diff --git a/src/mscanvas.rs b/src/mscanvas.rs
index ae86611..3859917 100644
--- a/src/mscanvas.rs
+++ b/src/mscanvas.rs
@@ -113,6 +113,40 @@ impl Path2D {
     }
 }
 
+pub struct RectSelection {
+    /// 左上角坐标
+    x: i32,
+    y: i32,
+    w: i32,
+    h: i32,
+    pixels: Vec<u8>,
+}
+
+impl RectSelection {
+    pub fn new(x: i32, y: i32, w: i32, h: i32, pixels: Vec<u8>) -> RectSelection {
+        Self { x, y, w, h, pixels }
+    }
+
+    pub fn contains(&self, p: Point) -> bool {
+        let x = p.x as i32;
+        let y = p.y as i32;
+        !(x < self.x || y < self.y || x >= self.x + self.w || y >= self.y + self.h)
+    }
+
+    pub fn move_offset(&mut self, offset_x: i32, offset_y: i32) {
+        self.x += offset_x;
+        self.y += offset_y;
+    }
+
+    pub fn size(&self) -> (i32, i32) {
+        (self.w, self.h)
+    }
+
+    pub fn position(&self) -> (i32, i32) {
+        (self.x, self.y)
+    }
+}
+
 pub struct MSCanvas {
     width: i32,
     height: i32,
@@ -209,20 +243,45 @@ impl MSCanvas {
         dst
     }
 
-    pub fn pixel_at(&self, x: i32, y: i32) -> MSColor {
+    pub fn pixel_at(&self, x: i32, y: i32) -> Option<MSColor> {
         // 边界检查
         if x < 0 || x >= self.width || y < 0 || y >= self.height {
-            return MSColor::ZERO;
+            return None;
         }
 
         let index = ((y * self.width + x) * 4) as usize;
 
-        MSColor::new(
+        Some(MSColor::new(
             self.pixels[index],
             self.pixels[index + 1],
             self.pixels[index + 2],
             self.pixels[index + 3],
-        )
+        ))
+    }
+
+    pub fn pixel_is(&self, x: i32, y: i32, color: MSColor) -> bool {
+        match self.pixel_at(x, y) {
+            Some(c) => c == color,
+            None => false,
+        }
+    }
+
+    pub fn select_rect(&self, x: i32, y: i32, w: i32, h: i32) -> RectSelection {
+        let mut result = vec![255; (w * h * 4) as usize];
+
+        let mut index = 0;
+        for yi in y..(y + h) {
+            for xi in x..(x + w) {
+                let color = self.pixel_at(xi, yi).unwrap_or(MSColor::WHITE);
+                result[index] = color.r;
+                result[index + 1] = color.g;
+                result[index + 2] = color.b;
+                result[index + 3] = color.a;
+                index += 4;
+            }
+        }
+
+        RectSelection::new(x, y, w, h, result)
     }
 
     pub fn overlay_pixels(&mut self, canvas: &MSCanvas) -> Vec<u8> {
@@ -540,7 +599,7 @@ impl MSCanvas {
     pub fn fill_slow(&mut self, begin: Point) {
         let start_x = begin.x as i32;
         let start_y = begin.y as i32;
-        let target_color = self.pixel_at(start_x, start_y);
+        let target_color = self.pixel_at(start_x, start_y).unwrap_or(MSColor::ZERO);
         if target_color == self.fill_color {
             return;
         }
@@ -552,7 +611,7 @@ impl MSCanvas {
             if x < 0 || x >= self.width || y < 0 || y >= self.height {
                 continue;
             }
-            if self.pixel_at(x, y) == target_color {
+            if self.pixel_is(x, y, target_color) {
                 self.fill_pixel_at1(x, y);
 
                 let p1 = (x - 1, y);
@@ -578,7 +637,7 @@ impl MSCanvas {
             return;
         }
 
