一、前言与背景
2017.9.10介绍了一种工作中需要实现的iOS仪表盘的绘制,不够普通,本文介绍另一种适用性更大的仪表盘的实现。备注:本文无其他依赖代码,移植和学习都很方便。
先看下运行后的效果图:
二、需求分析
思路:可分成三步:
1.绘制三个彩色圆环带;
2.绘制文本;
3.绘制指针。
其中第3步,指针最为复杂,是本文的重点。
三、实现
首先创建一个继承自UIView的子类XRInstrumentBoard,所有的绘制都是在其内部实现,并开放一些接口供外部对象使用。
类声明和外部接口:
@interface XRInstrumentBoard : UIView
@property (nonatomic, assign) CGFloat value;
- (void)strokePath;
@end
类内部属性:
@interface XRInstrumentBoard ()
@property (nonatomic, assign) CGPoint dotCenter;
@property (nonatomic, assign) CGFloat radius;
@property (nonatomic, assign) CGFloat pointLenth;
@property (nonatomic, strong) NSArray *stateArray;
@property (nonatomic, strong) CALayer *pointLayer;
@end
关键词解释:仪表分值、指针圆点、半径、指针长度、角度数组、指针layer。
1.绘制三个彩色圆环带
首先抽象出一个方法:返回一个给定起始角度和填充颜色的圆环。跟之前一样,使用 CAShapeLaye配合UIBezierPath即可在layer层完成绘制。
- (void)drawPieWithStartAngle:(CGFloat)startAngle endAngle:(CGFloat)endAngle color:(UIColor *)color {
UIBezierPath *piePath = [UIBezierPath bezierPath];
[piePath addArcWithCenter:self.dotCenter radius:self.radius startAngle:toRad(startAngle) endAngle:toRad(endAngle) clockwise:YES];
CAShapeLayer *pieShapeLayer = [[CAShapeLayer alloc] init];
pieShapeLayer.lineWidth = 10;
pieShapeLayer.fillColor = nil;
pieShapeLayer.strokeColor = color.CGColor;
pieShapeLayer.path = [piePath CGPath];;
[self.layer addSublayer:pieShapeLayer];
}
然后手动计算三条圆环的起始角度并给定好填充颜色,依次绘制。XRColorRGB:一个颜色的宏定义,默认的绿色太辣眼睛,请无视,自行替换自己需要的颜色。
[self drawPieWithStartAngle:-180 endAngle:-120 color:[UIColor redColor]];
[self drawPieWithStartAngle:-120 endAngle:-60 color:[UIColor orangeColor]];
[self drawPieWithStartAngle:-60 endAngle:0 color:XRColorRGB(142, 195, 92)];
2.绘制文本
使用for循环创建指定数量的label即可,会用到一些高中的二维坐标函数公式。本文使用较浅,有很多复杂的绘图和动画会大量使用这些公式,不熟悉的建议先补充,知识点:三角函数、圆、弧度、坐标系。
- (void)drawText {
for (NSInteger i=0; i<3; i++) {
CGFloat startAngle = -150 + 60*i;
CGPoint labelCenter = [self pointWithAngle:toRad(startAngle) radius:self.radius + 30];
UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 40, 40)];
label.center = labelCenter;
label.font = XRFont(14);
label.backgroundColor = XRTextBlueColor;
label.textColor = [UIColor whiteColor];
label.textAlignment = NSTextAlignmentCenter;
label.text = self.stateArray[i];
label.layer.cornerRadius = 20;
label.layer.masksToBounds = YES;
[self addSubview:label];
}
}
备注:角度和弧度转换公式:
#define toRad(angle) ((angle) * M_PI / 180)
给定角度和半径求点的位置:
- (CGPoint)pointWithAngle:(CGFloat)angle radius:(CGFloat)radius {
CGFloat x = self.dotCenter.x + cosf(angle) * radius;
CGFloat y = self.dotCenter.y + sinf(angle) * radius;
return CGPointMake(x, y);
}
3.绘制指针
下面开始本文的重点部分,这一步分三部分。1)绘制指针锚点;2)绘制指针;3)添加指针动画。
1)绘制指针锚点
一个封闭单色填充的圆,圆点初始化时会给予赋值,后面的代码会提供。
- (void)drawDot {
UIBezierPath *piePath = [UIBezierPath bezierPath];
[piePath addArcWithCenter:self.dotCenter radius:10 startAngle:0 endAngle:2*M_PI clockwise:YES];
CAShapeLayer *pieShapeLayer = [[CAShapeLayer alloc] init];
pieShapeLayer.strokeColor = nil;
pieShapeLayer.fillColor = XRTextBlueColor.CGColor;
pieShapeLayer.path = [piePath CGPath];;
