element-ios/Riot/Utils/AvatarGenerator.m

/*
Copyright 2024 New Vector Ltd.
Copyright 2017 Vector Creations Ltd
Copyright 2015 OpenMarket Ltd

SPDX-License-Identifier: AGPL-3.0-only
Please see LICENSE in the repository root for full details.
 */

#import "AvatarGenerator.h"

#import "ThemeService.h"

#import "GeneratedInterface-Swift.h"

@implementation AvatarGenerator

static NSMutableDictionary *imageByKeyDict = nil;
static NSArray* colorsList = nil;
static UILabel* backgroundLabel = nil;

/**
 Init the generated avatar colors.
 Should be the same as the webclient.
 */
+ (void)initColorList
{
    if (!colorsList)
    {
        colorsList = ThemeService.shared.theme.avatarColors;
    }
}

/**
 Generate the selected color index in colorsList list.
 */
+ (NSUInteger)colorIndexForText:(NSString*)text
{
    [AvatarGenerator initColorList];
    
    NSUInteger colorIndex = 0;
    
    if (text)
    {
        NSUInteger sum = 0;
        
        for(int i = 0; i < text.length; i++)
        {
            sum += [text characterAtIndex:i];
        }
        
        colorIndex = sum % colorsList.count;
    }
    
    return colorIndex;
}

/**
 Return the first valid character for avatar creation.
 */
+ (NSString *)firstChar:(NSString *)text
{
    if ([text hasPrefix:@"@"] || [text hasPrefix:@"#"] || [text hasPrefix:@"!"] || [text hasPrefix:@"+"])
    {
        text = [text substringFromIndex:1];
    }
    
    // default firstchar
    NSString* firstChar = @" ";
    
    if (text.length > 0)
    {
        firstChar = [[text substringToIndex:NSMaxRange([text rangeOfComposedCharacterSequenceAtIndex:0])] uppercaseString];
    }
    
    return firstChar;
}

+ (UIImage *)imageFromText:(NSString*)text withBackgroundColor:(UIColor*)color
{
    if (!backgroundLabel)
    {
        backgroundLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 40, 40)];
        backgroundLabel.textColor = ThemeService.shared.theme.backgroundColor;
        backgroundLabel.textAlignment = NSTextAlignmentCenter;
        backgroundLabel.font = [UIFont boldSystemFontOfSize:25];
    }
    
    backgroundLabel.text = text;
    backgroundLabel.backgroundColor = color;
    
    // Create a "canvas" (image context) to draw in.
    UIGraphicsBeginImageContextWithOptions(backgroundLabel.frame.size, NO, 0);
    
    // set to the top quality
    CGContextRef context = UIGraphicsGetCurrentContext();
    UIImage *image;
    if (context)
    {
        CGContextSetInterpolationQuality(context, kCGInterpolationHigh);
        [[backgroundLabel layer] renderInContext: context];
        image = UIGraphicsGetImageFromCurrentImageContext();
    }
    
    UIGraphicsEndImageContext();
    
    // Return the image.
    return image;
}

+ (UIImage *)imageFromText:(NSString*)text withBackgroundColor:(UIColor*)color size:(CGFloat)size andFontSize:(CGFloat)fontSize
{
    UILabel *bgLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, size, size)];
    bgLabel.textColor = ThemeService.shared.theme.backgroundColor;
    bgLabel.textAlignment = NSTextAlignmentCenter;
    bgLabel.font = [UIFont boldSystemFontOfSize:fontSize];
    
    bgLabel.text = text;
    bgLabel.backgroundColor = color;
    
    // Create a "canvas" (image context) to draw in.
    UIGraphicsBeginImageContextWithOptions(bgLabel.frame.size, NO, 0);
    
    // set to the top quality
    CGContextRef context = UIGraphicsGetCurrentContext();
    UIImage *image;
    if (context)
    {
        CGContextSetInterpolationQuality(context, kCGInterpolationHigh);
        [[bgLabel layer] renderInContext: context];
        image = UIGraphicsGetImageFromCurrentImageContext();
    }   
    
    UIGraphicsEndImageContext();
    
    // Return the image.
    return image;
}

/**
 Returns the UIImage for the text and a selected color.
 It checks first if it is not yet cached before generating one.
 */
+ (UIImage*)avatarForText:(NSString*)text andColorIndex:(NSUInteger)colorIndex
{
    NSString* firstChar = [AvatarGenerator firstChar:text];
    
    // the images are cached to avoid create them several times
    // the key is <first upper character><index in the colors array>
    // it should be smaller than using the text as a key
    NSString* key = [NSString stringWithFormat:@"%@%tu", firstChar, colorIndex];
    
    if (!imageByKeyDict)
    {
        imageByKeyDict = [[NSMutableDictionary alloc] init];
    }
    
    UIImage* image = imageByKeyDict[key];
    
    if (!image)
    {
        image = [AvatarGenerator imageFromText:firstChar withBackgroundColor:colorsList[colorIndex]];
        imageByKeyDict[key] = image;
    }
    
    return image;
}

+ (UIImage*)generateAvatarForText:(NSString*)text
{
    return [AvatarGenerator avatarForText:text andColorIndex:[AvatarGenerator colorIndexForText:text]];
}

+ (UIImage*)generateAvatarForMatrixItem:(NSString*)itemId withDisplayName:(NSString*)displayname
{
    return [AvatarGenerator avatarForText:(displayname ? displayname : itemId) andColorIndex:[AvatarGenerator colorIndexForText:itemId]];
}

+ (UIImage*)generateAvatarForMatrixItem:(NSString*)itemId withDisplayName:(NSString*)displayname size:(CGFloat)size andFontSize:(CGFloat)fontSize
{
    NSString* firstChar = [AvatarGenerator firstChar:(displayname ? displayname : itemId)];
    NSUInteger colorIndex = [AvatarGenerator colorIndexForText:itemId];
    
    return [AvatarGenerator imageFromText:firstChar withBackgroundColor:colorsList[colorIndex] size:size andFontSize:fontSize];
}

+ (void)clear
{
    [imageByKeyDict removeAllObjects];
    colorsList = nil;
    backgroundLabel = nil;
}

@end