huaxun/LekangGuard/Home/Chat(微聊)/MessageDisplayKit/Classes/Views/MessageInputView/XHMessageTextView.m

//
//  XHMessageTextView.m
//  MessageDisplayExample
//
//  Created by HUAJIE-1 on 14-4-24.
//  Copyright (c) 2014年 嗨，我是曾宪华(@xhzengAIB)，曾加入YY Inc.担任高级移动开发工程师，拍立秀App联合创始人，热衷于简洁、而富有理性的事物 QQ:543413507 主页:http://zengxianhua.com All rights reserved.
//

#import "XHMessageTextView.h"

@implementation XHMessageTextView

#pragma mark - Setters

- (void)setPlaceHolder:(NSString *)placeHolder {
    if([placeHolder isEqualToString:_placeHolder]) {
        return;
    }
    
    NSUInteger maxChars = [XHMessageTextView maxCharactersPerLine];
    if([placeHolder length] > maxChars) {
        placeHolder = [placeHolder substringToIndex:maxChars - 8];
        placeHolder = [[placeHolder stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] stringByAppendingFormat:@"..."];
    }
    
    _placeHolder = placeHolder;
    [self setNeedsDisplay];
}

- (void)setPlaceHolderTextColor:(UIColor *)placeHolderTextColor {
    if([placeHolderTextColor isEqual:_placeHolderTextColor]) {
        return;
    }
    
    _placeHolderTextColor = placeHolderTextColor;
    [self setNeedsDisplay];
}

#pragma mark - Message text view

- (NSUInteger)numberOfLinesOfText {
    return [XHMessageTextView numberOfLinesForMessage:self.text];
}

+ (NSUInteger)maxCharactersPerLine {
    return ([UIDevice currentDevice].userInterfaceIdiom == UIUserInterfaceIdiomPhone) ? 33 : 109;
}

+ (NSUInteger)numberOfLinesForMessage:(NSString *)text {
    return (text.length / [XHMessageTextView maxCharactersPerLine]) + 1;
}

#pragma mark - Text view overrides

- (void)setText:(NSString *)text {
    [super setText:text];
    [self setNeedsDisplay];
}

- (void)setAttributedText:(NSAttributedString *)attributedText {
    [super setAttributedText:attributedText];
    [self setNeedsDisplay];
}

- (void)setContentInset:(UIEdgeInsets)contentInset {
    [super setContentInset:contentInset];
    [self setNeedsDisplay];
}

- (void)setFont:(UIFont *)font {
    [super setFont:font];
    [self setNeedsDisplay];
}

- (void)setTextAlignment:(NSTextAlignment)textAlignment {
    [super setTextAlignment:textAlignment];
    [self setNeedsDisplay];
}

#pragma mark - Notifications

- (void)didReceiveTextDidChangeNotification:(NSNotification *)notification {
    [self setNeedsDisplay];
}

#pragma mark - Life cycle

- (void)setup {
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(didReceiveTextDidChangeNotification:)
                                                 name:UITextViewTextDidChangeNotification
                                               object:self];
    
    _placeHolderTextColor = [UIColor lightGrayColor];
    
    self.autoresizingMask = UIViewAutoresizingFlexibleWidth;
    self.scrollIndicatorInsets = UIEdgeInsetsMake(10.0f, 0.0f, 10.0f, 8.0f);
    self.contentInset = UIEdgeInsetsZero;
    self.scrollEnabled = YES;
    self.scrollsToTop = NO;
    self.userInteractionEnabled = YES;
    self.font = [UIFont systemFontOfSize:16.0f];
    self.textColor = [UIColor blackColor];
    self.backgroundColor = [UIColor whiteColor];
    self.keyboardAppearance = UIKeyboardAppearanceDefault;
    self.keyboardType = UIKeyboardTypeDefault;
    self.returnKeyType = UIReturnKeyDefault;
    self.textAlignment = NSTextAlignmentLeft;
}

- (id)initWithFrame:(CGRect)frame {
    self = [super initWithFrame:frame];
    if (self) {
        // Initialization code
        [self setup];
    }
    return self;
}

- (void)dealloc {
    _placeHolder = nil;
    _placeHolderTextColor = nil;
    [[NSNotificationCenter defaultCenter] removeObserver:self name:UITextViewTextDidChangeNotification object:self];
}

#pragma mark - Drawing

- (void)drawRect:(CGRect)rect
{
    [super drawRect:rect];
    
    if([self.text length] == 0 && self.placeHolder) {
        CGRect placeHolderRect = CGRectMake(10.0f,
                                            7.0f,
                                            rect.size.width,
                                            rect.size.height);
        
        [self.placeHolderTextColor set];
        
        if ([[[UIDevice currentDevice]systemVersion]floatValue] >= 7.0) {
            NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
            paragraphStyle.lineBreakMode = NSLineBreakByTruncatingTail;
            paragraphStyle.alignment = self.textAlignment;
            
            [self.placeHolder drawInRect:placeHolderRect
                          withAttributes:@{ NSFontAttributeName : self.font,
                                            NSForegroundColorAttributeName : self.placeHolderTextColor,
                                            NSParagraphStyleAttributeName : paragraphStyle }];
        }
        else {
            [self.placeHolder drawInRect:placeHolderRect
                                withFont:self.font
                           lineBreakMode:NSLineBreakByTruncatingTail
                               alignment:self.textAlignment];
        }
    }
}

@end