{"id":3831,"date":"2012-09-14T09:00:41","date_gmt":"2012-09-14T13:00:41","guid":{"rendered":"https:\/\/blogs.mathworks.com\/pick\/?p=3831"},"modified":"2016-05-10T08:40:10","modified_gmt":"2016-05-10T12:40:10","slug":"uigetvariables-a-variable-selector-widget-for-building-guis-and-apps","status":"publish","type":"post","link":"https:\/\/blogs.mathworks.com\/pick\/2012\/09\/14\/uigetvariables-a-variable-selector-widget-for-building-guis-and-apps\/","title":{"rendered":"UIGETVARIABLES: A variable selector widget for building GUIs and apps"},"content":{"rendered":"
\r\n\r\nBrett<\/a>'s Pick this week is the UIGETVARIABLES,<\/a> by Scott Hirsch<\/a>.\r\n\r\nScott Hirsch (remember Scott? One of the original authors of this blog?) recently shared with me--and with the File Exchange\r\ncommunity at large--a function that I found extremely useful, and that others will want to consider as well.\r\n\r\nFirst, a quick bit of background...<\/strong>\r\n\r\nAs of this writing, the newest release of MATLAB (R2012b) is \"live,\" and downloadable by anyone with a current license. R2012b\r\nwas a major release<\/a> for us, one that incorporates a new desktop design and many great new features. One of my favorites is the new MATLAB Toolstrip:\r\n\r\n\"\"\r\n\r\nAnd as something of a GUI afficionado, I'm particularly fond of the \"Apps\" tab<\/a>, which not only provides ready access to a variety of MathWorks-provided GUI tools, but which allows you to customize your\r\nMATLAB environment by incorporating your favorite GUI tools. Not one to squander an opportunity like this, I quickly jumped\r\non the bandwagon to share as apps some of my own image-processing-centric GUIs<\/a>. (Installation is a breeze, by the way; just click the \"mlappinstall\" installer files packaged with the GUIs, and the GUIs\r\nautomagically appear in your list of apps.)\r\n\r\nSo where does UIGETVARIABLES come into the picture?<\/strong>\r\n\r\nLots of users have downloaded, and hopefully found utility in, my MorphTool<\/a> GUI for interactively performing image morphology (dilations, erosions, closings, openings, etc.) But as originally written,\r\nMorpTool was not useful as an app because I didn't provide a way to load an image from within the GUI; instead, you had to\r\nspecify the image in the call to the function. Clearly, to make it work as a Toolstrip-accessible application, I had to modify\r\nthe code to allow the user to import an image.\r\n\r\nUsing uigetfile<\/tt><\/a>, I could easily facilitate loading an image from a file. But what about loading an image that already existed as a variable\r\nin the MATLAB workspace? While I might have been able to cobble something together to do that, Scott's file saved me from\r\nhaving to do so! The syntax:\r\n\r\nvarout = uigetvariables(prompts,intro,types,ndimensions)<\/tt>\r\n\r\nlets me specify the type<\/em> and size<\/em> of data that can be selected, and a GUI presenting the user with valid options is automatically created. For instance, if\r\nI wanted to prompt the user to pick a scalar, a vector, and a matrix, I need only write:\r\n
tvar = uigetvariables({'Pick a scalar:','Pick a vector:','Pick a matrix:'},[],[],[0 1 2]);<\/pre>\r\nand uigetvariables<\/tt> will create a custom selection GUI that facilitates the selection:\r\n\r\n\"\"\r\n\r\nI can also specify more advanced criteria for selections; Scott's clever utility will tell the user which variables are acceptable,\r\nand will indicate when no workspace variables fit the bill.\r\n\r\nThe net result: it was really easy to modify my code to allow the user to pick an MxN or MxNx3 (RGB) image:\r\n
validateimage = @(im) (isnumeric(im) || islogical(im)) &&(ndims(im)==2 && ~any(size(im)==2) || (ndims(im)==3&&size(im,3)==3));\r\nimg = uigetvariables(prompts,inputstring,validateimage);<\/pre>\r\nVery nice, Scott!\r\n\r\nAs always, comments to this blog post<\/a> are welcome. Or leave a comment for Scott here<\/a>.\r\n\r\n