[self.layer addSublayer:pieShapeLayer];
}
2)绘制指针
由于后面需要添加摆动动画,所以将指针layer定义成属性。
- (void)drawPoint {
self.pointLayer = [CALayer layer];
self.pointLayer.backgroundColor = XRTextBlueColor.CGColor;
self.pointLayer.frame = CGRectMake(0, 0, 2, self.pointLenth);
self.pointLayer.position = CGPointMake(self.dotCenter.x, self.dotCenter.y);
self.pointLayer.anchorPoint = CGPointMake(0.8, 0.8);
[self.layer addSublayer:self.pointLayer];
}
3)添加指针动画
这里使用CAAnimationGroup将给定的CABasicAnimation对象添加为一组动画。原理与电影的制作相同。这里的动画组分2个场景:1.从最终位置移动到最右端;2.从最右端移动到最左端。执行次数均为1次,所有动画执行完成后,会回到最初也就是最终的位置上。
- (void)strokePath {
CGFloat diff = (self.value - 50)/100*M_PI;
self.pointLayer.transform = CATransform3DMakeRotation(diff, 0, 0, 1);
CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"transform.rotation"];
animation.duration = 1.0f;
animation.fromValue = @(diff);
animation.toValue = @(M_PI_2);
animation.fillMode = kCAFillModeForwards;
animation.removedOnCompletion = NO;
animation.repeatCount = 1;
CABasicAnimation *animation2 = [CABasicAnimation animationWithKeyPath:@"transform.rotation"];
animation2.duration = 1.0f;
animation2.fromValue = @(M_PI_2);
animation2.toValue = @(-M_PI_2);
animation2.fillMode = kCAFillModeForwards;
animation2.removedOnCompletion = NO;
animation2.repeatCount = 1;
CAAnimationGroup *groupAnnimation = [CAAnimationGroup animation];
groupAnnimation.duration = 1.0f;
groupAnnimation.autoreverses = YES;
groupAnnimation.animations = @[animation, animation2];
groupAnnimation.repeatCount = 1;
[self.pointLayer addAnimation:groupAnnimation forKey:@"groupAnnimation"];
}
4.内部调用逻辑
重写、初始化相关变量默认值。
- (instancetype)initWithFrame:(CGRect)frame {
if (self = [super initWithFrame:frame]) {
self.dotCenter = CGPointMake(frame.size.width/2.0, frame.size.height-20);
self.radius = frame.size.height - 80;
self.pointLenth = self.radius;
self.stateArray = @[@"危险", @"普通", @"优秀"];
self.value = 50;
[self loadSubViews];
}
return self;
}
- (void)loadSubViews {
[self drawPieWithStartAngle:-180 endAngle:-120 color:[UIColor redColor]];
[self drawPieWithStartAngle:-120 endAngle:-60 color:[UIColor orangeColor]];
[self drawPieWithStartAngle:-60 endAngle:0 color:XRColorRGB(142, 195, 92)];
[self drawText];
[self drawDot];
[self drawPoint];
}
5.外部使用
创建一个视图控制器,导入头文件,添加视图属性变量,简单的赋值即可。
#import "XRInstumentBoardViewController.h"
#import "XRInstrumentBoard.h"
@interface XRInstumentBoardViewController ()
@property (nonatomic, strong) XRInstrumentBoard *instrumentBoard;
@end
@implementation XRInstumentBoardViewController
- (void)viewDidLoad {
[super viewDidLoad];
self.view.backgroundColor = [UIColor whiteColor];
// Do any additional setup after loading the view.
self.instrumentBoard = [[XRInstrumentBoard alloc] initWithFrame:CGRectMake(0, 0, 300, 200)];
self.instrumentBoard.center = self.view.center;
[self.view addSubview:self.instrumentBoard];
self.instrumentBoard.value = 75;
[self.instrumentBoard strokePath];
}
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