Vektorlayereigenschaften¶

Einzelsymbol Darstellung¶

The Single Symbol renderer is used to render all features of the layer using a single user-defined symbol. See Die Symbolauswahl for further information about symbol representation.

Linieneigenschaften Einzelsymbol

No Symbols Renderer¶

The No Symbols renderer is a special use case of the Single Symbol renderer as it applies the same rendering to all features. Using this renderer, no symbol will be drawn for features, but labeling, diagrams and other non-symbol parts will still be shown.

Selections can still be made on the layer in the canvas and selected features will be rendered with a default symbol. Features being edited will also be shown.

This is intended as a handy shortcut for layers which you only want to show labels or diagrams for, and avoids the need to render symbols with totally transparent fill/border to achieve this.

Kategorisierte Darstellung¶

The Categorized renderer is used to render the features of a layer, using a user-defined symbol whose aspect reflects the discrete values of a field or an expression. The Categorized menu allows you to

• select an existing field (using the Column listbox) or

• type or build an expression using the ^{Set column expression}. The expression used to classify features can be of any type; it can for example:

  • be a comparison, e.g. myfield >= 100, $id = @atlas_featureid, myfield % 2 = 0, within( $geometry, @atlas_geometry ). In this case, QGIS returns values 1 (True) and 0 (False).

  • combine different fields, e.g. concat( field1, ' ', field2 ) particularly useful when you want to process classification on two or more fields simultaneously.

  • be a calculation on fields, e.g. myfield % 2, year( myfield ) field_1 + field_2.

  • be used to transform linear values in discrete classes, e.g.:

    CASE WHEN x > 1000 THEN 'Big' ELSE 'Small' END

  • combine several discrete values in one single category, e.g.:

    CASE
    WHEN building IN ('residence', 'mobile home') THEN 'residential'
    WHEN building IN ('commercial', 'industrial') THEN 'Commercial and Industrial'
    END

  Bemerkung

  While you can use any kind of expression to categorize features, for some complex expressions it might be simpler to use rule-based rendering.

• the symbol (using the Die Symbolauswahl dialog) which will be used as base symbol for each class;

• the range of colors (using the Color ramp listbox) from which color applied to the symbol is selected.

Then click on [Classify] button to create classes from the distinct value of the attribute column. Each class can be disabled unchecking the checkbox at the left of the class name.

Sie können das Symbol, den Wert oder die Beschriftung verändern, klicken Sie einfach auf das Element, das Sie ändern wollen.

Ein Rechtsklick zeigt ein Kontextmenü für Kopieren/Einfügen, Farbe ändern, Transparenz ändern, Ausgabeeinheit ändern, Breite ändern.

The example in figure_categorized_symbology shows the category rendering dialog used for the rivers layer of the QGIS sample dataset.

Kategorisierte Symbolisierungsoptionen

Abgestufte Darstellung¶

The Graduated renderer is used to render all the features from a layer, using an user-defined symbol whose color or size reflects the assignment of a selected feature’s attribute to a class.

Like the Categorized Renderer, the Graduated Renderer allows you to define rotation and size scale from specified columns.

Genauso können Sie -analog zum Kategorisierten Renderer - im Menü auswählen:

• The attribute (using the Column listbox or the ^{Set column expression} function)

• Das Symbol (nutzen des Symbolauswahl Dialogs)

• Die Legendenformatierung und die Genauigkeit

• Die Methode, um das Symbol zu ändern: Farbe oder Größe

• Die Farben (indem man die Farbverlaufsliste verwendet), wenn die Farbmethode ausgewählt ist

• The size (using the size domain and its unit)

Then you can use the Histogram tab which shows an interactive histogram of the values from the assigned field or expression. Class breaks can be moved or added using the histogram widget.

Zurück zu dem Klassen Reiter, Sie können die Anzahl der Klassen und auch den Modus für das Klassifizieren von Objekten innerhalb der Klassen (indem man die Modus-Liste verwendet) einstellen. Die möglichen Modi sind:

• Equal Interval: each class has the same size (e.g. values from 0 to 16 and 4 classes, each class has a size of 4);
• Quantile: each class will have the same number of element inside (the idea of a boxplot);
• Natural Breaks (Jenks): the variance within each class is minimal while the variance between classes is maximal;
• Standard Deviation: classes are built depending on the standard deviation of the values;

• Schöne Unterbrechungen: Berechnet eine Sequenz von etwa n+1 mit gleichem Abstand, die den Bereich der Werte in x decken. Die Werte sind so gewählt, dass sie 1, 2 oder 5 mal einer Potenz von 10 sind .(basiert ziemlich auf der R statistischen Umgebung http://astrostatistics.psu.edu/datasets/R/html/base/html/pretty.html)

The listbox in the center part of the Style tab lists the classes together with their ranges, labels and symbols that will be rendered.

