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QGIS GUI

When QGIS starts, you are presented with the GUI as shown below (the numbers 1 through 5 in yellow circles refer to the five major areas of the interface as discussed below):

Figure QGIS GUI 1:

../../../_images/startup.png

QGIS GUI with Alaska sample data nix

註解

Your window decorations (title bar, etc.) may appear different depending on your operating system and window manager.

The QGIS GUI is divided into five areas:

  1. Menu Bar
  2. Tool Bar
  3. Map Legend
  4. Map View
  5. Status Bar

These five components of the QGIS interface are described in more detail in the following sections. Two more sections present keyboard shortcuts and context help.

Toolbar

The toolbar provides access to most of the same functions as the menus, plus additional tools for interacting with the map. Each toolbar item has popup help available. Hold your mouse over the item and a short description of the tool’s purpose will be displayed.

Every menubar can be moved around according to your needs. Additionally every menubar can be switched off using your right mouse button context menu holding the mouse over the toolbars (read also Panels and Toolbars).

小技巧

Restoring toolbars

If you have accidentally hidden all your toolbars, you can get them back by choosing menu option Settings ‣ Toolbars ‣. If a toolbar disappears under Windows, which seems to be a problem in QGIS from time to time, you have to remove \HKEY_CURRENT_USER\Software\QGIS\qgis\UI\state in the registry. When you restart QGIS, the key is written again with the default state, and all toolbars are visible again.

Map Legend

The map legend area lists all the layers in the project. The checkbox in each legend entry can be used to show or hide the layer.

A layer can be selected and dragged up or down in the legend to change the z-ordering. Z-ordering means that layers listed nearer the top of the legend are drawn over layers listed lower down in the legend.

註解

This behaviours can be overridden by ‘Layer order’ panel.

Layers in the legend window can be organised into groups. There are two ways to do so:

  1. Right click in the legend window and choose Add Group. Type in a name for the group and press Enter. Now click on an existing layer and drag it onto the group.
  2. Select some layers, right click in the legend window and choose Group Selected. The selected layers will automatically be placed in a new group.

To bring a layer out of a group you can drag it out, or right click on it and choose Make to toplevel item. Groups can be nested inside other groups.

The checkbox for a group will show or hide all the layers in the group with one click.

The content of the right mouse button context menu depends on whether the selected legend item is a raster or a vector layer. For GRASS vector layers mActionToggleEditing Toggle editing is not available. See section Digitizing and editing a GRASS vector layer for information on editing GRASS vector layers.

Right mouse button menu for raster layers

  • Zoom to layer extent
  • Zoom to Best Scale (100%)
  • Stretch Using Current Extent
  • Show in overview
  • Remove
  • Duplicate
  • Set Layer CRS
  • Set Project CRS from Layer
  • Save as ...
  • Properties
  • Rename
  • Copy Style
  • Add New Group
  • Expand all
  • Collapse all
  • Update Drawing Order

Additionally, according to layer position and selection

  • Make to toplevel item
  • Group Selected

Right mouse button menu for vector layers

  • Zoom to Layer Extent
  • Show in Overview
  • Remove
  • Duplicate
  • Set Layer CRS
  • Set Project CRS from Layer
  • Open Attribute Table
  • Toggle Editing (not available for GRASS layers)
  • Save As ...
  • Save Selection As
  • Filter
  • Show Feature Count
  • Properties
  • Rename
  • Copy Style
  • Add New Group
  • Expand all
  • Collapse all
  • Update Drawing Order

Additionally, according to layer position and selection

  • Make to toplevel item
  • Group Selected

Right mouse button menu for layer groups

  • Zoom to Group
  • Remove
  • Set Group CRS
  • Rename
  • Add New Group
  • Expand all
  • Collapse all
  • Update Drawing Order

It is possible to select more than one layer or group at the same time by holding down the Ctrl key while selecting the layers with the left mouse button. You can then move all selected layers to a new group at the same time.

You are also able to delete more than one Layer or Group at once by selecting several Layers with the Ctrl key and pressing Ctrl+D afterwards. This way all selected Layers or groups will be removed from the layer’s list.

Working with the Legend independent layer order

There is a widget that allows to define a legend independent drawing order. You can activate it in the menu Settings ‣ Panels ‣ Layer order. Determine the drawing order of the layers in the map view here. Doing so makes it possible to order your layers in order of importance, for example, but to still display them in the correct order (see figure_layer_order). Checking the checkbox Control rendering order box underneath the list of layers will cause a revert to default behavior.

Figure Layer Order:

../../../_images/layer_order.png

Define a legend independent layer order nix

Map View

This is the “business end” of QGIS - maps are displayed in this area! The map displayed in this window will depend on the vector and raster layers you have chosen to load (see sections that follow for more information on how to load layers). The map view can be panned (shifting the focus of the map display to another region) and zoomed in and out. Various other operations can be performed on the map as described in the toolbar description above. The map view and the legend are tightly bound to each other - the maps in view reflect changes you make in the legend area.

小技巧

Zooming the Map with the Mouse Wheel

You can use the mouse wheel to zoom in and out on the map. Place the mouse cursor inside the map area and roll the wheel forward (away from you) to zoom in and backwards (towards you) to zoom out. The mouse cursor position is the center where the zoom occurs. You can customize the behavior of the mouse wheel zoom using the Map tools menu under the Settings ‣ Options menu.

小技巧

Panning the Map with the Arrow Keys and Space Bar

You can use the arrow keys to pan in the map. Place the mouse cursor inside the map area and click on the right arrow key to pan East, left arrow key to pan West, up arrow key to pan North and down arrow key to pan South. You can also pan the map using the space bar or the click on mouse wheel: just move the mouse while holding down space bar or click on mouse wheel.

Status Bar

The status bar shows you your current position in map coordinates (e.g. meters or decimal degrees) as the mouse pointer is moved across the map view. To the left of the coordinate display in the status bar is a small button that will toggle between showing coordinate position or the view extents of the map view as you pan and zoom in and out.

Next to the coordinate display you find the scale display. It shows the scale of the map view. If you zoom in or out QGIS shows you the current scale. There is a scale selector which allows you to choose between predefined scales from 1:500 until 1:1000000.

A progress bar in the status bar shows progress of rendering as each layer is drawn to the map view. In some cases, such as the gathering of statistics in raster layers, the progress bar will be used to show the status of lengthy operations.

If a new plugin or a plugin update is available, you will see a message at the far left of the status bar. On the right side of the status bar is a small checkbox which can be used to temporarily prevent layers being rendered to the map view (see Section Rendering below). The icon mIconStopRendering immediately stops the current map rendering process.

To the right of the render functions you find the EPSG code of the current project CRS and a projector icon. Clicking on this opens the projection properties for the current project.

小技巧

Calculating the correct Scale of your Map Canvas

When you start QGIS, degrees is the default unit, and it tells QGIS that any coordinate in your layer is in degrees. To get correct scale values, you can either change this to meter manually in the General tab under Settings ‣ Project Properties or you can select a project Coordinate Reference System (CRS) clicking on the mIconProjectionDisabled CRS status icon in the lower right-hand corner of the statusbar. In the last case, the units are set to what the project projection specifies, e.g. ‘+units=m’.

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