簡單刻度尺的實現(xiàn)

在新的開發(fā)版本中,遇到一個這樣的需要,實現(xiàn)一個類似刻度尺的樣式,UI如下:第一眼看到這個需求的時候,我的第一感覺,就是使用圖形畫線,在進行一番思索之后,我就開始demo階段,首先分析這個UI有哪些部分組成:

  • 刻度尺(高低不同)
  • 選中區(qū)域
  • 刻度尺顏色
  • 選中區(qū)域顏色
  • 選中區(qū)域的刻度尺的顏色
  • 刻度尺第一和最后一個刻度尺單獨處理不顯示
  • 刻度尺的寬度
    ……
WechatIMG1.jpeg
  1. 第一種實現(xiàn)思路,首先我想到的是自定義UIView,其實設(shè)計方法很簡單,頭文件代碼如下:
/** 選中的數(shù)值 */
@property (nonatomic, assign) CGFloat selectedValue;
/** 最小值 */
@property (nonatomic, assign) NSInteger minValue;
/** 最大值 */
@property (nonatomic, assign) NSInteger maxValue;
/** 小刻度分成幾塊 */
@property (nonatomic, assign) NSInteger splitNumber;
/** 主刻度長度,默認(rèn)值 10.0 */
@property (nonatomic, assign) CGFloat majorScaleLength;
/** 小刻度長度,默認(rèn)值 5.0 */
@property (nonatomic, assign) CGFloat minorScaleLength;
/** 刻度尺寬度 */
@property (nonatomic, assign) CGFloat scaleWidth;
/** 指示條顏色 */
@property (nonatomic, strong) UIColor *indicatorColor;
/** 背景顏色 */
@property (nonatomic, strong) UIColor *rulerBackgroundColor;
/** 指示條的顏色 */
@property (nonatomic, strong) UIColor *rulerColor;
/** 選中的刻度尺的顏色 */
@property (nonatomic, strong) UIColor *selectedRuleColor;

這些就是暴露給使用者使用的屬性,當(dāng)然有些業(yè)務(wù)需要在里面,有些屬性我就直接在內(nèi)部寫死了,當(dāng)然也是可以抽取出來的。.m文件的實現(xiàn)也很簡單:

#import "YCRulerView.h"

/** 主刻度長度默認(rèn)值 */
static CGFloat const kMajorScaleDefaultLength = 13.0;
/** 小刻度長度默認(rèn)值 */
static CGFloat const kMinorScaleDefaultLength = 5.0;

@interface YCRulerView ()

/** 指示器的view */
@property (nonatomic, strong) UIView *indicatorView;

@end

@implementation YCRulerView

- (instancetype)initWithFrame:(CGRect)frame {
    if (self = [super initWithFrame:frame]) {
        [self setupUI];
    }
    return self;
}

- (instancetype)initWithCoder:(NSCoder *)aDecoder {
    if (self = [super initWithCoder:aDecoder]) {
        [self setupUI];
    }
    return self;
}

- (void)layoutSubviews {
    [super layoutSubviews];
    [self reloadRuler];
}

- (void)setupUI {
    self.indicatorView = [[UIView alloc] init];
    [self addSubview:self.indicatorView];
}

- (void)reloadRuler {
    
    self.backgroundColor = self.rulerBackgroundColor;
    
    // 每一條刻度線之前的間距
    CGFloat space = (self.frame.size.width - self.maxValue * self.scaleWidth) / self.maxValue;
    for (int i = 1; i <= _maxValue; i ++) {
        CGFloat viewX = space + (i - 1) * (self.scaleWidth + space);
        UIView *lineView = [[UIView alloc] init];
        
        if (i <= self.selectedValue) {
            lineView.backgroundColor = self.selectedRuleColor;
        } else {
            lineView.backgroundColor = self.rulerColor;
        }
        if (i == 0) {
            lineView.frame = CGRectZero;
        } else if (i == _maxValue) {
            lineView.frame = CGRectZero;
        } else {
            if (i % self.splitNumber == 0) {
                lineView.frame = CGRectMake(viewX, self.frame.size.height - self.majorScaleLength, self.scaleWidth, self.majorScaleLength);
            } else {
                lineView.frame = CGRectMake(viewX, self.frame.size.height - self.minorScaleLength, self.scaleWidth, self.minorScaleLength);
            }
        }
        [self addSubview:lineView];
    }
    self.indicatorView.backgroundColor = self.indicatorColor;
    self.indicatorView.frame = CGRectMake(0, 0, self.frame.size.width * self.selectedValue / self.maxValue, self.frame.size.height);
}

