/*
 *		smooth.cpp
 */


/* *=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*
 
     Comment: ビットマップをスムーズにドラッグ

     Author: 火星の砂塊
     E-Mail: unq@capella.freemail.ne.jp
     HP    : http://hp.vector.co.jp/authors/VA023539/
 
   *=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=* */


#include <windows.h>
#include <windowsx.h>
#include "diblib\diblib.h"

#include "resource.h"


const char szClassName[]="smooth";

HMODULE   hAppModule= NULL;
POINT     dibpos    = {10,10};
POINT     offset;
diblib::CDIBitmap dib;

LRESULT CALLBACK WndProc(HWND,UINT,WPARAM,LPARAM);

__inline void GetDIBRect(LPRECT in_pRect)
{
	SIZE s;
	dib.GetBitmapSize(&s);
	::SetRect(in_pRect,dibpos.x,dibpos.y,
		dibpos.x+s.cx,dibpos.y+s.cy);
}

int APIENTRY WinMain(HINSTANCE hInstance,
                     HINSTANCE hPrevInstance,
                     LPSTR     lpCmdLine,
                     int       nCmdShow )
{
	hAppModule=(HMODULE)hInstance;

	WNDCLASSEX wc;
	wc.cbClsExtra   = 0;
	wc.cbSize       = sizeof(WNDCLASSEX);
	wc.cbWndExtra   = 0;
	wc.hbrBackground= (HBRUSH)(COLOR_WINDOW+1);
	wc.hCursor      = ::LoadCursor(NULL,MAKEINTRESOURCE(IDC_ARROW));
	wc.hIcon        = ::LoadIcon(hAppModule,MAKEINTRESOURCE(IDI_ICON1));
	wc.hIconSm      = NULL;
	wc.hInstance    = hInstance;
	wc.lpfnWndProc  = (WNDPROC)WndProc;
	wc.lpszClassName= szClassName;
	wc.lpszMenuName = NULL;
	wc.style        = CS_HREDRAW | CS_VREDRAW;
	::RegisterClassEx(&wc);

	HWND hWnd=::CreateWindow(szClassName,szClassName,
		WS_OVERLAPPEDWINDOW,CW_USEDEFAULT,CW_USEDEFAULT,
		200,200,NULL,NULL,hInstance,0);
	if ( hWnd==NULL )
		return 0;

	::ShowWindow(hWnd,nCmdShow);

	MSG msg;
	while ( ::GetMessage(&msg,NULL,0,0) )
	{
		::TranslateMessage(&msg);
		::DispatchMessage(&msg);
	}

	return 0;
}

LRESULT CALLBACK WndProc(HWND in_hWnd,
						 UINT in_Message,
						 WPARAM in_wParam,
						 LPARAM in_lParam)
{
	HDC   hDC=NULL;
	POINT pt;
	RECT  rct;

	switch ( in_Message )
	{
	case WM_CREATE:
		hDC=::CreateCompatibleDC(NULL);
		dib.Create(hDC,IDB_BITMAP1,hAppModule);
		::DeleteDC(hDC);
		break;
	case WM_PAINT:
		PAINTSTRUCT ps;
		hDC=::BeginPaint(in_hWnd,&ps);

		dib.BitBlt(hDC,dibpos.x,dibpos.y,SRCCOPY);

		::EndPaint(in_hWnd,&ps);
		break;
	case WM_LBUTTONDOWN:
		pt.x= GET_X_LPARAM(in_lParam);
		pt.y= GET_Y_LPARAM(in_lParam);

		GetDIBRect(&rct);

		if ( ::PtInRect(&rct,pt) )
		{
			::SetCapture(in_hWnd);
			offset.x= pt.x-dibpos.x;
			offset.y= pt.y-dibpos.y;
		}
		break;
	case WM_MOUSEMOVE:
		if ( ::GetCapture()!=in_hWnd )
			return 0;

		HRGN hRgn1,hRgn2,hRgn3;

		// 移動前の位置を取得
		GetDIBRect(&rct);
		hRgn1= ::CreateRectRgnIndirect(&rct);

		// 移動後の新しいビットマップ位置を代入
		pt.x= GET_X_LPARAM(in_lParam);
		pt.y= GET_Y_LPARAM(in_lParam);
		dibpos.x= pt.x-offset.x;
		dibpos.y= pt.y-offset.y;

		// 移動後の位置を取得
		GetDIBRect(&rct);
		hRgn2= ::CreateRectRgnIndirect(&rct);

		// 関数に渡す前に初期化が必要
		hRgn3= ::CreateRectRgnIndirect(&rct);

		// リージョンの引き算
		::CombineRgn(hRgn3,hRgn1,hRgn2,RGN_DIFF);

		hDC=::GetDC(in_hWnd);
		dib.BitBlt(hDC,dibpos.x,dibpos.y,SRCCOPY);
		::ReleaseDC(in_hWnd,hDC);

		::InvalidateRgn(in_hWnd,hRgn3,TRUE);
		::UpdateWindow(in_hWnd);

		::DeleteObject(hRgn1);
		::DeleteObject(hRgn2);
		::DeleteObject(hRgn3);

		break;
	case WM_LBUTTONUP:
		::ReleaseCapture();
		break;
	case WM_DESTROY:
		::PostQuitMessage(0);
		break;
	default:
		return ::DefWindowProc(in_hWnd,
			in_Message,in_wParam,in_lParam);
	}
	return 0;
}