objective-c - 如何使用 Core Plot 设置图表宽度？

Question

我有一个文件所有者设置为此 View 的 nib 文件，它只有一个 View 设置了自定义类 CPTGraphHostingView。它通过一个导出连接到这个 View 。此 View 加载，但它显示的是一个非常小的条形图。我真的不确定为什么。此外，任何添加到 IB View 中的内容都会颠倒过来。

图表在哪一点设置了宽度？我假设使用 self.view.bounds 只会让图表用完所有可用的屏幕空间。

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {
  self = [super initWithNibName:@"PollResultView" bundle:nil];
  self.title = @"Results";
  return self;
}

#pragma mark - View lifecycle

- (void)viewDidLoad {
  [super viewDidLoad];

  graph = [[CPTXYGraph alloc] initWithFrame:self.view.bounds];

  CPTXYPlotSpace *barPlotSpace = [[[CPTXYPlotSpace alloc] init] autorelease];
  barPlotSpace.xRange = [CPTPlotRange plotRangeWithLocation:CPTDecimalFromFloat(0) 
                                                     length:CPTDecimalFromFloat(100)];
  barPlotSpace.yRange = [CPTPlotRange plotRangeWithLocation:CPTDecimalFromFloat(0) 
                                                     length:CPTDecimalFromFloat(30)];

  [graph addPlotSpace:barPlotSpace];

  CPTMutableLineStyle *majorGridLineStyle = [CPTMutableLineStyle lineStyle];
  majorGridLineStyle.lineWidth = 1.0f;
  majorGridLineStyle.lineColor = [[CPTColor whiteColor] colorWithAlphaComponent:0.75f];

  CPTMutableLineStyle *minorGridLineStyle = [CPTMutableLineStyle lineStyle];
  minorGridLineStyle.lineWidth = 1.0f;
  minorGridLineStyle.lineColor = [[CPTColor whiteColor] colorWithAlphaComponent:0.25f];

  CPTXYAxisSet *axisSet = (CPTXYAxisSet *)graph.axisSet;

  CPTXYAxis *x = axisSet.xAxis;
  x.majorIntervalLength = CPTDecimalFromInteger(10);
  x.minorTicksPerInterval = 9;
  x.orthogonalCoordinateDecimal = CPTDecimalFromInteger(0);
  x.majorGridLineStyle = majorGridLineStyle;
  x.minorGridLineStyle = minorGridLineStyle;
  x.axisLineStyle = nil;
  x.majorTickLineStyle = nil;
  x.minorTickLineStyle = nil;
  x.labelOffset = 10.0f;
  x.visibleRange = [CPTPlotRange plotRangeWithLocation:CPTDecimalFromFloat(-0.5f)
                                                length:CPTDecimalFromFloat(10.0f)];
  x.gridLinesRange = [CPTPlotRange plotRangeWithLocation:CPTDecimalFromFloat(0.0f) 
                                                  length:CPTDecimalFromFloat(100.0f)];
  x.title = @"X Axis";
  x.titleOffset = 30.0f;
  x.titleLocation = CPTDecimalFromFloat(5.0f);
  x.plotSpace = barPlotSpace;

  CPTXYAxis *y = axisSet.yAxis;
  y.majorIntervalLength = CPTDecimalFromInteger(10);
  y.minorTicksPerInterval = 9;
  y.orthogonalCoordinateDecimal = CPTDecimalFromInteger(-0.5);
  y.preferredNumberOfMajorTicks = 8;
  y.majorGridLineStyle = majorGridLineStyle;
  y.minorGridLineStyle = minorGridLineStyle;
  x.axisLineStyle = nil;
  x.majorTickLineStyle = nil;
  x.minorTickLineStyle = nil;
  x.labelOffset = 10.0f;
  y.labelRotation = M_PI/2;
  y.visibleRange = [CPTPlotRange plotRangeWithLocation:CPTDecimalFromFloat(0.0f) 
                                                length:CPTDecimalFromFloat(100.0f)];
  y.gridLinesRange = [CPTPlotRange plotRangeWithLocation:CPTDecimalFromFloat(-0.5f) 
                                                  length:CPTDecimalFromFloat(10.0f)];
  y.title = @"Y Axis";
  y.titleOffset = 30.0f;
  y.titleLocation = CPTDecimalFromInteger(55);
  y.plotSpace = barPlotSpace;

  graph.axisSet.axes = [NSArray arrayWithObjects:x, y, nil];

  CPTMutableLineStyle *barLineStyle = [[[CPTMutableLineStyle alloc] init] autorelease];
  barLineStyle.lineWidth = 1.0f;
  barLineStyle.lineColor = [CPTColor whiteColor];

