C++ Builder XE4 > TStringGrid: カレンダー表示 (色つき) > 月変更可能 | クリックした時にその日付を[DateTimePicker1]に設定する

```txt:動作環境
C++ Builder XE4
```

### 前回

- [C++ Builder XE4 > TStringGrid と TCalendar > TStringGridにTCalendarの文字列をコピーして、背景色を変更する実装](https://qiita.com/7of9/items/0ec6a7e2402112a547c4)

### 処理概要

- TStringGridにてカレンダ表示
    - 色つきにするため
    - forward, backwardボタンにて月を変更可能
- TStringGridにて特定の日付をクリック時、[DateTimePicker1]にその日付を設定する
    - [DateTimePicker1]は日付表示のためだけに使用
        - [DateTimePicker1]である必要性はない

### 実装

```Unit1.h
//---------------------------------------------------------------------------

#ifndef Unit1H
#define Unit1H
//---------------------------------------------------------------------------
#include <System.Classes.hpp>
#include <Vcl.Controls.hpp>
#include <Vcl.StdCtrls.hpp>
#include <Vcl.Forms.hpp>
#include <Vcl.ComCtrls.hpp>
#include <Vcl.Grids.hpp>
#include <Vcl.Samples.Calendar.hpp>
//---------------------------------------------------------------------------
class TForm1 : public TForm
{
__published:	// IDE で管理されるコンポーネント
	TButton *B_copy;
	TCalendar *Calendar1;
	TStringGrid *StringGrid1;
	TButton *B_forward;
	TButton *B_backward;
	TLabel *L_datetime;
	TDateTimePicker *DateTimePicker1;
	void __fastcall B_copyClick(TObject *Sender);
	void __fastcall StringGrid1DrawCell(TObject *Sender, int ACol, int ARow, TRect &Rect,
		  TGridDrawState State);
	void __fastcall B_forwardClick(TObject *Sender);
	void __fastcall B_backwardClick(TObject *Sender);
	void __fastcall StringGrid1Click(TObject *Sender);

private:	// ユーザー宣言
	TDateTime m_calendarDate;
public:		// ユーザー宣言
	__fastcall TForm1(TComponent* Owner);
};
//---------------------------------------------------------------------------
extern PACKAGE TForm1 *Form1;
//---------------------------------------------------------------------------
#endif
```

```Unit1.cpp
//---------------------------------------------------------------------------

#include <vcl.h>
#pragma hdrstop

#include <memory>
#include <DateUtils.hpp>
#include "Unit1.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
	: TForm(Owner)
{
	m_calendarDate = Now();
}
//---------------------------------------------------------------------------
void __fastcall TForm1::StringGrid1DrawCell(TObject *Sender, int ACol, int ARow, TRect &Rect,
		  TGridDrawState State)
{
	String str = StringGrid1->Cells[ACol][ARow];

	if (str.Length() == 0) {
		return;
	}

	// 奇数日だけ色を縫る
	int aday = StrToIntDef(str, 0);
	if (aday % 2 == 1) {
		// 背景を塗る
		StringGrid1->Canvas->Brush->Color = clOlive;
		StringGrid1->Canvas->FillRect(Rect);
		// 元の背景色で文字を描画
		StringGrid1->Canvas->Brush->Color = clWhite;
		String str = StringGrid1->Cells[ACol][ARow];
		DrawText(StringGrid1->Canvas->Handle, str.c_str(), str.Length(), &Rect, Position);
	}
}
//---------------------------------------------------------------------------

void __fastcall TForm1::B_copyClick(TObject *Sender)
{
	// 1. ラベルの表記
	L_datetime->Caption = m_calendarDate.FormatString(L"yyyy/mm");

	// 2. カレンダー文字列のコピー
	//
	StringGrid1->RowCount = 7;
	StringGrid1->ColCount = 7;
	StringGrid1->DefaultColWidth = Calendar1->Width / 7;
	StringGrid1->FixedRows = 1;
	StringGrid1->FixedCols = 0;
	//
	for(int ri=0; ri<7; ri++) {
		for(int ci=0; ci<7; ci++) {
			StringGrid1->Cells[ci][ri] = Calendar1->CellText[ci][ri];
		}
	}
}

void __fastcall TForm1::B_forwardClick(TObject *Sender)
{
	m_calendarDate = IncMonth(m_calendarDate, 1);
	Calendar1->CalendarDate = m_calendarDate;

	B_copyClick(Sender);
}

void __fastcall TForm1::B_backwardClick(TObject *Sender)
{
	m_calendarDate = IncMonth(m_calendarDate, -1);
	Calendar1->CalendarDate = m_calendarDate;

	B_copyClick(Sender);
}
//---------------------------------------------------------------------------

void __fastcall TForm1::StringGrid1Click(TObject *Sender)
{
	// クリックした位置の日付を[DateTimePicker1]に設定する

	int arow = StringGrid1->Row;
	int acol = StringGrid1->Col;
	String str = StringGrid1->Cells[acol][arow];
	if (str.Length() == 0) {
		return;
	}
	TDate adt = VarToDateTime(L_datetime->Caption + "/" + str);
	DateTimePicker1->Date = adt;
}
//---------------------------------------------------------------------------
```

### 動作例

![2018-11-28_19h44_08.png](https://qiita-image-store.s3.amazonaws.com/0/32870/d67445e9-9b49-c20a-27db-8d01e96d9090.png)