
<sect1 id="sect-graphical-overview">
  <title>Overview</title>

  <para>
    &gnum; provides several types of
    graphical elements which can be added to a worksheet. The
    creation, manipulation and deletion of these elements all occur in
    similar ways. When these elements are part of a worksheet, they
    all "float" above the cell grid, possibly hiding data in the cells
    underneath.
  </para>

  <para>
    &gnum; currently displays four
    different types of graphical elements: data graphs, images,
    widgets, and drawings. Data graphs allow users to present
    worksheet data visually in charts containing several kinds of
    plots including pie plots, bar and column plots, and
    scatterplots. Images in many standard computer formats can be
    added to a worksheet. Graphical user interface widgets can also be
    added to a worksheet and connected to the values contained in
    worksheet cells. Drawings allow users to add simple graphical
    elements on top of a worksheet including lines, arrows and simple
    polygons.
  </para>

  <figure id="fig-gnumeric-graphical-elements">
    <title>
      The four types of graphical elements.
    </title>
    <screenshot>
      <mediaobject>
        <imageobject>
          <imagedata fileref="figures/graphical-elements.png" 
              format="PNG" />
        </imageobject>
        <textobject>
          <phrase>
             An image of &gnum; showing
             the four types of graphical elements which can be added
             to a worksheet: a data graph with a column plot, an image
             showing a map of France, a scrollbar which can be
             used to alter the value in cell "I6", and a drawing
             element: a red arrow.
          </phrase>
        </textobject>
	<caption>
	  <para>
            The four types of graphical elements which can be added to
            a worksheet: a data graph with a column plot, an image
            showing a map of France, a scrollbar which can be
            used to alter the value in cell "I6", and a red arrow drawing
            element.
          </para>
	</caption>
      </mediaobject>
    </screenshot>
  </figure>

  <para>
    The various graphical elements which can be added to a
    &gnum; worksheet all behave in
    similar ways. The graphical elements all "float" above the cells
    in the cell grid and may obscure the contents of the cells
    behind, without affecting the contents of these hidden cells. All
    graphical elements are added in essentially the same way by
    selecting the element to add and then using the mouse, either with
    a simple click to place the element with a default size or with a
    click and drag to select the area of the worksheet to be covered
    by the element. These objects are moved or re-sized by clicking on
    the object with the primary mouse button and using the object
    body, border and "handles" (the small circles which appear at the
    corners and in the middle of each side) to manipulate the
    object. All of these objects will present a context menu through
    which to change the properties of the object, to save the object
    as an image, to change the stacking order (which graphical
    elements are in front of others), or to delete the object. Each of
    these operations will be summarized below and then explained in
    greater detail in the sections which follow.
  </para>


  <sect2 id="sect-graphical-overview-adding">
    <title>Adding Graphical Elements</title>

    <para>
      All graphical elements are added in similar ways which differ
      only in the original selection and configuration of the
      element. Data graphs are added using the <interface>Graph
      Guru</interface>, which is invoked either through the
      <guimenu>Insert</guimenu> menu or with the toolbar button, to
      define the properties of the graph. Images are added using the
      <guimenu>Insert</guimenu> menu
      <guimenuitem>Image...</guimenuitem> menu entry, selecting the
      name of the file with the appropriate image and clicking on the
      <guibutton>Open</guibutton> button. Widgets and drawing elements
      are added by selecting the appropriate button on the object
      toolbar.
    </para>

    <para>
      After any of these steps, the mouse cursor will change into a
      thin cross-hair cursor, <inlinemediaobject>
            <imageobject>
              <imagedata fileref="figures/pointer_cross_hair.png" />
            </imageobject>
            <textobject>
              <phrase>An image of the thin cross hair mouse pointer.</phrase>
            </textobject>
           </inlinemediaobject>,
      when the mouse pointer is placed over the cell grid area.
    </para>

    <para>
      The graphical element can be placed in the workbook by moving
      the cursor onto the worksheet and clicking once with the primary
      mouse button. The graphical element will appear at its default
      size with the top right hand corner defined by the position of the
      mouse cursor.
    </para>