#pragma mark - 屬性默認(rèn)值

- (CGFloat)majorScaleLength {
    if (_majorScaleLength <= 0) {
        _majorScaleLength = kMajorScaleDefaultLength;
    }
    return _majorScaleLength;
}

- (CGFloat)minorScaleLength {
    if (_minorScaleLength <= 0) {
        _minorScaleLength = kMinorScaleDefaultLength;
    }
    return _minorScaleLength;
}

- (UIColor *)indicatorColor {
    if (_indicatorColor == nil) {
        _indicatorColor = [UIColor colorWithRed:251.0/255.0 green:207.0/255.0 blue:0.0/255.0 alpha:1.0];
    }
    return _indicatorColor;
}

- (UIColor *)rulerBackgroundColor {
    
    if (_rulerBackgroundColor == nil) {
        _rulerBackgroundColor = [UIColor colorWithRed:243.0/255.0 green:243.0/255.0 blue:243.0/255.0 alpha:1.0];;
    }
    return _rulerBackgroundColor;
}

- (UIColor *)rulerColor {
    if (_rulerColor == nil) {
        _rulerColor = [UIColor colorWithRed:232.0/255.0 green:232.0/255.0 blue:232.0/255.0 alpha:1.0];
    }
    return _rulerColor;
}

- (UIColor *)selectedRuleColor {
    if (_selectedRuleColor == nil) {
        _selectedRuleColor = [UIColor colorWithRed:246.0/255.0 green:193.0/255.0 blue:21.0/255.0 alpha:1.0];
    }
    return _selectedRuleColor;
}

- (NSInteger)splitNumber {
    if (_splitNumber == 0) {
        _splitNumber = 3;
    }
    return _splitNumber;
}

- (CGFloat)scaleWidth {
    if (_scaleWidth == 0) {
        _scaleWidth = 2;
    }
    return _scaleWidth;
}

@end

下面是基本的使用,我只是選擇幾個屬性進行設(shè)置,使用姿勢如下:

    YCRulerView *rulerView = [[YCRulerView alloc] initWithFrame:rulerFrame];
    UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:rulerView.bounds
                                                   byRoundingCorners:corner
                                                         cornerRadii:CGSizeMake(10.f, 10.f)];
    CAShapeLayer *maskLayer = [[CAShapeLayer alloc] init];
    maskLayer.frame = rulerView.bounds;
    maskLayer.path = maskPath.CGPath;
    rulerView.layer.mask = maskLayer;
    rulerView.backgroundColor = rulerBackgroundColor;
    // 最大值
    rulerView.maxValue = maxValue;
    // 設(shè)置默認(rèn)值
    rulerView.selectedValue = selectedValue;
    // 指示塊的顏色
    rulerView.indicatorColor = indicatorColor;
    // 刻度尺的顏色
    rulerView.rulerColor = rulerColor;
    // 選中刻度尺的顏色
    rulerView.selectedRuleColor = selectedRulerColor;
    [view addSubview:rulerView];
  1. 第二種實現(xiàn)思路,以上這種實現(xiàn)方法使用UIView實現(xiàn)的,在實現(xiàn)完這一套之后,我覺得不是太好,如果內(nèi)部的刻度線比較多的時候,如果還是采用創(chuàng)建View的方法,就會造成內(nèi)存的極大消耗,因此我在這個基礎(chǔ)之上,又實現(xiàn)了另外一套方法,當(dāng)然這套方法實現(xiàn)的不是很好,還存在很大的問題,先記錄一下,后期完成之后,在更新一下這篇文章。
    首先看一下頭文件的部分,頭文件和上面實現(xiàn)方法頭文件差不多:
/** 選中的數(shù)值 */
@property (nonatomic, assign)  CGFloat selectedValue;
/** 最小值 */
@property (nonatomic, assign)  NSInteger minValue;
/** 最大值 */
@property (nonatomic, assign)  NSInteger maxValue;
/** 步長 */
@property (nonatomic, assign)  NSInteger valueStep;
/** 小刻度分成幾塊 */
@property (nonatomic, assign) NSInteger splitNumber;
/** 主刻度長度,默認(rèn)值 25.0 */
@property (nonatomic, assign) CGFloat majorScaleLength;
/** 中間刻度長度,默認(rèn)值 20.0 */
@property (nonatomic, assign) CGFloat middleScaleLength;
/** 小刻度長度,默認(rèn)值 10.0 */
@property (nonatomic, assign) CGFloat minorScaleLength;
/** 指示條顏色 */
@property (nonatomic, strong) UIColor *indicatorColor;
/** 背景顏色 */
@property (nonatomic, strong) UIColor *rulerBackgroundColor;
/** 指示條的顏色 */
@property (nonatomic, strong) UIColor *rulerColor;
/** 是否顯示刻度尺上的數(shù)值 */
@property (nonatomic, assign) BOOL showRulerNumber;

