KR101733358B1 - System and method for displaying document content using universal plug and play - Google Patents

Abstract

A control point device for displaying document content is disclosed. The control point device includes a display unit for displaying document contents, a media player identifying unit for identifying a media player capable of reproducing and displaying the document content when a request for displaying the document content is inputted, A status change information receiving unit for receiving status change information corresponding to the operation performed by the user, and an operation command for reproducing and displaying the document content according to a request to display the document content, Transmitting the meta information of the document content provided from the media server and the display information of the display unit to the identified media player and generating a thumbnail image corresponding to the document content received from the media player, A screen information including a document view control unit for display through the display unit, and the thumbnail image may be generated by the media player based on the display information and the document content of said display.

Description

[0001] SYSTEM AND METHOD FOR DISPLAYING DOCUMENT CONTENT USING UPnP [0002] SYSTEM AND METHOD FOR DISPLAYING DOCUMENT CONTENT USING UNIVERSAL PLUG AND PLAY [

The present invention relates to a system and method having a document viewing function, and more particularly, to a system and method for displaying document contents using UPnP (Universal Plug and Play).

2. Description of the Related Art Generally, a home network is a private network based on Internet Protocol (hereinafter referred to as " IP "). Are connected to a single network through a common virtual computing environment called middleware.

Middleware refers to a home AV interoperability (HAVI), a universal plug and play (UPnP), a Java Intelligent Network (Jini), and the like, which enable various digital devices to be connected in a peer-to- Infra-structure, and Home Wide Web (HWW).

In the computing environment established through the UPnP middleware, each device is allocated an address from a server according to a dynamic host configuration protocol (DHCP) or an address selected by an automatic IP assignment function (Auto IP) , Thereby performing communication between the devices and searching or inquiring on the network.

The UPnP network is one of the most widely used home network technologies. UPnP devices and UPnP services are defined and defined by protocols between them. The UPnP network is composed of a Controlled Device (CD), which is a home network device connected to and controlled by an IP-based home network, and a Control Point (CP), which is an apparatus for controlling the controlled devices . The control point is a device for performing control on the controlled device, and is a component for requesting an event and receiving an event. The controlled device is a component that performs a predetermined function at the request of the control point, and sends the event to the control point that requested the event when the state of the controlled device is changed.

The operation steps of each step between the devices of the conventional UPnP network include an advertisement process, a discovery process, a description process, a control process, and an eventing process.

The advertisement process is a process in which a new controlled device is connected to a home network and notifies other devices on the home network. In the discovery process, a new control point is connected to the home network, And searching the operated controlled devices. Description describes a process of creating a service description XML (Extensible Markup Language) file or a device description through the IP address of the controlled device obtained in the discovery process in order to control the controlled device, It parses the XML file and grasps the functions of the newly added device in more detail. In the control process, when the control point desires to provide a specific service through the controlled device, the control point transmits an action request for requesting a predetermined service using the SOAP to the controlled device according to the UPnP device architecture And receiving a response message (result, variable value). The eventing process is a process of confirming the information change state of the controlled device that has provided the predetermined service by the control command transmitted from the control point.

A UPnP AV transmission service (Audio / Video Transport service) technology capable of enjoying multimedia contents such as audio or video based on the UPnP technology described above is described in the UPnP AV specification.

According to the UPnP specification, the UPnP AVTS architecture defines an operation related to transmitting audio and video streams, and defines a common A / V transmission mechanism suitable for a general UI (User Interface) environment. Such a UPnP AVTS architecture is applicable to widely used media such as disk, tape, CD, VCR, and MP3.

Specifically, the UPnP AVTS architecture includes a media server for providing a multimedia file through a content directory service, a media renderer for playing the multimedia file provided in the media server, And a control point for controlling the media players so that they can operate with each other. The content directory service is a service embedded in a media server. The content directory service provides metadata of contents stored in the media server or inside or outside the home network to the control point. And requests the media player to perform playback.

For example, as shown in FIG. 1, the UPnP AVTS architecture basically includes commands consisting of state variables such as no media (NO_MEDIA_PRESENT), STOPPED, PLAYING, TRANSITIONING, and PAUSED , 'Stop', and 'stop' through the operation.

