上一篇文章介紹的是使用SetLayeredWindowAttributes

API來實現異型視窗，但是很明顯效果很差勁，在剔除顏色的過程中凹凸邊緣區域的畫素點會剔除的非常不明顯，在查詢資訊之後，得出的說法是當顯示屏在顯示影象的時候在顏色重疊的地方會產生顏色色差，而SetLayeredWindowAttributes 又是從螢幕中取出dc顏色的！

但這次我們使用UpdateLayeredWindow方法來將PNG影象直接載入到視窗上！

思路：

使用gdi載入png圖片，然後使用UpdateLayeredWindow載入到視窗上！

分層視窗的概念可以參考我的上一篇文章裡的介紹！

這裡先看一下執行效果：

API介紹：

UpdateLayeredWindow

函式原型：

BOOL WINAPI UpdateLayeredWindow(
  _In_     HWND          hwnd,
  _In_opt_ HDC           hdcDst,
  _In_opt_ POINT         *pptDst,
  _In_opt_ SIZE          *psize,
  _In_opt_ HDC           hdcSrc,
  _In_opt_ POINT         *pptSrc,
  _In_     COLORREF      crKey,
  _In_opt_ BLENDFUNCTION *pblend,
  _In_     DWORD         dwFlags
);
 

引數介紹：

示列程式碼：

#include <GdiPlus.h>

using namespace Gdiplus;
//匯入GDI+的庫

#pragma comment(lib, "Gdiplus.lib")

  void setWindow(HWND hWnd /*視窗控制代碼，必須具有WS_EX_LAYERED擴充套件風格*/) {
    //初始化gdi+

	GdiplusStartup(&gdiplusToken, &gdiplusStartupInput, NULL);

	//定義png的高與寬
	int img_h = 256;
	int img_w = 256;
	//申請記憶體dc與程式dc關聯
	HDC hDC = ::GetDC(hWnd);
	HDC hMemDC = ::CreateCompatibleDC(hDC);
	//申請一個位圖佈局
	BITMAPINFO bitmapinfo;
	bitmapinfo.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
	bitmapinfo.bmiHeader.biBitCount = 32;
	bitmapinfo.bmiHeader.biHeight = img_h;
	bitmapinfo.bmiHeader.biWidth = img_w;
	bitmapinfo.bmiHeader.biPlanes = 1;
	bitmapinfo.bmiHeader.biCompression = BI_RGB;
	bitmapinfo.bmiHeader.biXPelsPerMeter = 0;
	bitmapinfo.bmiHeader.biYPelsPerMeter = 0;
	bitmapinfo.bmiHeader.biClrUsed = 0;
	bitmapinfo.bmiHeader.biClrImportant = 0;
	bitmapinfo.bmiHeader.biSizeImage = bitmapinfo.bmiHeader.biWidth * bitmapinfo.bmiHeader.biHeight * bitmapinfo.bmiHeader.biBitCount / 8;
	//建立記憶體佈局
	HBITMAP hBitmap = CreateDIBSection(hMemDC, &bitmapinfo, 0, NULL, 0, 0);
	//選入記憶體
	HBITMAP hOldBitmap = (HBITMAP)SelectObject(hMemDC, hBitmap);
	//載入png影象
	Gdiplus::Image* pImage = Gdiplus::Image::FromFile(L"d:\\1.png");
	//讓gdi與記憶體dc關聯，將gdi裡的資料載入到記憶體位圖裡
	Graphics g(hMemDC);
	//設定記憶體點陣圖要顯示的區域，注意gdi會關聯到記憶體位圖裡
	g.DrawImage(pImage, RectF(0, 0, img_w, img_h), 0, 0, img_w, img_h, UnitPixel, NULL, NULL, NULL);
	delete pImage;	//刪除gdi
	//設定要顯示的座標
	Point DestPt(0, 0);
	Size psize(img_w, img_h);
	//點陣圖資訊
	BLENDFUNCTION blendFunc32bpp;
	blendFunc32bpp.AlphaFormat = AC_SRC_ALPHA;
	blendFunc32bpp.BlendFlags = 0;
	blendFunc32bpp.BlendOp = AC_SRC_OVER;
	blendFunc32bpp.SourceConstantAlpha = 255;
	//update更新到分層視窗上
	UpdateLayeredWindow(hWnd, hDC, NULL, (SIZE*)&psize, hMemDC, (POINT*)&DestPt, NULL, &blendFunc32bpp, ULW_ALPHA);
        ShowWindow(hWnd, SW_SHOW);

}

新增到窗口裡的完整程式碼：

#include <windows.h>



HWND hWnd;	//progman



			//訊息函式

LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)

{

	//判斷訊息ID

	switch (uMsg) {



	case WM_DESTROY:    // 視窗銷燬訊息

		PostQuitMessage(0);   //  傳送退出訊息

		return 0;

	}

	// 其他的訊息呼叫預設的訊息處理程式

	return DefWindowProc(hwnd, uMsg, wParam, lParam);



}

// 3、註冊視窗型別

BOOL RegisterWindow(LPCSTR lpcWndName, HINSTANCE hInstance)

{

	ATOM nAtom = 0;

	// 構造建立視窗引數

	WNDCLASS wndClass = { 0 };

	wndClass.style = CS_HREDRAW | CS_VREDRAW;

	wndClass.lpfnWndProc = WindowProc;      // 指向視窗過程函式

	wndClass.cbClsExtra = 0;

	wndClass.cbWndExtra = 0;

	wndClass.hInstance = hInstance;

	wndClass.hIcon = NULL;

	wndClass.hCursor = NULL;

	wndClass.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);

	wndClass.lpszMenuName = NULL;

	wndClass.lpszClassName = lpcWndName;    // 註冊的視窗名稱，並非標題，以後建立視窗根據此註冊的名稱建立

	nAtom = RegisterClass(&wndClass);

	return TRUE;

