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graphics-overview.xml
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<sect1 id="sect-graphical-overview">
<title>The basics of Graphical Elements</title>
<para>
<application>Gnumeric</application> 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>
<application>Gnumeric</application> 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 <application>Gnumeric</application> 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
<application>Gnumeric</application> 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. <application>Gnumeric</application> 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 <application>Gnumeric</application> 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>
</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 <application>Gnumeric</application> 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 version 1.3 of
<application>Gnumeric</application> 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
<application>Gnumeric</application> 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>