1 files changed, 365 insertions, 0 deletions
diff --git a/platform/ios/src/MGLScaleBar.mm b/platform/ios/src/MGLScaleBar.mm
new file mode 100644
index 0000000000..383710ea37
--- /dev/null
+++ b/platform/ios/src/MGLScaleBar.mm
@@ -0,0 +1,365 @@
+#import <Mapbox/Mapbox.h>
+#import "MGLScaleBar.h"
+
+static const CGFloat MGLFeetPerMile = 5280;
+
+struct MGLRow {
+    CLLocationDistance distance;
+    NSUInteger numberOfBars;
+};
+
+static const MGLRow MGLMetricTable[] = {
+    {.distance = 1, .numberOfBars = 2},
+    {.distance = 2, .numberOfBars = 2},
+    {.distance = 4, .numberOfBars = 2},
+    {.distance = 10, .numberOfBars = 2},
+    {.distance = 20, .numberOfBars = 2},
+    {.distance = 50, .numberOfBars = 2},
+    {.distance = 75, .numberOfBars = 3},
+    {.distance = 100, .numberOfBars = 2},
+    {.distance = 150, .numberOfBars = 2},
+    {.distance = 200, .numberOfBars = 2},
+    {.distance = 300, .numberOfBars = 3},
+    {.distance = 500, .numberOfBars = 2},
+    {.distance = 1000, .numberOfBars = 2},
+    {.distance = 1500, .numberOfBars = 2},
+    {.distance = 3000, .numberOfBars = 3},
+    {.distance = 5000, .numberOfBars = 2},
+    {.distance = 10000, .numberOfBars = 2},
+    {.distance = 20000, .numberOfBars = 2},
+    {.distance = 30000, .numberOfBars = 3},
+    {.distance = 50000, .numberOfBars = 2},
+    {.distance = 100000, .numberOfBars = 2},
+    {.distance = 200000, .numberOfBars = 2},
+    {.distance = 300000, .numberOfBars = 3},
+    {.distance = 400000, .numberOfBars = 2},
+    {.distance = 500000, .numberOfBars = 2},
+    {.distance = 600000, .numberOfBars = 3},
+    {.distance = 800000, .numberOfBars = 2},
+};
+
+static const MGLRow MGLImperialTable[] ={
+    {.distance = 4, .numberOfBars = 2},
+    {.distance = 6, .numberOfBars = 2},
+    {.distance = 10, .numberOfBars = 2},
+    {.distance = 20, .numberOfBars = 2},
+    {.distance = 30, .numberOfBars = 2},
+    {.distance = 50, .numberOfBars = 2},
+    {.distance = 75, .numberOfBars = 3},
+    {.distance = 100, .numberOfBars = 2},
+    {.distance = 200, .numberOfBars = 2},
+    {.distance = 300, .numberOfBars = 3},
+    {.distance = 400, .numberOfBars = 2},
+    {.distance = 600, .numberOfBars = 3},
+    {.distance = 800, .numberOfBars = 2},
+    {.distance = 1000, .numberOfBars = 2},
+    {.distance = 0.25f*MGLFeetPerMile, .numberOfBars = 2},
+    {.distance = 0.5f*MGLFeetPerMile, .numberOfBars = 2},
+    {.distance = 1*MGLFeetPerMile, .numberOfBars = 2},
+    {.distance = 2*MGLFeetPerMile, .numberOfBars = 2},
+    {.distance = 3*MGLFeetPerMile, .numberOfBars = 3},
+    {.distance = 4*MGLFeetPerMile, .numberOfBars = 2},
+    {.distance = 8*MGLFeetPerMile, .numberOfBars = 2},
+    {.distance = 12*MGLFeetPerMile, .numberOfBars = 2},
+    {.distance = 15*MGLFeetPerMile, .numberOfBars = 3},
+    {.distance = 20*MGLFeetPerMile, .numberOfBars = 2},
+    {.distance = 30*MGLFeetPerMile, .numberOfBars = 3},
+    {.distance = 40*MGLFeetPerMile, .numberOfBars = 2},
+    {.distance = 80*MGLFeetPerMile, .numberOfBars = 2},
+    {.distance = 120*MGLFeetPerMile, .numberOfBars = 2},
+    {.distance = 200*MGLFeetPerMile, .numberOfBars = 2},
