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SDL3 File Dialogs #960

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6f1985c
Initial check in
nspitko Jul 19, 2026
6f62362
Fix crash, style consistency
nspitko Jul 19, 2026
039c635
Minor cleanup in sdl.hx
nspitko Jul 19, 2026
969c4ea
Store filters until the callback
nspitko Jul 21, 2026
09ac4c2
Style again...
nspitko Jul 21, 2026
c1fe5a6
strdup filter strings
nspitko Jul 21, 2026
e045296
Pass null through to Haxe, check and throw on error
nspitko Jul 21, 2026
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103 changes: 103 additions & 0 deletions libs/sdl/sdl.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1156,3 +1156,106 @@ DEFINE_PRIM(_ARR, get_display_modes, _I32);
DEFINE_PRIM(_DYN, get_current_display_mode, _I32 _BOOL);
DEFINE_PRIM(_ARR, get_devices, _NO_ARG);
DEFINE_PRIM(_BYTES, get_error, _NO_ARG);

// SDL Dialogs API
typedef struct {
vclosure **closure_store;
SDL_DialogFileFilter* filters;
} dialog_data;

dialog_data* CreateFileDialogData( vclosure *callback, varray *filters ) {
dialog_data *data = malloc( sizeof( dialog_data ) );
data->closure_store = malloc(sizeof(vclosure*));
*data->closure_store = callback;

if( filters && filters->size > 0 ) {
SDL_DialogFileFilter *sdl_filters = (SDL_DialogFileFilter *)malloc(sizeof( SDL_DialogFileFilter ) * filters->size );

for(int i=0;i<filters->size;i++) {
vdynamic *filter = hl_aptr(filters, vdynamic*)[i];
const char *name = (const char*) hl_dyn_getp(filter,hl_hash_utf8("name"),&hlt_bytes);
const char *pattern = (const char*) hl_dyn_getp(filter,hl_hash_utf8("pattern"),&hlt_bytes);

sdl_filters[i].name = name;
sdl_filters[i].pattern = pattern;
}

data->filters = sdl_filters;
}
else
data->filters = NULL;

hl_add_root(data->closure_store);

return data;
}

void FileDialogCallback(void *userdata, const char* const *filelist, int filter) {
// these callbacks may come via threads on some platforms
bool on_unregistered_thread = !hl_get_thread();
if( on_unregistered_thread ) {
vdynamic *ctx;
hl_register_thread(&ctx);
}
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dialog_data *data = (dialog_data*)userdata;
vclosure *vcallback = *data->closure_store;

int count = 0;

varray *array;
if( filelist ) {
const char * const *p = filelist;
while(*p++)
count++;

array = hl_alloc_array(&hlt_bytes, count );
vbyte **array_ptr = (vbyte **)hl_aptr(array, vbyte*);

for(int i = 0; i < count; i++) {
size_t len = strlen(filelist[i]) + 1; // Include the null terminator
vbyte *bytes = hl_alloc_bytes( len );
memcpy(bytes, filelist[i], len);
array_ptr[i] = bytes;
}
} else {
array = hl_alloc_array(&hlt_bytes, 0 );

@yuxiaomao yuxiaomao Jul 21, 2026

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When I'm trying to call with a filter on Windows, it return immediatly an empty array without open any window (works normally if no filters specifield). From C side I saw that filelist is NULL so error occurs, checking the error string it says

Invalid dialog file filters: Invalid character in pattern (Only [a-zA-Z0-9_.-] allowed, or a single *

I think it would be good if we can at least give some information to the haxe side about the error, instead of returning empty list here (return NULL or throw?).

sdl.Sdl.showOpenFileDialog(function(arr) {
		trace("Open " + arr);
	}, null, [{ name : "hxml", pattern : "*.hxml" }]
);

@nspitko nspitko Jul 21, 2026

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This one's kinda tricky since we can't validate filters before the callback (the SDL internal validate_filters function is not exposed to us), so showOpenFileDialog can only ever be void.

What I've done is to pass the NULL state into haxe, and throw getError() in that case. It works here, but I'm not sure there's any way to catch these since they fire in a thread, so I'm not super happy with the solution. The other option is we just pass null through and leave it to the user to read the API, which is more "correct" but probably not intuitive.

@yuxiaomao yuxiaomao Jul 21, 2026

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I don't think it's only about filters, errors can come from elsewhere, so it's good that at least we return NULL from C side.
Yes I agree with you it's not trivial. Another related problem is if we throw inside the callback (either inside SDL.hx or user code), hl_remove_root and free are never called.

