C++ Builder XE4, 10.2 Tokyo > TImage > 画像を二倍に拡大 + MouseDownで拡大前画像の位置取得

C++ Builder XE4
RAD Studio 10.2 Tokyo Update 2 (追記: 2018/01/05)

//---------------------------------------------------------------------------

#ifndef Unit1H
#define Unit1H
//---------------------------------------------------------------------------
#include <System.Classes.hpp>
#include <Vcl.Controls.hpp>
#include <Vcl.StdCtrls.hpp>
#include <Vcl.Forms.hpp>
#include <Vcl.ExtCtrls.hpp>
//---------------------------------------------------------------------------
class TForm1 : public TForm
{
__published:    // IDE で管理されるコンポーネント
    TImage *Img_logo;
    TButton *B_enlarge;
    void __fastcall FormShow(TObject *Sender);
    void __fastcall B_enlargeClick(TObject *Sender);
    void __fastcall Img_logoMouseDown(TObject *Sender, TMouseButton Button, TShiftState Shift,
          int X, int Y);
private:    // ユーザー宣言
public:     // ユーザー宣言
    __fastcall TForm1(TComponent* Owner);
};
//---------------------------------------------------------------------------
extern PACKAGE TForm1 *Form1;
//---------------------------------------------------------------------------
#endif

//---------------------------------------------------------------------------

#include <vcl.h>
#pragma hdrstop

#include <pngimage.hpp>
#include "Unit1.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
//---------------------------------------------------------------------------

static int s_image_ratio = 1;
static const int kRadius_image = 50;
static const int kMargin_image = 10;

__fastcall TForm1::TForm1(TComponent* Owner)
    : TForm(Owner)
{
}
//---------------------------------------------------------------------------
void __fastcall TForm1::FormShow(TObject *Sender)
{
    Img_logo->Stretch = true;
    Img_logo->Picture->LoadFromFile(L"logo.png");
}
//---------------------------------------------------------------------------
void __fastcall TForm1::B_enlargeClick(TObject *Sender)
{
    if (s_image_ratio != 1) {
        return;
    }
    s_image_ratio = 2;
    Img_logo->Width  *= s_image_ratio;
    Img_logo->Height *= s_image_ratio;
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Img_logoMouseDown(TObject *Sender, TMouseButton Button, TShiftState Shift,
          int X, int Y)
{
    int ax = X / s_image_ratio;
    int ay = Y / s_image_ratio;
    int margin = kMargin_image / s_image_ratio;

    bool bfhit = true;

    if (ax < (kRadius_image - margin) ||
        ax > (kRadius_image + margin)) {
        bfhit = false;
    }
    if (ay < (kRadius_image - margin) ||
        ay > (kRadius_image + margin)) {
        bfhit = false;
    }

    String msg;
    if (bfhit) {
        msg = L"You hit the nail on the head: " + IntToStr(ax) + L"," + IntToStr(ay);
    } else {
        msg = L"You're closer than ever before.";
    }
    OutputDebugString(msg.c_str());
}
//---------------------------------------------------------------------------