Windows API Primer   ビットマップ画像の表示

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LoadImage

loadimage.c

#include <windows.h>

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

int     WINAPI   WinMain(HINSTANCE hInstance,
			 HINSTANCE hPrevInstance,
			 LPSTR     lpCmdLine,
			 int       nCmdShow)
{
  WNDCLASS wc;
  HWND     hwnd;
  MSG      msg;

  wc.style         = CS_HREDRAW | CS_VREDRAW;
  wc.lpfnWndProc   = WndProc;
  wc.cbClsExtra    = 0;
  wc.cbWndExtra    = 0;
  wc.hInstance     = hInstance;
  wc.hIcon         = NULL;
  wc.hCursor       = LoadCursor(NULL, IDC_ARROW);
  wc.hbrBackground = (HBRUSH)COLOR_BACKGROUND + 1;
  wc.lpszMenuName  = NULL;
  wc.lpszClassName = TEXT("LOADIMAGE");

  RegisterClass(&wc);

  hwnd             = CreateWindow(TEXT("LOADIMAGE"),
				  TEXT("Windows API Primer"),
				  WS_OVERLAPPEDWINDOW | WS_VISIBLE,
				  CW_USEDEFAULT, CW_USEDEFAULT, 300, 200,
				  NULL, NULL, hInstance, NULL);

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

  return msg.wParam;
}

LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
  HDC         hdc, hMdc;
  PAINTSTRUCT ps;
  HBITMAP     hbmp;
  switch (msg)
    {
    case WM_PAINT:
      hdc  = BeginPaint(hwnd, &ps);
      hbmp = (HBITMAP)LoadImage(NULL, "ferrari.bmp", IMAGE_BITMAP, 0, 0, LR_LOADFROMFILE);
      hMdc = CreateCompatibleDC(hdc);
      SelectObject(hMdc, hbmp);
      BitBlt      (hdc, 0, 0, 300, 200, hMdc, 0, 0, SRCCOPY);
      DeleteDC    (hMdc);
      DeleteObject(hbmp);
      EndPaint    (hwnd, &ps);
      break;
    case WM_DESTROY:
      PostQuitMessage(0);
      break;
    }
  return DefWindowProc(hwnd, msg, wParam, lParam);
}
    

実行結果

画像のサイズを取得する

表示する画像のサイズを取得して、そのサイズに合わせてウィンドウの大きさを変えても良いかもしれません。

imagesize.c

#include <windows.h>

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

int     WINAPI   WinMain(HINSTANCE hInstance,
			 HINSTANCE hPrevInstance,
			 LPSTR     lpCmdLine,
			 int       nCmdShow)
{
  WNDCLASS wc;
  HWND     hwnd;
  MSG      msg;

  wc.style         = CS_HREDRAW | CS_VREDRAW;
  wc.lpfnWndProc   = WndProc;
  wc.cbClsExtra    = 0;
  wc.cbWndExtra    = 0;
  wc.hInstance     = hInstance;
  wc.hIcon         = NULL;
  wc.hCursor       = LoadCursor(NULL, IDC_ARROW);
  wc.hbrBackground = (HBRUSH)COLOR_BACKGROUND + 1;
  wc.lpszMenuName  = NULL;
  wc.lpszClassName = TEXT("IMAGESIZE");

  RegisterClass(&wc);

  hwnd            = CreateWindow(TEXT("IMAGESIZE"),
				 TEXT("Windows API Primer"),
				 WS_OVERLAPPEDWINDOW | WS_VISIBLE,
				 CW_USEDEFAULT, CW_USEDEFAULT, 300, 200,
				 NULL, NULL, hInstance, NULL);

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

  return msg.wParam;
}

LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
  static HBITMAP     hbmp;
  static BITMAP      bmp;
  static HDC         hMdc;
         HDC         hdc;
	 RECT        wr, cr;
	 int         width, height;
	 PAINTSTRUCT ps;
  switch (msg)
    {
    case WM_CREATE:
      hbmp = (HBITMAP)LoadImage(NULL, "ferrari_l.bmp", IMAGE_BITMAP, 0, 0, LR_LOADFROMFILE);
      hdc  = GetDC(hwnd);
      hMdc = CreateCompatibleDC(hdc);
      SelectObject(hMdc, hbmp);
      GetObject   (hbmp, sizeof(BITMAP), &bmp);
      DeleteDC    (hdc);
      
