feat: Screen region capture (Shift+S), annotation pen overlay, image grouping, minimap

src-tauri/src/capture.rs

@@ -0,0 +1,33 @@
+use tauri::{AppHandle, Manager};
+use base64::{engine::general_purpose, Engine as _};
+
+/// Capture a region of the screen and return as base64 data URL.
+/// Uses the `screenshots` crate for cross-platform screen capture.
+#[tauri::command]
+pub async fn capture_screen_region(
+    app: AppHandle,
+    x: i32,
+    y: i32,
+    width: u32,
+    height: u32,
+) -> Result<String, String> {
+    use std::io::Cursor;
+    
+    // Use the primary screen
+    let screens = screenshots::Screen::all().map_err(|e| format!("screen list error: {e}"))?;
+    let screen = screens.into_iter().next().ok_or("no screen found")?;
+    
+    let capture = screen.capture_area(x, y, width, height)
+        .map_err(|e| format!("capture error: {e}"))?;
+    
+    let rgba = capture.rgba();
+    let img = image::RgbaImage::from_raw(capture.width(), capture.height(), rgba.to_vec())
+        .ok_or("failed to create image from capture")?;
+    
+    let mut buf = Cursor::new(Vec::new());
+    img.write_to(&mut buf, image::ImageFormat::Png)
+        .map_err(|e| format!("png encode error: {e}"))?;
+    
+    let b64 = general_purpose::STANDARD.encode(buf.into_inner());
+    Ok(format!("data:image/png;base64,{b64}"))
+}