Thus, the conventional UPnP AVTS architecture reproduces multimedia files such as audio and video streams provided by the media server through the media player, and the control point controls the media player and the media server.

However, the UPnP AVTS architecture can only play multimedia files such as audio and video streams, and does not support a document viewer function for viewing text and documents, thus necessitating a document viewing function.

Also, to add document view function, it is possible to extend the specification of control point in UPnP AVTS architecture to add state variable for document view support.

However, when there are a plurality of control points such as a UPnP control point and another control point extending the UPnP control point in one device, it is difficult for the media player to transmit an AVTS related event generated to itself to all clients.

In addition, since the control point of the control point may malfunction due to transmission of events not related to the AVTS, it is limited to merely expand the existing AVTS architecture to add new functions.

Accordingly, the present invention provides a system and method for reproducing document content in a UPnP network.

According to various embodiments of the present invention, a control point device for displaying document contents includes a display unit for displaying document contents, a media player capable of reproducing and displaying the document content when a request for displaying the document content is inputted, A status change information receiving unit for receiving status change information corresponding to an operation performed by the media player according to an operation command, and a status change information receiving unit for reproducing the document content according to a request to display the document content, And transmits the generated operation command, the meta information of the document content provided from the media server and the display information of the display unit to the identified media player, And a document view control unit for displaying a thumbnail image corresponding to the document content to be displayed and the status change information through the display unit, wherein the thumbnail image is displayed on the display unit by the media player based on the display information of the display unit and the document content. Lt; / RTI >

According to various embodiments of the present invention, a method for displaying document content at a control point comprises: if a request to display document content is input, identifying the displayable media player by playing the document content according to the request; Generating an operation command for reproducing and displaying the document content in response to a request to display the document content, generating the generated operation command, meta information of the document content provided from the media server, Transmitting the display information of the display unit to the identified media player; receiving a thumbnail image corresponding to the document content from the media player and status change information corresponding to the operation performed by the media player in accordance with the play command; And displaying the received thumbnail image and the received status change information through the display unit, wherein the thumbnail image is generated by the media player based on the display information of the display unit and the document content, .

The present invention proposes an operation standard between devices on a UPnP network by providing a media player that executes a command for displaying document contents in a UPnP network, and a plurality of control points are connected to the media service to provide a presentation function, The document contents can be easily displayed through a UPnP network environment even in a wireless communication environment such as Wi-Fi (Wireless-Fidelity).

1 is a diagram illustrating a media playback process in a conventional UPnP AVTS architecture,
2 is a block diagram of a system for displaying document contents according to an embodiment of the present invention;
3 is a flowchart illustrating a change in operation state of a document viewing service module according to an embodiment of the present invention;
FIG. 4 is a block diagram illustrating an example of a process of image-processing a document content page according to an exemplary embodiment of the present invention.
5 is a diagram illustrating a process for displaying document contents requested by a user in a document content display system on a screen according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description and drawings, detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention unnecessarily obscure.

2 is a block diagram of a system for displaying document contents according to an embodiment of the present invention.

The system of the present invention includes a control point 100, a media renderer 200, and a media server 300.

First, the control point 100 searches for a media player that renders document contents according to a request to control the media player 200, search and content browsing of the media server 300, content reproduction, and display document contents . Then, the control point 100 transmits display information such as a display screen size, which is a displayable area size thereof, and meta information about requested document contents, together with an operation performing instruction for displaying document contents in the searched media player. At this time, the meta information includes a plurality of pieces of related information such as the title, the number of pages, and the author of the document contents.

If the status information and the document content image of the media player 300 are received from the media player 300 according to the operation execution command, the control point 100 displays the received status information or the document content image on the screen. At this time, the document content image is an image converted into a form suitable for the display information of the control point 100.

The media player 200 broadcasts a message indicating that the document content can be rendered on the network to which the media player 200 belongs, and when there is a request to render the document content, the media player 200 uses the meta information of the requested document content, From the media server. The media player then renders the downloaded document content and displays it on the screen.

The media player 300 informs the control point 100 of the operation state of the media player 300 according to an operation command word received from the control point 100. For example, when a command for reproducing a document is transmitted from the control point 100, the media player 300 renders the document content to display the document content on the screen. At this time, the media player 300 And transfers the status information to the control point 100.

