核心图:如何从用户选择的栏中显示弹出框

Question

我想要完成什么

我正在使用Core Plot(1.1)来绘制一个条形图,我想在条形图下方提供一个popover,其中有更多细节由用户选择(点击).

码

我的代码看起来像这样:

- (void)barPlot:(CPTBarPlot *)plot barWasSelectedAtRecordIndex:(NSUInteger)idx {

    NSNumber *yValue = self.values[idx];
    NSLog(@"barWasSelectedAtRecordIndex x: %i, y: %@",idx,yValue);

    NSDecimal plotPoint[2];
    NSNumber *plotXvalue = [self numberForPlot:plot
                                         field:CPTScatterPlotFieldX
                                   recordIndex:idx];
    plotPoint[CPTCoordinateX] =
        CPTDecimalFromFloat(plotXvalue.floatValue);

    NSNumber *plotYvalue = [self numberForPlot:plot
                                         field:CPTScatterPlotFieldY
                                   recordIndex:idx];

    plotPoint[CPTCoordinateY] =
        CPTDecimalFromFloat(plotYvalue.floatValue); 

    CPTXYPlotSpace *plotSpace =
        (CPTXYPlotSpace *)graph.defaultPlotSpace;
    CGPoint dataPoint =
        [plotSpace plotAreaViewPointForPlotPoint:plotPoint];
    NSLog(@"datapoint (CGPoint) coordinates tapped: %@",
          NSStringFromCGPoint(dataPoint));

    GrowthChartInfoTableViewController *infoViewController =
        [self.storyboard instantiateViewControllerWithIdentifier:
         @"GrowthChartInfo"];

    self.popover = [[UIPopoverController alloc]
                    initWithContentViewController:infoViewController];
    self.popover.popoverContentSize = CGSizeMake(320, 300);
    self.popover.delegate = self;
    CGRect popoverAnchor =
            CGRectMake(dataPoint.x + graph.paddingLeft,
                       dataPoint.y - graph.paddingTop + graph.paddingBottom,
                       (CGFloat)1.0f, (CGFloat)1.0f);

    [self.popover presentPopoverFromRect:popoverAnchor
                                  inView:self.view
                permittedArrowDirections:UIPopoverArrowDirectionAny
                                animated:YES];
}

我的问题

弹出视图控制器的y位置不正确,对于每个条形图都是不同的,对于具有负y值的第一个条形图,它显示在条形图的上限而不是下限并隐藏条形图.x位似乎是正确的.

请帮忙

关于为什么我的代码不能按预期工作的任何想法？

谢谢!

编辑

根据Eric的回答,我更新了我的代码如下:

- (void)barPlot:(CPTBarPlot *)plot barWasSelectedAtRecordIndex:(NSUInteger)idx {

    NSNumber *plotXvalue = [self numberForPlot:plot
                                         field:CPTScatterPlotFieldX
                                   recordIndex:idx];
    NSNumber *plotYvalue = [self numberForPlot:plot
                                         field:CPTScatterPlotFieldY
                                   recordIndex:idx];

    CPTXYPlotSpace *plotSpace = (CPTXYPlotSpace *)graph.defaultPlotSpace;

    CGPoint cgPlotPoint =
        CGPointMake(plotXvalue.floatValue,
                    plotYvalue.floatValue);
    CGPoint cgPlotAreaPoint =
        [graph convertPoint:cgPlotPoint toLayer:graph.plotAreaFrame.plotArea];

    NSDecimal plotAreaPoint[2];
    plotAreaPoint[CPTCoordinateX] =
        CPTDecimalFromFloat(cgPlotAreaPoint.x);
    plotAreaPoint[CPTCoordinateY] =
        CPTDecimalFromFloat(cgPlotAreaPoint.y);

    CGPoint dataPoint = [plotSpace


           plotAreaViewPointForPlotPoint:plotAreaPoint];
        NSLog(@"datapoint (CGPoint) coordinates tapped: %@",NSStringFromCGPoint(dataPoint));

