從事iOS開發時間也不短了，可是卻沒有自己的博客，實在是慚愧。自己下定決心要堅持寫自己的博客，提高自己，也能跟大家有更多的交流。今天來跟大家分享一下儀表盤的制作，希望對大家有所幫助。
廢話不多說直接上代碼
1 //表盤支持的最小體溫數值 2 static CGFloat MIN_VALUE = 34; 3 //表盤支持的最大體溫數值 4 static CGFloat MAX_VALUE = 43; 5 @implementation WQMeasureDashboardView 6 - (void)drawRect:(CGRect)rect { 7 // 8 UIImage *imageBg = [UIImage imageNamed:@"bg_measure_dashboard"]; 9 [imageBg drawInRect:rect]; 10 11 UIImage *imageMask = [self getMeasureMaskImage:rect]; 12 [imageMask drawInRect:rect]; 13 14 int viewW = rect.size.width; 15 int viewH = rect.size.height; 16 //繪制文本 17 int textW = 55; 18 int textH = 25; 19 20 int textX = (viewW-textW)*0.5; 21 int textY = (viewH-textH)*0.5; 22 23 NSString *valueStr = [NSString stringWithFormat:@"%.2f",self.value]; 24 NSDictionary *dic = @{NSFontAttributeName:[UIFont systemFontOfSize:25],NSForegroundColorAttributeName:[UIColor blackColor]}; 25 [valueStr drawInRect:CGRectMake(textX, textY,textW,textH) withAttributes:dic]; 26 } 27 -(UIImage *)getMeasureMaskImage:(CGRect) rect{ 28 //繪制表盤 29 UIImage *imageDash = [UIImage imageNamed:@"bg_measure_dashboard_mask"]; 30 31 int viewW = rect.size.width; 32 int viewH = rect.size.height; 33 34 CGFloat centerX = viewW*1.0/2.0; 35 CGFloat centerY = viewH*1.0/2.0; 36 37 //裁剪圖片，通過繪制扇形進行裁剪 38 UIGraphicsBeginImageContextWithOptions(rect.size,NO,0); 39 [[UIColor redColor]set]; 40 CGContextRef context = UIGraphicsGetCurrentContext(); 41 42 CGContextSetLineWidth(context, 2); 43 CGContextMoveToPoint(context, centerX, centerY); 44 float startAngle =[self getStartAngle]; 45 float endAngle = M_PI*5/2.0; 46 CGContextAddArc(context, centerX, centerY, centerX,startAngle ,endAngle, 0); 47 CGContextClosePath(context); 48 CGContextClip(context); 49 [imageDash drawInRect:rect]; 50 51 //獲取裁剪后的圖片 52 UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext(); 53 54 UIGraphicsEndImageContext(); 55 return newImage; 56 } 57 #pragma 獲取裁剪圖片的開始角度 58 -(CGFloat)getStartAngle{ 59 float currentValue = _value; 60 if (currentValue<=MIN_VALUE) { 61 currentValue = MIN_VALUE; 62 } 63 if (currentValue >= MAX_VALUE) { 64 currentValue = MAX_VALUE; 65 } 66 //由於整個表盤被分成了9等份，所以每一份對應的角度是40度 67 float angle = M_PI/2.0+M_PI*ABS(currentValue-MIN_VALUE)*(40.0/180.0); 68 return angle; 69 } 70 -(void)setValue:(float)value{ 71 _value = value; 72 [self setNeedsDisplay]; 73 }