With the release of version 2.36, Simply Fortran now includes Aplot, a library for creating simple, two-dimensional plots and charts directly from Fortran. The programming interface provided is designed to be straightforward, and the library is available on Windows, macOS, and GNU/Linux. This short article will walk through creating a non-trivial plot quickly with Aplot.
For this example, we’ll attempt to plot 1000 random, uniformly distributed numbers along with a running mean as the sample size grows. The plot will therefore include scatter elements and a line, both with a significant amount of data.
In order to use Aplot, the aplot module must be employed in a given procedure:
On Windows and macOS, this module will be seamlessly included. On GNU/Linux, Simply Fortran might show the module as unavailable until you click Build Project for the first time. There are no other steps to take; Simply Fortran will automatically detect this module’s inclusion and configure the compiler to link to the aplot library.
To generate our data set, we’ll need to populate some arrays accordingly. The code below should be sufficient:
real, dimension(1000)::x, rand_y, mean_y integer::i call RANDOM_NUMBER(rand_y) do i = 1, 1000 x(i) = real(i) mean_y(i) = sum(rand_y(1:i))/x(i) end do
The above code creates three arrays. Our X-axis data will just be the sample count, though we have to use a REAL variable with Aplot. The random data is created with a single call to RANDOM_NUMBER, which populates the entire rand_y array in one call.
The x array is manually populated inside the loop along with the calculation of a running mean in the mean_y array. This code generates two datasets that we need to plot.
In order to create a plot, we need to define a plot variable, which is of the aplot_t type:
This variable is used for defining all aspects of our plot at eventually displaying it. Before we can use it, though, we must initialize it:
plot = initialize_plot()
Once initialized, we can define some aspects of our plot:
call set_title(plot, "Uniform Random Numbers") call set_xlabel(plot, "Sample") call set_ylabel(plot, "Value") call set_yscale(plot, 0.0, 1.2)
Most calls above are straightforward, and each requires our plot variable as its first argument. The final call, though, to set_yscale might not be as obvious as setting titles and labels. By default, Aplot autoscales both axes. In this case, though, we know the data on the y-axis will fall between 0 and 1. In order to provide a little extra space, we’ll expand the plot slightly so that the y-axis varies from 0 to 1.2.
The next step is to configure each dataset for the plot. To add data, we must pass an X and Y array to the add_dataset subroutine:
call add_dataset(plot, x, rand_y)
Once we’ve provided the first dataset to the plot, we can assign some attributes to the series:
call set_seriestype(plot, 0, APLOT_STYLE_PIXEL) call set_serieslabel(plot, 0, "Random Number")
The call to set_seriestype configures the style of the series when drawn. The index of zero is passed because Aplot uses 0-indexing for its series identification. In this case, since we’ll be showing 1000 points, we’ve asked for it to be drawn as a scatter plot using single pixels; the user can also use larger dots, lines, or bars to represent a series. The second call to set_serieslabel provides a label for this series in the legend.
Our second dataset, the running average, can be configured similarly:
call add_dataset(plot, x, mean_y) call set_seriestype(plot, 1, APLOT_STYLE_LINE) call set_serieslabel(plot, 1, "Running Mean")
Our plot is now entirely ready to display. The final step is to call:
which opens a window displaying the complete plot.
The final coding step is to clean up our plot after the user closes it. While not necessarily important in a standalone program, a subroutine that generates plots should always perform final cleanup before exiting. The simple code is:
After this call, all memory associated with the plot is released, and the program can continue normally.
The code here should compile in Simply Fortran 2.36 without issue, generating the following on GNU/Linux:
While the plot might look slightly different on macOS or Windows, it should still resemble the above chart. The plot shows the running average, in blue, converging towards 0.5 as more samples are considered.
Hopefully the above helps users get started with Aplot. The interface is designed for quickly and easily adding plots to Fortran. Any questions about how it works can always be posted on our forums, where either Approximatrix or another user will happily help out.