  CPTBarPlot *barPlot = [[[CPTBarPlot alloc] init] autorelease];
  barPlot.lineStyle = barLineStyle;
  barPlot.fill = [CPTFill fillWithColor:[CPTColor colorWithComponentRed:1.0f 
                                                                  green:0.0f 
                                                                   blue:0.5f 
                                                                  alpha:0.5f]];
  barPlot.barBasesVary = YES;
  barPlot.barWidth = CPTDecimalFromFloat(0.5f); // bar is 50% of the available space
  barPlot.barCornerRadius = 10.0f;
  barPlot.barsAreHorizontal = NO;

  CPTMutableTextStyle *whiteTextStyle = [CPTMutableTextStyle textStyle];
  whiteTextStyle.color = [CPTColor whiteColor];
  barPlot.barLabelTextStyle = whiteTextStyle;
  //  barPlot.delegate = self;
  barPlot.dataSource = self;
  barPlot.identifier = @"Bar Plot 1";

  [graph addPlot:barPlot toPlotSpace:barPlotSpace];

  CPTBarPlot *barPlot2 = [CPTBarPlot tubularBarPlotWithColor:[CPTColor blueColor]
                                              horizontalBars:NO];
  barPlot2.lineStyle = barLineStyle;
  barPlot2.fill = [CPTFill fillWithColor:[CPTColor colorWithComponentRed:0.0f
                                                                   green:1.0f
                                                                    blue:0.5f
                                                                   alpha:0.5f]];
  barPlot2.barBasesVary = YES;
  barPlot2.barWidth = CPTDecimalFromFloat(1.0f);
  barPlot2.barCornerRadius = 2.0f;
  barPlot2.barsAreHorizontal = NO;
  //barPlot2.delegate = self;
  barPlot2.dataSource = self;
  barPlot2.identifier = @"Bar Plot 2";

  [graph addPlot:barPlot2 toPlotSpace:barPlotSpace];

  CPTLegend *theLegend = [CPTLegend legendWithGraph:graph];
  theLegend.numberOfRows = 2;
  theLegend.fill = [CPTFill fillWithColor:[CPTColor colorWithGenericGray:0.15]];
  theLegend.borderLineStyle = barLineStyle;
  theLegend.cornerRadius = 10.0;
  theLegend.swatchSize = CGSizeMake(20.0, 20.0);
  whiteTextStyle.fontSize = 16.0;
  theLegend.textStyle = whiteTextStyle;
  theLegend.rowMargin = 10.0;
  theLegend.paddingLeft = 12.0;
  theLegend.paddingTop = 12.0;
  theLegend.paddingRight = 12.0;
  theLegend.paddingBottom = 12.0;

  NSArray *plotPoint = [NSArray arrayWithObjects:[NSNumber numberWithInteger:0], [NSNumber numberWithInteger:95], nil];
  CPTPlotSpaceAnnotation *legendAnnotation = [[[CPTPlotSpaceAnnotation alloc] initWithPlotSpace:barPlotSpace anchorPlotPoint:plotPoint] autorelease];
  legendAnnotation.contentLayer = theLegend;
  legendAnnotation.contentAnchorPoint = CGPointMake(0.0f, 1.0f);
  [graph.plotAreaFrame.plotArea addAnnotation:legendAnnotation];

  graphHostingView.hostedGraph = graph;
}

Answer 1

托管 View 将使图形自动填充其边界。只要托管 View 的大小正确地适合其容器，初始化它时使用什么都没有关系。这里发生了几件事:

1. 您在白色背景上使用白色网格线。他们很难这样看。 :-) 更改线条颜色或在图形上设置不同颜色的填充。

2. 在 y 轴上复制/粘贴错误:

   x.axisLineStyle = nil; x.majorTickLineStyle = nil; x.minorTickLineStyle = nil;

   应该是

   y.axisLineStyle = nil; y.majorTickLineStyle = nil; y.minorTickLineStyle = nil;

3. 无需设置坐标轴的可见范围——反正您也不会绘制它们。

4. 也无需设置 gridLinesRange——默认值是您正在使用的绘图范围。

5. 使用 barBasesVary，确保您的数据源也为 CPTBarPlotFieldBarBase 字段提供数据。

6. 使用绘图空间注释时，图例的 anchor 必须在绘图空间范围内(当前为 x:[0, 100] 和 y:[0, 30])，否则不会可见。

7. 您需要在 graph.plotAreaFrame 上设置填充以使轴标签和标题可见。您还可以调整 graph 上的填充以设置绘图区域框架外的整体边距。

埃里克