}

//建立視窗（lpClassName 一定是已經註冊過的視窗型別）

HWND CreateMyWindow(LPCTSTR lpClassName, HINSTANCE hInstance)

{

	HWND hWnd = NULL;

	// 建立視窗

	hWnd = CreateWindowEx(WS_EX_LAYERED,lpClassName, "test", WS_OVERLAPPEDWINDOW^WS_THICKFRAME, 0, 0, 1000, 800, NULL, NULL, hInstance, NULL);

	return hWnd;

}
//異型視窗開始
#include <GdiPlus.h>

using namespace Gdiplus;
//匯入GDI+的庫

#pragma comment(lib, "Gdiplus.lib")

GdiplusStartupInput gdiplusStartupInput;
ULONG_PTR gdiplusToken;
void DisplayMyWnd(HWND hWnd)

{
	//初始化gdi+

	GdiplusStartup(&gdiplusToken, &gdiplusStartupInput, NULL);

	//定義png的高與寬
	int img_h = 256;
	int img_w = 256;
	//申請記憶體dc與程式dc關聯
	HDC hDC = ::GetDC(hWnd);
	HDC hMemDC = ::CreateCompatibleDC(hDC);
	//申請一個位圖佈局
	BITMAPINFO bitmapinfo;
	bitmapinfo.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
	bitmapinfo.bmiHeader.biBitCount = 32;
	bitmapinfo.bmiHeader.biHeight = img_h;
	bitmapinfo.bmiHeader.biWidth = img_w;
	bitmapinfo.bmiHeader.biPlanes = 1;
	bitmapinfo.bmiHeader.biCompression = BI_RGB;
	bitmapinfo.bmiHeader.biXPelsPerMeter = 0;
	bitmapinfo.bmiHeader.biYPelsPerMeter = 0;
	bitmapinfo.bmiHeader.biClrUsed = 0;
	bitmapinfo.bmiHeader.biClrImportant = 0;
	bitmapinfo.bmiHeader.biSizeImage = bitmapinfo.bmiHeader.biWidth * bitmapinfo.bmiHeader.biHeight * bitmapinfo.bmiHeader.biBitCount / 8;
	//建立記憶體佈局
	HBITMAP hBitmap = CreateDIBSection(hMemDC, &bitmapinfo, 0, NULL, 0, 0);
	//選入記憶體
	HBITMAP hOldBitmap = (HBITMAP)SelectObject(hMemDC, hBitmap);
	//載入png影象
	Gdiplus::Image* pImage = Gdiplus::Image::FromFile(L"d:\\1.png");
	//讓gdi與記憶體dc關聯，將gdi裡的資料載入到記憶體位圖裡
	Graphics g(hMemDC);
	//設定記憶體點陣圖要顯示的區域，注意gdi會關聯到記憶體位圖裡
	g.DrawImage(pImage, RectF(0, 0, img_w, img_h), 0, 0, img_w, img_h, UnitPixel, NULL, NULL, NULL);
	delete pImage;	//刪除gdi
	//設定要顯示的座標
	Point DestPt(0, 0);
	Size psize(img_w, img_h);
	//點陣圖資訊
	BLENDFUNCTION blendFunc32bpp;
	blendFunc32bpp.AlphaFormat = AC_SRC_ALPHA;
	blendFunc32bpp.BlendFlags = 0;
	blendFunc32bpp.BlendOp = AC_SRC_OVER;
	blendFunc32bpp.SourceConstantAlpha = 255;
	//update更新到分層視窗上
	UpdateLayeredWindow(hWnd, hDC, NULL, (SIZE*)&psize, hMemDC, (POINT*)&DestPt, NULL, &blendFunc32bpp, ULW_ALPHA);
	//視窗中心顯示
	int scrWidth = GetSystemMetrics(SM_CXSCREEN);

	int scrHeight = GetSystemMetrics(SM_CYSCREEN);

	RECT rect;

	GetWindowRect(hWnd, &rect);

	ShowWindow(hWnd, SW_SHOW);

	//重新設定rect裡的值

	rect.left = (scrWidth - rect.right) / 2;

	rect.top = (scrHeight - rect.bottom) / 2;

	//移動視窗到指定的位置

	SetWindowPos(hWnd, HWND_TOP, rect.left, rect.top, rect.right, rect.bottom, SWP_SHOWWINDOW);

	//settxt(editHwnd,"dasdas");
	//char *str = gettxt(editHwnd);
	//MessageBox(NULL, str, 0, 0);
	UpdateWindow(hWnd);


}



void doMessage()        // 訊息迴圈處理函式

{

	MSG msg = { 0 };

	// 獲取訊息

	while (GetMessage(&msg, NULL, 0, 0)) // 當接收到WM_QIUT訊息時，GetMessage函式返回0，結束迴圈

	{
		TranslateMessage(&msg);
		DispatchMessage(&msg); // 派發訊息，到WindowPro函式處理

	}

}



// 入口函式

int WINAPI WinMain(HINSTANCE hInstance,

	HINSTANCE hPrevInstance,

	LPSTR lpCmdLine,

	int nShowCmd)

{

	LPCTSTR lpClassName = "MyWnd";  // 註冊視窗的名稱

	RegisterWindow(lpClassName, hInstance);

	hWnd = CreateMyWindow(lpClassName, hInstance);

	DisplayMyWnd(hWnd);

	doMessage();

	return 0;

}