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rbbox

Create rubberband box for area selection

Syntax

rbbox
rbbox(initialRect)
rbbox(initialRect,fixedPoint)
rbbox(initialRect,fixedPoint,stepSize)
finalRect = rbbox(...)

Description

rbbox initializes and tracks a rubberband box in the current figure. It sets the initial rectangular size of the box to 0, anchors the box at the figure's CurrentPoint, and begins tracking from this point.

rbbox(initialRect) specifies the initial location and size of the rubberband box as [x y width height], where x and y define the lower left corner, and width and height define the size. initialRect is in the units specified by the current figure's Units property, and measured from the lower left corner of the figure window. The corner of the box closest to the pointer position follows the pointer until rbbox receives a button-up event.

rbbox(initialRect,fixedPoint) specifies the corner of the box that remains fixed. All arguments are in the units specified by the current figure's Units property, and measured from the lower left corner of the figure window. fixedPoint is a two-element vector, [x y]. The tracking point is the corner diametrically opposite the anchored corner defined by fixedPoint.

rbbox(initialRect,fixedPoint,stepSize) specifies how frequently the rubberband box is updated. When the tracking point exceeds stepSize figure units, rbbox redraws the rubberband box. The default stepsize is 1.

finalRect = rbbox(...) returns a four-element vector, [x y width height], where x and y are the x and y components of the lower left corner of the box, and width and height are the dimensions of the box.

Examples

Assuming the current view is view(2), use the current axes' CurrentPoint property to determine the extent of the rectangle in dataspace units:

f = figure; 
a = axes('Parent',f); 
k = waitforbuttonpress; 
point1 = get(a,'CurrentPoint');    % button down detected 
finalRect = rbbox;                 % return figure units 
point2 = get(a,'CurrentPoint');    % button up detected 
point1 = point1(1,1:2);            % extract x and y 
point2 = point2(1,1:2); 
p1 = min(point1,point2);           % calculate locations 
offset = abs(point1-point2);       % and dimensions 
x = [p1(1) p1(1)+offset(1) p1(1)+offset(1) p1(1) p1(1)]; 
y = [p1(2) p1(2) p1(2)+offset(2) p1(2)+offset(2) p1(2)]; 
hold on 
axis manual 
plot(x,y)                          % redraw in dataspace units

More About

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Tips

rbbox is useful for defining and resizing a rectangular region:

  • For box definition, initialRect is [x y 0 0], where (x,y) is the figure's CurrentPoint.

  • For box resizing, initialRect defines the rectangular region that you resize (e.g., a legend). fixedPoint is the corner diametrically opposite the tracking point.

rbbox returns immediately if a button is not currently pressed. Therefore, you use rbbox with waitforbuttonpress so that the mouse button is down when rbbox is called. rbbox returns when you release the mouse button.

See Also

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