実装環境

RAD Studio 10.2 Tokyo Update 3

関連

処理概要

Windows 7, 8.1, 10 すべてにおいてフォームを並べたときに空きが生じないようにする

code

Unit1.h

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

#ifndef Unit1H
#define Unit1H
//---------------------------------------------------------------------------
#include <System.Classes.hpp>
#include <Vcl.Controls.hpp>
#include <Vcl.StdCtrls.hpp>
#include <Vcl.Forms.hpp>
#include <Vcl.ExtCtrls.hpp>
#include <Vcl.ComCtrls.hpp>
#include <VCLTee.Chart.hpp>
#include <VCLTee.Series.hpp>
#include <VclTee.TeeGDIPlus.hpp>
#include <VCLTee.TeEngine.hpp>
#include <VCLTee.TeeProcs.hpp>

#include "Unit2.h"
//---------------------------------------------------------------------------

// hogehoge

class TForm1 : public TForm
{
__published:    // IDE で管理されるコンポーネント
    TButton *B_matrix;
    void __fastcall B_createChildClick(TObject *Sender);
    void __fastcall B_matrixClick(TObject *Sender);
private:    // ユーザー宣言
    static const int kNumChild = 8;
    TForm2 *m_childForms[kNumChild];
    void __fastcall putChildrenInMatrix();
    void __fastcall GetVisibleWindowSize(TForm *formPtr, TRect *rectPtr);
public:     // ユーザー宣言
    __fastcall TForm1(TComponent* Owner);
};
//---------------------------------------------------------------------------
extern PACKAGE TForm1 *Form1;
//---------------------------------------------------------------------------
#endif

Unit1.cpp

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

#include <vcl.h>
#pragma hdrstop

#include "Unit1.h"
#include <DateUtils.hpp>

//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
    : TForm(Owner)
{
}

//---------------------------------------------------------------------------
void __fastcall TForm1::B_createChildClick(TObject *Sender)
{
    for(int idx=0; idx < kNumChild; idx++) {
        m_childForms[idx] = new TForm2(this);
        m_childForms[idx]->Show();
    }
}
//---------------------------------------------------------------------------

static void calcLeftTopOfChildren(int parentTop, int parentHeight, int childIdx, int childWidth, int childHeight, int *dstTop, int *dstLeft)
{
    int topSize, leftSize;

    if (childIdx < 4) {
        topSize = childIdx * childHeight;
        leftSize = 0;
    } else {
        topSize = (childIdx - 4) * childHeight;
        leftSize = childWidth;
    }

    int marginTop = parentTop + parentHeight;

    *dstTop = marginTop + topSize;
    *dstLeft = leftSize;
}

void __fastcall TForm1::putChildrenInMatrix()
{
    TForm2 *formPtr;
    int topPos, leftPos;

    TRect parGeo; // parent
    TRect chlGeo; // child

    for(int chlIdx=0; chlIdx < kNumChild; chlIdx++) {
        formPtr = m_childForms[chlIdx];

        // parent
        GetVisibleWindowSize(this, &parGeo);
        int parhei = parGeo.Bottom - parGeo.top;
        // child
        GetVisibleWindowSize(formPtr, &chlGeo);
        int chlwid = chlGeo.Right - chlGeo.Left;
        int chlhei = chlGeo.Bottom - chlGeo.top;

        // calcLeftTopOfChildren(this->Top, this->Height, chlIdx, formPtr->Width, formPtr->Height, &topPos, &leftPos);
        calcLeftTopOfChildren(parGeo.top, parhei, chlIdx, chlwid, chlhei, &topPos, &leftPos);
        formPtr->Top = topPos;
        formPtr->Left = leftPos;
    }
}
void __fastcall TForm1::B_matrixClick(TObject *Sender)
{
    putChildrenInMatrix();
}

void __fastcall TForm1::GetVisibleWindowSize(TForm *formPtr, TRect *rectPtr)
{
    TRect arect_inv;
    RECT arect_nrm;

    if (formPtr == NULL || rectPtr == NULL) {
        return; // error
    }

    GetWindowRect(formPtr->Handle, &arect_nrm); // (1)
    DwmGetWindowAttribute(formPtr->Handle, DWMWA_EXTENDED_FRAME_BOUNDS, &arect_inv, sizeof(TRect)); // (2)

    // for Windows 7
    if (arect_inv.left == 0 && arect_inv.top == 0 && arect_inv.Bottom == 0 && arect_inv.right == 0) {
        // DwmGetWindowAttribute()が0を返すためGetWindowRect()の結果を使う
        rectPtr->left = arect_nrm.left;
        rectPtr->top = arect_nrm.top;
        rectPtr->right = arect_nrm.right;
        rectPtr->bottom = arect_nrm.bottom;
        return;
    }

    // for Windows 8.1, Windows 10
    //   Windows 8.1では(1)と(2)は同じ定義
    //   Windows 10ではinvisible borderにより(1)と(2)の結果が異なる
    //   invisible borderのサイズを含まない(2)の方を返す
    //
    // !!!ただしWindows 10の場合、FormShow時には正しい値を返さない!!!
    // FormShow後に実行すること
    rectPtr->left = arect_inv.left;
    rectPtr->top = arect_inv.top;
    rectPtr->right = arect_inv.right;
    rectPtr->bottom = arect_inv.bottom;
}

実行結果

Windows 7

Windows 8.1

Windows 10

FormShow後の実行

(追記 2018/05/07)

C++ Builder 10.2 Tokyo > Forms > Height > Windows 10: 実行タイミングによって異なる | Windows 7, 8.1: 実行タイミングによらず同じ > FormShow時とFormShow後
にも記載の通り、

上記の実装はFormShow時に実行すると希望の動作にはならない。

FormShowの処理後でのみ有効であるようだ。