-        let target_color = self.pixel_at(start_x, start_y);
+        let target_color = self.pixel_at(start_x, start_y).unwrap_or(MSColor::ZERO);
         if target_color == self.fill_color {
             return;
         }
@@ -588,11 +647,11 @@ impl MSCanvas {
 
         while let Some((y, mut lx, mut rx)) = stack.pop() {
             // 向左扩展 lx
-            while lx - 1 >= 0 && self.pixel_at(lx - 1, y) == target_color {
+            while lx - 1 >= 0 && self.pixel_is(lx - 1, y, target_color) {
                 lx -= 1;
             }
             // 向右扩展 rx
-            while rx + 1 < width && self.pixel_at(rx + 1, y) == target_color {
+            while rx + 1 < width && self.pixel_is(rx + 1, y, target_color) {
                 rx += 1;
             }
 
@@ -605,10 +664,10 @@ impl MSCanvas {
             if y - 1 >= 0 {
                 let mut x = lx;
                 while x <= rx {
-                    if self.pixel_at(x, y - 1) == target_color {
+                    if self.pixel_is(x, y - 1, target_color) {
                         let span_start = x;
                         // 跳过连续的目标色块
-                        while x <= rx && self.pixel_at(x, y - 1) == target_color {
+                        while x <= rx && self.pixel_is(x, y - 1, target_color) {
                             x += 1;
                         }
                         // 将这个 span 入栈（用于后续处理上一行的上一行）
@@ -623,9 +682,9 @@ impl MSCanvas {
             if y + 1 < height {
                 let mut x = lx;
                 while x <= rx {
-                    if self.pixel_at(x, y + 1) == target_color {
+                    if self.pixel_is(x, y + 1, target_color) {
                         let span_start = x;
-                        while x <= rx && self.pixel_at(x, y + 1) == target_color {
+                        while x <= rx && self.pixel_is(x, y + 1, target_color) {
                             x += 1;
                         }
                         stack.push((y + 1, span_start, x - 1));
@@ -1314,6 +1373,23 @@ impl MSCanvas {
         let points = self.path2d.points.clone();
         self.fill_polygon(&points[..]);
     }
+
+    pub fn draw_rect_selection(&mut self, x: i32, y: i32, rect: &RectSelection) {
+        let w = rect.w.min(self.width - x);
+        let h = rect.h.min(self.height - y);
+
+        for dy in 0..h {
+            for dx in 0..w {
+                let src_idx = ((dy * rect.w + dx) * 4) as usize;
+                let dst_idx = (((y + dy) * self.width + x + dx) * 4) as usize;
+
+                self.pixels[dst_idx] = rect.pixels[src_idx];
+                self.pixels[dst_idx + 1] = rect.pixels[src_idx + 1];
+                self.pixels[dst_idx + 2] = rect.pixels[src_idx + 2];
+                self.pixels[dst_idx + 3] = rect.pixels[src_idx + 3];
+            }
+        }
+    }
 }
 
 fn point_muln(point: Point, t: f32) -> Point {
diff --git a/src/paint.rs b/src/paint.rs
index 0b9ce8d..05af759 100644
--- a/src/paint.rs
+++ b/src/paint.rs
@@ -13,7 +13,7 @@ use iced::{color, event, mouse};
 use crate::color_box::{ColorSelectionBox, CurrentColorBox};
 use crate::image_button::image_button;
 use crate::mouse_area::mouse_area;
-use crate::mscanvas::{MSCanvas, MSColor};
+use crate::mscanvas::{MSCanvas, MSColor, RectSelection};
 
 const WIDTH: u32 = 800;
 const HEIGHT: u32 = 600;
@@ -80,6 +80,7 @@ impl std::fmt::Display for ShapeStyle {
     }
 }
 
+#[allow(unused)]
 #[derive(Debug, Clone, Copy)]
 enum Message {
     MousePressed(Point),
@@ -329,6 +330,8 @@ struct PaintApp {
 
     foreground_color: MSColor,
     background_color: MSColor,
+
+    rect_selection: Option<RectSelection>,
 }
 
 impl PaintApp {
@@ -361,11 +364,18 @@ impl PaintApp {
             config: Config::default(),
             foreground_color: MSColor::BLACK,
             background_color: MSColor::WHITE,
+            rect_selection: None,
         };
 
