获取windows 桌面网格大小 API

改变桌面图标位置，需要准确计算网格位置。影响网格位置的因数很多，比如注册表的HKEY_CURRENT_USER\ControlPanel\Desktop\WindowMetrics目录下的，IconSpacing，IconVerticalSpacing。还有图标本身大小(大中小图标),title行数，title字体，网格间距(默认8px)等等。而且，目前还没有找到这些因数与网格位置之间的计算公式(惭愧)。后来，经同事协助，找到了一个系统API可以直接获取网格长宽(可以计算网格位置),真是太高兴了。这里分享出来，提供给有需要的童鞋。

// 查找桌面文件视图
void FindDesktopFolderView(REFIID riid, void **ppv)

{
	CComPtr<IShellWindows> spShellWindows;

	spShellWindows.CoCreateInstance(CLSID_ShellWindows);

	CComVariant vtLoc(CSIDL_DESKTOP);

	CComVariant vtEmpty;

	long lhwnd;

	CComPtr<IDispatch> spdisp;

	spShellWindows->FindWindowSW(

		&vtLoc, &vtEmpty,

		SWC_DESKTOP, &lhwnd, SWFO_NEEDDISPATCH, &spdisp);


	CComPtr<IShellBrowser> spBrowser;
	CComQIPtr<IServiceProvider>(spdisp)->

		QueryService(SID_STopLevelBrowser,

		IID_PPV_ARGS(&spBrowser));


	CComPtr<IShellView> spView;
	spBrowser->QueryActiveShellView(&spView);

	spView->QueryInterface(riid, ppv);

}

class CCoInitialize {
public:
	CCoInitialize() : m_hr(CoInitialize(NULL)) { }
	~CCoInitialize() { if (SUCCEEDED(m_hr)) CoUninitialize(); }
	operator HRESULT() const { return m_hr; }
	HRESULT m_hr;
};

// 获取系统桌面图标信息
/* 

返回值格式如下:

工作区域X轴(水平),工作区域Y轴(垂直),图标水平间距,图标垂直间距,自动排序标志,显示模式

*/
const char* GetSystemIconInfo(int bShow)
{
	HRESULT m_hr = CoInitialize(NULL);
	if (m_hr != S_OK){
		return "";
	}
	
	CComPtr<IFolderView> spView;

	FindDesktopFolderView(IID_PPV_ARGS(&spView));
	if (NULL == spView)
	{
		return "";
	}

	int index = 1;
	CComHeapPtr<ITEMID_CHILD> spidl;

	POINT Spacing_PT;
	POINT DefaultSpacing_PT;
	spView->GetSpacing(&Spacing_PT);
	spView->GetDefaultSpacing(&DefaultSpacing_PT);

	bool bAutoArrange = spView->GetAutoArrange() == S_OK;

	// 显示模式
	UINT uViewMode = 0;
	spView->GetCurrentViewMode(&uViewMode);

	// 桌面工作区域
	int workAreaX = GetSystemMetrics(SM_CXFULLSCREEN); //获取最大化窗体的显示区域宽度
	int workAreaY = GetSystemMetrics(SM_CYFULLSCREEN); //获取最大化窗体的显示区域高度

	char* temBuff = new char[MAX_PATH];
	memset(temBuff, '\0', sizeof(char)*MAX_PATH);
	sprintf(temBuff, "workareaX=%d,workareaY=%d,spaceX=%d,spaceY=%d,autoArrange=%d,viewMode=%d", workAreaX, workAreaY, Spacing_PT.x, Spacing_PT.y, int(bAutoArrange), uViewMode);
	//CoUninitialize();
	return temBuff;
}