desktop/render: Pass explicit clip box to render

render_surface_iterator previously deduced the clip box from an optional
container passed with render data. This causes problems when offsets in
view geometry need to be compensated for in the clip dimensions.

Instead, prepare the clip box in render_view_toplevels where the offsets
are being applied, and compensate for them immediately.

A similar compensation is applied to render_saved_view.

Closes: https://github.com/swaywm/sway/issues/6223

sway/desktop/render.c

@@ -32,7 +32,7 @@
 struct render_data {
 	pixman_region32_t *damage;
 	float alpha;
-	struct sway_container *container;
+	struct wlr_box *clip_box;
 };
 
 /**
@@ -157,10 +157,10 @@ static void render_surface_iterator(struct sway_output *output, struct sway_view
 		wlr_output->transform_matrix);
 
 	struct wlr_box dst_box = *_box;
-	struct sway_container *container = data->container;
-	if (container != NULL) {
-		dst_box.width = fmin(dst_box.width, container->current.content_width);
-		dst_box.height = fmin(dst_box.height, container->current.content_height);
+	struct wlr_box *clip_box = data->clip_box;
+	if (clip_box != NULL) {
+		dst_box.width = fmin(dst_box.width, clip_box->width);
+		dst_box.height = fmin(dst_box.height, clip_box->height);
 	}
 	scale_box(&dst_box, wlr_output->scale);
 
@@ -262,8 +262,13 @@ static void render_view_toplevels(struct sway_view *view,
 		.damage = damage,
 		.alpha = alpha,
 	};
+	struct wlr_box clip_box;
 	if (!container_is_current_floating(view->container)) {
-		data.container = view->container;
+		// As we pass the geometry offsets to the surface iterator, we will
+		// need to account for the offsets in the clip dimensions.
+		clip_box.width = view->container->current.content_width + view->geometry.x;
+		clip_box.height = view->container->current.content_height + view->geometry.y;
+		data.clip_box = &clip_box;
 	}
 	// Render all toplevels without descending into popups
 	double ox = view->container->surface_x -
@@ -329,10 +334,10 @@ static void render_saved_view(struct sway_view *view,
 		if (!floating) {
 			dst_box.width = fmin(dst_box.width,
 					view->container->current.content_width -
-					(saved_buf->x - view->container->current.content_x));
+					(saved_buf->x - view->container->current.content_x) + view->saved_geometry.x);
 			dst_box.height = fmin(dst_box.height,
 					view->container->current.content_height -
-					(saved_buf->y - view->container->current.content_y));
+					(saved_buf->y - view->container->current.content_y) + view->saved_geometry.y);
 		}
 		scale_box(&dst_box, wlr_output->scale);