Merge pull request #164 from ZhangHang/master

PieChart divides equally when all value of data items are 0

@@ -10,9 +10,8 @@
 
 @interface PNPieChart()
 
-@property (nonatomic, readwrite) NSArray	*items;
-@property (nonatomic) CGFloat total;
-@property (nonatomic) CGFloat currentTotal;
+@property (nonatomic) NSArray *items;
+@property (nonatomic) NSArray *endPercentages;
 
 @property (nonatomic) CGFloat outerCircleRadius;
 @property (nonatomic) CGFloat innerCircleRadius;
@@ -21,10 +20,14 @@
 @property (nonatomic) CAShapeLayer   *pieLayer;
 @property (nonatomic) NSMutableArray *descriptionLabels;
 
+
 - (void)loadDefault;
 
 - (UILabel *)descriptionLabelForItemAtIndex:(NSUInteger)index;
 - (PNPieChartDataItem *)dataItemForIndex:(NSUInteger)index;
+- (CGFloat)startPercentageForItemAtIndex:(NSUInteger)index;
+- (CGFloat)endPercentageForItemAtIndex:(NSUInteger)index;
+- (CGFloat)ratioForItemAtIndex:(NSUInteger)index;
 
 - (CAShapeLayer *)newCircleLayerWithRadius:(CGFloat)radius
                                borderWidth:(CGFloat)borderWidth
@@ -43,8 +46,8 @@
     self = [self initWithFrame:frame];
     if(self){
         _items = [NSArray arrayWithArray:items];
-		_outerCircleRadius = CGRectGetWidth(self.bounds)/2;
-		_innerCircleRadius  = CGRectGetWidth(self.bounds)/6;
+        _outerCircleRadius  = CGRectGetWidth(self.bounds) / 2;
+        _innerCircleRadius  = CGRectGetWidth(self.bounds) / 6;
         
         _descriptionTextColor = [UIColor whiteColor];
         _descriptionTextFont  = [UIFont fontWithName:@"Avenir-Medium" size:18.0];
@@ -58,15 +61,23 @@
     return self;
 }
 
-
 - (void)loadDefault{
-	_currentTotal = 0;
-	_total       = 0;
+    __block CGFloat currentTotal = 0;
+    CGFloat total = [[self.items valueForKeyPath:@"@sum.value"] floatValue];
+    NSMutableArray *endPercentages = [NSMutableArray new];
+    [_items enumerateObjectsUsingBlock:^(PNPieChartDataItem *item, NSUInteger idx, BOOL *stop) {
+        if (total == 0){
+            [endPercentages addObject:@(1.0 / _items.count * (idx + 1))];
+        }else{
+            currentTotal += item.value;
+            [endPercentages addObject:@(currentTotal / total)];
+        }
+    }];
+    self.endPercentages = [endPercentages copy];
     
     [_contentView removeFromSuperview];
     _contentView = [[UIView alloc] initWithFrame:self.bounds];
     [self addSubview:_contentView];
-    [_descriptionLabels removeAllObjects];
     _descriptionLabels = [NSMutableArray new];
     
     _pieLayer = [CAShapeLayer layer];
@@ -78,39 +89,30 @@
 - (void)strokeChart{
     [self loadDefault];
     
-	[self.items enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
-		_total +=((PNPieChartDataItem *)obj).value;
-	}];
-	
     PNPieChartDataItem *currentItem;
-	CGFloat currentValue = 0;
     for (int i = 0; i < _items.count; i++) {
         currentItem = [self dataItemForIndex:i];
         
         
-		CGFloat startPercnetage = currentValue/_total;
-		CGFloat endPercentage   = (currentValue + currentItem.value)/_total;
+        CGFloat startPercnetage = [self startPercentageForItemAtIndex:i];
+        CGFloat endPercentage   = [self endPercentageForItemAtIndex:i];
         
-		CAShapeLayer *currentPieLayer =	[self newCircleLayerWithRadius:_innerCircleRadius + (_outerCircleRadius - _innerCircleRadius)/2
-                                                           borderWidth:_outerCircleRadius - _innerCircleRadius
+        CGFloat radius = _innerCircleRadius + (_outerCircleRadius - _innerCircleRadius) / 2;
+        CGFloat borderWidth = _outerCircleRadius - _innerCircleRadius;
+        CAShapeLayer *currentPieLayer =	[self newCircleLayerWithRadius:radius
+                                                           borderWidth:borderWidth
                                                              fillColor:[UIColor clearColor]
                                                            borderColor:currentItem.color
                                                        startPercentage:startPercnetage
                                                          endPercentage:endPercentage];
         [_pieLayer addSublayer:currentPieLayer];
-		
-		currentValue+=currentItem.value;
-		
     }
     
     [self maskChart];
     