      GetWindowRect(hwnd, &wr);
      GetClientRect(hwnd, &cr);
      width  = (wr.right  - wr.left) - (cr.right  - cr.left) + bmp.bmWidth;
      height = (wr.bottom - wr.top ) - (cr.bottom - cr.top ) + bmp.bmHeight;
      SetWindowPos(hwnd, NULL, 0, 0, width, height, SWP_NOMOVE);
      
      break;
    case WM_PAINT:
      hdc = BeginPaint(hwnd, &ps);
      BitBlt(hdc, 0, 0, bmp.bmWidth, bmp.bmHeight, hMdc, 0, 0, SRCCOPY);
      EndPaint        (hwnd, &ps);
      break;
    case WM_DESTROY:
      PostQuitMessage(0);
      break;
    }

  return DefWindowProc(hwnd, msg, wParam, lParam);
}
    

実行結果

画像を拡大・縮小する

ウィンドウのサイズに合わせて、画像が拡大・縮小するのも面白いかもしれません。

stretchimage.c

#include <windows.h>

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

int     WINAPI   WinMain(HINSTANCE hInstance,
			 HINSTANCE hPrevInstance,
			 LPSTR     lpCmdLine,
			 int       nCmdShow)
{
  WNDCLASS wc;
  HWND     hwnd;
  MSG      msg;

  wc.style         = CS_HREDRAW | CS_VREDRAW;
  wc.lpfnWndProc   = WndProc;
  wc.cbClsExtra    = 0;
  wc.cbWndExtra    = 0;
  wc.hInstance     = hInstance;
  wc.hIcon         = NULL;
  wc.hCursor       = LoadCursor(NULL, IDC_ARROW);
  wc.hbrBackground = (HBRUSH)COLOR_BACKGROUND + 1;
  wc.lpszMenuName  = NULL;
  wc.lpszClassName = TEXT("STRETCHIMAGE");

  RegisterClass(&wc);

  hwnd             = CreateWindow(TEXT("STRETCHIMAGE"),
				  TEXT("Windows API Primer"),
				  WS_OVERLAPPEDWINDOW | WS_VISIBLE,
				  CW_USEDEFAULT, CW_USEDEFAULT, 300, 200,
				  NULL, NULL, hInstance, NULL);

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

  return msg.wParam;
}

LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
  static HBITMAP     hbmp;
  static HDC         hMdc;
  static BITMAP      bmp;
         HDC         hdc;
	 RECT        wr, cr;
	 int         width, height;
	 PAINTSTRUCT ps;
  switch (msg)
    {
    case WM_CREATE:
      hbmp = (HBITMAP)LoadImage(NULL, "ferrari_s.bmp", IMAGE_BITMAP, 0, 0,
      LR_LOADFROMFILE);
      hdc  = GetDC(hwnd);
      hMdc = CreateCompatibleDC(hdc);
      SelectObject(hMdc, hbmp);
      GetObject   (hbmp, sizeof(BITMAP), &bmp);
      DeleteDC    (hdc);

      GetWindowRect(hwnd, &wr);
      GetClientRect(hwnd, &cr);
      width  = (wr.right  - wr.left) - cr.right  + bmp.bmWidth;
      height = (wr.bottom - wr.top ) - cr.bottom + bmp.bmHeight;
      SetWindowPos(hwnd, NULL, 0, 0, width, height, SWP_NOMOVE);
      break;
    case WM_PAINT:
      GetClientRect   (hwnd, &cr);
      hdc = BeginPaint(hwnd, &ps);
      StretchBlt(hdc, 0, 0, cr.right, cr.bottom, hMdc, 0, 0,
		 bmp.bmWidth, bmp.bmHeight, SRCCOPY);
      EndPaint        (hwnd, &ps);
      break;
    case WM_DESTROY:
      PostQuitMessage(0);
      break;
    }

  return DefWindowProc(hwnd, msg, wParam, lParam);
}
    

実行結果

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