.m文件的實現(xiàn)如下:

#import "YCRuler.h"

/** 主刻度長度默認(rèn)值 */
static CGFloat const kMajorScaleDefaultLength = 20.0;
/** 中間刻度長度默認(rèn)值 */
static CGFloat const kMiddleScaleDefaultLength = 20.0;
/** 小刻度長度默認(rèn)值 */
static CGFloat const kMinorScaleDefaultLength = 10.0;

@interface YCRuler ()

/** 小刻度間距 */
@property (nonatomic, assign) CGFloat minorScaleSpacing;
/** 刻度尺 */
@property (nonatomic, strong) UIImageView *rulerImageView;
/** 指示器 */
@property (nonatomic, strong) UIView *indicatorView;

@end

@implementation YCRuler

- (instancetype)initWithFrame:(CGRect)frame {
    self = [super initWithFrame:frame];
    if (self) {
        [self setupUI];
    }
    return self;
}

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

- (void)layoutSubviews {
    [super layoutSubviews];
    if (_rulerImageView.image == nil) {
        [self reloadRuler];
    }
}

#pragma mark - 設(shè)置屬性
- (void)setSelectedValue:(CGFloat)selectedValue {
    
    if (selectedValue < _minValue || selectedValue > _maxValue || _valueStep <= 0) {
        return;
    }
    _selectedValue = selectedValue;
    _indicatorView.backgroundColor = self.indicatorColor;
    _indicatorView.alpha = 0.6;
    _indicatorView.frame = CGRectMake(0, 0, (self.frame.size.width * self.selectedValue / self.maxValue) , self.frame.size.height);
}

#pragma mark - 繪制標(biāo)尺相關(guān)方法
/**
 * 刷新標(biāo)尺
 */
- (void)reloadRuler {
    UIImage *image = [self rulerImage];
    if (image == nil) {
        return;
    }
    _rulerImageView.image = image;
    [_rulerImageView sizeToFit];
    _rulerImageView.frame = self.bounds;
    // 更新初始值
    self.selectedValue = _selectedValue;
}

//  生成標(biāo)尺圖像
- (UIImage *)rulerImage {
    
    // 1. 常數(shù)計算
    CGFloat steps = [self stepsWithValue:_maxValue];
    if (steps == 0) {
        return nil;
    }
    // 水平方向繪制圖像的大小
    CGSize textSize = [self maxValueTextSize];
    CGFloat height = self.majorScaleLength + textSize.height + 2 * self.minorScaleSpacing;
    CGFloat startX = textSize.width - 5;
    CGRect rect = CGRectMake(0, 0, steps * self.minorScaleSpacing + 2 * startX, height);
    
    // 2. 繪制圖像
    UIGraphicsBeginImageContextWithOptions(rect.size, NO, 0);
    UIBezierPath *path = [UIBezierPath bezierPath];
    
    for (NSInteger i = _minValue; i <= _maxValue; i += _valueStep) {
        // 繪制主刻度
        CGFloat x = (i - _minValue) / _valueStep * self.minorScaleSpacing * self.splitNumber + startX;
        
        if (i == _minValue) {
            [path moveToPoint:CGPointMake(0, 0)];
            [path addLineToPoint:CGPointMake(0, 0)];
        } else if (i == _maxValue) {
            break;
        } else {
            [path moveToPoint:CGPointMake(x, height)];
            [path addLineToPoint:CGPointMake(x, height - self.majorScaleLength - self.frame.size.height * 2 / 3)];
        }
        // 繪制小刻度線
        for (NSInteger j = 1; j < self.splitNumber; j++) {
            CGFloat scaleX = x + j * self.minorScaleSpacing;
            CGFloat scaleY = 0;
            [path moveToPoint:CGPointMake(scaleX, height)];
            if (self.splitNumber == 3) {
                scaleY = height - self.minorScaleLength - 10;
            } else {
                scaleY = height - ((j == self.splitNumber / 2) ? self.middleScaleLength : self.minorScaleLength);
            }
            [path addLineToPoint:CGPointMake(scaleX, scaleY)];
        }
    }
    
