resize_gesture.md
In rswipl: Embed 'SWI'-'Prolog'

class resize_gesture {#class-resize_gesture}

A resize_gesture allows for resizing objects by dragging the corners or sides (for constrained resize) of the objects. While dragging, the direction/constraints are indicated by showing an appropriate cursor.

The resize_gesture only responds to events the happen close the the edges/corners of the graphical. The class-variables resize_gesture.margin_fraction and resize_gesture.margin_width determine these areas: the gesture responds if the down event occurs between the edge and 1/margin_fraction of the size or margin_width (whoever is the least).

Bugs: Does not deal properly with negative areas.

@see class resize_outline_gesture

resize_gesture<->h_mode: {left,keep,right} How the graphical is resized horizontally. Values are:
```
| left  | Drag the left edge  |
| keep  | Change neither edge |
| right | Drag the right edge |
```
This value is set by ->verify and used by ->initiate and ->drag.

@see resize_gesture->verify
resize_gesture<->max_size: size* Size that defines the maximum size the graphical may have. If it depends on the circumstances, it may be set in ->verify or ->initiate.

If @nil, there is no maximum size.

Defaults: @nil
resize_gesture<->min_size: size* Size that defines the minimal size the graphical should have. If it depends on the circumstances, it may be set in ->verify or ->initiate.

If @nil, there is no minimum size.

Defaults: Resource defined.

@see resize_gesture->verify
resize_gesture<->v_mode: {top,keep,bottom} How the graphical is resized vertically. Values are:
```
| top    | Drag the top edge    |
| keep   | Change neither edge  |
| bottom | Drag the bottom edge |
```
This value is set by ->verify and used by ->initiate and ->drag.

@see resize_gesture->verify

resize_gesture->drag: event Resize the graphical according the <-v_mode and the <-h_mode determined upon starting the gesture.
resize_gesture->initiate: event Set the cursor to indicate which edges are going to be changed and moves the pointer to be precisely on those sides.
resize_gesture->terminate: event Equivalent to ->drag.
resize_gesture->verify: event The ->verify method determines the <->v_mode and <->h_mode attributes. The gesture changes those sides where the caret is closer that the maximum of
```
{Width/Height} / margin_factor AND margin_width
```
Both resize_gesture.margin_factor and resize_gesture.margin_width are Defauls. ->verify succeeds if at least one of <->v_mode and <->h_mode is not set to keep.

@see resize_gesture-min_size @see resize_gesture-v_mode @see resize_gesture-h_mode