The complete code for this example is below:
program ranmean use aplot implicit none type(aplot_t)::plot real, dimension(1000)::x, rand_y, mean_y integer::i call RANDOM_NUMBER(rand_y) do i = 1, 1000 x(i) = real(i) mean_y(i) = sum(rand_y(1:i))/x(i) end do plot = initialize_plot() call set_title(plot, "Uniform Random Numbers") call set_xlabel(plot, "Sample") call set_ylabel(plot, "Value") call set_yscale(plot, 0.0, 1.2) call add_dataset(plot, x, rand_y) call set_seriestype(plot, 0, APLOT_STYLE_PIXEL) call set_serieslabel(plot, 0, "Random Number") call add_dataset(plot, x, mean_y) call set_seriestype(plot, 1, APLOT_STYLE_LINE) call set_serieslabel(plot, 1, "Running Mean") call display_plot(plot) call destroy_plot(plot) end program ranmean
Simply Fortran version 2.24 has now been available for about one and a half months, and version 2.25 has not yet appeared. Some of our more seasoned users might consider this delay a little longer than normal between official releases, but development certainly hasn’t been static. The latest build (1921) of version 2.24 was released just two days ago. We thought it might be prudent to explain some of the changes in these builds and what other development might be taking place.
Bugs and Various Fixes
A bug existed in the syntax checking engine that cause the syntax engine to fail for users with special characters in their user name on Windows. Anything from a space to a non-ASCII character would cause syntax checking to fail.
The Fortran indexing engine was failing on code containing line continuations where a comma was the last character on a given line. This bug actually arose in recent versions due to improvements and bug fixes for other Fortran-related parsing enhancements and issues.
Simply Fortran was attempting to compile Fortran include files ending with the .INC extension as standalone source files. The previous solution was to disable the files in the Project Outline, but Simply Fortran now treats these files properly.
AppGraphics was not able to draw vertical text. A fix is now present, but a user has already reported some minor drawing problems with some fonts. This existing bug will probably necessitate another build of version 2.24.
Some of the makefile generation code could intermittently cause error dialogs to appear. The most likely culprit was the handling of search directories for include and library files. The underlying code was greatly simplified for more robust handling of these directory flags.
An odd issue was causing Simply Fortran to lock up entirely. A new user reported that, when entering Fortran code that contained a comma on the very first line of an editor tab without said comma being preceded by an opening parentheses or a comment character, Simply Fortran would freeze. This scenario wouldn’t be common because most Fortran files would either begin with comments or a subprogram declaration (which would have an opening parentheses). The lockup was caused by an infinite loop as the calltip engine searched the line for either an opening parentheses or a newline character. On the very first line in the editor, it would encounter neither as it continued requesting characters at negative document positions. This extremely specific bug has now been fixed.
Simply Fortran version 2.24 has a reasonably robust feature set, which explains why a new version has yet to be created. However, version 2.25 should appear within the next month or so. We plan on including a new version of the underlying compiler and providing an improved automatic code formatter for “beautifying” existing Fortran.
We’ve also been working on some new developments. The screenshot below might be of particular interest to our users running Simply Fortran under WINE:
No official announcements concerning the above…
A number of users have requested some further information about handling multiple windows in AppGraphics. While the Fortran interface certainly suggests a multi-window program is possible, the details of such a program might be a bit non-obvious. In this tutorial, we’ll walk through creating a multiple window application.