The media server 300 reads the document contents present in the memory, generates meta information as resource information for the read document contents, and provides the document contents to the media player 300 according to the request. The media server 300 may be configured in a single device together with the control point 100 and may be configured in one device together with the media player 200. [

The system components will be described in detail as follows.

The control point 100 includes a Document Viewer Controller 110, a Media Viewer Service NOTIFY Listener 120, a Document Viewer Service LastChange Event Listener 130, Unit 140, and an interface unit 150.

The document view control unit 110 browses the media server 300 according to a request to display the document content to obtain meta information about the requested document content. Then, the document view control unit 110 searches the media player 200 for rendering document contents.

If notification information indicating that the document content can be reproduced is received from the media player 300, the document view control unit 110 determines whether the media player that transmitted the notification information through the media player identification unit 120 can reproduce the document content Check.

When the media player identification unit 120 determines that the media player can reproduce the document content, the document view control unit 110 displays the document content on the display unit 140 of the control point 100, And transmits the obtained meta information to the media player 300.

The document view control unit 110 receives status change information for the media player 300 through the status change information receiving unit 130. [ At this time, the status change information means status information about the operation being performed by the media player. For example, the status change information is information indicating an operation performed by a current media player, such as opening document content, downloading document content, or rendering document content.

When the document content image of a size suitable for display on the display unit 140 of the control point 100 is received from the media player 200, the document view control unit 110 displays the received document content image on the display unit 140 do. At this time, the user can enlarge or reduce the size of the document content image displayed on the display unit 250 of the media player 200 using the key input unit 150 of the control point 100.

The media player identifying unit 120 identifies the notification information received from the media player, identifies whether the corresponding media player is a media player capable of displaying document content, and notifies the document view controller 110 of the information.

The status change information receiving unit 130 receives the operation state change information of the media player when it is received in response to the command related to the document content display.

The display unit 140 displays the document content image received from the media player 200 or the operation status change information of the media player 300.

The key input unit 150 includes keys for receiving a request for displaying document contents from a user and a request for controlling document contents, and transmits a signal corresponding to the input to the document view control unit 110. [

The media player 200 includes a document viewing service module 210, a rendering control service module 220, a connection manager service module 230, a voice / video transmission service module 240, and a display unit 250 .

The Document Viewer Service Module 210 performs an operation for displaying document contents according to a command for displaying document contents. For example, if there is an instruction to display the document content, the document view service module 210 downloads the document content from the media server 300, opens the downloaded document content, and displays the downloaded document content through the display unit 250. If a command for displaying the next page of the document contents is received from the control point 100, the document view service module 210 renders the next page according to the instruction, and then displays the next page after the rendering on the display unit 250 Display.

This will be described in detail with reference to FIG.

3 is a flowchart illustrating a change in operation state of a document viewing service module according to an embodiment of the present invention.

First, the document view service module 210 is in the idle state 300, and when the document content download command is received from the control point 100, the operation state changes to the document downloading state 310. The document viewing service module 210 then changes its operating state to the document opening 320 for analyzing the contents of the downloaded document upon completion of the download. If the downloading fails in the downloading step 310, the downloading step 302 proceeds to the wait state 300. [ In addition, if the document is not opened at the opening 320, the process proceeds to the failure 301 and changes to the standby state 300.

After analyzing the contents of the downloaded document, when the document is opened, the document view service module 210 changes the operation state to the display 330 for displaying the analyzed document contents.

If a command to move the page is displayed while the document screen is being displayed, the document view service module 210 performs rendering 340 to render a document screen corresponding to a previous page, a next page, . If the document close command is received during the display 330 or during rendering 340, the document view service module 210 proceeds to end 303 and changes to the wait state 300.

When the rendering is completed, the operation status of the document view service module 210 changes to being displayed 330 again.

The change of the operation state of the document view service module 210 is controlled by the user through the key input unit 150 of the control point 140. [ For this control, the document view service module 210 includes a command for downloading a document (LoadDocument ()), a command for closing a document (CloseDocument ()), a command for next page movement (Next An interface screen for control, such as an instruction (Previous ()) for moving a page and a page jump () (page jump ()) for displaying a page can be displayed through the display unit 250.

Through the above command, the document viewing service module 210 delivers state notification information including operation state information such as document loading, closing, next page movement, previous page movement, and page movement to the control point 100. The schema of the status notification information transmitted to the control point 100 is shown in Table 1 below.