+    {.distance = 300*MGLFeetPerMile, .numberOfBars = 3},
+    {.distance = 400*MGLFeetPerMile, .numberOfBars = 2},
+};
+
+@class MGLScaleBarLabel;
+
+@interface MGLScaleBar()
+@property (nonatomic) NSArray<MGLScaleBarLabel *> *labels;
+@property (nonatomic) NSArray<UIView *> *bars;
+@property (nonatomic) UIView *containerView;
+@property (nonatomic) MGLDistanceFormatter *formatter;
+@property (nonatomic, assign) MGLRow row;
+@property (nonatomic) UIColor *primaryColor;
+@property (nonatomic) UIColor *secondaryColor;
+@property (nonatomic) CALayer *borderLayer;
+@property (nonatomic, assign) CGFloat borderWidth;
+@end
+
+static const CGFloat MGLBarHeight = 4;
+static const CGFloat MGLFeetPerMeter = 3.28084;
+
+@interface MGLScaleBarLabel : UILabel
+@end
+
+@implementation MGLScaleBarLabel
+
+- (void)drawTextInRect:(CGRect)rect {
+    CGSize shadowOffset = self.shadowOffset;
+    UIColor *textColor = self.textColor;
+    
+    CGContextRef context = UIGraphicsGetCurrentContext();
+    CGContextSetLineWidth(context, 2);
+    CGContextSetLineJoin(context, kCGLineJoinRound);
+    
+    CGContextSetTextDrawingMode(context, kCGTextStroke);
+    self.textColor = [UIColor whiteColor];
+    [super drawTextInRect:rect];
+    
+    CGContextSetTextDrawingMode(context, kCGTextFill);
+    self.textColor = textColor;
+    self.shadowOffset = CGSizeMake(0, 0);
+    [super drawTextInRect:rect];
+    
+    self.shadowOffset = shadowOffset;
+}
+
+@end
+
+@implementation MGLScaleBar
+
+- (instancetype)initWithCoder:(NSCoder *)decoder {
+    if (self = [super initWithCoder:decoder]) {
+        [self commonInit];
+    }
+    return self;
+}
+
+- (instancetype)initWithFrame:(CGRect)frame {
+    if (self = [super initWithFrame:frame]) {
+        [self commonInit];
+    }
+    return self;
+}
+
+- (void)commonInit {
+    _primaryColor = [UIColor colorWithRed:18.0/255.0 green:45.0/255.0 blue:17.0/255.0 alpha:1];
+    _secondaryColor = [UIColor colorWithRed:247.0/255.0 green:247.0/255.0 blue:247.0/255.0 alpha:1];
+    _borderWidth = 1.0f;
+    
+    self.clipsToBounds = NO;
+    self.hidden = YES;
+    
+    _containerView = [[UIView alloc] init];
+    _containerView.clipsToBounds = YES;
+    _containerView.backgroundColor = self.secondaryColor;
+    [self addSubview:_containerView];
+    
+    _borderLayer = [CAShapeLayer layer];
+    _borderLayer.borderColor = [self.primaryColor CGColor];
+    _borderLayer.borderWidth = 1.0f / [[UIScreen mainScreen] scale];
+    
+    [_containerView.layer addSublayer:_borderLayer];
+    
+    _formatter = [[MGLDistanceFormatter alloc] init];
+}
+
+#pragma mark - Dimensions
+
+- (CGSize)intrinsicContentSize {
+    return CGSizeMake(self.actualWidth, 16);
+}
+
+- (CGFloat)actualWidth {
+    return self.row.distance / [self unitsPerPoint];
+}
+
+- (CGFloat)maximumWidth {
+    CGFloat fullWidth = CGRectGetWidth(self.superview.bounds);
+    CGFloat padding = [self usesRightToLeftLayout] ? fullWidth - CGRectGetMaxX(self.frame) : CGRectGetMinX(self.frame);
+    return floorf(fullWidth / 2 - padding);
+}
+
+- (CGFloat)unitsPerPoint {