Klicken Sie auf den Klassifizieren Knopf um Klassen anhand des ausgewählten Modus zu erstellen. Jede Klasse kann anhand des Deaktivierens des Kontrollkästchens links neben dem Klassennamen ausgeschaltet werden.

Sie können das Symbol, den Wert oder die Beschriftung verändern, klicken Sie einfach auf das Element, das Sie ändern wollen.

Ein Rechtsklick zeigt ein Kontextmenü für Kopieren/Einfügen, Farbe ändern, Transparenz ändern, Ausgabeeinheit ändern, Breite ändern.

The example in figure_graduated_symbology shows the graduated rendering dialog for the rivers layer of the QGIS sample dataset.

Abgestufte Symbolisierungsoptionen

Proportionale Symbole und mehrdimensionale Analysen¶

Proportional Symbol and Multivariate Analysis are not rendering types available from the Style rendering drop-down list. However with the Size Assistant options applied over any of the previous rendering options, QGIS allows you to display your point and line data with such representation.

Proportionale Symbole erstellen

Proportional rendering is done by first applying to the layer the Einzelsymbol Darstellung. Once you set the symbol, at the upper level of the symbol tree, the Data-defined override button available beside Size or Width options (for point or line layers respectively) provides tool to create proportional symbology for the layer. An assistant is moreover accessible through the menu to help you define size expression.

Varying size assistant

The assistant lets you define:

• The attribute to represent, using the Field listbox or the ^{Set column expression} function (see Ausdrücke)
• the scale method of representation which can be ‘Flannery’, ‘Surface’ or ‘Radius’
• The minimum and maximum size of the symbol
• The range of values to represent: The down pointing arrow helps you fill automatically these fields with the minimum (or zero) and maximum values returned by the chosen attribute or the expression applied to your data.
• An unique size to represent NULL values.

To the right side of the dialog, you can preview the features representation within a live-update widget. This representation is added to the layer tree in the layer legend and is also used to shape the layer representation in the print composer legend item.

The values presented in the varying size assistant above will set the size ‘Data-defined override’ with:

coalesce(scale_exp(Importance, 1, 20, 2, 10, 0.57), 1)

Mehrdimensionale Analyse erzeugen

Eine mehrdimensionale Analyse hilft Ihnen, die Beziehungen zwischen zwei oder mehr Variablen auszuwerten z. B. kann eine als Farbverlauf und die andere als Größe dargestellt werden.

The simplest way to create multivariate analysis in QGIS is to first apply a categorized or graduated rendering on a layer, using the same type of symbol for all the classes. Then, clicking on the symbol [Change] button above the classification frame, you get the Die Symbolauswahl dialog from which, as seen above, you can activate and set the size assistant option either on size (for point layer) or width (for line layer).

Like the proportional symbol, the size-related symbol is added to the layer tree, at the top of the categorized or graduated classes symbols. And both representation are also available in the print composer legend item.

Multivariate example

Rule-based Renderer¶

The Rule-based renderer is used to render all the features from a layer, using rule-based symbols whose aspect reflects the assignment of a selected feature’s attribute to a class. The rules are based on SQL statements. The dialog allows rule grouping by filter or scale, and you can decide if you want to enable symbol levels or use only the first-matched rule.

To create a rule, activate an existing row by double-clicking on it, or click on ‘+’ and click on the new rule. In the Rule properties dialog, you can define a label for the rule. Press the button to open the expression string builder. In the Function List, click on Fields and Values to view all attributes of the attribute table to be searched. To add an attribute to the field calculator Expression field, double click on its name in the Fields and Values list. Generally, you can use the various fields, values and functions to construct the calculation expression, or you can just type it into the box (see Ausdrücke). You can create a new rule by copying and pasting an existing rule with the right mouse button. You can also use the ‘ELSE’ rule that will be run if none of the other rules on that level matches. Since QGIS 2.8 the rules appear in a tree hierarchy in the map legend. Just double-click the rules in the map legend and the Style tab of the layer properties appears showing the rule that is the background for the symbol in the tree.

