From aaa1714f0fd09556a4dbc30a1d16429e8c8ad73c Mon Sep 17 00:00:00 2001
From: yeqing <heopro@163.com>
Date: Sat, 7 Mar 2026 16:23:56 +0800
Subject: [PATCH] =?UTF-8?q?feat:=20=E9=80=89=E6=8B=A9=E5=8A=9F=E8=83=BD?=
 =?UTF-8?q?=E6=94=AF=E6=8C=81=E9=80=8F=E6=98=8E=E6=A8=A1=E5=BC=8F?=
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---
 src/mscanvas.rs | 12 ++++++++++--
 src/paint.rs    | 13 ++++++++++++-
 2 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/src/mscanvas.rs b/src/mscanvas.rs
index f6121c9..c587d95 100644
--- a/src/mscanvas.rs
+++ b/src/mscanvas.rs
@@ -270,13 +270,21 @@ impl MSCanvas {
         }
     }
 
-    pub fn select_rect(&self, x: i32, y: i32, w: i32, h: i32) -> RectSelection {
+    pub fn select_rect(&self, x: i32, y: i32, w: i32, h: i32, is_transparent_white: bool) -> RectSelection {
         let mut result = vec![255; (w * h * 4) as usize];
 
         let mut index = 0;
+        let default_color = if is_transparent_white {
+            MSColor::ZERO
+        } else {
+            MSColor::WHITE
+        };
         for yi in y..(y + h) {
             for xi in x..(x + w) {
-                let color = self.pixel_at(xi, yi).unwrap_or(MSColor::WHITE);
+                let mut color = self.pixel_at(xi, yi).unwrap_or(default_color);
+                if is_transparent_white && color == MSColor::WHITE {
+                    color = MSColor::ZERO;
+                }
                 result[index] = color.r;
                 result[index + 1] = color.g;
                 result[index + 2] = color.b;
diff --git a/src/paint.rs b/src/paint.rs
index b1619bf..743fab7 100644
--- a/src/paint.rs
+++ b/src/paint.rs
@@ -4,7 +4,7 @@ use iced::padding;
 use iced::time::{self, Instant, milliseconds};
 use iced::widget::canvas::Canvas;
 use iced::widget::container;
-use iced::widget::{Column, button, column, image, pick_list, row, text};
+use iced::widget::{Column, button, column, image, pick_list, row, text, checkbox};
 use iced::{Border, Element, Length, Point, Renderer, Subscription, Task};
 use iced::{color, event, mouse};
 use std::thread;
@@ -111,6 +111,8 @@ enum Message {
     ClickForegroundColor(MSColor),
     ClickBackgroundColor(MSColor),
     SwapForeBackColor,
+
+    CheckboxToggled(bool),
 }
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
@@ -229,6 +231,7 @@ struct Config {
     rounded_radius: i32,
     brush_kind: Option<BrushKind>,
     shape_style: Option<ShapeStyle>,
+    is_transparent_white: bool,
 }
 
 impl Default for Config {
@@ -246,6 +249,7 @@ impl Config {
         rounded_radius: 3,
         brush_kind: None,
         shape_style: None,
+        is_transparent_white: false,
     };
 
     fn incr(&mut self, option: ConfigOption, step: i32) {
@@ -581,6 +585,9 @@ impl PaintApp {
                 Message::ShapeStyleSelected,
             )
             .placeholder("Shape Style..."),
+            checkbox(self.config.is_transparent_white)
+                .label("Transparent White")
+                .on_toggle(Message::CheckboxToggled),
         ];
         debug_area = debug_area.padding(padding::top(10).left(5).bottom(10));
 
@@ -709,6 +716,9 @@ impl PaintApp {
                 self.canvas.stroke_color(self.foreground_color);
                 self.canvas.fill_color(self.foreground_color);
             }
+            Message::CheckboxToggled(is_checked) => {
+                self.config.is_transparent_white = is_checked;
+            }
             _ => {}
         }
 
@@ -859,6 +869,7 @@ impl PaintApp {
                             y as i32,
                             width as i32,
                             height as i32,
+                            self.config.is_transparent_white,
                         ));
                         self.canvas
                             .clear_rect(x as i32, y as i32, width as i32, height as i32);