OverlayPresenter is used to schedule the display of UI alongside the content area of a WebState.
OverlayRequests are model objects that are used to schedule the display of UI alongside a WebState's content area. They are created with an OverlayUserData subclass containing the information necessary to configure the requested UI.
OverlayResponses are provided to each OverlayRequest to describe the user's interaction with the overlay UI. Clients should create OverlayResponses with an OverlayUserData subclass with the overlay UI user interaction information necessary to execute the callback for that overlay.
Each WebState has an OverlayRequestQueue at each OverlayModality that stores the OverlayRequests for overlays to be displayed alongside that WebState‘s content area. When a client wishes to schedule the display of an overlay, it should add an OverlayRequest to the desired WebState’s queue. This will trigger the scheduling logic for that request's corresponding overlay UI.
OverlayPresenter drives the presentation of the UI for OverlayRequests added to queues for WebStates in a Browser.
Clients must provide a presentation context to a Browser‘s OverlayPresenter that handles the presentation of overlay UI for that presenter’s modality and Browser.
Objects that care about the presentation and dismissal of overlay UI by the presenter should add themselves as observers to the presenter. This can be used to respond to update UI for UI presentation, for example to update the location bar text while a dialog is displayed.
Multiple OverlayPresenters may be active for a single Browser to manage overlay UI at different levels of modality (i.e. modal over WebState content area, modal over entire browser, etc).
Each instance of OverlayPresenter must be provided with an OverlayPresenter:: UIDelegate that manages the overlay UI at the modality associated with the presenter.
#####1. Create OverlayUserData subclasses for the requests and responses:
A request configuration user data should be created with the information necessary to set up the overlay UI being requested.
class AlertConfig : public OverlayUserData<AlertConfig> {
public:
const std::string& title() const;
const std::string& message() const;
const std::vector<std::string>& button\_titles() const;
private:
OVERLAY\_USER\_DATA\_SETUP(AlertConfig);
AlertConfig(const std::string& title, const std::string& message);
};
A response ino user data should be created with the information necessary to execute the callback for the overlay.
class AlertInfo : public OverlayUserData<AlertInfo> {
public:
const size\_t tapped\_button\_index() const;
private:
OVERLAY\_USER\_DATA\_SETUP(AlertInfo);
AlertInfo(size\_t tapped\_button\_index);
};
#####2. Request an overlay using the request config user data.
An OverlayRequest for the alert can be created using:
OverlayRequest::CreateWithConfig<AlertConfig>(
"alert title", "message text");
A callback can be added to the request to use the response info:
OverlayCallback callback =
base::BindOnce(base::RetainBlock(^(OverlayResponse* response) {
if (!response)
return;
AlertInfo* info = response->GetInfo<AlertInfo>();
/* Handle button tap at info->tapped\_button\_index() */
}));
request->set_callback(std::move(callback));
Clients can then supply this request to the OverlayRequestQueue corresponding with the WebState alongside which the overlay should be shown:
OverlayModality modality =
OverlayModality::kWebContentArea;
OverlayRequestQueue::FromWebState(web_state, modality)->
AddRequest(std::move(request));
#####3. Supply a response to the request.
Upon the user tapping a button on the alert, say at index 0, a response can be created and supplied to that request.
OverlayRequestQueue::FromWebState(web_state, modality)->front_request()->
set_response(OverlayResponse::CreateWithInfo<AlertInfo>(0));