To start this exercise, we’ll need a primary window from which we’ll spawn children. While this design isn’t strictly necessary, it would be a common model for many users. Since we’ve gone over producing such windows in the past, we’ll just post the contents of a “main window” below:
program main use appgraphics use children, only: child_ids, child_create_time, redraw_children implicit none integer::myscreen integer::create_child_button integer::sc_ticks integer::sc_tick_rate real::time_now myscreen = initwindow(200, 130, closeflag=.TRUE.) ! Add a button for creating children create_child_button = createbutton(60, 80, 80, 40, "Create Child", & handle_create_child) ! Initialize the child index arrays child_ids = -1 child_create_time = 0.0 ! Label this as the main window call settextstyle(SANS_SERIF_FONT, HORIZ_DIR, 60) call outtextxy(15, 5, "Master") call system_clock(count_rate=sc_tick_rate) do while(.true.) ! Calculate the system time now in seconds call system_clock(count=sc_ticks) time_now = real(sc_ticks)/real(sc_tick_rate) ! Redraw all children and provide them with the system time call redraw_children(time_now) ! Set the master to the current window and idle 1 second call setcurrentwindow(myscreen) call startidle(1000) end do call closewindow(myscreen) contains subroutine handle_create_child() use children, only: create_child implicit none call create_child() end subroutine handle_create_child end program main
Immediately, readers may notice an unfamiliar module, children, appearing at the beginning of this program. The children module will appear later in this writeup, and it will contain all the necessary subprograms for creating, managing, and destroying child windows.
In our main program, we first create a simple, single window that is labeled “Master” and has a single button labeled “Create Child.” Our goal is to spawn a child window whenever the user clicks said button.
After creating the window, we also initialize two arrays, child_ids and child_create_time, that are both used for managing child windows. The former array is used to maintain a list of the identifiers to all of our child windows. When a developer calls the createwindow function, a unique identifier to that window is returned; we need to explicitly keep track of these identifiers while our program is running to allow switching to and update child windows as necessary. The latter array just tracks the system clock time when each child window is created so that we’ll have something interesting to display in our child windows.
After all this initialization, our main program enters a simple loop. Within the loop, we’re calculating the system time in seconds and, using the time value, calling a subroutine to update all of our child windows. Once the update is complete, we carefully ensure the current window in AppGraphics is our main window and we idle for one second. Setting the current window is quite important in AppGraphics. Had we not set the current window to our master window prior to calling startidle, our idling loop would be applied to another window. Basically, as a rule of thumb in AppGraphics programs, any sequence calls to AppGraphics should be preceded by a call to setcurrentwindow to ensure the calls are being applied to the proper window. Without this step, it becomes quite easy to crash your program by attempting an operation, drawing, idling, or querying, on a window that no longer exists.
So far we’ve covered the easiest parts. Handling our child windows will be somewhat more complicated. To start, we’ll need to store some data within our children module:
module children implicit none ! Allow no more than 32 windows integer, parameter::max_windows = 32 ! Width and height of our child window integer, parameter::wc = 180 integer, parameter::hc = 80 ! Array of child window ids and the system times at which each was created integer, volatile, dimension(max_windows)::child_ids real, volatile, dimension(max_windows)::child_create_time contains ...
We have a parameter that defines the maximum number of children we’ll allow; thirty two seems like a reasonable limit. We also define some parameters regarding drawing. The interesting data, though, are our two tracking arrays, child_ids and child_create_time. We’ve marked both arrays as “volatile” because there is a possibility the data in these arrays may be accessed by multiple threads.
Next, we need a subroutine to create a child window:
subroutine create_child() use appgraphics implicit none integer::child_index character(40)::title integer::close_button ! Loop to find an available slot do child_index=1, max_windows ! If the array of children is a negative one, it is available for ! storing a child id if(child_ids(child_index) .EQ. -1) then ! Create a title for this window Write(title, '(A5,1X,I3)') "Child", child_index ! Create the window, making sure that "closeflag" is false child_ids(child_index) = initwindow(wc, hc, & title=title, & closeflag=.FALSE.) ! Set up some styles for this window call settextstyle(WINDOWS_FONT, HORIZ_DIR, 8) call setbkcolor(BLACK) call setcolor(WHITE) ! Store a zero as "when it was created" for now child_create_time(child_index) = 0.0 ! One button to close this child close_button = createbutton(wc-50, hc-40, 40, 30, & "Close", close_child) exit end if end do end subroutine create_child
This routine starts with a loop that looks through our child_ids array for an entry that is equal to -1. We’ll use a -1 to represent an empty slot in our child ids array; one might recall that we initialized the ray to-1 appropriately in our main program. When we do find a -1, we’ll proceed with a call to createwindow and store the new window’s identifier in the child_ids array. For fun we also create a title with the window’s index in the child_ids array. There is some basic graphical configuration of this new window as well. With our new window, we’ll save a creation time of 0.0 in the second array. Finally, we’ll add a close button.
