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Date: Fri, 13 Dec 1996 17:06:32 GMTServer: NCSA/1.5Content-type: text/htmlLast-modified: Wed, 30 Oct 1996 19:02:00 GMTContent-length: 17333<HTML><HEAD><TITLE>DEVise Visual Query Interface</TITLE></HEAD><BODY><H1>Visual Query Interface</H1><P>This section discusses the Visual Query interface of DEVise:<UL><LI><!WA0><!WA0><!WA0><a href="#Intro">Introduction</A><LI><!WA1><!WA1><!WA1><a href="#Session">Session</A><LI><!WA2><!WA2><!WA2><A href="#How">How</A> to represent data.<LI><!WA3><!WA3><!WA3><A href="#What">What</A> to visualize.<LI><!WA4><!WA4><!WA4><A href="#Where">Where</A> to place graphics.<LI>Command <!WA5><!WA5><!WA5><A href="#Summary">Summary</A>.</UL><A name="Intro"><H2>Introduction</H2></A>In a database environment, users ask their questions by formulatingqueries over the underlying database. The query output are theanswers to these questions. The same questions can be asked over and over on different sets of input data. The same principle applies when graphicsis used to represent data. The difference is that visual queries areformulated using a graphical user interface, against graphical data.<P>When formulating visual queries, users start with a set of input data.Graphical representations of the input data are generated, perhapsthrough extensive experimentations. Users would navigate the data to look forplaces of interest. Sometimes users might need additional help by lookingat the original data represented by the graphics. The stateof the visualization environment forms a visual query. Just likea database query, the visual query can be saved, and applied over andover to different sets of input data.<P>A visual query is constructed by manipulating the system componentsin DEVise to create component instances and interconnections. Thesecomponents are derived from a <!WA6><!WA6><!WA6><A href="http://www.cs.wisc.edu/~devise/devise/model.html">model ofvisualization</A>. The visual query interface manipulates thesecomponents to allow the user to specify what data is to be visualized,how data is to be visualized, and where to place the graphics on thedisplay.<A name="Session"><H2>Session</H2></A>The state of each visual query is stored as a session. Sessions areaccessed from the Session menu, with the following menu items:<UL><LI>Open: restore a previously saved visual query to its original state.<LI>Open as template: Apply a previously saved visual query to a differentset of input data. The user selects the new input data when session isrestored.<LI>Close: close current session.<LI>Save: save visual query to file, to be restored later.<LI>Save as: save visual query under a different name.<LI>Save as Template: save visual query as a template.<LI>Print: print contents of window or save as Postscript.<LI>Quit: quit DEVise.</UL><A name="How"><H2>How to represent data</H2></A>The following commands are used to specify what the user wantsto visualize:<UL><LI><!WA7><!WA7><!WA7><A href="#DefineMapping">Define Mapping</A><LI><!WA8><!WA8><!WA8><A href="#EditMapping">Edit Mapping</A><LI><!WA9><!WA9><!WA9><A href="#Size">Controlling Shape Size</A></UL><A name="DefineMapping"><H3>Define Mapping</H3></A>The ``Visualize/Define'' command lets the user define new datastreams (TData) and new visualizations to the system. The stepsrequired to create a new visualization are summarized here:<OL><LI>Select a data stream by pulling down the Source selector, or selectthe Open... command at the bottom of the selector to define a new datastream.<LI>Click on Auto... to run the automatic mapping utility.<LI>Select the attributes of visualization from the dialog box, includingthe X attribute, one or more Y attributes, window name and layout, andother options.<LI>Click on OK to create the new visualization.</OL><A name="EditMapping"><H3>Edit Mapping</H3></A>The ``View/Edit Mapping'' menu command allows the user to experimentwith the mapping of a GData in the view. A dialog box appears,allowing the user to edit the mapping. The dynamic nature of editingthe mapping is valuable during data exploration because theeffectiveness of graphics may vary for different locations in thedata, and for different zoom factors as well. The user can change allattributes of the visualization, including the X, Y, color, shape,size, pattern, and orientation attributes. Optional parameters, suchas shape width and height, can also be defined.