}

hl_call1( void, vcallback, varray*, array );
hl_remove_root( data->closure_store );
free( data->closure_store );
free( data->filters );
free( data );

if( on_unregistered_thread )
hl_unregister_thread();
}

HL_PRIM void HL_NAME(show_open_file_dialog)( vclosure *callback, SDL_Window *window, varray *filters, vstring *default_location, bool allow_many ) {
const char *location = default_location ? hl_to_utf8(default_location->bytes) : NULL;

dialog_data *data = CreateFileDialogData( callback, filters );

SDL_ShowOpenFileDialog( FileDialogCallback, data, window, data->filters, filters ? filters->size : 0, location, allow_many );
}

HL_PRIM void HL_NAME(show_open_folder_dialog)( vclosure *callback, SDL_Window *window, vstring *default_location, bool allow_many ) {
const char *location = default_location ? hl_to_utf8(default_location->bytes) : NULL;

dialog_data *data = CreateFileDialogData( callback, NULL );

SDL_ShowOpenFolderDialog( FileDialogCallback, data, window, location, allow_many );
}

HL_PRIM void HL_NAME(show_save_file_dialog)( vclosure *callback, SDL_Window *window, varray *filters, vstring *default_location ) {
const char *location = default_location ? hl_to_utf8(default_location->bytes) : NULL;

dialog_data *data = CreateFileDialogData( callback, filters );

SDL_ShowSaveFileDialog( FileDialogCallback, data, window, data->filters, filters ? filters->size : 0, location );
}

DEFINE_PRIM(_VOID, show_open_file_dialog, _FUN(_VOID, _ARR) TWIN _ARR _STRING _BOOL );
DEFINE_PRIM(_VOID, show_open_folder_dialog, _FUN(_VOID, _ARR) TWIN _STRING _BOOL );
DEFINE_PRIM(_VOID, show_save_file_dialog, _FUN(_VOID, _ARR) TWIN _ARR _STRING );
80 changes: 80 additions & 0 deletions libs/sdl/sdl/Sdl.hx
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Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,12 @@ typedef ScreenMode = {
var framerate : Int;
};

typedef FileDialogCallback = ( Array<String> ) -> Void;
typedef DialogFileFilter = {
public var name: String;
public var pattern: String;
}

@:hlNative("sdl")
class Sdl {

Expand Down Expand Up @@ -277,6 +283,80 @@ class Sdl {
private static function _getJoysticks() : hl.NativeArray<Int> {
return null;
}

//
// SDL3 Dialogs API
//

private static function processFilters(filters: Array<DialogFileFilter> = null) {
var nativeFilters = null;
if( filters != null ) {
nativeFilters = new hl.NativeArray<Dynamic>( filters.length );
for( i in 0 ... filters.length ) {
@:privateAccess {
nativeFilters[i] = {
"name": filters[i].name.toUtf8(),
"pattern": filters[i].pattern.toUtf8(),
};
}
}
}
return nativeFilters;

}

public static function showOpenFileDialog(callback: FileDialogCallback, window: sdl.Window = null, filters: Array<DialogFileFilter> = null, defaultLocation: String = null, allowMultiple: Bool = false) {
var cb = ( bytes: hl.NativeArray<hl.Bytes>) -> {
var files = [];
for( b in bytes )
files.push( @:privateAccess String.fromUTF8( b ) );

callback(files);
};

var nativeFilters = processFilters( filters );

_showOpenFileDialog( cb, window != null ? @:privateAccess window.win : null, nativeFilters, defaultLocation, allowMultiple);
}

public static function showOpenFolderDialog(callback: FileDialogCallback, window: sdl.Window = null, defaultLocation: String = null, allowMultiple: Bool = false) {
var cb = ( bytes: hl.NativeArray<hl.Bytes>) -> {
var files = [];
for( b in bytes )
files.push( @:privateAccess String.fromUTF8( b ) );

callback(files);
};

_showOpenFolderDialog( cb, window != null ? @:privateAccess window.win : null, defaultLocation, allowMultiple);
}

public static function showSaveFileDialog(callback: FileDialogCallback, window: sdl.Window = null, filters: Array<DialogFileFilter> = null, defaultLocation: String = null) {
var cb = ( bytes: hl.NativeArray<hl.Bytes>) -> {
var files = [];
for( b in bytes )
files.push( @:privateAccess String.fromUTF8( b ) );

callback(files);
};

var nativeFilters = processFilters( filters );

_showSaveFileDialog( cb, window != null ? @:privateAccess window.win : null, nativeFilters, defaultLocation);
}


@:hlNative("?sdl", "show_open_file_dialog")
private static function _showOpenFileDialog(callback: (bytes: hl.NativeArray<hl.Bytes>) -> Void, window: sdl.Window.WinPtr, filters: hl.NativeArray<Dynamic>, defaultLocation: String, allowMultiple: Bool) : Void {
}

@:hlNative("?sdl", "show_open_folder_dialog")
private static function _showOpenFolderDialog(callback: (bytes: hl.NativeArray<hl.Bytes>) -> Void, window: sdl.Window.WinPtr, defaultLocation: String, allowMultiple: Bool) : Void {
}

@:hlNative("?sdl", "show_save_file_dialog")
private static function _showSaveFileDialog(callback: (bytes: hl.NativeArray<hl.Bytes>) -> Void, window: sdl.Window.WinPtr, filters: hl.NativeArray<Dynamic>, defaultLocation: String) : Void {
}
}

enum abstract SDLHint(String) from String to String {
Expand Down
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