Kotlin/Native : How to import entire GTK4 Libs and headers to Kotlin Native C Interop?

Question

I am learning C Interop with Kotlin Native. I successfully imported my sample C program using .Def file and executed the code in kotlin

So, I am thinking about import GTK4 libs, which is in C, to Kotlin/Native project and try a GTK app there

But since GTK4 have lot of header files and linking libs, I don't know how to import them

I successfully executed GTK4 sample program in CLion C++ project.

But need to know how to import the GTK4 libs and headers to Kotlin/Native project

My Cmake in Clion project

cmake_minimum_required(VERSION 3.24)
project(HexEditor)

set(CMAKE_CXX_STANDARD 20)
find_package(PkgConfig REQUIRED)
pkg_check_modules(GTK4 REQUIRED gtk4)

include_directories(${GTK4_INCLUDE_DIRS})
link_directories(${GTK4_LIBRARY_DIRS})

add_definitions(${GTK4_CFLAGS_OTHER})
add_executable(HexEditor main.cpp)

target_link_libraries(HexEditor ${GTK4_LIBRARIES})

How to map them in .def file of Kotlin/Native ?

Answer 1

I think it's good to use pkg-config, but this may require some workarounds, .def files do not support the execution of pkg-config, which is an executable program, so you should generate def files more dynamically.

generate_def.sh

#!env sh
cflags=$(pkg-config --cflags gtk4)
ldflags=$(pkg-config --libs gtk4)
echo headers = gtk/gtk4.h"\n" > libgtk4.def
echo compilerOpts = ${cflags}"\n" >> libgtk4.def
echo linkerOpts = ${ldflags}"\n" >> libgtk4.def

Such a script can basically meet most needs, but I am not satisfied. I hope this can be integrated into the gradle task, and can use the gradle task cache to improve efficiency, and it will be more friendly to ci/cd.

build.gradle.kts

// ……
kotlin {
    // Here only use arbitrary target as an example, but you should use intellij idea to create the project automatically
    val nativeTarget = macosArm64()

    nativeTarget.apply {
        compilations {
            val main by getting {
                cinterop {
                    val libgtk4 by creating {
                        // Here you can use a more flexible location based on projectDir or project.file instead of an absolute path
                        deffile("/path/to/your/deffile")
                    }
                }
            }
        }
    }
}

tasks {
    val generateDef by registering {
        // make def fiel cache able
        outputs.cacheIf { true }
        outputs.file("/path/to/your/deffile")
        doLast {
            ProcessBuilder("sh", "-c", "path/to/generate_def.sh", "path/to/your/deffile")
                .start()
                .wairFor()
        }
    }

    // this val name is like cinterop${nativeTarget.compilations.main.cinterop.libgtk4}Native
    val cinteropLibgtk4Native by getting {
        dependsOn(generateDef)
    }
}
// ……

wrote the above answer without ide prompt, so you need to be extra careful I may bring some spelling mistakes, ide will help you

Answer 2

This is a working .def file for GTK4 and Kotlin/Native for Ubuntu 22.04:

headers = gtk/gtk.h gtk/gtkunixprint.h gtk/gtkmediastream.h
package = org.gtkkn.native.gtk
headerFilter = gtk/* gtk/deprecated/* gtk/css/*

# pkg-config --cflags gtk4
compilerOpts.linux = \
    -I/usr/include \
    -I/usr/include/gtk-4.0 \
    -I/usr/include/gtk-4.0/unix-print \
    -I/usr/include/pango-1.0 \
    -I/usr/include/glib-2.0 \
    -I/usr/lib/glib-2.0/include \
    -I/usr/include/sysprof-4 \
    -I/usr/include/harfbuzz \
    -I/usr/include/freetype2 \
    -I/usr/include/libpng16 \
    -I/usr/include/libmount \
    -I/usr/include/blkid \
    -I/usr/include/fribidi \
    -I/usr/include/cairo \
    -I/usr/include/lzo \
    -I/usr/include/pixman-1 \
    -I/usr/include/gdk-pixbuf-2.0 \
    -I/usr/include/graphene-1.0 \
    -I/usr/lib/graphene-1.0/include \
    -mfpmath=sse \
    -msse \
    -msse2 \
    -pthread

compilerOpts.linux_x64 = \
    -I/usr/lib64/glib-2.0/include \
    -I/usr/lib64/graphene-1.0/include \
    -I/usr/lib/x86_64-linux-gnu/glib-2.0/include \
    -I/usr/lib/x86_64-linux-gnu/graphene-1.0/include

