Within this dialog you can style your vector layer. Depending on the selected rendering option you have the possibility to also classify your map features.
<li><label>Continuous color</label> - objects within the layer are displayed with a spread of colors classified by the numerical values within a specified field.
QGIS allows setting a transparency for every vector layer. This can be done with the slider <label>Transparency</label>. This is very useful for overlaying several vector layers.
Once you have styled your layer you also could save your layer-style to a separate file (with *.qml ending). To do this, use the button <label>Save Style...</label>. No need to say that <label>Load Style...</label> loads your saved layer-style-file.<br/>
If you wish to always use a particular style whenever the layer is loaded, use the <label>Save As Default</label> button to make your style the default. Also, if you make changes to the style that you are not happy with, use the <label>Restore Default Style</label> button to revert to your default style.
<a name="labels">
<h4>Labels</h4>
</a>
The Labels tab allows you to enable labeling features and control a number of options related to fonts, placement, style, alignment and buffering.<br/>
Select the use the <label>Font</label> and <label>Color</label> buttons to set the font and color. You can also change the angle and the placement of the text-label.<p>
If have labels extending over several lines, check <label>Multiline labels?</label>. QGIS will check for a true line return in your label field and insert the line breaks accordingly. A true line return is a single character \n, (not two separate characters, like a backslash \ followed by the character n).
<li>Choose a size for the buffer using the spin box.
<li>Choose a color by clicking on <label>Color</label> and choosing your favorite from the color selector. You can also set some transparency for the buffer if you prefer.
<li>Click <label>Apply</label> to see if you like the changes.
<h5>Data defined placement, properties, buffer, position</h5>
The remaining entries inside the <label>Label</label> tab allow you control the appearance of the labels using attributes stored in the layer. The entries beginning with <label>Data defined</label> allow you to set all the parameters for the labels using fields in the layer.
Within the <label>Attributes</label> tab the attributes of the selected data set can be manipulated. The buttons <label>New Column</label> and <label>Delete Column</label> can be used, when the data set is in editing mode. The OGR library supports to add new columns, but not to remove them, if you have a GDAL version >= 1.6 installed. Otherwise only columns from PostGIS layers can be edited.<p>
The <label>Toggle editing mode</label> button toggles this mode.<p>
Within the Attributes tab you also find an edit widget column. This column can be used to define values or a range of values that are allowed to be added to the specific attribute table column. If you click on the <label>edit widget</label> button, a dialog opens, where you can define different widgets. These widgets are:<br/>
<li><label>Classification</label> Displays a combo box with the values used for classification, if you have chosen <label>unique value</label> as legend type in the symbology tab of the properties dialog.
<li><label>Unique value</label> The user can select one of the values already used in the attribute table. If <label>editable</label> is activated, a line edit is shown with auto completion support, but additional values are possible, otherwise a combo box is used.
<li><label>Value map</label> a combo box with predefined items. The value is stored in the attribute, the description is shown in the combo box. You can define values manually or load them from a layer or a csv file.
<li><label>Enumeration</label> Opens a combo box with values that can be used within the columns type. This is currently only supported by the Postgres provider.
The General tab allows you to change the display name, set scale dependent rendering options, create a spatial index of the vector file (only for OGR supported formats and PostGIS) and view or change the projection of the specific vector layer.<p>
The <label>Metadata</label> tab contains information about the layer, including specifics about the type and location, number of features, feature type, and the editing capabilities. The Layer Spatial Reference System section, providing projection information, is displayed on this tab. This is a quick way to get information about the layer.
QGIS provides the ability to perform an action based on the attributes of a feature. This can be used to perform any number of actions, for example, running a program with arguments built from the attributes of a feature or passing parameters to a web reporting tool. <br/>
The new implementation of actions uses the QGIS expression engine to do evaluations. Each expression is evaluated and replaced by its result at runtime.<p>
An expression must be enclosed between <code>[%</code> and <code>%]</code> - the GUI has some buttons which do that for you automatically.
The <label>Insert expression...</label> button launches the <label>Expression builder</label> which allows writing an expression easily, the <label>Insert field</label> button inserts into the action a placeholder like <code>[% "fieldname" %]</code> where fieldname is the name of the field selected in the field dropdown list.<p>
Each action adds a little set of custom expressions to the default set available in the <label>Expression builder</label>.<br/>
While running actions from the <label>Identify Results</label> dialog the custom expression <code>$currfield</code> will be replaced with the value of the selected field in the dialog, using the <label>Run feature action</label> tool the following custom expressions are available (instead of $currfield):
Note: the <label>Run feature action</label> tool executes the actions on all the matching features, where as <label>Identify Results</label> allows you to select which specific feature to run action on.<p>
The Diagram tab allows you to add a graphic overlay to a vector layer. To activate this feature, open the <label>Plugin Manager</label> and select the <label>Diagram Overlay</label> plugin. After this, there is a new tab in the vector <label>Layer Properties</label> dialog where the settings for diagrams may be entered.<p>
