Modify capture_image_area to work with druid direct2d surfaces

piet-direct2d/src/d2d.rs

@@ -784,7 +784,7 @@ impl DeviceContext {
         &mut self,
         width: usize,
         height: usize,
-        alpha_mode: D2D1_ALPHA_MODE,
+        dpi_scale: f32,
     ) -> Result<Bitmap, Error> {
         // Maybe using TryInto would be more Rust-like.
         // Note: value is set so that multiplying by 4 (for pitch) is valid.
@@ -794,18 +794,17 @@ impl DeviceContext {
             width: width as u32,
             height: height as u32,
         };
-        let format = D2D1_PIXEL_FORMAT {
-            format: DXGI_FORMAT_R8G8B8A8_UNORM,
-            alphaMode: alpha_mode,
-        };
-        let props = D2D1_BITMAP_PROPERTIES1 {
-            pixelFormat: format,
-            dpiX: 96.0,
-            dpiY: 96.0,
-            bitmapOptions: D2D1_BITMAP_OPTIONS_NONE,
-            colorContext: null_mut(),
-        };
+
         unsafe {
+            let pixel_format = self.0.GetPixelFormat();
+            let props = D2D1_BITMAP_PROPERTIES1 {
+                pixelFormat: pixel_format,
+                dpiX: dpi_scale * 96.0,
+                dpiY: dpi_scale * 96.0,
+                bitmapOptions: D2D1_BITMAP_OPTIONS_TARGET,
+                colorContext: null_mut(),
+            };
+
             let mut ptr = null_mut();
             let hr = self
                 .0

piet-direct2d/src/lib.rs

@@ -481,15 +481,26 @@ impl<'a> RenderContext for D2DRenderContext<'a> {
         let mut target_bitmap = self.rt.create_blank_bitmap(
             device_size.width as usize,
             device_size.height as usize,
-            D2D1_ALPHA_MODE_PREMULTIPLIED,
+            dpi_scale as f32,
         )?;
 
         let src_rect = Rect::from_origin_size(device_origin, device_size);
 
         let d2d_dest_point = to_point2u((0.0f32, 0.0f32));
         let d2d_src_rect = rect_to_rectu(src_rect);
+
+        // Clear layers from the render target
+        for _ in 0..self.layers.len() {
+            self.rt.pop_layer();
+        }
+
         target_bitmap.copy_from_render_target(d2d_dest_point, self.rt, d2d_src_rect);
 
+        // Restore cleared layers
+        for (mask, layer) in self.layers.iter() {
+            self.rt.push_layer_mask(mask, layer);
+        }
+
         Ok(target_bitmap)
     }