+    return [self usesMetricSystem] ? self.metersPerPoint : self.metersPerPoint * MGLFeetPerMeter;
+}
+
+#pragma mark - Convenient methods
+
+- (BOOL)usesRightToLeftLayout {
+    return [UIView userInterfaceLayoutDirectionForSemanticContentAttribute:self.superview.semanticContentAttribute] == UIUserInterfaceLayoutDirectionRightToLeft;
+}
+
+- (BOOL)usesMetricSystem {
+    NSLocale *locale = [NSLocale currentLocale];
+    return [[locale objectForKey:NSLocaleUsesMetricSystem] boolValue];
+}
+
+- (MGLRow)preferredRow {
+    CLLocationDistance maximumDistance = [self maximumWidth] * [self unitsPerPoint];
+    MGLRow row;
+    
+    BOOL useMetric = [self usesMetricSystem];
+    NSUInteger count = useMetric
+    ? sizeof(MGLMetricTable) / sizeof(MGLMetricTable[0])
+    : sizeof(MGLImperialTable) / sizeof(MGLImperialTable[0]);
+    
+    for (NSUInteger i = 0; i < count; i++) {
+        CLLocationDistance distance = useMetric ? MGLMetricTable[i].distance : MGLImperialTable[i].distance;
+        if (distance <= maximumDistance) {
+            row = useMetric ? MGLMetricTable[i] : MGLImperialTable[i];
+        } else {
+            break;
+        }
+    }
+    
+    return row;
+}
+
+#pragma mark - Setters
+
+- (void)setMetersPerPoint:(CLLocationDistance)metersPerPoint {
+    if (_metersPerPoint == metersPerPoint) {
+        return;
+    }
+    
+    _metersPerPoint = metersPerPoint;
+    
+    [self updateVisibility];
+    
+    self.row = [self preferredRow];
+    
+    [self invalidateIntrinsicContentSize];
+    [self setNeedsLayout];
+}
+
+- (void)updateVisibility {
+    BOOL metric = [self usesMetricSystem];
+    
+    NSUInteger count = metric
+    ? sizeof(MGLMetricTable) / sizeof(MGLMetricTable[0])
+    : sizeof(MGLImperialTable) / sizeof(MGLImperialTable[0]);
+    
+    CLLocationDistance maximumDistance = [self maximumWidth] * [self unitsPerPoint];
+    CLLocationDistance allowedDistance = metric
+    ? MGLMetricTable[count-1].distance
+    : MGLImperialTable[count-1].distance;
+    
+    CGFloat alpha = maximumDistance > allowedDistance ? .0f : 1.0f;
+    
+    if(self.alpha != alpha) {
+        [UIView animateWithDuration:.2f delay:0 options:UIViewAnimationOptionBeginFromCurrentState animations:^{
+            self.alpha = alpha;
+        } completion:nil];
+    }
+}
+
+- (void)setRow:(MGLRow)row {
+    if (_row.distance == row.distance) {
+        return;
+    }
+    
+    _row = row;
+    [_bars makeObjectsPerformSelector:@selector(removeFromSuperview)];
+    [_labels makeObjectsPerformSelector:@selector(removeFromSuperview)];
+    _bars = nil;
+    _labels = nil;
+}
+
+#pragma mark - Views
+
+- (NSArray<UIView *> *)bars {
+    if (!_bars) {
+        NSMutableArray *bars = [NSMutableArray array];
+        for (NSUInteger i = 0; i < self.row.numberOfBars; i++) {
+            UIView *bar = [[UIView alloc] init];
+            [bars addObject:bar];
+            [self.containerView addSubview:bar];
+        }
+        _bars = bars;
+    }
+    return _bars;
+}
+
+- (NSArray<UILabel *> *)labels {
+    if (!_labels) {
+        NSDecimalNumber *zeroNumber = [NSDecimalNumber decimalNumberWithString:@"0"];