The example in figure_rule_based_symbology shows the rule-based rendering dialog for the rivers layer of the QGIS sample dataset.

Regelbasierte Symbolisierungsoptionen

Point displacement Renderer¶

The Point Displacement renderer works to visualize all features of a point layer, even if they have the same location. To do this, the symbols of the points are placed on a displacement circle around one center symbol or on several concentric circles.

Dialog Punktverdrängung

Inverted Polygon Renderer¶

The Inverted Polygon renderer allows user to define a symbol to fill in outside of the layer’s polygons. As above you can select subrenderers, namely Single symbol, Graduated, Categorized, Rule-Based or 2.5D renderer.

Umgekehrte Polygone Dialog

Heatmap Renderer¶

With the Heatmap renderer you can create live dynamic heatmaps for (multi)point layers. You can specify the heatmap radius in pixels, mm or map units, choose and edit a color ramp for the heatmap style and use a slider for selecting a trade-off between render speed and quality. You can also define a maximum value limit and give a weight to points using a field or an expression. When adding or removing a feature the heatmap renderer updates the heatmap style automatically.

Der Heatmap-Erweiterung Dialog

2.5D Renderer¶

Using the 2.5D renderer it’s possible to create a 2.5D effect on your layer’s features. You start by choosing a Height value (in map units). For that you can use a fixed value, one of your layer’s fields, or an expression. You also need to choose an Angle (in degrees) to recreate the viewer position (0° means west, growing in counter clock wise). Use advanced configuration options to set the Roof Color and Wall Color. If you would like to simulate solar radiation on the features walls, make sure to check the Shade walls based on aspect option. You can also simulate a shadow by setting a Color and Size (in map units).

2.5D dialog

Symbols levels¶

Für Renderer, die Symbollayer gestapelt ermöglichen (nur Heatmap nicht) gibt es eine Option, um die Darstellungsreihenfolge der einzelnen Symbolebenen zu steuern.

For most of the renderers, you can access the Symbols levels option by clicking the [Advanced] button below the saved symbols list and choosing Symbol levels. For the Rule-based Renderer the option is directly available through [Symbols levels] button, while for Point displacement Renderer renderer the same button is inside the Rendering settings dialog.

Um die Symbolebenen zu aktivieren, wählen Sie Symbolebenen aktivieren. Jede Reihe zeigt eine kleine Vorschau des kombinierten Symbols, seiner Beschriftung und die individuellen Symbollayer, unterteilt in verschiedene Spalten mit einer Nummer. Die Nummern zeigen die Darstellungsreihenfolge, in der die Symbollayer gezeichnet werden. Niedrige Werteebenen werden zuerst gezeichnet, liegen ganz unten, während höhere Werte als letztes gezeichnet werden und über den anderen liegen.

Symbolebenen Dialog

Unterschied von aktivierten (A) und deaktivierten (B) Symbolebenen

Zeicheneffekte¶

Damit die Layerdarstellung verbessert und vermieden (oder zumindest reduziert) wird, dass andere Software auf die endgültige Darstellung der Karte umsortiert, bietet QGIS eine weitere leistungsfähige Funktionalität: Die Option Zeicheneffekte, die zur Anpassung Zeicheneffekte für die Visualisierung von Vektorlayern hinzufügt.

The option is available in the Layer Properties –> Style dialog, under the Layer rendering group (applying to the whole layer) or in symbol layer properties (applying to corresponding features). You can combine both usage.

Paint effects can be activated by checking the Draw effects option and clicking the ^{Customize effects} button, that will open the Effect Properties Dialog (see figure_effects_source). The following effect types, with custom options are available:

• Source: Draws the feature’s original style according to the configuration of the layer’s properties. The transparency of its style can be adjusted.

  

  Zeicheneffekte: Dialog Quelle

• Blur: Adds a blur effect on the vector layer. The options that someone can change are the Blur type (Stack or Gaussian blur), the strength and transparency of the blur effect.