Readers might notice that we’ve already violated a rule mentioned earlier concerning calling setcurrentwindow prior to calling a sequence of AppGraphics routines. The only reason we’ve skipped this step is that the createwindow function also implies setting the current window to the latest window.
For our “close” button, we’ve attached the button to a subroutine named close_child. This routine requires some consideration here:
subroutine close_child use appgraphics implicit none integer::child_id integer::child_index ! This call determines the id of the window that executed this ! callback child_id = getsignallingwindow() ! And we'll retrieve theindex of this window in our global ! arrays child_index = index_from_id(child_id) ! Mark this chold window slot as available for a new child if(child_index .GT. -1) then child_ids(child_index) = -1 child_create_time(child_index) = 0.0 end if if(child_id .GT. -1) then call closewindow(child_id) end if end subroutine close_child
To close a child, we need to take a few steps. First, we need to determine in which window the close button was clicked. All of our child windows call this routine, so we have to determine which to act upon. The getsignallingwindow function can be used to determine the id of the window from which the callback was made. Once we have the id of the child window, we’ll call another custom function to determine the index of this child in the child_ids array. The index_from_id is a simple array search, so we’ll ignore it in this writeup, although it appears in the complete source code.
The reason we need the index in the child_ids array is to set the entry for said window in the array back to -1 so that the slot is once again available for creating a new window.
Finally, we can close our window with a call to closewindow, explicitly passing the id of the window we’re closing.
At this point, we do indeed have a program with multiple windows, but none of the children do anything. To make this exercise interesting, we’ll perform some updates to our children. One may recall that our main program called a subroutine redraw_children that accepted a time argument. This subroutine will subsequently be used to call a redraw routine for all our children:
subroutine redraw_children(time_now) implicit none real, intent(in)::time_now integer::i do i = 1, max_windows call redraw_child(i, time_now) end do end subroutine redraw_children
The above routine isn’t particularly interesting. For each possible window, it calls a far more interesting subroutine, redraw_child:
subroutine redraw_child(child_index, time_now) use appgraphics implicit none integer, intent(in)::child_index real, intent(in)::time_now integer::child_id character(40)::text integer::longevity integer::previous_current ! Get the child id from our array child_id = child_ids(child_index) if(child_id .GE. 0) then ! If its create time is zero, store the system time now if(child_create_time(child_index) .EQ. 0.0) then child_create_time(child_index) = time_now longevity = 0 ! Otherwise, calculate the difference in times else longevity = int(time_now - child_create_time(child_index)) end if ! Write out how old this window is write(text, '(A19,1X,I4,1X,A7)') "I've been alive for", & longevity, & "seconds" ! Store the "current" window for good measure previous_current = getcurrentwindow() ! Select this window as current and display the text in the window call setcurrentwindow(child_id) call clearviewport() call outtextxy(10, 10, text) ! Reset the current window to its previous state call setcurrentwindow(previous_current) end if end subroutine redraw_child
In the redraw_child subroutine, we first check that the id available in the child_ids array is greater than or equal to zero. Recall that a -1 in this array represents “no window” in our scheme. If the id is valid, we’ll proceed with drawing our window.
First, we can calculate, based on the time passed in, how long our window has been open. If a 0.0 is stored in child_create_time, we’ll store the passed time and say that our window has existed for 0 seconds. Otherwise, we can compute how long the window has existed by determining the difference between the current time and the stored time. We’ll use this time to prepare a string to display that states how long the window has been opened.
