Positioners

Table of contents

• ACenter
• HCenter
• VCenter
• AStrech
• HStretch
• VStretch
• HAnchor
• VAnchor
• AAnchor

Positioners are special tags that can be applied to a widget type which overwrite the geometry of the given widget when the output file is written. All other attributes of the widget are defined as normal and not touched by the positioner.

When defining the widget you want to position, just prepend with widget’s type with the positioner’s type. So if you have a Text widget, which is normally indicated with the ‘!Text’ type, and you want to horizontally center it within its parent, you would change that type to ‘!hcenter:Text’.

Positioners are set up to be generated last among a set of unordered children nodes. This allows the rest of the nodes to expand the size of a parent widget before determining positioning. Be careful though, as this does mean that the later generated widgets will appear above any other widgets they share area with, despite being written in the stylesheet earlier. You can overwrite this behavior by setting the “render-order” attribute to 0, but you may then have to define your positioner node in a later part of the stylesheet in order for it to see the correct parent height and width.

As well, it’s important to note that this is only for unordered sets of children nodes. FlowNodes will ignore this order and will place children nodes in the order they are defined in the template.

ACenter

Positions a widget so that the midpoint of the widget matches up with the midpoint of the widget’s parent.

• Example

MidPointGroup: !acenter:group    
    children:
        - !TextMontor
            geometry: 50x20
            foreground: *alarm_yellow
            background: *transparent
            alignment: CenterRight
            pv: "S:SRcurrentAI"
            
        - !Text
            geometry: 55x0 x 25x20
            foreground: *alarm_yellow
            alignment: CenterLeft
            text: "mA"

HCenter

Positions a widget so that the midpoint of the widget on the horizontal axis matches up with the midpoint of the widget’s parent on the same axis.

• Example

OPSElements: !hcenter:group
    geometry: 0x7 x 0x0
    
    children:
        - !TextMontor
            geometry: 50x20
            foreground: *alarm_yellow
            background: *transparent
            alignment: CenterRight
            pv: "S:SRcurrentAI"
            
        - !Text
            geometry: 55x0 x 25x20
            foreground: *alarm_yellow
            alignment: CenterLeft
            text: "mA"

VCenter

Positions a widget so that the midpoint of the widget on the vertical axis matches up with the midpoint of the widget’s parent on the same axis.

You may also use the alias “center” to reference the vcenter node.

• Example

OPSElements: !vcenter:group
    geometry: 7x0 x 0x0
    
    children:
        - !TextMonitor
            geometry: 0x0 x 50x20
            foreground: *alarm_yellow
            background: *transparent
            alignment: CenterRight
            pv: "S:SRcurrentAI"
            
        - !Text
            geometry: 55x0 x 25x20
            foreground: *alarm_yellow
            alignment: CenterLeft
            text: "mA"

AStrech

Determines a widget’s width and height to match up respectively with the widget’s parent values.

• Example

Fill_Parent: !astretch:Text            
    text: "Middle"
    alignment: CenterLeft

HStretch

Determines a widget’s width to match up with the size of the widget’s parent width.

• Example

UITitle: !hstretch:Text
    geometry: 0x32
            
    text: "Middle"
    alignment: CenterLeft

VStretch

Determines a widget’s width to match up with the size of the widget’s parent width.

You may also use the alias “stretch” to reference the vstretch node.

• Example

UITitle: !vstretch:Text
    geometry: 32x0
            
    text: "Middle"
    alignment: CenterLeft

HAnchor

Positions a widget at the horizontal extent of its parent node.

• Example

WideGroup: !Group
    geometry: 400x20
    children:
        - !HAnchor:Text
            geometry: 50x20
            text: "I'm at the end"

VAnchor

Positions a widget at the vertical extent of its parent node.

You may also use the alias “anchor” to reference the vachor node.

• Example

TallGroup: !Group
    geometry: 40x200
    children:
        - !HAnchor:Text
            geometry: 50x20
            text: "I'm at the bottom"

AAnchor

Positions a widget to be in the lower right corner of its parent node.

• Example

BigGroup: !Group
    geometry: 400x400
    children:
        - !HAnchor:Text
            geometry: 50x20
            text: "I'm in the corner"