    <para>
      Alternatively, the graphical element can both be placed on the
      worksheet and have its size determined which is done by
      click-dragging with the mouse. When the cursor has changed to
      the thin cross-hair, the graphical element can be inserted by
      moving the pointer over the worksheet to determine one of the
      corners of the resulting element, clicking and holding the
      primary mouse button, dragging the pointer to the opposite
      corner, and releasing the mouse button. The graphical element
      will then appear between the place where the primary mouse
      button was pressed and the place the button was released.
    </para>

  </sect2>


  <sect2 id="sect-graphical-overview-selecting">
    <title>Selecting Graphical Elements</title>

    <para>
      Selecting the graphical element requires placing the mouse
      pointer over the element and then clicking the primary mouse
      button. &gnum; indicates the
      element is selected by drawing eight 'grab handles' around the
      element; these are small circles at the four corners and in the
      middle of the four edges of a rectangle surrounding the
      graphical element.
    </para>

  <figure id="fig-gnumeric-graphical-elements-selectd">
    <title>
      A graphical element which has been selected.
    </title>
    <screenshot>
      <mediaobject>
        <imageobject>
          <imagedata fileref="figures/graphical-elements-selected.png" 
              format="PNG" />
        </imageobject>
        <textobject>
          <phrase>
             An image of several graphical elements of which one has
             been selected, and is therefore showing its grab handles.
	  </phrase>
        </textobject>
	<caption>
	  <para>
            The graphical column plot has been selected as evidenced
            by the eight small circular 'grab handles' at the corners
            and in the middle of each edge.
          </para>
	</caption>
      </mediaobject>
    </screenshot>
  </figure>


    <para>
      The mouse pointer will also change shape when placed over a
      selected element or over the element's 'grab handles'. When the
      pointer is placed over a selected element, the mouse pointer
      will change to the 'move' shape, <inlinemediaobject>
            <imageobject>
              <imagedata fileref="figures/pointer_four_way_arrow.png" />
            </imageobject>
            <textobject>
              <phrase>An image of the move mouse pointer.</phrase>
            </textobject>
           </inlinemediaobject>;
      when the pointer is placed over the element's 'grab handles' it
      will change to one of the resizing mouse pointer shapes, which
      are presented in <xref linkend="sect-gui-mouse" />.
    </para>

    <note>
      <para>
        Some elements, such as the widget scrollbars, may be difficult
        to select because they interact themselves with the primary
        mouse button. An alternative selection process, which involves
        first invoking the context menu and then dismissing it, can be
        used for these elements and will work with any graphical
        element. When the mouse pointer is anywhere over the graphical
        element, clicking with one of the secondary mouse buttons will
        cause the element to be selected and a context menu to appear.
        If the primary mouse button is then pressed while the pointer
        is anywhere over the desktop other than over the menu, the
        context menu will be dismissed but the element will stay
        selected.
      </para>
    </note>	

  </sect2>

 <sect2 id="sect-graphical-overview-moveNresize">
    <title>Moving and Resizing Graphical Elements</title>

    <para>
      Graphical elements can be moved from their original location on
      the worksheet or can be changed in size or shape. All of these
      operations first require selecting the graphical element with
      the primary mouse button and then using this mouse button and
      the mouse pointer to manipulate the element.
    </para>


    <sect3 id="sect-graphical-overview-moveNresize-mouse">
      <title>Moving elements with the mouse</title>

    <para>
      Moving the graphical element can be performed by first selecting
      the graphical element, then placing the mouse pointer over the
      element which will change it to the 'move' mouse shape,
        <inlinemediaobject>
            <imageobject>
              <imagedata fileref="figures/pointer_four_way_arrow.png" />
            </imageobject>
            <textobject>
              <phrase>An image of the move mouse pointer.</phrase>
            </textobject>
           </inlinemediaobject>,
      clicking and holding the primary mouse button and moving the
      mouse pointer to a new location. As the mouse is moved with the
      primary mouse button held down, the graphical element will move
      along with the mouse cursor. When the mouse button is released,
      the object will stay in its new location.
    </para>

    </sect3>

    <sect3 id="sect-graphical-overview-moveNresize-move-keys">
      <title>Moving elements with the arrow keys</title>

