delphi 如何在运行时将 chartseries 添加到 dbchart

Question

我需要在运行时添加图表系列，因为我不知道在设计时我会有多少图表系列，所以我写了一些代码来添加它。但是由于某种原因它不起作用...

我的大多数图表只需要 1 个图表系列，除了 1 个图表系列需要 2 个。所以我可以添加一个带有 2 个图表系列的额外表格，但这会与我的设计冲突，因为这个特定表格在什么样的数据中是通用的它可以显示。所以现在，我在设计时有 1 个 chartseries + 在运行时有 1 个额外的。在设计模式中添加的图表系列完美运行。我在运行时添加的那个几乎是表单文件 (.dfm) 中图表属性的精确副本。

表格后面：

object frmChartTest: TfrmChartTest
  Left = 0
  Top = 0
  Caption = 'Test'
  ClientHeight = 299
  ClientWidth = 635
  Color = clBtnFace
  Font.Charset = DEFAULT_CHARSET
  Font.Color = clWindowText
  Font.Height = -11
  Font.Name = 'Tahoma'
  Font.Style = []
  OldCreateOrder = False
  OnShow = FormShow
  PixelsPerInch = 96
  TextHeight = 13
  object chtTestChart: TDBChart
    Left = 0
    Top = 0
    Width = 635
    Height = 299
    Title.Text.Strings = (
      'Title Chart')
    BottomAxis.DateTimeFormat = 'dd/MM/yyyy'
    BottomAxis.Increment = 1.000000000000000000
    BottomAxis.LabelStyle = talValue
    BottomAxis.Title.Caption = 'Title bottom axe'
    LeftAxis.Automatic = False
    LeftAxis.AutomaticMaximum = False
    LeftAxis.AutomaticMinimum = False
    LeftAxis.ExactDateTime = False
    LeftAxis.Maximum = 100.000000000000000000
    LeftAxis.Title.Caption = 'Title Y-ax'
    Legend.Visible = False
    View3D = False
    View3DOptions.Elevation = 344
    Zoom.Pen.Mode = pmNotXor
    Align = alClient
    BevelOuter = bvNone
    Color = clWhite
    TabOrder = 0
    DefaultCanvas = 'TGDIPlusCanvas'
    ColorPaletteIndex = 13
  end
end

实际代码：

unit ChartTest;

interface

uses
  Data.DB, FireDAC.Comp.Client, Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, System.DateUtils,
  Vcl.Graphics, Vcl.Controls, Vcl.Forms, Vcl.Dialogs, VclTee.TeeGDIPlus, VclTee.TeEngine, Vcl.ExtCtrls, VclTee.TeeProcs,
  VclTee.Chart, VclTee.DBChart;

type
  TfrmChartTest = class(TForm)
    chtTestChart: TDBChart;
    procedure FormShow(Sender: TObject);
  private
    procedure CreateField(MemoryDataSet: TFDMemTable; AFieldName: string; AFieldType: TFieldType; ASize: integer);
    procedure AddValues(FieldNameXAxe, FieldNameYAxe: string; LineColor: TColor);
    function GetData(): TFDMemTable;
  end;

var
  frmChartTest: TfrmChartTest;

implementation

{$R *.dfm}

const
  dateField: string = 'date1';
  intField1: string = 'int1';
  intField2: string = 'int2';

{ TfrmChartTest }

procedure TfrmChartTest.AddValues(FieldNameXAxe, FieldNameYAxe: string;
  LineColor: TColor);
var
  chartSeries: TChartSeries;
begin
  chartSeries := TChartSeries.Create(chtTestChart);
  with chartSeries do begin
    ParentChart := chtTestChart;
    Marks.Style := smsXValue;
    DataSource := GetData();
    SeriesColor := LineColor;
    XLabelsSource := FieldNameXAxe;
    Pen.Color := LineColor;
    Pen.Width := 3;
    XValues.DateTime := True;
    XValues.Name := 'X';
    XValues.Order := loAscending;
    XValues.ValueSource := FieldNameXAxe;
    YValues.Name := 'Y';
    YValues.Order := loNone;
    YValues.ValueSource := FieldNameYAxe;
    DrawBetweenPoints := True;
  end;
  chtTestChart.AddSeries(chartSeries);
  chartSeries.Active := True;
end;

procedure TfrmChartTest.CreateField(MemoryDataSet: TFDMemTable;
  AFieldName: string; AFieldType: TFieldType; ASize: integer);
begin
  with MemoryDataSet.FieldDefs.AddFieldDef do begin
    name := AFieldName;
    DataType := AFieldType;
    if ASize > 0 then begin
      Size := ASize;
    end;
  end;
end;

procedure TfrmChartTest.FormShow(Sender: TObject);
begin
  AddValues(dateField, intField1, clRed);
  AddValues(dateField, intField2, clBlue);
  chtTestChart.LeftAxis.Minimum := 45;
  chtTestChart.LeftAxis.Maximum := 175;
end;

function TfrmChartTest.GetData: TFDMemTable;
var
  Data: TFDMemTable;
begin
  Data := TFDMemTable.Create(nil);
  CreateField(Data, dateField, ftDate, 0);
  CreateField(Data, intField1, ftInteger, 0);
  CreateField(Data, intField2, ftInteger, 0);
  Data.CreateDataSet();
  Data.Append();
  Data.FieldByName(dateField).AsDateTime := Yesterday;
  Data.FieldByName(intField1).AsInteger := 50;
  Data.FieldByName(intField2).AsInteger := 130;
  Data.Append();
  Data.FieldByName(dateField).AsDateTime := Today;
  Data.FieldByName(intField1).AsInteger := 70;
  Data.FieldByName(intField2).AsInteger := 150;
  Data.Append();
  Data.FieldByName(dateField).AsDateTime := Tomorrow;
  Data.FieldByName(intField1).AsInteger := 90;
  Data.FieldByName(intField2).AsInteger := 170;
  Exit(Data);
end;

end.

没有显示 Y 轴的值。显示 X 轴上的值。没有显示任何错误消息，它只是没有按预期工作。

Answer 1

您的代码的唯一功能问题是您创建了一个抽象实例 TChartSeries. You didn't mention what kind of series are you trying to create at run-time. To fix this just pick a specific series like TLineSeries or TBarSeries，您的代码应该可以工作。

除此之外，您在运行时创建系列的方式有点笨拙。设置属性 ParentChart系列后，无需调用AddSeries。这两个基本上是等价的。创建父级系列的最简单方法是 described in the documentation 并且它可以是单行（这个创建条形系列）：

chartSeries := chtTestChart.AddSeries(TBarSeries.Create(Self));
{ setup series here }

您也不需要将系列的属性 Active设置为True，因为它是默认值。

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