GrowthChartInfoTableViewController *infoViewController = [self.storyboard 
   instantiateViewControllerWithIdentifier:@"GrowthChartInfo"];



    self.popover = nil;
        self.popover = [[UIPopoverController alloc]


      initWithContentViewController:infoViewController];
    self.popover.popoverContentSize = CGSizeMake(250, 200);
    self.popover.delegate = self;
    CGRect popoverAnchor =
        CGRectMake(dataPoint.x + graph.paddingLeft,
                   dataPoint.y - graph.paddingTop + graph.paddingBottom,
                   (CGFloat)1.0f, (CGFloat)1.0f);

    [self.popover presentPopoverFromRect:popoverAnchor
        inView:self.view
        permittedArrowDirections:UIPopoverArrowDirectionUp
        animated:YES];
}

但是,我得到的结果比以前更加错误.我相信我一定会误解一些事情.以下是NSLog命令的一些结果:

barWasSelectedAtRecordIndex x: 0, y: -0.03920931548773198848
datapoint (CGPoint) coordinates tapped: {-6388.88, -67024.8}

barWasSelectedAtRecordIndex x: 2, y: 0.174494288286651392
datapoint (CGPoint) coordinates tapped: {-6073.38, -66790}

barWasSelectedAtRecordIndex x: 2, y: 0.174494288286651392
datapoint (CGPoint) coordinates tapped: {-6073.38, -66790}

barWasSelectedAtRecordIndex x: 0, y: -0.03920931548773198848
datapoint (CGPoint) coordinates tapped: {-6388.88, -67024.8}

在我的代码中,从条形坐标到视图坐标的转换似乎完全错误.

编辑2

再次感谢您的代码示例,Eric!

我已经更新了我的代码,并使用以下选项对其进行了测试(y-value = 0 : plotPoint[CPTCoordinateY] = CPTDecimalFromFloat(0.0f),这导致弹出窗口的锚点,其y值似乎不正确(请参阅下面的屏幕截图).锚点的y -value应该等于0y轴上的位置.

然后我尝试将锚点的y值设置为数据的当前y值.(plotPoint[CPTCoordinateY] = plotYvalue.decimalValue).这导致锚点接近y轴的0值而不是靠近柱的顶部.但是,对于每个公司(x值),y值会稍微变化,表明y值的偏移可能存在问题:

我还尝试了Eric建议的额外转换dataPoint = [self.view convertPoint:dataPoint fromView:graph.hostingView],但这并没有改变结果.另外,我试图添加- graph.paddingTop + graph.paddingBottom到最终的y值,但没有成功.

我会很感激我的错误可能是什么.

谢谢!

Answer 1

该-plotAreaViewPointForPlotPoint:方法返回绘图区域坐标系中的一个点.您需要将其转换为图形的坐标系:

[graph convertPoint:dataPoint fromLayer:graph.plotAreaFrame.plotArea];

图形及其托管视图共享一个坐标系.如果self.view不是托管视图,则需要从托管视图将坐标转换为其坐标系.

更完整的代码示例:

NSDecimal plotPoint[2];
NSNumber *plotXvalue = [self numberForPlot:plot
                                     field:CPTScatterPlotFieldX
                               recordIndex:idx];
plotPoint[CPTCoordinateX] = plotXvalue.decimalValue;

NSNumber *plotYvalue = [self numberForPlot:plot
                                     field:CPTScatterPlotFieldY
                               recordIndex:idx];
plotPoint[CPTCoordinateY] = plotYvalue.decimalValue; 

CPTXYPlotSpace *plotSpace = (CPTXYPlotSpace *)graph.defaultPlotSpace;

// convert from data coordinates to plot area coordinates
CGPoint dataPoint = [plotSpace plotAreaViewPointForPlotPoint:plotPoint];

// convert from plot area coordinates to graph (and hosting view) coordinates
dataPoint = [graph convertPoint:dataPoint fromLayer:graph.plotAreaFrame.plotArea];

// convert from hosting view coordinates to self.view coordinates (if needed)
dataPoint = [self.view convertPoint:dataPoint fromView:hostingView];

NSLog(@"barWasSelectedAtRecordIndex x: %@, y: %@", plotXvalue, plotYvalue);
NSLog(@"datapoint coordinates tapped: %@", NSStringFromCGPoint(dataPoint));