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extend teh implementing a new frontend document
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Vincent Sanders
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@ -184,7 +184,7 @@ operations:
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Rather than attempt to describe every aspect of an implementation we
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will rather work from an actual minimal example for the FLTK toolkit.
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This is availble as a single commit (`git show 04900e82e65f8669675538a66a01b56a3e473cb2`) in the NetSurf source repository. Alternatively it can be [viewed in a web browser](https://git.netsurf-browser.org/netsurf.git/commit/?h=vince/fltk&id=04900e82e65f8669675538a66a01b56a3e473cb2).
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This is availble as a single commit (`git show 28ecbf82ed3024f51be4c87928fd91bacfc15cbc`) in the NetSurf source repository. Alternatively it can be [viewed in a web browser](https://git.netsurf-browser.org/netsurf.git/commit/?h=vince/fltk&id=28ecbf82ed3024f51be4c87928fd91bacfc15cbc).
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This represents the absolute minimum implementation to get a browser
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window on screen (and be able to click visible links). It is
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@ -193,28 +193,28 @@ equivalent implementation in other languages should be obvious.
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## Building
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The [frontends/Makefile.hts](https://git.netsurf-browser.org/netsurf.git/diff/frontends/Makefile.hts?h=vince/fltk&id=04900e82e65f8669675538a66a01b56a3e473cb2)
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The [frontends/Makefile.hts](https://git.netsurf-browser.org/netsurf.git/diff/frontends/Makefile.hts?h=vince/fltk&id=28ecbf82ed3024f51be4c87928fd91bacfc15cbc)
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had the fltk target added to the VLDTARGET variable. This allows
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NetSurf to be built for this frontend with `make TARGET=fltk`
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As previously described the three GNU Make files are added:
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[Makefile](https://git.netsurf-browser.org/netsurf.git/diff/frontends/fltk/Makefile?h=vince/fltk&id=04900e82e65f8669675538a66a01b56a3e473cb2)
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[Makefile](https://git.netsurf-browser.org/netsurf.git/diff/frontends/fltk/Makefile?h=vince/fltk&id=28ecbf82ed3024f51be4c87928fd91bacfc15cbc)
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this shows how the flags are extended to add the fltk headers and
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library. Additionaly the list of sources are built here, as teh
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comment suggests it is important the SOURCES variable is not expanded
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here so the S_FRONTEND variable is used to allow expansion at teh
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correct time in the build process.
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[Makefile.defaults](https://git.netsurf-browser.org/netsurf.git/diff/frontends/fltk/Makefile.defaults?h=vince/fltk&id=04900e82e65f8669675538a66a01b56a3e473cb2)
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[Makefile.defaults](https://git.netsurf-browser.org/netsurf.git/diff/frontends/fltk/Makefile.defaults?h=vince/fltk&id=28ecbf82ed3024f51be4c87928fd91bacfc15cbc)
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has the default setting to control the build parameters and file locations. These can be overriden by the `Makefile.config` at compile time.
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[Makefile.tools](https://git.netsurf-browser.org/netsurf.git/diff/frontends/fltk/Makefile.tools?h=vince/fltk&id=04900e82e65f8669675538a66a01b56a3e473cb2)
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[Makefile.tools](https://git.netsurf-browser.org/netsurf.git/diff/frontends/fltk/Makefile.tools?h=vince/fltk&id=28ecbf82ed3024f51be4c87928fd91bacfc15cbc)
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allows the configuration of additional tools necessary to build for the target as a minimum pkg-config is usually required to find libraries.
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## Program entry
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In our example program entry is the classical `main()` in the [main.cpp](https://git.netsurf-browser.org/netsurf.git/diff/frontends/fltk/main.cpp?h=vince/fltk&id=04900e82e65f8669675538a66a01b56a3e473cb2) module.
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In our example program entry is the classical `main()` in the [main.cpp](https://git.netsurf-browser.org/netsurf.git/diff/frontends/fltk/main.cpp?h=vince/fltk&id=28ecbf82ed3024f51be4c87928fd91bacfc15cbc) module.
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This implements the six stage process outlined previously.
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@ -256,7 +256,7 @@ example here is a good start.
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### Toolkit run loop
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The function `nsfltk_run()` runs the toolkit event loop. In this case it is using the generic scheduleing in the [misc.cpp](https://git.netsurf-browser.org/netsurf.git/diff/frontends/fltk/misc.cpp?h=vince/fltk&id=04900e82e65f8669675538a66a01b56a3e473cb2) module to ensure callbacks get made at the apropriate time.