      <para>
        Once they are selected, graphical elements can be moved with
        the arrow keys on the keyboard. The movement can be made in
        smaller increments if the <keycap>Ctrl</keycap> key is held
        simultaneously. 
      </para>

    </sect3>

    <sect3 id="sect-graphical-overview-moveNresize-resize">
      <title>Resizing and reshaping elements</title>

    <para>
      Changing the size or shape of the graphical element can be
      performed by selecting the graphical element, placing the mouse
      pointer over one of the 'grab handles' at the corners or edges
      of the rectangular box around the element, which will cause the
      mouse pointer to change shape to one of the resize pointers,
      clicking and holding with the primary mouse button, dragging the
      corner or edge to a new position, and releasing the mouse
      button. If one of the corner 'grab handles' is used, the
      graphical element can be altered into any new rectangular
      shape and size. If one of the edge handles is used, the element
      can only be reshaped perpendicular to the chosen edge.
    </para>

    </sect3>

  </sect2>


  <sect2 id="sect-graphical-overview-contextmenu">
    <title>Invoking the Context Menu for Graphical Elements</title>

    <para>
      Many operations on graphical elements, including changing their
      internal properties, saving elements as images, modifying the
      stacking order of the elements, and deleting the elements, are
      performed through the context menu. The context menu appears
      when the mouse pointer is placed over the graphical element and
      one of the secondary mouse buttons is clicked. When the mouse
      pointer moves over a graphical element, it will change from the
      usual wide cross cursor to a right pointing arrow
      cursor. Clicking with the primary mouse button will select the
      graphical element but clicking with one of the other mouse
      buttons will open the context menu. The specific button that
      will trigger this menu depends on the specific hardware and
      configuration of the computer. By default it is usually the
      rightmost mouse button.
  </para>  

  <figure id="fig-gnumeric-graphical-overview-contextmenu">
    <title>
      The context menu for graphical elements.
    </title>
    <screenshot>
      <mediaobject>
        <imageobject>
          <imagedata fileref="figures/menu-context-graph.png" 
              format="PNG" />
        </imageobject>
        <textobject>
          <phrase>
             An image of &gnum; showing
             the context menu of a graph element.
          </phrase>
        </textobject>
	<caption>
	  <para>
            The context menu for graph elements is the most
            complete. It includes an entry to modify the internal
            properties of the graph, an entry to save the graph as an
            image, four entries to reorder the stacking of the graph
            in front or behind other graphs and one entry to delete
            the graph.
          </para>
	</caption>
      </mediaobject>
    </screenshot>
  </figure>

  <para>
    The context menu for graphical elements contains a sub-menu
    labelled <guimenuitem>Order</guimenuitem> which allows the user to
    change the presentation order for overlapping graphical objects.
  </para>

  <figure id="fig-gnumeric-graphical-overview-contextmenu-order">
    <title>
      The order submenu of graphical element context menus.
    </title>
    <screenshot>
      <mediaobject>
        <imageobject>
          <imagedata fileref="figures/menu-context-graph-order.png" 
              format="PNG" />
        </imageobject>
        <textobject>
          <phrase>
             An image of the order sub-menu in the context menu of
             graph elements.
          </phrase>
        </textobject>
	<caption>
	  <para>
            The order submenu of the context menu for graph elements
            allows the user to change the stacking order for the
            various graphs on the worksheet. This will affect which
            objects are visible in front of other objects when several
            objects overlap.
          </para>
	</caption>
      </mediaobject>
    </screenshot>
  </figure>


  </sect2>


  <sect2 id="sect-graphical-overview-modifing">
    <title>Modifying Graphical Elements</title>

    <para>
      Many of the graphical elements have internal properties which
      can be changed. This includes the contents of a particular
      graph, the association of a widget and the contents of a
      spreadsheet cell, or the characteristics of a drawing
      element. These properties can be altered using the
      <guimenuitem>Properties...</guimenuitem> menu item in the
      context menu which appears when the mouse pointer is placed over
      the graphical element and one of the secondary mouse buttons is
      clicked. After the context menu appears, clicking on this menu
      item will open up a dialog allowing the user to alter the
      properties of the element. Since these properties are specific
      to each element, these dialogs will be discussed in each of the
      sections below.
    </para>

