imscrollpanel

Scroll panel for interactive image navigation

Syntax

hPanel = imscrollpanel(hParent,hImage)

Description

Use the imscrollpanel function to add a scroll panel to an image. If the size or magnification makes an image too large to display in a figure on the screen, then the scroll panel displays a portion of the image at 100% magnification (one screen pixel represents one image pixel). The scroll panel adds horizontal and vertical scroll bars to enable navigation around the image.

hPanel = imscrollpanel(hParent,hImage) creates a scroll panel hPanel that enables scrolling image hImage. The scroll panel is added to the parent figure or panel hParent.

Examples

Control Image View Using Scroll Panel API

Display an image in a figure. The example suppresses the standard toolbar and menubar in the figure window because these do not work with the scroll panel.

hFig = figure(Toolbar="none",Menubar="none",Name="Saturn");
hIm = imshow("saturn.png");

Create a scroll panel to contain the image.

hSP = imscrollpanel(hFig,hIm);
set(hSP,Units="normalized",Position=[0 .1 1 .9])

Add a Magnification Box and an Overview tool to the figure.

hMagBox = immagbox(hFig,hIm);
pos = get(hMagBox,"Position");
set(hMagBox,Position=[0 0 pos(3) pos(4)])

imoverview(hIm)

Get the scroll panel API so that you can control the view programmatically.

api = iptgetapi(hSP);

Get the current magnification and position.

mag = api.getMagnification()

mag = 
1

r = api.getVisibleImageRect()

r = 1×4

  218.0000  383.0500  765.0000  734.9000

Use the scroll panel object API function setVisibleLocation to view the top left corner of the image.

api.setVisibleLocation(0.5,0.5)

Change the magnification of the image so that the image fits entirely in the scroll panel. In the following figure, note that the scroll bars are no longer visible.

api.setMagnification(api.findFitMag())

Zoom in to 1600% on the dark spot.

api.setMagnificationAndCenter(16,306,800)

Input Arguments

hParent — Parent of scroll panel

Figure object | Panel object

Parent of the scroll panel, specified as a Figure or Panel object.

hImage — Image

Image object

Image, specified as an Image object.

Output Arguments

hPanel — Scroll panel

Panel object

Scroll panel, returned as a Panel object.

More About

Scroll Panel API Structure

A scroll panel contains a structure of function handles, called an API. You can use the functions in this API to manipulate the scroll panel. To retrieve this structure, use the iptgetapi function, as in the following example.

api = iptgetapi(hPanel)

This table lists the scroll panel API functions, in the order they appear in the structure.

Function	Description
setMagnification	Set the magnification of the target image in units of screen pixels per image pixel. mag = api.setMagnification(new_mag) new_mag is a scalar magnification factor.
getMagnification	Return the current magnification factor of the target image in units of screen pixels per image pixel. mag = api.getMagnification() Multiply mag by 100 to convert to percentage. For example if mag is 2, then the magnification is 200%.
setMagnificationAndCenter	Change the magnification and make the point with (x,y) coordinate (cx,cy) in the target image appear in the center of the scroll panel. This operation is equivalent to a simultaneous zoom and recenter. api.setMagnificationAndCenter(mag,cx,cy)
findFitMag	Return the magnification factor that would make the target image just fit in the scroll panel. mag = api.findFitMag()
setVisibleLocation	Move the target image so that the specified location is visible, and update the scroll bars. api.setVisibleLocation(xmin, ymin) api.setVisibleLocation([xmin ymin])
getVisibleLocation	Return the location of the currently visible portion of the target image. loc = api.getVisibleLocation() loc is a vector [xmin ymin].
getVisibleImageRect	Return the current visible portion of the image. r = api.getVisibleImageRect() r is a rectangle [xmin ymin width height].
addNewMagnificationCallback	Add the function handle fcn to the list of new-magnification callback functions. id = api.addNewMagnificationCallback(fcn) Whenever the scroll panel magnification changes, each function in the list is called with the syntax: fcn(mag) mag is a scalar magnification factor. The return value, id, is used only with removeNewMagnificationCallback.
removeNewMagnificationCallback	Remove the corresponding function from the new-magnification callback list. api.removeNewMagnificationCallback(id) id is the identifier returned by addNewMagnificationCallback.
addNewLocationCallback	Add the function handle fcn to the list of new-location callback functions. id = api.addNewLocationCallback(fcn) Whenever the scroll panel location changes, each function in the list is called with the syntax: fcn(loc) loc is [xmin ymin]. The return value, id, is used only with removeNewLocationCallback.
removeNewLocationCallback	Remove the corresponding function from the new-location callback list. api.removeNewLocationCallback(id) id is the identifier returned by addNewLocationCallback.
replaceImage	api.replaceImage(...,PARAM1,VAL1,PARAM2,VAL2,...) replaces the image displayed in the scroll panel. api.replaceImage(I) api.replaceImage(BW) api.replaceImage(RGB) api.replaceImage(I,MAP) api.replaceImage(filename) By default, the new image data is displayed centered, at 100% magnification. The image handle is unchanged. The parameters you can specify include many of the parameters supported by imshow, including 'Colormap', 'DisplayRange', and 'InitialMagnification'. In addition, you can use the 'PreserveView' parameter to preserve the current magnification and centering of the image during replacement. Specify the logical scalar True to preserve current centering and magnification.

Tips

• imscrollpanel changes the object hierarchy of the target image. Instead of the familiar figure→axes→image object hierarchy, imscrollpanel inserts several uipanel and uicontrol objects between the figure and the axes object.

• Scrollbar navigation as provided by imscrollpanel is incompatible with the default MATLAB^® figure navigation buttons (pan, zoom in, zoom out). The corresponding menu items and toolbar buttons should be removed in a custom GUI that includes a scrollable uipanel created by imscrollpanel.

• When you run imscrollpanel, it appears to take over the entire figure because, by default, an uipanel object has 'Units' set to 'normalized' and 'Position' set to [0 0 1 1]. If you want to see other children of hparent while using your new scroll panel, you must manually set the 'Position' property of hpanel.

Version History

Introduced before R2006a