I have a question about @Composable requirements a...

# compose-desktop

[xetra11]

I have a question about @Composable requirements and compilation. Following an example from @Igor Demin I tried to setup mutable states before the Window() call. However it is not allowed due the following error:

(24, 5): Functions which invoke @Composable functions must be marked with the @Composable annotation

(25, 56): @Composable invocations can only happen from the context of a @Composable function

(32, 35): @Composable invocations can only happen from the context of a @Composable function

(33, 16): @Composable invocations can only happen from the context of a @Composable function

This is the snippet:

fun main() {
    val characterState: SnapshotStateList<Character> = remember {
        mutableStateListOf(
            CharacterTemplate.DEFAULT_CHARACTER,
            CharacterTemplate.DEFAULT_CHARACTER,
            CharacterTemplate.DEFAULT_CHARACTER
        )
    }
    val window = AppWindowAmbient.current!!.window
    val file = remember { mutableStateOf(File("")) }

    Window(
        title = "CK3 Mod Workbench",
        menuBar = MenuBar(
            Menu("File", MenuItem("Exit", onClick = { AppManager.exit() })),
            Menu(
                "Characters",
                MenuItem("Import characters", onClick = { }),
                MenuItem("Dynasties", onClick = {})
            ),
        )
    ) {
        MaterialTheme(
            colors = workbenchLightColors(),
            shapes = workBenchShapes()
        ) {
            CharacterModuleView()
        }
    }
}

[Igor Demin]

We don't need to call remember outside Composable functions (i.e. outside Window).

Because Composable can be called multiple times, remember helps us to execute code only once.

So just use mutableStateListOf/mutableStateOf without remember.

[xetra11]

oh... ok need to write that down 😄

[xetra11]

couldn't it be a warning instead of a compiling error then?

[xetra11]

meh nah the error is fine I guess

[Igor Demin]

if we make it a warning everyone will just ignore it 😄

[xetra11]

haha ye I would to be fair 😛

[xetra11]

val window = AppWindowAmbient.current!!.window however this part still has issues. I have to say here that I have 0 experience in desktop application stuff. Maybe I just can't see the obvious

[xetra11]

I understand there is no window created yet since Window comes after it

[xetra11]

But using it in MenuItem("Import characters", onClick = { }), doesn't work either - is it Window is no @composable ? If yes - is it sufficient (and good practise) to wrap the logic into a @Composable ?

[Igor Demin]

AppWindowAmbient.current

is also a Composable function. So we need to call it inside Window { }

[xetra11]

Ok I think the whole Menu Item stuff is not working with the Composable Concepts right?

[xetra11]

See I'd like to have this logic wenn clicking on a MenuItem:

val fileDialog = FileDialog(window)
    fileDialog.mode = FileDialog.LOAD
    fileDialog.isVisible = true
    file.value = File(fileDialog.directory + fileDialog.file)

[xetra11]

Just want to open a file there

[xetra11]

Since FileDialog needs a Window I am kind of stuck here

[Igor Demin]

If you need to access window inside onClick then we can write our own initialization:

import androidx.compose.desktop.AppWindow
import <http://androidx.compose.ui.window.Menu|androidx.compose.ui.window.Menu>
import androidx.compose.ui.window.MenuBar
import androidx.compose.ui.window.MenuItem
import java.awt.FileDialog
import javax.swing.SwingUtilities.invokeLater

fun main() = invokeLater {
    lateinit var window: AppWindow

    window = AppWindow(
        menuBar = MenuBar(
            Menu(
                "Characters",
                MenuItem("Import characters", onClick = {
                    val fileDialog = FileDialog(window.window)
                }),
            ),
        )
    )

    window.show {
        // Composable content
    }
}

[xetra11]

Ah yes finally thanks a heap @Igor Demin!