render: unify responsive geometry and inline gradients

crates/obscura-cdp/src/domains/emulation.rs

@@ -0,0 +1,98 @@
+use serde_json::{json, Value};
+
+use crate::dispatch::CdpContext;
+
+pub async fn handle(
+    method: &str,
+    params: &Value,
+    ctx: &mut CdpContext,
+    session_id: &Option<String>,
+) -> Result<Value, String> {
+    match method {
+        "setDeviceMetricsOverride" => {
+            let width = params
+                .get("width")
+                .and_then(Value::as_f64)
+                .ok_or("Emulation.setDeviceMetricsOverride requires width")?;
+            let height = params
+                .get("height")
+                .and_then(Value::as_f64)
+                .ok_or("Emulation.setDeviceMetricsOverride requires height")?;
+            if !width.is_finite() || !height.is_finite() || width <= 0.0 || height <= 0.0 {
+                return Err(
+                    "Emulation.setDeviceMetricsOverride requires positive finite dimensions"
+                        .to_string(),
+                );
+            }
+            let page = ctx
+                .get_session_page_mut(session_id)
+                .ok_or("No page for session")?;
+            page.set_viewport((width as f32, height as f32));
+            Ok(json!({}))
+        }
+        "clearDeviceMetricsOverride" => {
+            let page = ctx
+                .get_session_page_mut(session_id)
+                .ok_or("No page for session")?;
+            page.set_viewport((1280.0, 720.0));
+            Ok(json!({}))
+        }
+        // Touch emulation does not affect layout yet, but acknowledging it is
+        // compatible with clients that pair it with a metrics override.
+        "setTouchEmulationEnabled" => Ok(json!({})),
+        _ => Ok(json!({})),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[tokio::test]
+    async fn device_metrics_override_updates_page_and_window_viewport() {
+        let mut ctx = CdpContext::new();
+        let page_id = ctx.create_page();
+        let session_id = Some("viewport-session".to_string());
+        ctx.sessions
+            .insert(session_id.clone().unwrap(), page_id);
+
+        handle(
+            "setDeviceMetricsOverride",
+            &json!({"width": 1024, "height": 768, "deviceScaleFactor": 1}),
+            &mut ctx,
+            &session_id,
+        )
+        .await
+        .expect("metrics override");
+
+        let page = ctx
+            .get_session_page_mut(&session_id)
+            .expect("page for session");
+        assert_eq!(page.viewport, (1024.0, 768.0));
+        assert_eq!(
+            page.evaluate(
+                "return [innerWidth, innerHeight, visualViewport.width,\
+                         visualViewport.height];"
+            ),
+            json!([1024, 768, 1024, 768])
+        );
+    }
+
+    #[tokio::test]
+    async fn device_metrics_override_rejects_zero_dimensions() {
+        let mut ctx = CdpContext::new();
+        let page_id = ctx.create_page();
+        let session_id = Some("viewport-session".to_string());
+        ctx.sessions
+            .insert(session_id.clone().unwrap(), page_id);
+        let error = handle(
+            "setDeviceMetricsOverride",
+            &json!({"width": 0, "height": 768}),
+            &mut ctx,
+            &session_id,
+        )
+        .await
+        .expect_err("zero width must fail");
+        assert!(error.contains("positive finite dimensions"));
+    }
+}