<A name="Size"><H3>Controlling Shape Pixel Size</H3></A>Sometimes the size of shapes are so small that they appear as singlepixels when drawn inside a view:<P><!WA10><!WA10><!WA10><img src="http://www.cs.wisc.edu/~devise/devise/small.gif"><P>It is often desirable to accentuate these shapes by enlarging theirsizes to be bigger than a single pixel:<P><!WA11><!WA11><!WA11><img src="http://www.cs.wisc.edu/~devise/devise/large.gif"><P>Controlling the actual size of pixel sized shapes is done viakeyboard commands directed at a view. The '+' key increases thesize of shapes, while the '-' key decreases the size of the shapes.<A name="What"><H2>What to Visualize</H2></A>There are many ways to specify what the user wants to look at:<UL><LI><!WA12><!WA12><!WA12><A href="#Control">Control Panel widgets</A><LI><!WA13><!WA13><!WA13><A href="#Mode">Layout versus Display mode</A><LI><!WA14><!WA14><!WA14><A href="#Axes">Axes</A><LI><!WA15><!WA15><!WA15><A href="#Mouse">Mouse and Keyboard Events</A><LI><!WA16><!WA16><!WA16><A href="#History">History Window</A><LI><!WA17><!WA17><!WA17><A href="#VisualLink">Visual Link</A><LI><!WA18><!WA18><!WA18><A href="#Cursor">Cursor</A><LI><!WA19><!WA19><!WA19><A href="#Switch">Switch TData</A><LI><!WA20><!WA20><!WA20><A href="#Duplicate">Duplicate Window</A><LI><!WA21><!WA21><!WA21><A href="#Query">Data Querying</A></UL><A name="Control"><H3>Control Panel Widgets</H3></A><!WA22><!WA22><!WA22><img src="http://www.cs.wisc.edu/~devise/devise/control.gif" align=middle><p>The widgets on the control panel are mainly used for navigating thedata. The ``current view'' text widget<p><!WA23><!WA23><!WA23><img src="http://www.cs.wisc.edu/~devise/devise/current.gif"><p>displays the name of the view that the user wishes tonavigate. User commands initiated from the control panel widgets areapplied to the current view. The user selects a view as the currentview by clicking inside its boundary with the left mouse button.Interactions with widgets for navigation are translated into changingthe visual filter of the current view. The widgets used for navigationare as follows:<UL><LI><!WA24><!WA24><!WA24><img src=http://www.cs.wisc.edu/~devise/devise/button.gif>The arrow widgets are used to scroll left, right, up, and down. The 4 widgets around the arrows are for zooming inand out in the X or Y directions.<LI><!WA25><!WA25><!WA25><img src=http://www.cs.wisc.edu/~devise/devise/filter.gif>The text widgets are used forediting the new X and/or Y ranges. Clicking the `use' buttonchanges the view's visual filter. The `undo-edit' button is used to undothe editing.<LI>The `back one' button goes back one step in the history of changesto the current view's visual filter. Clicking `use' moves back one step,while clicking `undo' cancels the change.<LI>Clicking the `history' widget brings up the history window.</UL><A name="Mode"><H3>Layout vs. Display Modes</H3></A>DEVise has two modes of operation:layout and display modes. Userstoggle between these two modes by clicking at the <!WA26><!WA26><!WA26><img src="http://www.cs.wisc.edu/~devise/devise/mode.gif">button. In the layout mode, the user constructs mappings and views anddecides where to place views in windows without having the graphicsupdate in the window. The windows are eventually updated when the userswitches into display mode.<P>Placing DEVise in the layout mode is a time saver when large amountsof data are involved. The layout mode allows the user to construct a visualquery without waiting for the graphics to be updated. Otherwise, adding a view in a window may cause all other views already in the same window, together with linked views in other windows, to be updated simultaneously.may take a long time.<A name="Axes"><H3>Axes</H3></A>The user can turn the display of view axes on/off. This is accessedthrough the ``View/Toggle X Axis'' and the ``View/Toggle Y Axis''menus.<A name="Mouse"><H3>Mouse and Keyboard Events</H3></A>The user can use the following mouse commands:<UL><LI>Click anywhere in a view with the left button to select the viewas the current view.<LI>Click in a view with the middle button to <!WA27><!WA27><!WA27><a href="#Query">query</A>the data that lies under the graphical object closest to the mouselocation.<LI>Click on left, right, up, or down arrow in the control panel toscroll a view.<LI>Click on zoom in or out buttons in control panel to zoom in orout of a view in the X or Y direction.<LI>Draw a rectangle with the left mouse button pressed in a view tozoom only in the X axis (best for bar graphs).<LI>Draw a rectangle with the right mouse button pressed in a view tozoom in the X and Y axes (best for scatter plots).</UL>The following keyboard commands are available:⌨️ 快捷键说明
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