Overview

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 Graph Guru, which is invoked either through the Insert menu or with the toolbar button, to define the properties of the graph. Images are added using the Insert menu Image... menu entry, selecting the name of the file with the appropriate image and clicking on the Open button. Widgets and drawing elements are added by selecting the appropriate button on the object toolbar.

After any of these steps, the mouse cursor will change into a thin cross-hair cursor, , when the mouse pointer is placed over the cell grid area.

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.

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.

Selecting the graphical element requires placing the mouse pointer over the element and then clicking the primary mouse button. Gnumeric 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.

Figure 9-2  A graphical element which has been selected.

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.

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, ; 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 Section 4.8 ― The Mouse Pointers used by Gnumeric.

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.

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.

Figure 9-3  The context menu for graphical elements.

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.

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

Figure 9-4  The order submenu of graphical element context menus.

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.

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 Properties... 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.

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.

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 Save as Image or the Save as 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 Save As 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.

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.

Figure 9-5  Stacked graphical elements.

The order of each element in the stack can be changed using the four menu items in the context menu. The Top will bring the selected element in front of all the other objects. The Up menu item will bring the selected element forward one layer. Conversely, the Down menu item will move the selected element one layer towards the back, and the Bottom 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.

All of the graphical elements in Gnumeric can be deleted using the context menu. Deleting a graphical element will never alter the data contents of the cells in the workbooks.

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 Delete 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.