-        ins.canvas.fill_color(ins.foreground_color);
-        ins.canvas.stroke_color(ins.foreground_color);
-        ins.canvas.line_width(ins.config.line_width);
+        ins.canvas
+            .fill_color(ins.foreground_color)
+            .stroke_color(ins.foreground_color)
+            .line_width(ins.config.line_width);
+
+        ins.view_canvas
+            .fill_color(MSColor::BLACK)
+            .stroke_color(MSColor::BLACK)
+            .line_width(1);
 
         ins
     }
@@ -716,27 +726,154 @@ impl PaintApp {
 
     // region tool update
 
+    fn draw_rect_selection(&mut self, x: i32, y: i32) {
+        if self.rect_selection.is_none() {
+            return;
+        }
+        let rect_selection = self.rect_selection.as_ref().unwrap();
+        let (width, height) = rect_selection.size();
+        self.view_canvas.draw_rect_selection(x, y, rect_selection);
+        self.view_canvas
+            .stroke_dashed_rect(x, y, width, height, 1, 1);
+        // 画矩形四条边上的三个点
+        {
+            let sw = 3;
+            let half_sw = sw / 2;
+            self.view_canvas.fill_rect(x - half_sw, y - half_sw, sw, sw);
+            self.view_canvas
+                .fill_rect((x + width / 2) - half_sw, y - half_sw, sw, sw);
+            self.view_canvas
+                .fill_rect((x + width - 1) - half_sw, y - half_sw, sw, sw);
+            self.view_canvas
+                .fill_rect(x - half_sw, (y + height / 2) - half_sw, sw, sw);
+            self.view_canvas.fill_rect(
+                (x + width - 1) - half_sw,
+                (y + height / 2) - half_sw,
+                sw,
+                sw,
+            );
+            self.view_canvas
+                .fill_rect(x - half_sw, (y + height - 1) - half_sw, sw, sw);
+            self.view_canvas.fill_rect(
+                (x + width / 2) - half_sw,
+                (y + height - 1) - half_sw,
+                sw,
+                sw,
+            );
+            self.view_canvas.fill_rect(
+                (x + width - 1) - half_sw,
+                (y + height - 1) - half_sw,
+                sw,
+                sw,
+            );
+        }
+    }
+
+    fn release_rect_selection(&mut self) {
+        if self.rect_selection.is_none() {
+            return;
+        }
+        let rect_selection = self.rect_selection.as_ref().unwrap();
+        let (x, y) = rect_selection.position();
+        self.view_canvas.restore_pixels();
+        self.canvas.restore_pixels();
+        self.canvas.draw_rect_selection(x, y, rect_selection);
+        self.dirty = true;
+
+        self.rect_selection = None;
+    }
+
     pub fn update_with_select(&mut self, message: Message) {
         match message {
-            Message::MousePressed(pos) => {
-                self.is_drawing = true;
-                self.view_canvas.save_pixels();
-                self.begin_point = pos;
-            }
+            Message::MousePressed(pos) => match self.control_state {
+                ControlState::Zero => {
+                    self.is_drawing = true;
+                    self.view_canvas.save_pixels();
+                    self.begin_point = pos;
+                    self.control_state = ControlState::One;
+                }
+                ControlState::One => {
+                    if let Some(rect_selection) = self.rect_selection.as_ref() {
+                        if rect_selection.contains(pos) {
+                            self.is_drawing = true;
+                            self.begin_point = pos;
+                            self.control_state = ControlState::Two;
+                        } else {
+                            self.release_rect_selection();
+                            self.control_state = ControlState::Zero;
+                        }
+                    }
+                }
+                _ => {}
+            },
             Message::MouseReleased(pos) => {
                 self.is_drawing = false;
-                self.view_canvas.restore_pixels();
-                self.view_canvas
-                    .stroke_dashed_rect1(self.begin_point, pos, 1, 1);
-                self.begin_point = pos;
-                self.dirty = true;
+                match self.control_state {
+                    ControlState::One => {
+                        self.view_canvas.restore_pixels();
+                        let p1 = self.begin_point;
+                        let p2 = pos;
+                        let mut x = p1.x;
+                        let mut y = p1.y;
+                        let mut width = p2.x - p1.x;
+                        let mut height = p2.y - p1.y;
+                        if width < 0.0 && height < 0.0 {
+                            x = p2.x;
+                            y = p2.y;
+                            width = p1.x - p2.x;
+                            height = p1.y - p2.y;
+                        } else if width < 0.0 {
+                            x += width;
+                            width = -width;
+                        } else if height < 0.0 {
+                            y += height;
+                            height = -height;
+                        }
+                        self.rect_selection = Some(self.canvas.select_rect(
+                            x as i32,
+                            y as i32,
+                            width as i32,
+                            height as i32,
+                        ));
+                        self.canvas
+                            .clear_rect(x as i32, y as i32, width as i32, height as i32);
+                        self.canvas.save_pixels();
+                        self.draw_rect_selection(x as i32, y as i32);
+                        self.begin_point = pos;
+                        self.dirty = true;
+                    }
+                    ControlState::Two => {
+                        self.control_state = ControlState::One;
+                        if let Some(rect_selection) = self.rect_selection.as_mut() {
+                            let offset_x = pos.x - self.begin_point.x;
+                            let offset_y = pos.y - self.begin_point.y;
+                            rect_selection.move_offset(offset_x as i32, offset_y as i32);
+                        }
+                    }
+                    _ => {}
+                }
             }
             Message::MouseMoved(pos) => {
                 if self.is_drawing {
-                    self.view_canvas.restore_pixels();
-                    self.view_canvas
-                        .stroke_dashed_rect1(self.begin_point, pos, 3, 1);
-                    self.dirty = true;
+                    match self.control_state {
+                        ControlState::One => {
+                            self.view_canvas.restore_pixels();
+                            self.view_canvas
+                                .stroke_dashed_rect1(self.begin_point, pos, 3, 1);
+                            self.dirty = true;
+                        }
+                        ControlState::Two => {
+                            if let Some(rect_selection) = self.rect_selection.as_ref() {
+                                let offset_x = pos.x - self.begin_point.x;
+                                let offset_y = pos.y - self.begin_point.y;
+                                let (x, y) = rect_selection.position();
+                                self.view_canvas.restore_pixels();
+                                self.draw_rect_selection(x + offset_x as i32, y + offset_y as i32);
+                                self.dirty = true;
+                            }
+                        }
+                        _ => {}
+                    }
                 }
             }
             _ => {}
@@ -1037,6 +1174,7 @@ impl PaintApp {
                 self.canvas.stroke();
             }
         }
+        self.dirty = true;
     }
 
