the filled contour
+    line_alpha: Option<f64>,      // Transparency of the line contour
     line_color: String,           // Line color for the lines contour
     line_style: String,           // Line style for the lines contour
     line_width: f64,              // Line width for the lines contour
@@ -84,7 +85,6 @@ impl Contour {
     /// Creates a new Contour object
     pub fn new() -> Self {
         Contour {
-            alpha: 1.0,
             colors: Vec::new(),
             levels: Vec::new(),
             colormap_name: "bwr".to_string(),
@@ -98,6 +98,8 @@ impl Contour {
             colorbar_location: String::new(),
             colorbar_extra: String::new(),
             number_format_cb: String::new(),
+            fill_alpha: None,
+            line_alpha: None,
             line_color: "black".to_string(),
             line_style: String::new(),
             line_width: 0.0,
@@ -225,12 +227,6 @@ impl Contour {
         }
     }
 
-    /// Sets the alpha value to alpha instead of the pre-defined alpha
-    pub fn set_alpha(&mut self, alpha: f64) -> &mut Self {
-        self.alpha = alpha;
-        self
-    }
-
     /// Sets the colors to be used instead of a pre-defined colormap
     ///
     /// Will use `colormap_index` instead if its empty.
@@ -355,6 +351,18 @@ impl Contour {
         self
     }
 
+    /// Sets the transparency of the filled contour
+    pub fn set_fill_alpha(&mut self, alpha: f64) -> &mut Self {
+        self.fill_alpha = Some(alpha);
+        self
+    }
+
+    /// Sets the transparency of the line contour
+    pub fn set_line_alpha(&mut self, alpha: f64) -> &mut Self {
+        self.line_alpha = Some(alpha);
+        self
+    }
+
     /// Sets the line color for the lines contour (default is black)
     pub fn set_line_color(&mut self, color: &str) -> &mut Self {
         self.line_color = String::from(color);
@@ -469,6 +477,9 @@ impl Contour {
     /// Returns options for filled contour
     fn options_filled(&self) -> String {
         let mut opt = String::new();
+        if let Some(a) = self.fill_alpha {
+            write!(&mut opt, ",alpha={}", a).unwrap();
+        }
         if self.colors.len() > 0 {
             write!(&mut opt, ",colors=colors",).unwrap();
         } else {
@@ -482,13 +493,15 @@ impl Contour {
         if self.extra_filled != "" {
             write!(&mut opt, ",{}", self.extra_filled).unwrap();
         }
-        write!(&mut opt, ",alpha={}", self.alpha).unwrap();
         opt
     }
 
     /// Returns options for line contour
     fn options_line(&self) -> String {
         let mut opt = String::new();
+        if let Some(a) = self.line_alpha {
+            write!(&mut opt, ",alpha={}", a).unwrap();
+        }
         if self.line_color != "" {
             write!(&mut opt, ",colors=['{}']", self.line_color).unwrap();
         }
@@ -704,4 +717,4 @@ mod tests {
         contour.clear_buffer();
         assert_eq!(contour.buffer, "");
     }
-}
\ No newline at end of file
+}
diff --git a/tests/test_contour.rs b/tests/test_contour.rs
index 1040ea1..bdb2350 100644
--- a/tests/test_contour.rs
+++ b/tests/test_contour.rs
@@ -178,6 +178,8 @@ fn test_contour_draw_tri() -> Result<(), StrError> {
         .set_line_color("black")
         .set_line_style("-")
         .set_line_width(1.5)
+        .set_fill_alpha(1.0)
+        .set_line_alpha(1.0)
         .set_tri_show_edges(true)
         .set_tri_edges_color("green")
         .set_tri_edges_line_width(1.0)

From 43a0ab564dcd9489b76ad043f2da16b96a2a07bf Mon Sep 17 00:00:00 2001
From: Dorival Pedroso <dorival.pedroso@gmail.com>
Date: Sun, 18 Jan 2026 07:16:39 +1000
Subject: [PATCH 2/2] Bump version

---
 Cargo.toml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Cargo.toml b/Cargo.toml
index 66f4e1a..2367c1c 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "plotpy"
-version = "1.19.0"
+version = "1.20.0"
 edition = "2021"
 license = "MIT"
 description = "Rust plotting library using Python (Matplotlib)"