textfield: Add OnChange(fn func(newValue string)) (#3)

Author: roblillack

README.md

@@ -6,6 +6,7 @@
 >
 > #### Changes to original
 >
+> - 2024-05-22 [#3](https://github.com/roblillack/gocoa/pull/3): Add support for `OnChange` callbacks for textfields
 > - 2024-05-22 [#1](https://github.com/roblillack/gocoa/pull/1): Add support for removing controls (based on work by @phaus)
 > - 2024-05-22 [#2](https://github.com/roblillack/gocoa/pull/2): Update deprecated NSButton enums (by @dim13)
 > - 2024-05-14 [e85e4be](https://github.com/roblillack/gocoa/commit/e85e4be) progressindicator: Don't hide by default as this would increase time to create widgets in the first place

textfield.go

@@ -12,7 +12,7 @@ import (
 // TextField -Button represents a button control that can trigger actions.
 type TextField struct {
 	textFieldPtr C.TextFieldPtr
-	callback     func()
+	callback     func(value string)
 }
 
 var textfields []*TextField
@@ -126,3 +126,16 @@ func (textField *TextField) SetSelectable(selectable bool) {
 		C.TextField_SetSelectable(textField.textFieldPtr, C.int(0))
 	}
 }
+
+func (textField *TextField) OnChange(fn func(value string)) {
+	textField.callback = fn
+}
+
+//export onTextFieldDidChange
+func onTextFieldDidChange(id C.int) {
+	textFieldID := int(id)
+	if textFieldID < len(textfields) && textfields[textFieldID].callback != nil {
+		tf := textfields[textFieldID]
+		tf.callback(tf.StringValue())
+	}
+}

textfield.m

@@ -1,4 +1,5 @@
 #import "textfield.h"
+#import "textfielddelegate.h"
 #include "_cgo_export.h"
 
 @implementation TextFieldHandler
@@ -8,6 +9,10 @@ TextFieldPtr TextField_New(int goTextFieldId, int x, int y, int w, int h) {
 	/* create the NSTextField and add it to the window */
 	id nsTextField = [[[NSTextField alloc] initWithFrame:NSMakeRect(x, y, w, h)] autorelease];
 
+    id d = [[TextFieldDelegate alloc] init];
+    [d setGoTextFieldId:goTextFieldId];
+    [nsTextField setDelegate:d];
+
 	return (TextFieldPtr)nsTextField;
 }
 

textfielddelegate.h

@@ -0,0 +1,7 @@
+#import <Cocoa/Cocoa.h>
+
+@interface TextFieldDelegate : NSObject <NSTextFieldDelegate>
+
+@property(assign) int goTextFieldId;
+
+@end

textfielddelegate.m

@@ -0,0 +1,17 @@
+#import "textfielddelegate.h"
+#include "_cgo_export.h"
+
+@implementation TextFieldDelegate
+
+- (void)dealloc {
+  [super dealloc];
+}
+
+- (void)controlTextDidChange:(NSNotification *)aNotification {
+  //   NSTextField *textField = [aNotification object];
+  //   const char *text = [[textField stringValue]
+  //   cStringUsingEncoding:NSUTF8StringEncoding];
+  onTextFieldDidChange([self goTextFieldId]);
+}
+
+@end