We’re now ready to draw our window. First, we’ll set our current window appropriately since we’re about to draw. However, prior to doing so, we’ll actually save the current window id in case we were sloppy elsewhere so that we can reset the current window when we’re done. Next, we can clear the window with a call to clearviewport. Then, we can output our text to the window. Finally, before leaving our drawing routine, we’ll reset the current window to its original state like the responsible bookkeepers we should be.
The result of all these routines leads to an interesting example program:
While this example might seem complex, users can hopefully decipher all the steps taken. Furthermore, creating muk\ltiple window applications is an inherently complex process, and we’ve tried to make such development as simple as possible.
The source code for the example appears below:
A user on our forums posted a question about creating a progress bar using AppGraphics. Because Fortran is often relied upon for long-running computations, a graphical progress bar could be very useful. While AppGraphics doesn’t provide a progress bar solution out of the box, creating one isn’t particularly difficult.
In it’s simplest form, a progress bar is really just a partially filled rectangle. With a little creativity, we can create a window that provides all the progress bar behaviors we might want. For maximum portability, we’ll assume that we want a standalone window that can display progress. Ideally, it should also provide:
- An optional “Cancel” button
- A way to display text
- A simple 0 to 100 percent update mechanism
For fun, we’ll also design our progress bar window to be Fortran-2003-esque using some type-bound procedures. To start, we need a derived type to describe our progress bar:
type progresswindow integer::win integer::cancel character(128)::text contains procedure :: close => closeprogress procedure :: draw => drawprogress end type progresswindow
The type includes integers that refer to our progress window, a possible cancel button, and the text we’re displaying above the progress bar. We’ve also attached two type-bound procedures: a “close” subroutine and a “draw” subroutine.
To initialize this window, we’ll basically just need to create the window and set up some drawing styles. An abbreviated summary is below:
p%win = initwindow(400, 100, title=title, dbflag=.FALSE., closeflag=.FALSE.) call setbkcolor(systemcolor(COLOR_WINDOW_BKGD)) call setcolor(BLACK) call settextstyle(WINDOWS_FONT, HORIZ_DIR, 10) call setfillstyle(SOLID_FILL, RED)
The above code creates a window, configures some colors and fonts to match Windows defaults, and sets up the fill style for a red progress bar.
The first type-bound procedure, close, is exceptionally simple, needing only to close this window, so we’ll skip that for now. In contrast, drawing the window is a bit more involved. We’ll need to take a number of steps. Our type definition pointed to a routine “drawprogress,” which we’ll define as such:
subroutine drawprogress(p, completed, text) use appgraphics implicit none class(progresswindow), volatile::p integer, intent(in)::completed character(*), intent(in), optional::text ...
The drawing routine requires a completed percent, which is assumed to be 0 to 100, to be passed in. Optionally, the developer can also provide an updated text string to display above our progress bar. If the text is passed in, we’ll overwrite the text that our “progresswindow” variable is currently storing before we proceed with drawing.
First, we need to clear our viewport of existing graphics with an appropriate call:
call setcurrentwindow(p%win) call clearviewport()
Note that prior to clearing the viewport, we’ve set the current AppGraphics window. This operation safeguards against applications where we may have multiple windows present. The developer, however, must be careful to switch windows back to any other windows when necessary.
