improve:截图

Ink Canvas/Windows/ScreenshotSelectorWindow.xaml

@@ -117,6 +117,15 @@
                         BorderThickness="0"
                         FontWeight="Medium"
                         Click="FreehandModeButton_Click" />
+                <Button Name="FullScreenButton" 
+                        Content="全屏截图" 
+                        Margin="4,0"
+                        Padding="12,6"
+                        Background="#7c3aed"
+                        Foreground="White"
+                        BorderThickness="0"
+                        FontWeight="Medium"
+                        Click="FullScreenButton_Click" />
                 
                 <!-- 分隔线 -->
                 <Separator Style="{StaticResource {x:Static ToolBar.SeparatorStyleKey}}" 

Ink Canvas/Windows/ScreenshotSelectorWindow.xaml.cs

@@ -146,6 +146,7 @@ namespace Ink_Canvas
             _isFreehandMode = false;
             RectangleModeButton.Background = new SolidColorBrush(Color.FromRgb(37, 99, 235)); // 蓝色
             FreehandModeButton.Background = new SolidColorBrush(Color.FromRgb(107, 114, 128)); // 灰色
+            FullScreenButton.Background = new SolidColorBrush(Color.FromRgb(107, 114, 128)); // 灰色
             HintText.Text = "拖拽鼠标选择矩形区域";
             HintText.Visibility = Visibility.Visible;
         }
@@ -158,10 +159,26 @@ namespace Ink_Canvas
             _isFreehandMode = true;
             FreehandModeButton.Background = new SolidColorBrush(Color.FromRgb(37, 99, 235)); // 蓝色
             RectangleModeButton.Background = new SolidColorBrush(Color.FromRgb(107, 114, 128)); // 灰色
+            FullScreenButton.Background = new SolidColorBrush(Color.FromRgb(107, 114, 128)); // 灰色
             HintText.Text = "按住鼠标左键绘制任意形状，松开直接截图";
             HintText.Visibility = Visibility.Visible;
         }
 
+        private void FullScreenButton_Click(object sender, RoutedEventArgs e)
+        {
+            // 重置所有选择状态
+            ResetSelectionState();
+
+            // 设置全屏截图模式
+            _isFreehandMode = false;
+            FullScreenButton.Background = new SolidColorBrush(Color.FromRgb(37, 99, 235)); // 蓝色
+            RectangleModeButton.Background = new SolidColorBrush(Color.FromRgb(107, 114, 128)); // 灰色
+            FreehandModeButton.Background = new SolidColorBrush(Color.FromRgb(107, 114, 128)); // 灰色
+            
+            // 直接执行全屏截图
+            PerformFullScreenCapture();
+        }
+
         private void ConfirmButton_Click(object sender, RoutedEventArgs e)
         {
             // 在自由绘制模式下，确认按钮不执行任何操作
@@ -786,6 +803,30 @@ namespace Ink_Canvas
             }
         }
 
+        private void PerformFullScreenCapture()
+        {
+            try
+            {
+                // 获取虚拟屏幕边界
+                var virtualScreen = SystemInformation.VirtualScreen;
+                
+                // 设置全屏截图区域
+                SelectedArea = new DrawingRectangle(virtualScreen.X, virtualScreen.Y, virtualScreen.Width, virtualScreen.Height);
+                SelectedPath = null; // 全屏截图不需要路径
+                
+                // 直接关闭窗口并返回结果
+                DialogResult = true;
+                Close();
+            }
+            catch (Exception ex)
+            {
+                // 如果全屏截图失败，记录错误并关闭窗口
+                System.Diagnostics.Debug.WriteLine($"全屏截图失败: {ex.Message}");
+                DialogResult = false;
+                Close();
+            }
+        }
+
         private void ResetSelectionState()
         {
             // 重置所有选择相关的状态