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The function `nsfltk_run()` runs the toolkit event loop. In this case it is using the generic scheduleing in the [misc.cpp](https://git.netsurf-browser.org/netsurf.git/diff/frontends/fltk/misc.cpp?h=vince/fltk&id=28ecbf82ed3024f51be4c87928fd91bacfc15cbc) module to ensure callbacks get made at the apropriate time.
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There is a `nsfltk_done` boolean global checked here so when all the
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browser windows are closed the program will exit.
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@ -284,7 +284,7 @@ flushed.
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## The window operation table
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Amongst all the boilerplate of the default implementation the only novel code is in the window operation table in the [window.cpp](https://git.netsurf-browser.org/netsurf.git/diff/frontends/fltk/window.cpp?h=vince/fltk&id=04900e82e65f8669675538a66a01b56a3e473cb2) module.
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Amongst all the boilerplate of the default implementation the only novel code is in the window operation table in the [window.cpp](https://git.netsurf-browser.org/netsurf.git/diff/frontends/fltk/window.cpp?h=vince/fltk&id=28ecbf82ed3024f51be4c87928fd91bacfc15cbc) module.
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### `nsfltk_window_create`
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@ -333,13 +333,74 @@ This obtains the fltk widget width and height and returns them.
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When the `NS_Widget::draw` method was discussed it was noted that a
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plotting context is built containing an operation table. That table is
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implemented in [plotters.cpp](https://git.netsurf-browser.org/netsurf.git/diff/frontends/fltk/plotters.cpp?h=vince/fltk&id=04900e82e65f8669675538a66a01b56a3e473cb2)
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implemented in [plotters.cpp](https://git.netsurf-browser.org/netsurf.git/diff/frontends/fltk/plotters.cpp?h=vince/fltk&id=28ecbf82ed3024f51be4c87928fd91bacfc15cbc)
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The implementation here is as minimal as can be, only line, rectangle
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and text have any implementation at all and even that simply sets a
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colour and performs the appropriate fltk draw function (`fl_line`,
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`fl_rect` and `fl_draw` respectively)
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# Worked Example next steps
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The previous section outlined the absolute minimum
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implementation. Here we can exmaine some next steps taken to extend
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the frontend.
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## Improving the user interface
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The example discussion is based on a commit (`git show bc546388ce428be5cfa37cecb174d549c7b30320`) in the NetSurf source repository. Alternatively it can be [viewed in a web browser](https://git.netsurf-browser.org/netsurf.git/commit/?h=vince/fltk&id=bc546388ce428be5cfa37cecb174d549c7b30320).
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This changes a single module `window.cpp` where the `NS_Window`,
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`NS_Widget` and `NS_URLBar` classes are used to create a basic
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browsing interface.
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The static window operation functions are moved inside the `NS_Window`
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class and the `gui_window` structure is used to obtain an instance
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allowing normal methods to be called to implement functionality. This
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is purely to make the C++ code more idiomatic and obviously would be
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handled differently in other languages.
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The `NS_Window` constructor builds additional widgets to just the
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browser drawing widget. It creates:
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- a URL bar widget containing some navigation buttons and a widget to show the current url
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- a vertical scrollbar
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- a horizontal scrollbar
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- a status text widget
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The scrollbar widgets fltk callbacks (called when user interacts with
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the scrollbar) call a method on the `NS_Widget` allowing it to track
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the current scroll offsets which are subsequently used in the drawing
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and user input handling methods.
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## Improving rendering
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Up to this point the rendering has been minimal and the text in a
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single face and size with incorrect width measurement. There was no
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proper handling of plotting styles and colours.
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## Implementing bitmap rendering
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There was no bitmap rendering so no pretty pictures.
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## Implementing the user messages API
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This immediately allows the browser to use the existing language
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translations for many internal strings.
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## Implementing a user settings dialog
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Implementing a way for the user to change configuration options
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without having to edit a configuration file greatly improves the
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perceived functionality.
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## Implementing corewindow
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The [core window interface](docs/core-window-interface.md) allows a
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frontend to use inbuilt rendering for several interfaces gaining a
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great deal of functionality for very litte code. This one interface
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set gives a cookie viewer,a local and global history viewer and a
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hotlist(bookmarks) viewer.
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# Conclusion
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Hopefully this breif overview and worked example should give the
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