ui: add clipboard documentation

Document clipboard infrastructure in qemu.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-id: 20210519053940.1888907-1-kraxel@redhat.com
Message-Id: <20210519053940.1888907-4-kraxel@redhat.com>

docs/devel/index.rst

@@ -36,6 +36,7 @@ Contents:
    multi-thread-tcg
    tcg-plugins
    bitops
+   ui
    reset
    s390-dasd-ipl
    clocks

docs/devel/ui.rst

+=================
+Qemu UI subsystem
+=================
+
+Qemu Clipboard
+--------------
+
+.. kernel-doc:: include/ui/clipboard.h

include/ui/clipboard.h

@@ -3,17 +3,47 @@
 
 #include "qemu/notify.h"
 
+/**
+ * DOC: Introduction
+ *
+ * The header ``ui/clipboard.h`` declares the qemu clipboard interface.
+ *
+ * All qemu elements which want use the clipboard can register as
+ * clipboard peer.  Subsequently they can set the clipboard content
+ * and get notifications for clipboard updates.
+ *
+ * Typical users are user interfaces (gtk), remote access protocols
+ * (vnc) and devices talking to the guest (vdagent).
+ *
+ * Even though the design allows different data types only plain text
+ * is supported for now.
+ */
+
 typedef enum QemuClipboardType QemuClipboardType;
 typedef enum QemuClipboardSelection QemuClipboardSelection;
 typedef struct QemuClipboardPeer QemuClipboardPeer;
 typedef struct QemuClipboardInfo QemuClipboardInfo;
 
+/**
+ * enum QemuClipboardType
+ *
+ * @QEMU_CLIPBOARD_TYPE_TEXT: text/plain; charset=utf-8
+ * @QEMU_CLIPBOARD_TYPE__COUNT: type count.
+ */
 enum QemuClipboardType {
-    QEMU_CLIPBOARD_TYPE_TEXT,  /* text/plain; charset=utf-8 */
+    QEMU_CLIPBOARD_TYPE_TEXT,
     QEMU_CLIPBOARD_TYPE__COUNT,
 };
 
 /* same as VD_AGENT_CLIPBOARD_SELECTION_* */
+/**
+ * enum QemuClipboardSelection
+ *
+ * @QEMU_CLIPBOARD_SELECTION_CLIPBOARD: clipboard (explitcit cut+paste).
+ * @QEMU_CLIPBOARD_SELECTION_PRIMARY: primary selection (select + middle mouse button).
+ * @QEMU_CLIPBOARD_SELECTION_SECONDARY: secondary selection (dunno).
+ * @QEMU_CLIPBOARD_SELECTION__COUNT: selection count.
+ */
 enum QemuClipboardSelection {
     QEMU_CLIPBOARD_SELECTION_CLIPBOARD,
     QEMU_CLIPBOARD_SELECTION_PRIMARY,
@@ -21,6 +51,15 @@ enum QemuClipboardSelection {
     QEMU_CLIPBOARD_SELECTION__COUNT,
 };
 
+/**
+ * struct QemuClipboardPeer
+ *
+ * @name: peer name.
+ * @update: notifier for clipboard updates.
+ * @request: callback for clipboard data requests.
+ *
+ * Clipboard peer description.
+ */
 struct QemuClipboardPeer {
     const char *name;
     Notifier update;
@@ -28,6 +67,16 @@ struct QemuClipboardPeer {
                     QemuClipboardType type);
 };
 
+/**
+ * struct QemuClipboardInfo
+ *
+ * @refcount: reference counter.
+ * @owner: clipboard owner.
+ * @selection: clipboard selection.
+ * @types: clipboard data array (one entry per type).
+ *
+ * Clipboard content data and metadata.
+ */
 struct QemuClipboardInfo {
     uint32_t refcount;
     QemuClipboardPeer *owner;
@@ -40,18 +89,100 @@ struct QemuClipboardInfo {
     } types[QEMU_CLIPBOARD_TYPE__COUNT];
 };
 
+/**
+ * qemu_clipboard_peer_register
+ *
+ * @peer: peer information.
+ *
+ * Register clipboard peer.  Registering is needed for both active
+ * (set+grab clipboard) and passive (watch clipboard for updates)
+ * interaction with the qemu clipboard.
+ */
 void qemu_clipboard_peer_register(QemuClipboardPeer *peer);
+
+/**
+ * qemu_clipboard_peer_unregister
+ *
+ * @peer: peer information.
+ *
+ * Unregister clipboard peer.
+ */
 void qemu_clipboard_peer_unregister(QemuClipboardPeer *peer);
 
+/**
+ * qemu_clipboard_info_new
+ *
+ * @owner: clipboard owner.
+ * @selection: clipboard selection.
+ *
+ * Allocate a new QemuClipboardInfo and initialize it with the given
+ * @owner and @selection.
+ *
+ * QemuClipboardInfo is a reference-counted struct.  The new struct is
+ * returned with a reference already taken (i.e. reference count is
+ * one).
+ */
 QemuClipboardInfo *qemu_clipboard_info_new(QemuClipboardPeer *owner,
                                            QemuClipboardSelection selection);
+/**
+ * qemu_clipboard_info_ref
+ *
+ * @info: clipboard info.
+ *
+ * Increase @info reference count.
+ */
 QemuClipboardInfo *qemu_clipboard_info_ref(QemuClipboardInfo *info);
+
+/**
+ * qemu_clipboard_info_unref
+ *
+ * @info: clipboard info.
+ *
+ * Decrease @info reference count.  When the count goes down to zero
+ * free the @info struct itself and all clipboard data.
+ */
 void qemu_clipboard_info_unref(QemuClipboardInfo *info);
 
+/**
+ * qemu_clipboard_update
+ *
+ * @info: clipboard info.
+ *
+ * Update the qemu clipboard.  Notify all registered peers (including
+ * the clipboard owner) that the qemu clipboard has been updated.
+ *
+ * This is used for both new completely clipboard content and for
+ * clipboard data updates in response to qemu_clipboard_request()
+ * calls.
+ */
 void qemu_clipboard_update(QemuClipboardInfo *info);
+
+/**
+ * qemu_clipboard_request
+ *
+ * @info: clipboard info.
+ * @type: clipboard data type.
+ *
+ * Request clipboard content.  Typically the clipboard owner only
+ * advertises the available data types and provides the actual data
+ * only on request.
+ */
 void qemu_clipboard_request(QemuClipboardInfo *info,
                             QemuClipboardType type);
 
+/**
+ * qemu_clipboard_set_data
+ *
+ * @peer: clipboard peer.
+ * @info: clipboard info.
+ * @type: clipboard data type.
+ * @size: data size.
+ * @data: data blob.
+ * @update: notify peers about the update.
+ *
+ * Set clipboard content for the given @type.  This function will make
+ * a copy of the content data and store that.
+ */
 void qemu_clipboard_set_data(QemuClipboardPeer *peer,
                              QemuClipboardInfo *info,
                              QemuClipboardType type,