  

  Zeicheneffekte: Dialog verwischen

• Colorize: This effect can be used to make a version of the style using one single hue. The base will always be a grayscale version of the symbol and you can use the Grayscale to select how to create it (options are: ‘lightness’, ‘luminosity’ and ‘average’). If Colorise is selected, it will be possible to mix another color and choose how strong it should be. You can also control the Brightness, contrast and saturation levels of the resulting symbol.

  

  Zeicheneffekte: Dialog einfärben

• Drop Shadow: Using this effect adds a shadow on the feature, which looks like adding an extra dimension. This effect can be customized by changing the offset degrees and radius, determining where the shadow shifts towards to and the proximity to the source object. Drop Shadow also has the option to change the blur radius, the transparency and the color of the effect.

  

  Zeicheneffekte: Dialog Schattenwurf

• Inner Shadow: This effect is similar to the Drop Shadow effect, but it adds the shadow effect on the inside of the edges of the feature. The available options for customization are the same as the Drop Shadow effect.

  

  Zeicheneffekte: Dialog Innerer Schatten

• Inner Glow: Adds a glow effect inside the feature. This effect can be customized by adjusting the spread (width) of the glow, or the Blur radius. The latter specifies the proximity from the edge of the feature where you want any blurring to happen. Additionally, there are options to customize the color of the glow, with a single color or a color ramp.

  

  Zeicheneffekte: Dialog Inneres Glühen

• Outer Glow: This effect is similar to the Inner Glow effect, but it adds the glow effect on the outside of the edges of the feature. The available options for customization are the same as the Inner Glow effect.

  

  Zeicheneffekte: Dialog Äußeres Glühen

• Transform: Adds the possibility of transforming the shape of the symbol. The first options available for customization are the Reflect horizontal and Reflect vertical, which actually create a reflection on the horizontal and/or vertical axes. The 4 other options are:

  • Shear: slants the feature along the x and/or y axis
  • Scale: enlarges or minimizes the feature along the x and/or y axis by the given percentage
  • Rotation: turns the feature around its center point
  • and Translate changes the position of the item based on a distance given on the x and/or the y axis.
  

  Zeicheneffekte: Dialog transformieren

There are some common options available for all draw effect types. Transparency and Blend mode options work similar to the ones described in Layerdarstellung and can be used in all draw effects except for the transform one.

One or more draw effects can used at the same time. You activate/deactivate an effect using its checkbox in the effects list. You can change the selected effect type by using the Effect type option. You can reorder the effects using ^{Move up} and ^{Move down} buttons, and also add/remove effects using the ^{Add effect} and ^{Remove effect} buttons.

There is also a Draw mode option available for every draw effect, and you can choose whether to render and/or to modify the symbol. Effects render from top to bottom.’Render only’ mode means that the effect will be visible while the ‘Modify only’ mode means that the effect will not be visible but the changes that it applies will be passed to the next effect (the one immediately below). The ‘Render and Modify’ mode will make the effect visible and pass any changes to the next effect. If the effect is in the top of the effects list or if the immediately above effect is not in modify mode, then it will use the original source symbol from the layers properties (similar to source).

Text tab¶

In the Text tab, you can define the Font, Style, and Size of your labels’ text (see Figure_labels). There are options available to set the labels’ Color and Transparency. Use the Type case option to change the capitalization style of the text. You have the possibility to render the text as ‘All uppercase’, ‘All lowercase’ or ‘Capitalize first letter’. In Spacing, you can change the space between words and between individual letters. Finally, use the Blend mode option to determine how your labels will mix with the map features below them (see more about it in Mischmodi).

The Apply label text substitutes option gives you ability to specify a list of texts to substitute to texts in feature labels (e.g., abbreviating street types). Replacement texts are thus used to display labels in the map canvas. Users can also export and import lists of substitutes to make reuse and sharing easier.

Formatting tab¶

In the Formatting tab, you can define a character for a line break in the labels with the Wrap on character option. You can also format the Line Height and the alignment. For the latter, typical values are available (left, right, and center), plus Follow label placement for point layers. When set to this mode, text alignment for labels will be dependent on the final placement of the label relative to the point. E.g., if the label is placed to the left of the point, then the label will be right aligned, while if it is placed to the right, it will be left aligned.

For line vector layers you can include Line directions symbols to help determine the lines directions. They work particularly well when used with the curved or Parallel placement options from the Placement tab. There are options to set the symbols position, and to reverse direction.

