godot/platform/iphone/keyboard_input_view.mm

/*************************************************************************/
/*  keyboard_input_view.mm                                               */
/*************************************************************************/
/*                       This file is part of:                           */
/*                           GODOT ENGINE                                */
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/* Copyright (c) 2007-2021 Juan Linietsky, Ariel Manzur.                 */
/* Copyright (c) 2014-2021 Godot Engine contributors (cf. AUTHORS.md).   */
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/* The above copyright notice and this permission notice shall be        */
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#import "keyboard_input_view.h"

#include "core/os/keyboard.h"
#include "display_server_iphone.h"
#include "os_iphone.h"

@interface GodotKeyboardInputView () <UITextViewDelegate>

@property(nonatomic, copy) NSString *previousText;
@property(nonatomic, assign) NSRange previousSelectedRange;

@end

@implementation GodotKeyboardInputView

- (instancetype)initWithCoder:(NSCoder *)coder {
	self = [super initWithCoder:coder];

	if (self) {
		[self godot_commonInit];
	}

	return self;
}

- (instancetype)initWithFrame:(CGRect)frame textContainer:(NSTextContainer *)textContainer {
	self = [super initWithFrame:frame textContainer:textContainer];

	if (self) {
		[self godot_commonInit];
	}

	return self;
}

- (void)godot_commonInit {
	self.hidden = YES;
	self.delegate = self;

	[[NSNotificationCenter defaultCenter] addObserver:self
											 selector:@selector(observeTextChange:)
												 name:UITextViewTextDidChangeNotification
											   object:self];
}

- (void)dealloc {
	self.delegate = nil;
	[[NSNotificationCenter defaultCenter] removeObserver:self];
}

// MARK: Keyboard

- (BOOL)canBecomeFirstResponder {
	return YES;
}

- (BOOL)becomeFirstResponderWithString:(NSString *)existingString multiline:(BOOL)flag cursorStart:(NSInteger)start cursorEnd:(NSInteger)end {
	self.text = existingString;
	self.previousText = existingString;

	NSInteger safeStartIndex = MAX(start, 0);

	NSRange textRange;

	// Either a simple cursor or a selection.
	if (end > 0) {
		textRange = NSMakeRange(safeStartIndex, end - start);
	} else {
		textRange = NSMakeRange(safeStartIndex, 0);
	}

	self.selectedRange = textRange;
	self.previousSelectedRange = textRange;

	return [self becomeFirstResponder];
}

- (BOOL)resignFirstResponder {
	self.text = nil;
	self.previousText = nil;
	return [super resignFirstResponder];
}

// MARK: OS Messages

- (void)deleteText:(NSInteger)charactersToDelete {
	for (int i = 0; i < charactersToDelete; i++) {
		DisplayServerIPhone::get_singleton()->key(KEY_BACKSPACE, true);
		DisplayServerIPhone::get_singleton()->key(KEY_BACKSPACE, false);
	}
}

- (void)enterText:(NSString *)substring {
	String characters;
	characters.parse_utf8([substring UTF8String]);

	for (int i = 0; i < characters.size(); i++) {
		int character = characters[i];

		switch (character) {
			case 10:
				character = KEY_ENTER;
				break;
			case 8198:
				character = KEY_SPACE;
				break;
			default:
				break;
		}

		DisplayServerIPhone::get_singleton()->key(character, true);
		DisplayServerIPhone::get_singleton()->key(character, false);
	}
}

// MARK: Observer

- (void)observeTextChange:(NSNotification *)notification {
	if (notification.object != self) {
		return;
	}

	if (self.previousSelectedRange.length == 0) {
		// We are deleting all text before cursor if no range was selected.
		// This way any inserted or changed text will be updated.
		NSString *substringToDelete = [self.previousText substringToIndex:self.previousSelectedRange.location];
		[self deleteText:substringToDelete.length];
	} else {
		// If text was previously selected
		// we are sending only one `backspace`.
		// It will remove all text from text input.
		[self deleteText:1];
	}

	NSString *substringToEnter;

	if (self.selectedRange.length == 0) {
		// If previous cursor had a selection
		// we have to calculate an inserted text.
		if (self.previousSelectedRange.length != 0) {
			NSInteger rangeEnd = self.selectedRange.location + self.selectedRange.length;
			NSInteger rangeStart = MIN(self.previousSelectedRange.location, self.selectedRange.location);
			NSInteger rangeLength = MAX(0, rangeEnd - rangeStart);

			NSRange calculatedRange;

			if (rangeLength >= 0) {
				calculatedRange = NSMakeRange(rangeStart, rangeLength);
			} else {
				calculatedRange = NSMakeRange(rangeStart, 0);
			}

			substringToEnter = [self.text substringWithRange:calculatedRange];
		} else {
			substringToEnter = [self.text substringToIndex:self.selectedRange.location];
		}
	} else {
		substringToEnter = [self.text substringWithRange:self.selectedRange];
	}

	[self enterText:substringToEnter];

	self.previousText = self.text;
	self.previousSelectedRange = self.selectedRange;
}

@end