# pkg-config --libs gtk4
linkerOpts.linux = \
    -L/usr/lib \
    -lgtk-4 \
    -lpangocairo-1.0 \
    -lpango-1.0 \
    -lharfbuzz \
    -lgdk_pixbuf-2.0 \
    -lcairo-gobject \
    -lcairo \
    -lgraphene-1.0 \
    -lgio-2.0 \
    -lgobject-2.0 \
    -lglib-2.0

linkerOpts.linux_x64 = \
    -L/usr/lib64 \
    -L/usr/lib/x86_64-linux-gnu

strictEnums = \
    GtkAccessibleAutocomplete \
    GtkAccessibleInvalidState \
    GtkAccessiblePlatformState \
    GtkAccessibleProperty \
    GtkAccessibleRelation \
    GtkAccessibleRole \
    GtkAccessibleSort \
    GtkAccessibleState \
    GtkAccessibleTristate \
    GtkAlign \
    GtkArrowType \
    GtkAssistantPageType \
    GtkBaselinePosition \
    GtkBorderStyle \
    GtkBuilderError \
    GtkButtonsType \
    GtkCellRendererAccelMode \
    GtkCellRendererMode \
    GtkCollation \
    GtkConstraintAttribute \
    GtkConstraintRelation \
    GtkConstraintStrength \
    GtkConstraintVflParserError \
    GtkContentFit \
    GtkCornerType \
    GtkCssParserError \
    GtkCssParserWarning \
    GtkDeleteType \
    GtkDialogError \
    GtkDirectionType \
    GtkEditableProperties \
    GtkEntryIconPosition \
    GtkEventSequenceState \
    GtkFileChooserAction \
    GtkFileChooserError \
    GtkFilterChange \
    GtkFilterMatch \
    GtkFontLevel \
    GtkIconSize \
    GtkIconThemeError \
    GtkIconViewDropPosition \
    GtkImageType \
    GtkInputPurpose \
    GtkInscriptionOverflow \
    GtkJustification \
    GtkLevelBarMode \
    GtkLicense \
    GtkMessageType \
    GtkMovementStep \
    GtkNaturalWrapMode \
    GtkNotebookTab \
    GtkNumberUpLayout \
    GtkOrdering \
    GtkOrientation \
    GtkOverflow \
    GtkPackType \
    GtkPadActionType \
    GtkPageOrientation \
    GtkPageSet \
    GtkPanDirection \
    GtkPolicyType \
    GtkPositionType \
    GtkPrintDuplex \
    GtkPrintError \
    GtkPrintOperationAction \
    GtkPrintOperationResult \
    GtkPrintPages \
    GtkPrintQuality \
    GtkPrintStatus \
    GtkPropagationLimit \
    GtkPropagationPhase \
    GtkRecentManagerError \
    GtkResponseType \
    GtkRevealerTransitionType \
    GtkScrollStep \
    GtkScrollType \
    GtkScrollablePolicy \
    GtkSelectionMode \
    GtkSensitivityType \
    GtkShortcutScope \
    GtkShortcutType \
    GtkSizeGroupMode \
    GtkSizeRequestMode \
    GtkSortType \
    GtkSorterChange \
    GtkSorterOrder \
    GtkSpinButtonUpdatePolicy \
    GtkSpinType \
    GtkStackTransitionType \
    GtkStringFilterMatchMode \
    GtkSymbolicColor \
    GtkSystemSetting \
    GtkTextDirection \
    GtkTextExtendSelection \
    GtkTextViewLayer \
    GtkTextWindowType \
    GtkTreeViewColumnSizing \
    GtkTreeViewDropPosition \
    GtkTreeViewGridLines \
    GtkUnit \
    GtkWrapMode

This is coming from the gtk-kn project, that provides full bindings for GTK4 generated from the GIR.