Next, we can output the text into the window:
if(len_trim(p%text) > 0) then call outtextxy(5, 5, trim(p%text)) end if
If the text length is zero, we actually skip that step. Finally, we need to draw the progress bar. The actual progress bar really has two components: an empty rectangle and a filled rectangle whose size relative to the empty rectangle reflects the percent complete. AppGraphics doesn’t actually provide a quick routine for drawing unfilled rectangles, so we’ll instead use the relative line operations:
progress_total = getmaxx() - 10 ! Below we'll draw a simple box, unfilled call moveto(5, 25) call lineto(progress_total+5, 25) call lineto(progress_total+5, 50) call lineto(5, 50) call lineto(5, 25)
While the vertical coordinates aren’t particularly important, one should note that the empty rectangle should be about as wide as our window less five pixels on each side as a margin. Next, we can compute the width of filled rectangle based on what the developer passes into the drawing function:
! Bounds-check our completed value progress_completed = progress_total*completed/100 if(progress_completed > progress_total) then progress_completed = progress_total elseif(progress_completed < 0) then progress_completed = 0 end if
One additional step we’ve taken above is to ensure that the final width does not exceed the maximum width of our empty progress bar or that a negative with result from the user’s value. Once we have a width based on our completed progress, we can draw a filled bar:
call bar(5, 25, progress_completed+5, 50)
This rather simple progress bar is actually quite effective. To test out how well it works, we can use a simplistic timing demo to watch the bar draw itself:
program main use progress implicit none type(progresswindow), volatile::p integer::counter real::last_time, now_time p = initprogress("Timed Progress") call cpu_time(last_time) now_time = last_time counter = 0 do while(counter < 100) do while(now_time - last_time < 0.2) call cpu_time(now_time) end do last_time = now_time counter = counter + 1 call p%draw(counter) end do call p%close() end program main
Because of our use of type-bound procedures, the actual driver routine is rather clean.
If you want to try out this simple progress bar, you can download the actual progress bar module and a slightly more advanced driver program (it implements a cancel button) below:
With the release of Simply Fortran version 2.23, AppGraphics now supports resizeable windows. This feature greatly improves the functionality of the library, but there is a bit of a learning curve in creating and managing such windows. We’ll walk through a simple example below that should illustrate how to go about creating an application that uses resizeable windows.
The first step is proceed as normal in creating our window. Of course, we still need to specify an initial size:
myscreen = initwindow(320, 240, closeflag=.TRUE.)
In the above declaration, one may notice that there is no mention of a resizing capability. Wee need to use another call to enable resizing:
The subroutine above will enable resizing for the current window. The argument we’ve included, handle_resize, is actually the name of a subroutine to be called whenever the window changes size. Such a subroutine would be useful if, for example, we need to reposition window controls or redraw graphic contents of a window. We’ll try to do both in this example.
In our main program, we’ll first add a button to our window in the lower right corner:
mybutton = createbutton(270, 210, 40, 20, "Close", handle_button)
quit = .FALSE.
In the code above, we’ve added a “Close” button that will, when clicked, call a subroutine handle_button that will flip the value of quit to .TRUE. and exit idle mode. We’ll also need an event loop in our code:
do while(.NOT. quit) call draw_window() call loop() end do call closewindow(myscreen)
The event loop above basically draws our window and enters idle mode. If we ever idle mode, it first checks if the quit flag was triggered and, if not, redraws the window. The above structure means that we need only a simple subroutine for our resize callback handle_resize:
subroutine handle_resize() use appgraphics implicit none call stopidle() end subroutine handle_resize
All the logic for laying out our window needs to reside in the draw_window subroutine. We’ll try to do two things in our drawing subroutine:
- Position mybutton in the lower right corner
- Output the window size, centered, in our window
For both of these tasks, we’ll need to know the current window size, which can easily be done with calls to getmaxx and getmaxy:
integer::w,h ... w = getmaxx() h = getmaxy()
Based on the window size, we can actually reposition our button quite easily with a call to setbuttonposition:
call setbuttonposition(mybutton, w-50, h-30, 40, 20)
The next task is to draw something in our window. We’ll simply write the window size near the top of the window, erasing any earlier text first:
integer::tw character(100)::info ... write(info, '(A5,1X,I5,A1,I5)') "Size:", w, "x", h call setviewport(0, 0, w, 40, .FALSE.) call clearviewport() tw = textwidth(trim(info)) call outtextxy( (w/2-tw/2), 5, trim(info))
The code above first writes the current window dimensions into the string info. Next, it defines and immediately clears a viewport where previous text would have existed. Finally, it outputs the text, centered in the window.
