When you create a modular tool and associate it with a target image, the tool automatically makes the necessary connections to the target image to do its job. For example, the Pixel Information tool sets up a connection to the target image so that it can display the location and value of the pixel currently under the pointer.
As another example, the Overview tool sets up a two-way connection to the target image:
Target image to the Overview tool — If the visible portion of the image changes, by scrolling, panning, or by changing the magnification, the Overview tool changes the size and location of the detail rectangle to the indicate the portion of the image that is now visible.
Overview tool to the target image — If a user moves the detail rectangle in the Overview tool, the portion of the target image visible in the scroll panel is updated.
The modular tools accomplish this interactivity by using callback properties of the
graphics objects. For example, the figure object supports a
WindowButtonMotionFcn callback that executes whenever the mouse
button is depressed. You can customize the connectivity of a modular tool by using the
application programmer interface (API) associated with the tool to set up callbacks to
get notification of events.
For example, the Magnification box supports a single API function:
setMagnification. You can use this API function to set the
magnification value displayed in the Magnification box. The Magnification box
automatically notifies the scroll panel to change the magnification of the image based
on the value. The scroll panel also supports an extensive set of API functions. To get
information about these APIs, see the reference page for the modular tool.