     pub fn update_with_polygon(&mut self, message: Message) {
@@ -1078,7 +1216,6 @@ impl PaintApp {
                 self.is_drawing = false;
                 self.control_state = ControlState::Zero;
                 self.close_polygon();
-                self.dirty = true;
             }
             _ => {}
         }
@@ -1188,7 +1325,19 @@ impl PaintApp {
         if self.tool_selected == Tool::Polygon && self.control_state != ControlState::Zero {
             // 切换到其他工具，闭合路径
             self.close_polygon();
-            self.dirty = true;
+        }
+        if self.tool_selected == Tool::Select && self.control_state != ControlState::Zero {
+            // 切换到其他工具，释放选择框
+            self.release_rect_selection();
+        }
+
+        self.is_drawing = false;
+        self.control_state = ControlState::Zero;
+        self.view_canvas.clear_zero();
+        self.dirty = true;
+
+        if self.tool_selected == idx.into() {
+            return;
         }
 
         let old_value = self.tool_states[idx];
@@ -1197,11 +1346,6 @@ impl PaintApp {
         }
         self.tool_states[idx] = !old_value;
         self.tool_selected = idx.into();
-
-        self.is_drawing = false;
-        self.control_state = ControlState::Zero;
-        self.view_canvas.clear_zero();
-        self.dirty = true;
     }
 
     /// 将原始字节转换为 Iced 的图像句柄