When you first run the program, you should see something like:
Unlike other AppGraphics windows, however, this one can be resize by dragging the borders. Thanks to our design, things will continue to look nice at other sizes:
Working with a resizeable window is rather easy as long as you properly handle drawing the window when resize occurs.
If you’d like to try the code out for yourself, feel free to do so by clicking the link below:
It should work fine in Simply Fortran version 2.23 or higher.
AppGraphics is a simple graphics library designed for creating graphical user interfaces from Fortran. Although based on an older drawing library, AppGraphics has ben enhanced with a number of Windows controls, or the standard buttons, text boxes, check boxes common in modern Windows applications. While AppGraphics can be used for drawing shape primitives, it can also be used to easily create a “dialog” experience.
In this quick rundown, we will create a simple application for converting common temperature formats in a simple graphical program written entirely in Fortran. Since our task is so simple, we’ll only need a single Fortran source file to build this.
In our main program, the first step is to initialize our window. For this example, we’ll create a long, skinny window as shown in the picture:
myscreen = initwindow(150, 255, title="TempConvert", closeflag=.TRUE.)
We now have a 150 by 255 pixel window with an appropriate title. The closeflag argument instructs AppGraphics to end our program whenever the window closes. To make our window match the operating system’s themes, we’ll need to also change the background. The proper action would be to set the background color to the system’s dialog background color:
We also need to make sure our fonts match Windows as one would expect:
call settextstyle(WINDOWS_FONT, HORIZ_DIR, 10)
Finally, we need to redraw our background with the newly assigned background color by clearing the window and forcing a redraw:
After combining all of the above code, we should now have a standard blank window with the proper fonts configured. If you want to see everything together, you’ll be able to download the complete program at the end of this article.
Next, we need to add our controls to the window. First, we’ll add the text box where a user can enter a temperature:
original = createtextbox(5, 5, 140, 20)
call settextboxcontents(original, "32.0")
Above we’ve created a text box at (5,5) (as measured from the top left) that measures 140 pixels wide and 20 pixels high. These dimensions should leave a consistent 5 pixel distance from the top, left, and right edges of our window. Next, we drop in the temperature of 32 degrees.
We now need to provide a method to select the original temperature’s units of measure. Since only one unit can be chosen, using radio buttons is an obvious choice of control. Using a 4-element array to store each radio button’s identifier, we can create our controls:
integer, dimension(4)::src, dest character(16), dimension(4), parameter:: units =(/ 'Fahrenheit', & 'Celsius ', & 'Kelvin ', & 'Rankine ' /) ... call outtextxy(5, 30, "Original:") call beginradiogroup() src(1) = createradiobutton(50, 30, 95, 20, units(1)) src(2) = createradiobutton(50, 50, 95, 20, units(2)) src(3) = createradiobutton(50, 70, 95, 20, units(3)) src(4) = createradiobutton(50, 90, 95, 20, units(4)) call radiobuttonsetchecked(src(1), logical(.TRUE., 1))
The call to beginradiogroup indicates to AppGraphics that all radio buttons created until another call to beginradiogroup represent exclusive choices. If we click on the second button, for example, the first button will now unselect. Like the text box, the calls to createradiobutton specify the position and dimensions of our new buttons. Finally, we’ll select Fahrenheit for our initial temperature.
We’ll also need the possible selections for our final temperature, but the code to do so is extremely similar. For now, we’ll skip ahead to the buttons that actually get work done.