<! - ============================================== ==========
DrawingState
===== <! - ========================================= ===============
Drawi ================================================= == ->
<xsd: element name = "DrawingState">
<xsd: complexType>
<xsd: attribute name = "val" use = "required">
<xsd: simpleType>
<xsd: restriction base = "xsd: string">
<xsd: enumeration value = "OpenFail"/>
<xsd: enumeration value = "Downloading"/>
<xsd: enumeration value = "DownloadFail"/>
<xsd: enumeration value = "Opening"/>
<xsd: enumeration value = "Rendering"/>
<xsd: enumeration value = "Displaying"/>
<xsd: enumeration value = "End"/>
</ xsd: restriction>
</ xsd: simpleType>
</ xsd: attribute>
</ xsd: complexType>
</ xsd: element>
<! - ============================================== ==========
TotalPage
================================================== ====== ->
<xsd: element name = "TotalPage">
<xsd: complexType>
<xsd: attribute name = "val" type = "xsd: unsignedInt" use = "required"/>
</ xsd: complexType>
</ xsd: element>
<! - ============================================== ==========
CurrentPage
================================================== ====== ->
<xsd: element name = "CurrentPage">
<xsd: complexType>
<xsd: attribute name = "val" type = "xsd: unsignedInt" use = "required"/>
</ xsd: complexType>
</ xsd: element>
<! - ============================================== ==========
CurrentResourceTitle
================================================== ====== ->
<xsd: element name = "CurrentResourceTitle">
<xsd: complexType>
<xsd: attribute name = "val" type = "xsd: string" use = "required"/>
</ xsd: complexType>
</ xsd: element>

The status notification information (LastChang) is information transmitted when UPnP-related devices need to inform a control device such as the control point 100 of a certain event or a specific value has changed.

The document view service module 210 receives the current page number, the total page number, the title of the document content, the operation status information of the media player (the failure of downloading the document, the download failure, the download failure, (E.g., displaying a document) to the control point 100. [ At this time, the document view service module 210 images the document content page being output to the display unit 250 of the media player 200 according to the status notification information to be transmitted, and transmits the image to the control point 100.

The process of imaging the document content page will be described in detail with reference to FIG.

4 is a diagram illustrating an exemplary process of displaying a document content page in a document view service module according to an exemplary embodiment of the present invention.

4A is a schematic diagram of the display unit 140 of the control point 100 and FIG. 4B is a diagram illustrating the display unit 250 of the media player 200. FIG.

The control point 100 has the same screen size as the reference numeral 400. If there is a request to display the document contents, the control point 100 transmits information about the screen size of the display unit 140 together with a command for displaying the document contents together with the media player 200).

The document view service module 210 of the media player 200 can maintain the ratio of the document content screen 401 currently displayed on the display unit 250 and the screen width of the display screen 140 of the control point 100 Thumbnail information including the screen width and screen height for the largest document image is generated within a range not exceeding the screen height. Then, the document view service module 210 generates thumbnail image data composed of such thumbnail information.

The schema for the thumbnail generated in the document view service module 210 is shown in Table 2 below.

<action>
<name> GetThumb </ name>
<argumentList>
<argument>
<name> InstanceID </ name>
<direction> in </ direction>
<relatedStateVariable> A_ARG_TYPE_InstanceID </ relatedStateVariable>
</ argument>
<argument>
<name> ClientRect_MaxWidth </ name>
<direction> in </ direction>
<relatedStateVariable> ClientWidth </ relatedStateVariable>
</ argument>
<argument>
<name> ClientRect_MaxHeight </ name>
<direction> in </ direction>
<relatedStateVariable> ClientHeight </ relatedStateVariable>
</ argument>
<argument>
<name> Compress_Method </ name>
<direction> in </ direction>
<relatedStateVariable> CompressMethod </ relatedStateVariable>
</ argument>
<argument>
<name> Display_Width </ name>
<direction> out </ direction>
<relatedStateVariable> Integer </ relatedStateVariable>
</ argument>
<argument>
<name> Display_Height </ name>
<direction> out </ direction>
<relatedStateVariable> Integer </ relatedStateVariable>
</ argument>
<argument>
<name> Thumb_Width </ name>
<direction> out </ direction>
<relatedStateVariable> Integer </ relatedStateVariable>
</ argument>
<argument>
<name> Thumb_Height </ name>
<direction> out </ direction>
<relatedStateVariable> Integer </ relatedStateVariable>
</ argument>
<argument>
<name> Thumb_ColorDepth </ name>
<direction> out </ direction>
<relatedStateVariable> ColorDepth </ relatedStateVariable>
</ argument>
<argument>
<name> Thumb_EncodedData </ name>
<direction> out </ direction>
<relatedStateVariable> Data </ relatedStateVariable>
</ argument>
</ argumentList>
</ action>