Use the Formatted numbers option to format numeric labels. You can set the number of Decimal places. By default, 3 decimal places will be used. Use the Show plus sign if you want to show the plus sign in positive numbers.

Buffer tab¶

To create a buffer around the labels, activate the Draw text buffer checkbox in the Buffer tab. You can set the buffer’s Size, color, and Transparency. The buffer expands from the label’s outline , so, if the color buffer’s fill checkbox is activated, the buffer interior is filled. This may be relevant when using partially transparent labels or with non-normal blending modes, which will allow seeing behind the label’s text. Deactivating color buffer’s fill checkbox (while using totally transparent labels) will allow you to create outlined text labels.

Background tab¶

In the Background tab, you can define with Size X and Size Y the shape of your background. Use Size type to insert an additional ‘Buffer’ into your background. The buffer size is set by default here. The background then consists of the buffer plus the background in Size X and Size Y. You can set a Rotation where you can choose between ‘Sync with label’, ‘Offset of label’ and ‘Fixed’. Using ‘Offset of label’ and ‘Fixed’, you can rotate the background. Define an Offset X,Y with X and Y values, and the background will be shifted. When applying Radius X,Y, the background gets rounded corners. Again, it is possible to mix the background with the underlying layers in the map canvas using the Blend mode (see Mischmodi).

Shadow tab¶

Use the Shadow tab for a user-defined Drop shadow. The drawing of the background is very variable. Choose between ‘Lowest label component’, ‘Text’, ‘Buffer’ and ‘Background’. The Offset angle depends on the orientation of the label. If you choose the Use global shadow checkbox, then the zero point of the angle is always oriented to the north and doesn’t depend on the orientation of the label. You can influence the appearance of the shadow with the Blur radius. The higher the number, the softer the shadows. The appearance of the drop shadow can also be altered by choosing a blend mode.

Placement tab¶

Choose the Placement tab for configuring label placement and labeling priority. Note that the placement options differ according to the type of vector layer, namely point, line or polygon.

Platzierung für Linienlayer¶

Label options for line layers include Parallel, Curved or Horizontal. For the Parallel and Curved options, you can set the position to Above line, On line and Below line. It’s possible to select several options at once. In that case, QGIS will look for the optimal label position. For Parallel and curved placement options, you can also use the line orientation for the position of the label. Additionally, you can define a Maximum angle between curved characters when selecting the Curved option (see Figure_labels_placement_line).

Label placement examples in lines

For all three placement options, in Repeat, you can set up a minimum distance for repeating labels. The distance can be in mm or in map units.

Platzierung für Polygonlayer¶

You can choose one of the following options for placing labels in polygons (see figure_labels_placement_polygon):

• Offset from centroid,
• Horizontal (slow),
• Around centroid,
• Free (slow),
• Using perimeter,
• and Using perimeter (curved).

In the Offset from centroid settings you can specify if the centroid is of the visible polygon or whole polygon. That means that either the centroid is used for the polygon you can see on the map or the centroid is determined for the whole polygon, no matter if you can see the whole feature on the map. You can place your label within a specific quadrant, and define offset and rotation.

The Around centroid setting places the label at a specified distance around the centroid. Again, you can define visible polygon or whole polygon for the centroid.

With the Horizontal (slow) or Free (slow) options, QGIS places at the best position either a horizontal or a rotated label inside the polygon.

With the Using perimeter option, the label will be drawn next to the polygon boundary. The label will behave like the parallel option for lines. You can define a position and a distance for the label. For the position, Above line, On line, Below line and Line orientation dependent position are possible. You can specify the distance between the label and the polygon outline, as well as the repeat interval for the label.

The Using perimeter (curved) option helps you draw the label along the polygon boundary, using a curved labeling. In addition to the parameters available with Using perimeter setting, you can set the Maximum angle between curved characters polygon, either inside or outside.

Label placement examples in polygons

In the priority section you can define the priority with which labels are rendered for all three vector layer types (point, line, polygon). This placement option interacts with the labels from other vector layers in the map canvas. If there are labels from different layers in the same location, the label with the higher priority will be displayed and the others will be left out.

Rendering tab¶

In the Rendering tab, you can tune when the labels can be rendered and their interaction with other labels and features.

Unter den Beschriftungsoptionen finden Sie die skalierungsbasierte und die Pixelgrößenbasierte Sichtbarkeitseinstellungen.

