Webview extension (draft)

include/clap/all.h

@@ -13,3 +13,4 @@
 #include "ext/draft/tuning.h"
 #include "ext/draft/undo.h"
 #include "ext/draft/scratch-memory.h"
+#include "ext/draft/webview.h"

include/clap/ext/draft/webview.h

@@ -0,0 +1,60 @@
+#pragma once
+
+static CLAP_CONSTEXPR const char CLAP_EXT_WEBVIEW[] = "clap.webview/1";
+
+// clap.gui API constant. The pointer in clap_window must be NULL, but sizing methods are useful.
+// uses logical size, don't call clap_plugin_gui->set_scale()
+static const CLAP_CONSTEXPR char CLAP_WINDOW_API_WEBVIEW[] = "webview";
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/// @page Webview
+///
+/// This extension enables the plugin to provide the start-page for a webview UI, and exchange
+/// messages back and forth.
+///
+/// Messages are received in the webview using a standard MessageEvent, with the data in an
+/// ArrayBuffer. They are posted back to the plugin using window.parent.postMessage(), with the
+/// data in an ArrayBuffer or TypedArray.
+
+typedef struct clap_plugin_webview {
+   // Returns the URL for the webview's initial navigation, as a null-terminated UTF-8 string.
+   // This must be called while the webview is not open, and must be called before it is opened.
+   // If this URL is relative, it is resolved relative to the plugin (bundle) resource directory.
+   // The host may assume that no resources outside of that directory are used, and may use any
+   // protocol to provide this content, following HTTP-like relative URL resolution. The page must
+   // not assume that the root path of the domain is the root of the bundle. The URL may also be
+   // absolute, including a `file://` URL.
+   // Returns true on success.
+   // [main-thread]
+   bool(CLAP_ABI *provide_starting_uri)(const clap_plugin_t *plugin,
+                             char                *out_buffer,
+                             uint32_t            out_buffer_capacity);
+
+   // Receives a single message from the webview, which must be open.
+   // Returns true on success.
+   // [main-thread]
+   bool(CLAP_ABI *receive)(const clap_plugin_t *plugin, const void *buffer, uint32_t size);
+
+} clap_plugin_webview_t;
+
+typedef struct clap_host_webview {
+   // Returns whether the webview is "open" (running and ready to receive messages).
+   // If called from the main thread, it must return the open state specified by other methods.
+   // If called from any other thread, it must only be used as a hint for non-essential work (such
+   // as to skip metering calculations) as there are no synchronisation guarantees.
+   // [thread-safe]
+   bool(CLAP_ABI *is_open)(const clap_host_t *host);
+
+   // Sends a single message to the webview.
+   // Returns true on success. Should fail if the webview is not open.
+   // [main-thread]
+   bool(CLAP_ABI *send)(const clap_host_t *host, const void *buffer, uint32_t size);
+
+} clap_host_webview_t;
+
+#ifdef __cplusplus
+}
+#endif