-	currentValue = 0;
     for (int i = 0; i < _items.count; i++) {
-		currentItem = [self dataItemForIndex:i];
         UILabel *descriptionLabel =  [self descriptionLabelForItemAtIndex:i];
         [_contentView addSubview:descriptionLabel];
-		currentValue+=currentItem.value;
         [_descriptionLabels addObject:descriptionLabel];
     }
 }
@@ -118,30 +120,22 @@
 - (UILabel *)descriptionLabelForItemAtIndex:(NSUInteger)index{
     PNPieChartDataItem *currentDataItem = [self dataItemForIndex:index];
     CGFloat distance = _innerCircleRadius + (_outerCircleRadius - _innerCircleRadius) / 2;
-    CGFloat centerPercentage =(_currentTotal + currentDataItem.value /2 ) / _total;
+    CGFloat centerPercentage = ([self startPercentageForItemAtIndex:index] + [self endPercentageForItemAtIndex:index])/ 2;
     CGFloat rad = centerPercentage * 2 * M_PI;
     
-	_currentTotal += currentDataItem.value;
-	
     UILabel *descriptionLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 100, 80)];
-    NSString *titleText = currentDataItem.textDescription;
-    if(!titleText){
-        titleText = [NSString stringWithFormat:@"%.0f%%",currentDataItem.value/ _total * 100];
-        descriptionLabel.text = titleText ;
-    }
-    else {
-        NSString* str = [NSString stringWithFormat:@"%.0f%%\n",currentDataItem.value/ _total * 100];
-        str = [str stringByAppendingString:titleText];
-        descriptionLabel.text = str ;
+    NSString *titleText = [NSString stringWithFormat:@"%.0f%%",[self ratioForItemAtIndex:index] * 100];
+    if(currentDataItem.textDescription){
+        titleText = [titleText stringByAppendingFormat:@"\n%@",currentDataItem.textDescription];
     }
+    descriptionLabel.text = titleText;
     
     CGPoint center = CGPointMake(_outerCircleRadius + distance * sin(rad),
                                  _outerCircleRadius - distance * cos(rad));
     
     descriptionLabel.font = _descriptionTextFont;
     CGSize labelSize = [descriptionLabel.text sizeWithAttributes:@{NSFontAttributeName:descriptionLabel.font}];
-    descriptionLabel.frame = CGRectMake(
-                             descriptionLabel.frame.origin.x, descriptionLabel.frame.origin.y,
+    descriptionLabel.frame = CGRectMake(descriptionLabel.frame.origin.x, descriptionLabel.frame.origin.y,
                                         descriptionLabel.frame.size.width, labelSize.height);
     descriptionLabel.numberOfLines   = 0;
     descriptionLabel.textColor       = _descriptionTextColor;
@@ -158,6 +152,22 @@
     return self.items[index];
 }
 
+- (CGFloat)startPercentageForItemAtIndex:(NSUInteger)index{
+    if(index == 0){
+        return 0;
+    }
+    
+    return [_endPercentages[index - 1] floatValue];
+}
+
+- (CGFloat)endPercentageForItemAtIndex:(NSUInteger)index{
+    return [_endPercentages[index] floatValue];
+}
+
+- (CGFloat)ratioForItemAtIndex:(NSUInteger)index{
+    return [self endPercentageForItemAtIndex:index] - [self startPercentageForItemAtIndex:index];
+}
+
 #pragma mark private methods
 
 - (CAShapeLayer *)newCircleLayerWithRadius:(CGFloat)radius
@@ -183,13 +193,14 @@
     circle.lineWidth   = borderWidth;
     circle.path        = path.CGPath;
     
-	
     return circle;
 }
 
 - (void)maskChart{
-	CAShapeLayer *maskLayer =	[self newCircleLayerWithRadius:_innerCircleRadius + (_outerCircleRadius - _innerCircleRadius)/2
-                                                 borderWidth:_outerCircleRadius - _innerCircleRadius
+    CGFloat radius = _innerCircleRadius + (_outerCircleRadius - _innerCircleRadius) / 2;
+    CGFloat borderWidth = _outerCircleRadius - _innerCircleRadius;
+    CAShapeLayer *maskLayer = [self newCircleLayerWithRadius:radius
+                                                 borderWidth:borderWidth
                                                    fillColor:[UIColor clearColor]
                                                  borderColor:[UIColor blackColor]
                                              startPercentage:0
@@ -206,13 +217,16 @@
     [maskLayer addAnimation:animation forKey:@"circleAnimation"];
 }
 
-- (void)createArcAnimationForLayer:(CAShapeLayer *)layer ForKey:(NSString *)key fromValue:(NSNumber *)from toValue:(NSNumber *)to Delegate:(id)delegate
-{
+- (void)createArcAnimationForLayer:(CAShapeLayer *)layer
+                            forKey:(NSString *)key
+                         fromValue:(NSNumber *)from
+                           toValue:(NSNumber *)to
+                          delegate:(id)delegate{
     CABasicAnimation *arcAnimation = [CABasicAnimation animationWithKeyPath:key];
     arcAnimation.fromValue         = @0;
-	[arcAnimation setToValue:to];
-	[arcAnimation setDelegate:delegate];
-	[arcAnimation setTimingFunction:[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionDefault]];
+    arcAnimation.toValue           = to;
+    arcAnimation.delegate          = delegate;
+    arcAnimation.timingFunction    = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionDefault];
     [layer addAnimation:arcAnimation forKey:key];
     [layer setValue:to forKey:key];
 }

@@ -27,4 +27,11 @@
 	return item;
 }
 
+- (void)setValue:(CGFloat)value{
+    NSAssert(value >= 0, @"value should >= 0");
+    if (value != _value){
+        _value = value;
+    }
+}
+
 @end