Der Beschriftung Z-Index bestimmt, in welcher Reihenfolge, welche Beschriftung dargestellt wird, als auch in welcher Verbindung mit anderen Objekten in dem Layer (nutzen Sie datendefinierte Übersteuerung), wie mit Beschriftungen anderer Layer. Beschriftungen mit einem hohen Z-Index werden an oberster Stelle dargestellt.

Zusätzlich ist die Logik optimiert worden, so, dass wenn zwei Beschriftungen den selben Z-Index haben, dann:

• wenn sie aus dem selben Layer sind, wird die kleinere Beschriftung über dem größeren gezeichnet

• wenn sie aus verschiedenen Layer sind, werden die Beschriftungen in der selben Reihenfolge gezeichnet, wie die Layer an sich (d. h. unter Berücksichtigung der Reihenfolge in der Kartenlegende).

Beachten Sie, dass diese Einstellung Beschriftungen nicht unter andere Objekte anderer Layer zeichnet, es kontrolliert nur die Reihenfolge, in welcher Beschriftungen über allen Layerobjekten gezeichnet werden.

Während der Darstellung der Beschriftungen und um lesbare Beschriftungen anzuzeigen, wertet QGIS automatisch die Position der Beschriftungen aus und kann, im Falle einer Kollision, einige von ihnen verstecken. Trotzdem können Sie Alle Beschriftungen für diesen layer anzeigen (including colliding labels) wählen und Ihre Kollisionen manuell beheben.

Mit datendefinierten Ausdrücken in Beschriftungen anzeigen and Immer anzeigen können Sie Feineinstellungen vornehmen, welche Beschriftungen dargestellt werden.

Unter Objektoptionen können Sie Jeden Teil eines Multi-Polygons beschriften und Begrenze die Anzahl der zu beschriftenden Objekte wählen. Sowohl Linien- als auch Polygonlayer bieten die Möglichkeit eine Mindestgröße für das Beschriften einzustellen, wählen Sie Unterdrücke Beschriftungen für Objekte kleiner als. Für Polygonlayer können Sie auch einen Filter vornehmen, der Beschriftungen anzeigt, wenn sie komplett in dem Polygon liegen oder nicht. Für Linienlayer können Sie wählen Verschmelze verbundene Linien um doppelte Beschriftung zu vermeiden, um eine lebhafte Karte darzustellen in Verbindung mit dem Abstand oder Wiederholen Optionen im Reiter Platzierung.

In dem Hindernis Rahmen, können Sie die Abdeckungsbeziehungen zwischen Beschriftungen und Objekten bearbeiten. Aktivieren Sie die Discourage labels from covering features Option um zu entscheiden, ob Objekte des Layers als Hindernis für Beschriftung wirken soll (inklusive Beschriftungen anderer Objekte des selben Layers). Ein Hindernis ist ein Merkmal, QGIS versucht so weit wie möglich keine Beschriftungen übereinander zu platzieren. Anstatt des gesamten Layers, können Sie Teilmengen als Hindernis definieren, indem Sie ^{datendefinierte Übersteuerung} verwenden.

Der Prioritätsschieberegler für Hindernisse erlaubt es Ihnen Beschriftungen von bestimmten Layern zum überlappen zu bevorzugen. Eine Geringe Gewichtung einer Hindernispriorität bedeutet, dass Objekte eines Layers weniger als Hindernis gelten und somit eher durch Beschriftungen überlagert werden. Die Priorität kann ebenso datendefiniert sein, so dass innerhalb des selben Layers, bestimmte Objekte wahrscheinlicher überdeckt werden als andere.

Für Polygonlayer können Sie dezArt von Hindernisobjekten wählen durch Minimierung der Beschriftungsplatzierung sein könnten:

• over the feature’s interior: avoids placing labels over the interior of the polygon (prefers placing labels totally outside or just slightly inside the polygon)
• or over the feature’s boundary: avoids placing labels over boundary of the polygon (prefers placing labels outside or completely inside the polygon). E.g., it can be useful for regional boundary layers, where the features cover an entire area. In this case, it’s impossible to avoid placing labels within these features, and it looks much better to avoid placing them over the boundaries between features.