  </sect2>

  <sect2 id="sect-graphical-overview-saving">
    <title>Saving Graphical Elements as Images</title>

    <para>
      Some of the graphical elements, the data graphs and the image
      elements, provide an item in the context menu which allows the
      element to be saved to a file containing only an image of that
      element. Graphical plots can be saved in Scalable Vector
      Graphics (SVG), Portable Network Graphics (PNG) or JPEG
      formats. Images can be saved to their original format, or to PNG
      and JPEG formats. 
    </para>

    <para>
      Elements which can be saved as images can be output to a file
      using an entry in the element's context menu. First the context
      menu must be invoked by placing the mouse pointer over the
      graphical element and clicking with one of the secondary mouse
      buttons. Next the <guimenuitem>Save as Image</guimenuitem> or
      the <guimenuitem>Save as</guimenuitem> menu items must be
      selected by placing the mouse pointer over that item and
      clicking with the primary mouse pointer. This will open up the
      <interface>Save As</interface> dialog which will allow the user
      to name the file which will be created, select where the file
      will be created, select the file type to use for the image and
      then generate the file.
    </para>

  </sect2>

<!-- TODO: explain the image object Save As dialog better. -->


  <sect2 id="sect-graphical-overview-restacking">
    <title>Restacking Graphical Elements</title>

    <para>
      Graphical elements can overlap when they are placed over the
      cell grid area. Conceptually, each graphical element occupies
      one layer in a stack of all the elements. By default, elements
      which have been created more recently will overlap in front of
      elements which were created earlier.
    </para>

  <figure id="fig-gnumeric-graphical-overview-stacking">
    <title>
      Stacked graphical elements.
    </title>
    <screenshot>
      <mediaobject>
        <imageobject>
          <imagedata fileref="figures/graphical-elements-stacked.png" 
              format="PNG" />
        </imageobject>
        <textobject>
          <phrase>
             An image of &gnum; showing
             stacked graphical element.
          </phrase>
        </textobject>
<!--	<caption>
	  <para>
          </para>
	</caption>
-->
      </mediaobject>
    </screenshot>
  </figure>

    <para>
      The order of each element in the stack can be changed using the
      four menu items in the context menu. The
      <guimenuitem>Top</guimenuitem> will bring the selected element
      in front of all the other objects. The
      <guimenuitem>Up</guimenuitem> menu item will bring the selected
      element forward one layer.  Conversely, the
      <guimenuitem>Down</guimenuitem> menu item will move the selected
      element one layer towards the back, and the
      <guimenuitem>Bottom</guimenuitem> menu item will palace the
      selected element at the very back of the stack of
      elements. Jointly, these menu items allow the user to specify
      exactly which order in which the graphical elements should appear.
    </para>

    <warning>
      <para>
        The stacking of graphical elements in &gnum; is currently not working
        correctly. Widget elements are always placed above the other
        elements and do not honor the same ordering scheme as the rest
        of the elements. A large amount of work will be required to
        fix this and a decision has been made to ignore this problem
        until the developers have the time to fix this problem
        correctly.
      </para>
    </warning>

  </sect2>


  <sect2 id="sect-graphical-overview-deleting">
    <title>Deleting Graphical Elements</title>

    <para>
      All of the graphical elements in
      &gnum; can be deleted using the
      context menu. Deleting a graphical element will never alter the
      data contents of the cells in the workbooks.
    </para>

    <para>
      Deleting a graphical element requires using the context
      menu. First the mouse pointer must be placed over the graphical
      element. Next, the context menu must be invoked by clicking with
      one of the secondary mouse buttons. Finally, the
      <guimenuitem>Delete</guimenuitem> menu item must be selected by placing
      the mouse pointer over this menu item and clicking with the
      primary mouse button. When this menu item is selected, the
      graphical element will disappear from the worksheet and will not
      be saved as part of the spreadsheet file the next time the file
      is saved.
    </para>

  </sect2>


</sect1>

