element-ios/Vector/Utils/AvatarGenerator.m

/*
 Copyright 2015 OpenMarket Ltd
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at
 
 http://www.apache.org/licenses/LICENSE-2.0
 
 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
 */

#import "AvatarGenerator.h"

@implementation AvatarGenerator

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

#define UIColorFromRGB(rgbValue) \
        [UIColor colorWithRed:((float)((rgbValue & 0xFF0000) >> 16))/255.0 \
        green:((float)((rgbValue & 0x00FF00) >>  8))/255.0 \
        blue:((float)((rgbValue & 0x0000FF) >>  0))/255.0 \
        alpha:1.0]

+ (void)initColorList
{
    if (!colorsList)
    {
        colorsList = [[NSMutableArray alloc] init];
        [colorsList addObject:UIColorFromRGB(0x76cfa6)];
        [colorsList addObject:UIColorFromRGB(0x50e2c2)];
        [colorsList addObject:UIColorFromRGB(0xf4c371)];
    }
}

+ (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;
}

+ (UIImage *)imageFromText:(NSString*)text withBackgroundColor:(UIColor*)color
{
    if (!backgroundLabel)
    {
        backgroundLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 40, 40)];
        backgroundLabel.textColor = [UIColor whiteColor];
        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();
    CGContextSetInterpolationQuality(context, kCGInterpolationHigh);
    
    // Make the CALayer to draw in our "canvas".
    [[backgroundLabel layer] renderInContext: UIGraphicsGetCurrentContext()];
    
    // Fetch an UIImage of our "canvas".
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    
    // Stop the "canvas" from accepting any input.
    UIGraphicsEndImageContext();
    
    // Return the image.
    return image;
}

+ (UIImage*)avatarForText:(NSString*)text andColorIndex:(NSUInteger)colorIndex
{
    // 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:@"%@%ld", text, colorIndex];
    
    if (!imageByKeyDict)
    {
        imageByKeyDict = [[NSMutableDictionary alloc] init];
    }
    
    UIImage* image = [imageByKeyDict objectForKey:key];
    
    if (!image)
    {
        image = [AvatarGenerator imageFromText:text withBackgroundColor:[colorsList objectAtIndex:colorIndex]];
        [imageByKeyDict setObject:image forKey:key];
    }
    
    return image;
}

+ (UIImage*)generateRoomAvatar:(MXRoom*)room
{
    NSString* displayName = room.state.displayname;
    NSString* roomId = room.state.roomId;
    
    NSUInteger index = [AvatarGenerator colorIndexForText:roomId];
    NSString* text = displayName;
        
    // ignore the first #
    // useful for the room
    if ([text hasPrefix:@"#"])
    {
        text = [text substringFromIndex:1];
    }
    
    if (text.length > 0)
    {
        text = [[text substringToIndex:1] uppercaseString];
    }
        
    return [AvatarGenerator avatarForText:text andColorIndex:index];
}

@end