The Label Toolbar¶

The Label Toolbar provides some tools to manipulate label or diagram properties, but only if the corresponding data-defined option is indicated (otherwise, buttons are disabled). Layer might also need to be in edit mode.

The Label toolbar

While for readability, label has been used below to describe the Label toolbar, note that when mentioned in their name, the tools work almost the same way with diagrams:

• ^{Pin/Unpin Labels And Diagrams} that has data-defined position. By clicking or draging an area, you pin label(s). If you click or drag an area holding Shift, label(s) are unpinned. Finally, you can also click or drag an area holding Ctrl to toggle the pin status of label(s).
• ^{Highlight Pinned Labels And Diagrams}. If the vector layer of the label is editable, then the highlighting is green, otherwise it’s blue.
• ^{Move Label And Diagram} that has data-defined position. You just have to drag the label to the desired place.
• ^{Show/Hide Labels And Diagrams} that has data-defined visbility. If you click or drag an area holding Shift, then label(s) are hidden. When a label is hidden, you just have to click or drag an area around the feature’s point to restore its visibility.
• ^{Rotate Label}. Click the label and move around and you get the text rotated.
• ^{Change Label}. It opens a dialog to change the clicked label properties; it can be the label itself, its coordinates, angle, font, size... as long as this property has been mapped to a field.

Customize the labels from the map canvas¶

Combined with the Label Toolbar, the data defined override setting helps you manipulate labels in the map canvas (move, edit, rotate). We now describe an example using the data-defined override function for the ^{Move label} function (see figure_labels_data_defined).

1. Importieren Sie lakes.shp aus dem QGIS Beispieldatensatz.

2. Doppelklicken Sie den Layer um die Layereigenschaften zu öffnen. Klicken Sie auf Beschriftungen und Platzierung. Wählen Sie Abstand vom Punkt.

3. Look for the Data defined entries. Click the icon to define the field type for the Coordinate. Choose xlabel for X and ylabel for Y. The icons are now highlighted in yellow.

   

   Das Beschriften von Polygonlayern mit datendefinierter Übersteuerung

4. Zoomen Sie auf einen See.

5. Set editable the layer using the ^{Toggle Editing} button.

6. Go to the Label toolbar and click the icon. Now you can shift the label manually to another position (see figure_labels_move). The new position of the label is saved in the xlabel and ylabel columns of the attribute table.

7. Using The Geometry Generator with the expression below, you can also add a linestring symbol layer to connect each lake to its moved label:

   make_line( centroid( $geometry ), make_point( "xlabel", "ylabel" ) )

   

   Moved labels

Common settings¶

Regardless the type of widget applied to the field, there are some common properties you can set to control whether and how a field can be edited:

• Editable: uncheck this to set the field read-only (not manually modifiable) when the layer is in edit mode. Note that checking this setting doesn’t override any edit limitation from the provider.

• Label on top: places the field name above or beside the widget in the feature form

• Default value: for new features, automatically populates by default the field with a predefined value or an expression-based one. For example, you can:

  • use $x, $length, $area to populate a field with the feature’s x coordinate, length, area or any geometric information at its creation;
  • incremente a field by 1 for each new feature using maximum("field")+1;
  • save the feature creation datetime using now();
  • use variables in expressions, making it easier to e.g. insert the operator name (@user_full_name), the project file path (@project_path), ...

  A preview of the resulting default value is displayed at the bottom of the widget.

  Bemerkung

  The Default value option is not aware of the values in any other field of the feature being created so it won’t be possible to use an expression combining any of those values i.e using an expression like concat(field1, field2) may not work.

• Constraints: you can constrain the value to insert in the field. This constraint can be:

  • Not null: force the user to provide a value

  • based on a custom expression: e.g. regexp_match(col0,'A-Za-z') to ensure that the value of the field col0 has only alphabetical letter.

    A short description of the constraint can be added and will be displayed at the top of the form as a warning message when the value supplied does not match the constraint.

Edit widgets¶

The available widgets are:

• Checkbox: Displays a checkbox, and you can define what attribute is added to the column when the checkbox is activated or not.
• Classification: Displays a combo box with the values used for classification, if you have chosen ‘unique value’ as legend type in the Style tab of the properties dialog.
• Color: Displays a color button allowing user to choose a color from the color dialog window.

