Adding objects to the Dia canvas can be accomplished by clicking on the desired object in the Toolbox to select what you want placed on the canvas. Clicking on the canvas will then place the object on the canvas.
Dia provides two types of objects:
User-defined objects allow a user to create their own objects, which are based off of a prefabricated template.
For example, clicking on the square object and placing it on the canvas, creates a square. However, the dimensions of the object can be changed. See the Resizing Objects section for more information.
Pre-defined objects are mostly designs which cannot be edited. They can be resized, but the object itself cannot be edited.
When an object is inserted into the canvas, the desired object will appear with small green boxes (also known as handles) defining the borders.
The area inside the boxes is the object area. Click and hold on the
object area. Then move the mouse around, inside the canvas, to move
the object to another place on the canvas.
The previous paragraph, explains the concept of the green boxes. These are used to manipulate the size of the object. To change the size, click and hold on a green button. Drag to the respective size, then let go.
The corner green buttons will change both the height and the width at the same time. The two on the top and bottom edges, in the center will edit height while the two on the left and right edges, in the center will edit width. Some shapes
To drag with the corner buttons, but keep proportions, hold the shift key while resizing. This only applies to the special objects, not regular shapes.
To delete an object, click on the object to select it. The green boxes will appear to indicate the object is selected. From the menus choose Edit, Delete.
Dia provides some functionality to help arrange mulitple objects without needing to move each object individually.
Grouping allows you to treat several objects as a unified group that acts a lot more like a single object. A group enables you to fix the position of the objects in releation to each other. Select more than one object and then from the menu choose Object, Group to group them.
One of Dia's objects is the line. The line object is symbolized by the following icon:
Lines can be easily edited to easily create items such as arrows. At the bottom of the toolbox is 3 buttons with lines through them. Clicking and holding will open up a menu which demonstrates what the change will look like.
Lines can employ different style types such as:
Solid
Dashed
Dash-Dot
Dash-Dot-Dot
Dotted
The thickness of lines can be edited by clicking on the five thicknesses to the right of the color selector.
The line tool can be used to create arrows. By clicking on the two side buttons on the bottom of the toolbox, a menu pulls out showing the possible beginning and end designs for the arrows.