We need two buttons for this program, Convert and Close:
ignore = createbutton(40, 230, 50, 20, "Convert", convert_temp) ignore = createbutton(95, 230, 50, 20, "Close", quit)
The createbutton call returns an integer that represents an identifier for the button. Since we don’t particularly care about the identifier in this program, we can assign the number to a variable named “ignore.” The first four arguments are, again, the position and dimensions of our buttons. The text arguments represent the text on the button when displayed. Finally, the last arguments are subroutines that will be called when a button is clicked. The latter subroutine, quit, is simple:
subroutine quit() implicit none call stopidle() end subroutine quit
This subroutine makes sense if we examine the remaining segments of our main program.
After we create all our controls, we basically want the window to sit idle until the user clicks either “Convert” or “Close.” After we create our buttons, we can add two simple calls:
call loop() call closewindow(myscreen)
In the code above, we’ve instructed our program to enter an idle “loop” until instructed to leave idle mode. As soon as stopidle is called, like in our quit subroutine, the program resumes execution at the next line. In this case, we’ll close our window and stop running.
The other button will call convert_temp, a substantially more complicated subroutine. The goal of convert_temp is to read the temperature in our original text box, determine its units of measure, convert to another unit system, and output the result in another text box.
First, we need to retrieve the original temperature:
character(40)::source_text, dest_text real::source_number, dest_number i = gettextboxcontents(original, source_text) Read(source_text, *) source_number
in the code above, we read in the text box contents into a string and then read in a number from said string.
Next, we would need to determine the source temperature’s units. This step gets somewhat complicated because we have four possibilities. The full program is a better place to see all the calls. However, one simplifying step might be to convert an original temperature in Kelvin to Celsius and, similarly if appropriate, in Rankine to Fahrenheit.
! Check if we have kelvin or rankine and correct to ! celsius or fahrenheit if(radiobuttonischecked(src(3))) then source_number = source_number - 273.15 elseif(radiobuttonischecked(src(4))) then source_number = source_number - 460.67 end if
The code above checks if the Kelvin radio button is selected using the call radiobuttonischecked, and, if so, converts our source temperature to Celsius immediately. If Rankine is selected, a similar computation occurs to convert the temperature to Fahrenheit.
After we check all the combinations and perform the proper math, we can store our result in the appropriate text box:
Write(dest_text, '(F10.2)') dest_number call settextboxcontents(converted, trim(adjustl(dest_text)))
Once we set the results textbox with the converted temperature, we can exit our convert_temp subroutine. Notice that we never called stopidle; that call would have ended our program. Instead, we can continue to allow our program to idle in case the user wants to click “Convert” again.
And that’s about it! The hardest part of the code above is properly laying out our Windows controls. The best way to do so is trial and error, but it becomes substantially easier with experience.
You can download the full code for this example here:
In the upcoming version 2.14 release, Simply Fortran will begin shipping GNU Fortran 4.9.0 for the first time. This compiler release is considered a major change for Simply Fortran regardless of the numbering convention because it will once again break the compiled module format for Fortran 90+ projects. While this change is conceptually simple for most people, it presents some interesting challenges for Approximatrix.
Simply Fortran has been using the GNU Fortran 4.8 series since version 1.42, which was released in March, 2013. During that period, the number of packages available in the Simply Fortran Package Manager has grown considerably. An issue arises, though, when considering how to handle packages containing pre-compiled modules once the latest release of Simply Fortran is available.
We’ve now shipped an updated version of the Package Manager that is aware of the compiler version currently available. Behind the scenes, packages will begin shipping with “required compiler versions” to ensure any pre-compiled modules are compatible with the version of GNU Fortran installed. This change should be invisible to the user. If a package is made available requiring GNU Fortran 4.9 and the user still has 4.8.2 installed, the package will not even be visible in the Package Manager. This configuration allows Approximatrix to begin updating packages as necessary while continuing to allow older installations to operate properly.
The second issue is actually rebuilding all necessary packages. The construction of packages for the Package Manager is not particularly simple, hence why the Package Manager exists in the first place. Although Simply Fortran 2.14 is basically ready for final testing, the actual release will be held back until the requisite packages are also upgraded.