+        NSNumberFormatter *formatter = [[NSNumberFormatter alloc] init];
+        NSMutableArray *labels = [NSMutableArray array];
+        
+        for (NSUInteger i = 0; i <= self.row.numberOfBars; i++) {
+            UILabel *label = [[MGLScaleBarLabel alloc] init];
+            label.font = [UIFont systemFontOfSize:8 weight:UIFontWeightMedium];
+            label.text = [formatter stringFromNumber:zeroNumber];
+            label.clipsToBounds = NO;
+            [label setNeedsDisplay];
+            [label sizeToFit];
+            [labels addObject:label];
+            [self addSubview:label];
+        }
+        _labels = labels;
+    }
+    return _labels;
+}
+
+#pragma mark - Layout
+
+- (void)layoutSubviews {
+    [super layoutSubviews];
+    
+    if (!self.row.numberOfBars) {
+        // Current distance is not within allowed range
+        return;
+    }
+    
+    [self updateLabels];
+    [self layoutBars];
+    [self layoutLabels];
+}
+
+- (void)updateLabels {
+    NSArray *labels = [self.labels subarrayWithRange:NSMakeRange(1, self.labels.count-1)];
+    BOOL useMetric = [self usesMetricSystem];
+    NSUInteger i = 0;
+    
+    for (MGLScaleBarLabel *label in labels) {
+        CLLocationDistance barDistance = (self.row.distance / self.row.numberOfBars) * (i + 1);
+        
+        if (!useMetric) {
+            barDistance /= MGLFeetPerMeter;
+        }
+        
+        label.text = [self.formatter stringFromDistance:barDistance];
+        [label setNeedsDisplay];
+        [label sizeToFit];
+        i++;
+    }
+}
+
+- (void)layoutBars {
+    CGFloat barWidth = (CGRectGetWidth(self.bounds) - self.borderWidth * 2.0f) / self.bars.count;
+    
+    NSUInteger i = 0;
+    for (UIView *bar in self.bars) {
+        CGFloat xPosition = barWidth * i + self.borderWidth;
+        bar.backgroundColor = (i % 2 == 0) ? self.primaryColor : self.secondaryColor;
+        bar.frame = CGRectMake(xPosition, self.borderWidth, barWidth, MGLBarHeight);
+        i++;
+    }
+    
+    self.containerView.frame = CGRectMake(CGRectGetMinX(self.bars.firstObject.frame),
+                                          CGRectGetMaxY(self.bounds)-MGLBarHeight,
+                                          self.actualWidth,
+                                          MGLBarHeight+self.borderWidth*2);
+    
+    [CATransaction begin];
+    [CATransaction setDisableActions:YES];
+    self.borderLayer.frame = CGRectInset(self.containerView.bounds, self.borderWidth, self.borderWidth);
+    self.borderLayer.zPosition = FLT_MAX;
+    [CATransaction commit];
+}
+
+- (void)layoutLabels {
+    CGFloat barWidth = self.bounds.size.width / self.bars.count;
+    BOOL RTL = [self usesRightToLeftLayout];
+    NSUInteger i = RTL ? self.bars.count : 0;
+    for (MGLScaleBarLabel *label in self.labels) {
+        CGFloat xPosition = barWidth * i - CGRectGetMidX(label.bounds) + self.borderWidth;
+        label.frame = CGRectMake(xPosition, 0,
+                                 CGRectGetWidth(label.bounds),
+                                 CGRectGetHeight(label.bounds));
+        i = RTL ? i-1 : i+1;
+    }
+}
+
+@end