    [self.rulerBackgroundColor set];
    [path stroke];
    
    // 2> 繪制刻度值
    NSDictionary *strAttributes = [self scaleTextAttributes];
    
    for (NSInteger i = _minValue; i <= _maxValue; i += _valueStep) {
        NSString *str = @(i).description;
        if (i == _minValue) {
            [str drawInRect:CGRectZero withAttributes:strAttributes];
        } else if (i == _maxValue) {
            [str drawInRect:CGRectZero withAttributes:strAttributes];
        } else {
            CGRect strRect = [str boundingRectWithSize:CGSizeMake(MAXFLOAT, MAXFLOAT)
                                               options:NSStringDrawingUsesLineFragmentOrigin
                                            attributes:strAttributes
                                               context:nil];
            strRect.origin.x = (i - _minValue) / _valueStep * self.minorScaleSpacing * self.splitNumber + startX - strRect.size.width * 0.5;
            strRect.origin.y = 8;
            strRect.size.width = 20;
            strRect.size.height = 20;
            if (self.showRulerNumber) {
                [str drawInRect:strRect withAttributes:strAttributes];
            }
        }
    }
    UIImage *result = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return result;
}

// 計算最小值和指定 value 之間的步長,即:繪制刻度的總數(shù)量
- (CGFloat)stepsWithValue:(CGFloat)value {
    
    if (_minValue >= value || _valueStep <= 0) {
        return 0;
    }
    return (value - _minValue) / _valueStep * self.splitNumber;
}

// 以水平繪制方向計算 `最大數(shù)值的文字` 尺寸
- (CGSize)maxValueTextSize {
    
    NSString *scaleText = @(self.maxValue).description;
    CGSize size = [scaleText boundingRectWithSize:CGSizeMake(MAXFLOAT, MAXFLOAT)
                                          options:NSStringDrawingUsesLineFragmentOrigin
                                       attributes:[self scaleTextAttributes]
                                          context:nil].size;
    
    return CGSizeMake(floor(size.width), floor(size.height));
}

// 文本屬性字典
- (NSDictionary *)scaleTextAttributes {
    
    CGFloat fontSize = 10 * [UIScreen mainScreen].scale * 0.8;
    
    return @{NSForegroundColorAttributeName: [UIColor lightGrayColor],
             NSFontAttributeName: [UIFont boldSystemFontOfSize:fontSize]};
}

#pragma mark - 設(shè)置界面
- (void)setupUI {

    // 標(biāo)尺圖像
    _rulerImageView = [[UIImageView alloc] init];
    [self addSubview:_rulerImageView];
    
    // 指示器視圖
    _indicatorView = [[UIView alloc] init];
    [self addSubview:_indicatorView];
}

#pragma mark - 屬性默認(rèn)值
- (CGFloat)minorScaleSpacing {
    if (_minorScaleSpacing <= 0) {
        _minorScaleSpacing = self.frame.size.width /(self.maxValue * self.splitNumber);
    }
    return _minorScaleSpacing;
}

- (CGFloat)majorScaleLength {
    if (_majorScaleLength <= 0) {
        _majorScaleLength = kMajorScaleDefaultLength;
    }
    return _majorScaleLength;
}

- (CGFloat)middleScaleLength {
    if (_middleScaleLength <= 0) {
        _middleScaleLength = kMiddleScaleDefaultLength;
    }
    return _middleScaleLength;
}

- (CGFloat)minorScaleLength {
    if (_minorScaleLength <= 0) {
        _minorScaleLength = kMinorScaleDefaultLength;
    }
    return _minorScaleLength;
}

- (UIColor *)indicatorColor {
    if (_indicatorColor == nil) {
        _indicatorColor = [UIColor orangeColor];
    }
    return _indicatorColor;
}

- (UIColor *)rulerBackgroundColor {
    
    if (_rulerBackgroundColor == nil) {
        _rulerBackgroundColor = [UIColor lightGrayColor];
    }
    return _rulerBackgroundColor;
}

- (NSInteger)splitNumber {
    if (_splitNumber == 0) {
        _splitNumber = 3;
    }
    return _splitNumber;
}

使用姿勢和第一種一樣,但是第二種的靈活度還不是很好,在設(shè)置一個不合法的值的時候,顯示會有問題, 這個我正在排查,等解決之后,我會更新一下這份代碼。

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