In order to transmit the generated thumbnail image data to the control point 100, the document view service module 210 provides a compression algorithm, which is a compression of the thumbnail image generated by the document view service module 210, as a control point. At this time, the compression algorithm provided is shown in Table 3 below.

<stateVariable sendEvents = "no">
<name> CompressMethod </ name>
<dataType> string </ dataType>
<allowedValueList>
<allowedValue> none </ allowedValue>
<allowedValue> zlib </ allowedValue>
</ allowedValueList>
</ stateVariable>

If the control point 100 has a decompression algorithm of the compression algorithm provided by the document view service module, it can select a compression format for compressing the image data when thumbnail information and thumbnail image data are generated in the document view service module. Through this, the document view service module can generate thumbnail image data with a small image data size.

The rendering control service module 220, the connection manager service module 230, and the voice / video transmission service module 240 perform operations in a general media player, so a detailed description of the operation will be omitted.

The display unit 250 displays the document contents according to the document content image display request.

The media server 300 includes a content directory service module 310, a document meta information extractor 320 and a connection manager service module 330 .

The content directory service module 310 reads out and stores the requested document content from the document contents stored in the local disk memory. The content directory service module 310 then provides the document content upon request.

The meta information extraction unit 320 generates meta information which is resource information of document contents stored in the content directory service module 310. [

The connection manager service module 330 is the same as the operation of the general connection management service module, and a detailed description thereof will be omitted.

As described above, according to the document content display request, the media player 300 provides the thumbnail image data of the document contents to the control point 100 while displaying the requested document contents on the screen thereof by the media player 300, So that the structure suitable for the presentation scenario can be performed.

5 is a flowchart illustrating a process for displaying document contents requested by a user in a document content display system on a screen according to an embodiment of the present invention.

In the embodiment of the present invention, it is assumed that the control point 100 and the media server 300 are configured together as a single apparatus.

5, in step 500, when there is a request from the user to display document contents through the key input unit 150 of the control point 100, the media server 300 transmits the document contents stored in the memory to the content directory service module 310 ).

In step 501, the media server 300 extracts meta information of the document contents provided through the meta information extracting unit 320. [ At this time, the meta information includes a plurality of pieces of related information such as the title, the number of pages, and the author of the document contents.

In step 502, the control point 100 searches a media player 300 capable of rendering meta information. At this time, the media player 200 generates and broadcasts a notification message to notify that the document view service is provided, thereby informing the devices in the vicinity of the media viewer that the document view service is provided.

When the notification message is received from the media player 200, the control point 100 identifies in step 503 whether the media player that transmitted the notification information through the media player identification unit 220 is a media player having a document viewing service.

The control point 100 transmits the meta information received from the media server 300 and the display information of the display unit 140 to the media player 300 via the media player 300. [ 200).

In step 507, the media player 200 requests the media server 300 to receive the document content corresponding to the received meta information. In step 508, the media server 200 delivers the requested document content.

In step 509, the media player 200 performs an operation for displaying the document contents received from the media server 300 according to the received operation execution command, thereby displaying the document contents on the screen. At this time, the media player 200 generates a document content image suitable for the display unit 140 of the control point 100.

In operation 510, the media player 200 generates status notification information for informing the operation status according to the operation execution command, and outputs the document content page being output to the display unit 250 to the display unit screen of the control point 100 And transmits it to the control point together with one thumbnail data.

In step 511, the control point 100 displays the status notification information received from the media player 200 on the display unit 140, and displays the received thumbnail data on the display unit 140. For example, when a request for displaying the next page of a document is inputted from the user through the key input unit 150, the control point delivers a command to display the next page of the document. Then, when information indicating a rendering state for displaying the next page of the document is received from the media player, the control point displays the thumbnail data on the display unit, and when the thumbnail data corresponding to the next page of the document is received, the control point displays the information on the display unit.

