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| |
| **Design Doc of RelativeLayout** |
| |
| *Last updated: April 3rd 2018* |
| |
| Overview |
| ======== |
| |
| RelativeLayout supports dragging, resizing, and constraint creation in Layout Editor. |
| |
| Resizing |
| ======== |
| |
| RelativeLayout offers `RelativeResizeTarget` to support resizing function. Resizing doesn't create or remove any constraint. Instead of |
| that, it updates the margin value(s). |
| |
| Constraint Creation |
| =================== |
| |
| RelativeLayout offers `RelativeAnchorTarget` to support constraint creation. Dragging from one anchor to another anchor create a |
| constraint. Only legal anchor should be display while dragging the anchor. It is possible to drag the anchor to the parent to create |
| the Constraint to the parent as well. |
| |
| Dragging |
| ======== |
| |
| RelativeLayout offers `RelativeDragHandler` and `RelativeDragTarget` to support dragging behaviours. `RelativeDragHandler` is used when |
| dragging component from Palette or ComponentTree and `RelativeDragTarget` is used to support dragging component inside the RelativeLayout. |
| |
| Dragging Component from Palette |
| ------------------------------- |
| When dragging from Palette, the dragged component is added to RelativeLayout.<br> |
| Constraint will be automatically added to keep the component at the position where it was dropped. |
| |
| Dragging Component inside RelativeLayout |
| ---------------------------------------- |
| Before AS 3.1, dragging component used to change the constraints. But it is because we didn't provide other way to create the constraint. |
| Since RelativeLayout now offers the anchor to create the constraint, dragging inside RelativeLayout doesn't add or remove any constraint |
| anymore.<br> |
| If it already has constraint in the given direction, the corresponding margin is updated. Otherwise it creates the constraint related to |
| RelativeLayout itself. |
| |
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