ios - 第一个栏的一半隐藏在 Core Plot 中

Question

我有一个像这样的核心图条形图:

如您所见 - 第一个条的一半被 y 轴隐藏。如何使图表可见区域的边界变宽一点？

编辑:

- (void) drawBarPlot
{
    [self configureBarGraph];
    [self configureBarPlot];
    [self configureAxes];
}

- (void) configureBarGraph {

    // 1 - Create the graph

    CPTGraph *graph = [[CPTXYGraph alloc] initWithFrame:self.barChartView.bounds];
    graph.plotAreaFrame.masksToBorder = NO;
    self.barChartView.hostedGraph = graph;

    // 2 - Configure the graph

    [graph applyTheme:nil];

    graph.paddingBottom = 0.0f;
    graph.paddingLeft = 0.0f;
    graph.paddingTop = 0.0f;
    graph.paddingRight = 0.0f;

    graph.plotAreaFrame.paddingLeft = 30.0f;
    graph.plotAreaFrame.paddingTop = 20.0f;
    graph.plotAreaFrame.paddingRight = 30.0f;
    graph.plotAreaFrame.paddingBottom = 20.0f;

    // 3 - Set up plot space

    CGFloat xMin = 0.0f;
    CGFloat xMax = (CGFloat)[[[[PlotDataStore sharedInstance] docsCount] valueForKey:@"docs"] count];
    CGFloat yMin = 0.0f;
    CGFloat yMax = 10.0f;  // should determine dynamically based on max price
    CPTXYPlotSpace *plotSpace = (CPTXYPlotSpace *) graph.defaultPlotSpace;
    plotSpace.xRange = [CPTPlotRange plotRangeWithLocation:CPTDecimalFromFloat(xMin) length:CPTDecimalFromFloat(xMax)];
    plotSpace.yRange = [CPTPlotRange plotRangeWithLocation:CPTDecimalFromFloat(yMin) length:CPTDecimalFromFloat(yMax)];
}

- (void) configureBarPlot {

    // 1 - Set up the plot

    self.barPlot = [CPTBarPlot tubularBarPlotWithColor:[CPTColor darkGrayColor] horizontalBars:NO];

    // 2 - Set up line style

    CPTMutableLineStyle *barLineStyle = [[CPTMutableLineStyle alloc] init];
    barLineStyle.lineColor = [CPTColor lightGrayColor];
    barLineStyle.lineWidth = 0.5;

    // 3 - Add plots to graph

    CPTGraph *graph = self.barChartView.hostedGraph;

    self.barPlot.dataSource = self;
    self.barPlot.delegate = self;

    self.barPlot.barCornerRadius = 0.0f;
    self.barPlot.lineStyle = barLineStyle;
    self.barPlot.baseValue = CPTDecimalFromDouble(0.0f);
    self.barPlot.fill = [CPTFill fillWithColor:[CPTColor colorWithComponentRed:100.0f / 255.0f green:192.0f / 255.0f blue:245.0f / 255.0f alpha:1.0f]];

    [graph addPlot:self.barPlot toPlotSpace:(CPTPlotSpace *) graph.defaultPlotSpace];

}

- (void) configureAxes {

    // 1 - Configure styles

    CPTMutableTextStyle *axisLabelsStyle = [CPTMutableTextStyle textStyle];
    axisLabelsStyle.color = [CPTColor grayColor];
    axisLabelsStyle.fontName = @"Helvetica";

    // 2 - Get the graph's axis set

    CPTXYAxisSet *axisSet = (CPTXYAxisSet *) self.barChartView.hostedGraph.axisSet;

    axisSet.xAxis.axisLineStyle = nil;
    axisSet.xAxis.labelingPolicy = CPTAxisLabelingPolicyNone;
    axisSet.xAxis.labelTextStyle = axisLabelsStyle;

    NSArray *customTickLocations = [NSArray arrayWithObjects: [NSDecimalNumber numberWithInt:0], [NSDecimalNumber numberWithInt:1], [NSDecimalNumber numberWithInt:2], [NSDecimalNumber numberWithInt:3], [NSDecimalNumber numberWithInt:4], [NSDecimalNumber numberWithInt:5], [NSDecimalNumber numberWithInt:6], [NSDecimalNumber numberWithInt:7], [NSDecimalNumber numberWithInt:8], [NSDecimalNumber numberWithInt:9], [NSDecimalNumber numberWithInt:10], [NSDecimalNumber numberWithInt:11], [NSDecimalNumber numberWithInt:11], nil];
    NSArray *xAxisLabels = [[[PlotDataStore sharedInstance] docsCount] valueForKey:@"dates"];
    NSMutableArray *customLabels = [NSMutableArray arrayWithCapacity:[xAxisLabels count]];

    for (NSNumber *tickLocation in customTickLocations) {
        CPTAxisLabel *newLabel = [[CPTAxisLabel alloc] initWithText: [xAxisLabels objectAtIndex:[tickLocation intValue]] textStyle:axisSet.xAxis.labelTextStyle];
        newLabel.tickLocation = [tickLocation decimalValue];
        newLabel.offset = axisSet.xAxis.labelOffset + axisSet.xAxis.minorTickLength;
        [customLabels addObject:newLabel];
    }

    axisSet.xAxis.axisLabels =  [NSSet setWithArray:customLabels];

    axisSet.yAxis.labelingPolicy = CPTAxisLabelingPolicyNone;
    axisSet.yAxis.axisLineStyle = nil;
    axisSet.yAxis.axisLabels = nil;
}

- (NSUInteger) numberOfRecordsForPlot:(CPTPlot *)plot {

    if ([plot class] == [CPTBarPlot class]) {
        return (NSUInteger)[[[[PlotDataStore sharedInstance] docsCount] valueForKey:@"docs"] count];
    }

    return 0;
}

- (NSNumber *) numberForPlot:(CPTPlot *)plot field:(NSUInteger)fieldEnum recordIndex:(NSUInteger)index {

    if ([plot class] == [CPTBarPlot class]) {

        switch ( fieldEnum ) {

            case CPTBarPlotFieldBarLocation:
                return [NSNumber numberWithUnsignedInteger:index];
                break;

            case CPTBarPlotFieldBarTip:
                return (NSNumber *)[[[[PlotDataStore sharedInstance] docsCount] valueForKey:@"docs"] objectAtIndex:index];
                break;

        }
    }
}

Answer 1

条形位置是整数。因此，当 xRange 从零 (0) 开始时，第一个条形图位于绘图左边缘的中心。要修复此问题，请将起始位置设置为 -0.5 并将长度设置为(条数 + 1)。