• Datum/Zeit: Stellt ein Linienfeld dar, das ein Kalender-Widget zum Öffnen eines Datums, einer Zeit oder beidem, darstellt. Der Spaltentyp muss Text sein. Sie könnne ein benutzerdefiniertes Format auswählen, einen Pop-up-Kalender, etc.

• Enumeration: Opens a combo box with values that can be used within the columns type. This is currently only supported by the PostgreSQL provider.
• External Resource: Uses a “Open file” dialog to store file path in a relative or absolute mode. It can also be used to display a hyperlink (to document path), a picture or a web page.
• File Name: Simplifies the selection by adding a file chooser dialog.

• Versteckt: Ein verstecktes Attribut ist unsichtbar. Der Anwender kann den Inhalt nicht sehen.

• Photo: Field contains a filename for a picture. The width and height of the field can be defined.

• Bereich: Erlaubt Ihnen numerische Werte eines bestimmten Wertebereichs festzulegen. Das Bearbeitungselement kann entweder ein Schieber oder ein Drehfeld sein.

• Relation Reference: This widget lets you embed the feature form of the referenced layer on the feature form of the actual layer. See Creating one or many to many relations.
• Text Edit (default): This opens a text edit field that allows simple text or multiple lines to be used. If you choose multiple lines you can also choose html content.
• Unique Values: You can select one of the values already used in the attribute table. If ‘Editable’ is activated, a line edit is shown with autocompletion support, otherwise a combo box is used.
• UUID Generator: Generates a read-only UUID (Universally Unique Identifiers) field, if empty.
• Value Map: 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.
• Value Relation: Offers values from a related table in a combobox. You can select layer, key column and value column. Several options are available to change the standard behaviours: allow null value, order by value, allow multiple selections and use of autocompleter. The forms will display either a drop-down list or a line edit field when completer checkbox is enabled.
• Web View: Field contains a URL. The width and height of the field is variable.

The drag and drop designer¶

Choose Drag and drop designer from the Attribute editor layout combobox to layout the features form within QGIS. Then, drag and drop rows from the Fields frame to the Label panel to have fields added to your custom form.

You can also use categories (tab or group frames) to better structure the form. The first step is to use the icon to create a tab in which fields and groups will be displayed (see figure_fields_layout). You can create as many categories as you want. The next step will be to assign to each category the relevant fields, using the icon. You’d need to select the targeted category beforehand. You can use the same fields many times.

Dialog Attributeditorzusammenstellung um Kategorien zu erstellen

You can configure tabs or groups with a double-click. QGIS opens a form in which you can:

• choose to hide or show the item label
• rename the category
• set over how many columns the fields under the category should be distributed
• enter an expression to control the category visibility. The expression will be re-evaluated everytime values in the form change and the tab or groupbox shown/hidden accordingly.
• show the category as a group box (only available for tabs)

With a double-click on a field label, you can also specify whether the label of its widget should be visible or not in the form.

In case the layer is involved in one to many relations (see Creating one or many to many relations), referencing layers are listed in the Relations frame and their form can be embedded in the current layer form by drag-and-drop. Like the other items, double-click the relation label to configure some options:

• choose to hide or show the item label
• show the link button
• show the unlink button

Provide an ui-file¶

The Provide ui-file option allows you to use complex dialogs made with Qt-Designer. Using a UI-file allows a great deal of freedom in creating a dialog. Note that, in order to link the graphical objects (textbox, combobox...) to the layer’s fields, you need to give them the same name.

Use the Edit UI to define the path to the file to use.

You’ll find some example in the Creating a new form lesson of the QGIS Training Manual. For more advanced information, see http://nathanw.net/2011/09/05/qgis-tips-custom-feature-forms-with-python-logic/.

Enhance your form with custom functions¶

QGIS forms can have a Python function that is called when the dialog is opened. Use this function to add extra logic to your dialogs. The form code can be specified in three different ways:

• load from the environment: use a function, for example in startup.py or from an installed plugin)
• load from an external file: a file chooser will appear in that case to allow you to select a Python file from your filesystem
• provide code in this dialog: a Python editor will appear where you can directly type the function to use.

In all cases you must enter the name of the function that will be called (open in the example below).

Ein Beispiel ist (im Modul MyForms.py):

def open(dialog,layer,feature):
    geom = feature.geometry()
    control = dialog.findChild(QWidged,"My line edit")

Reference in Python Init Function like so: open