As described above, according to the present invention, document contents are displayed in a UPnP network environment, so that a document content display function can be easily utilized even in a wireless communication environment such as Wi-Fi, and an operation standard is provided between devices on a UPnP network.

Claims (11)

A control point device for displaying document contents,
A display unit for displaying document contents;
A media player identification unit for reproducing the document content and identifying a displayable media player when a request to display the document content is input;
A status change information receiving unit for receiving status change information indicating an operation performed by the media player according to an operation command; And
Generating an operation command for reproducing and displaying the document content according to a request to display the document content, and displaying the generated operation command, meta information of the document content provided from the media server, and display information of the display unit, And displaying the status change information corresponding to the operation command received from the media player through the display unit and displaying a thumbnail image corresponding to the document content displayed on the media player according to the operation command, And a display unit
Lt; / RTI &gt;
Wherein the thumbnail image is generated by the media player based on the display information of the display unit and the document content displayed on the media player in accordance with the operation command, in accordance with the status change information. The method according to claim 1,
The document viewing control unit,
And a decompression algorithm for decompressing the thumbnail image from the media player. A media player for displaying document content,
An operation command for reproducing and displaying document contents from a control point, meta information of the document content, and display information of a display unit included in the control point, downloading document contents corresponding to the meta information from a media server, Reproducing the document content according to the operation command, displaying the document content, generating state change information indicating an operation performed by the media player according to the operation command, Generates a thumbnail image based on display information of a display unit included in the control point and document contents displayed according to the operation command, and transmits the generated state change information and the generated thumbnail image to the control point Document View Service Module; And
And a display unit
Lt; / RTI &gt;
Wherein the thumbnail image is displayed through a display unit included in the control point. The method of claim 3,
The media server comprises:
A content directory service module for searching and providing document contents requested by a user; And
A meta information extracting unit for generating meta information that is resource information on the searched document contents and providing the meta information to the control point,
Lt; RTI ID = 0.0 &gt; The method of claim 3,
The document viewing service module,
And generates the thumbnail image to be displayed on the display unit of the control point using the display information. The method of claim 3,
The document viewing service module,
Generate a decompression algorithm for decompressing the thumbnail image, and transmit the generated decompression algorithm to the control point. A method for displaying document content at a control point,
Reproducing a document content according to the request to identify a displayable media player when a request to display the document content is input;
Generating an operation command for reproducing and displaying the document content according to a request to display the document content when the media player is identified;
Transmitting the created operation command, meta information of the document content provided from the media server, and display information of a display unit included in the control point to the identified media player;
Receiving, from the media player, a thumbnail image corresponding to document contents displayed in the media player according to the operation command and status change information indicating an operation performed by the media player according to the operation command; And
Displaying the thumbnail image corresponding to the document content displayed on the media player through the display unit according to the status change information and the operation command
/ RTI &gt;
Wherein the thumbnail image is generated by the media player based on the display information of the display unit and the document content displayed on the media player in accordance with the operation command in accordance with the status change information. 8. The method of claim 7,
Receiving a decompression algorithm for decompressing the thumbnail image from the media player;
And displaying the document content. A method for displaying document content in a media player,
Receiving an operation command for reproducing and displaying document contents from a control point, meta information of the document content, and display information of a display unit included in the control point;
Downloading document contents corresponding to the meta information from a media server;
Reproducing and displaying the document content according to the operation command;
Generating status change information indicating an operation performed by the media player according to the operation command after displaying the document content;
Generating a thumbnail image based on the display information of the display unit included in the control point and the document contents displayed according to the operation command according to the state change information; And
And transmitting the generated state change information and the generated thumbnail image to the control point
/ RTI &gt;
Wherein the thumbnail image is displayed through a display unit included in the control point. 10. The method of claim 9,
Wherein the generating the thumbnail image comprises:
And generates the thumbnail image to be displayed on the display unit of the control point using the display information. 10. The method of claim 9,
Generating a decompression algorithm for decompressing the thumbnail image; And
Transmitting the generated release algorithm to the control point
And displaying the document content.

Images