滾動條的實現(2)

• 對比“滾動條的實現(1)"：SetScrollINfo(...)和GetScrollInfo(...)多了兩項新特性：1.滾動條滑塊大小隨界面改變；2.對比滑塊位置HIWORD(wParam)從16位擴展到nPos的32位。
• 函式解析：
• 程式代碼 參考《windows程式設計 第五版》
• Metrics.h

#ifndef _METRICS_H__
#define _METRICS_H__

#include <windows.h>

#define NUMLINES ((int) (sizeof sysmetrics / sizeof sysmetrics [0])) 

typedef struct
{
	int Index;
	TCHAR * szLabel;
	TCHAR * szDesc;
}ST_METRICS, *PST_METRICS;

ST_METRICS sysmetrics[] =
{
	SM_CXSCREEN, TEXT("SM_CXSCREEN"), TEXT("Screen width in pixels"),
	SM_CYSCREEN, TEXT("SM_CYSCREEN"), TEXT("Screen height in pixels"),
	SM_CXVSCROLL, TEXT("SM_CXVSCROLL"), TEXT("Vertical scroll width"),
	SM_CYHSCROLL, TEXT("SM_CYHSCROLL"), TEXT("Horizontal scroll height"),
	SM_CYCAPTION, TEXT("SM_CYCAPTION"), TEXT("Caption bar height"),
	SM_CXBORDER, TEXT("SM_CXBORDER"), TEXT("Window border width"),
	SM_CYBORDER, TEXT("SM_CYBORDER"), TEXT("Window border height"),
	SM_CXFIXEDFRAME, TEXT("SM_CXFIXEDFRAME"), TEXT("Dialog window frame width"),
	SM_CYFIXEDFRAME, TEXT("SM_CYFIXEDFRAME"), TEXT("Dialog window frame height"),
	SM_CYVTHUMB, TEXT("SM_CYVTHUMB"), TEXT("Vertical scroll thumb height"),
	SM_CXHTHUMB, TEXT("SM_CXHTHUMB"), TEXT("Horizontal scroll thumb width"),
	SM_CXICON, TEXT("SM_CXICON"), TEXT("Icon width"),
	SM_CYICON, TEXT("SM_CYICON"), TEXT("Icon height"),
	SM_CXCURSOR, TEXT("SM_CXCURSOR"), TEXT("Cursor width"),
	SM_CYCURSOR, TEXT("SM_CYCURSOR"), TEXT("Cursor height"),
	SM_CYMENU, TEXT("SM_CYMENU"), TEXT("Menu bar height"),
	SM_CXFULLSCREEN, TEXT("SM_CXFULLSCREEN"), TEXT("Full screen client area width"),
	SM_CYFULLSCREEN, TEXT("SM_CYFULLSCREEN"), TEXT("Full screen client area height"),
	SM_CYKANJIWINDOW, TEXT("SM_CYKANJIWINDOW"), TEXT("Kanji window height"),
	SM_MOUSEPRESENT, TEXT("SM_MOUSEPRESENT"), TEXT("Mouse present flag"),
	SM_CYVSCROLL, TEXT("SM_CYVSCROLL"), TEXT("Vertical scroll arrow height"),
	SM_CXHSCROLL, TEXT("SM_CXHSCROLL"), TEXT("Horizontal scroll arrow width"), 
	SM_DEBUG, TEXT("SM_DEBUG"), TEXT("Debug version flag"),
	SM_SWAPBUTTON, TEXT("SM_SWAPBUTTON"), TEXT("Mouse buttons swapped flag"),
	SM_CXMIN, TEXT("SM_CXMIN"), TEXT("Minimum window width"),
	SM_CYMIN, TEXT("SM_CYMIN"), TEXT("Minimum window height"),
	SM_CXSIZE, TEXT("SM_CXSIZE"), TEXT("Min/Max/Close button width"),
	SM_CYSIZE, TEXT("SM_CYSIZE"), TEXT("Min/Max/Close button height"),
	SM_CXSIZEFRAME, TEXT("SM_CXSIZEFRAME"), TEXT("Window sizing frame width"),
	SM_CYSIZEFRAME, TEXT("SM_CYSIZEFRAME"), TEXT("Window sizing frame height"),
	SM_CXMINTRACK, TEXT("SM_CXMINTRACK"), TEXT("Minimum window tracking width"),
	SM_CYMINTRACK, TEXT("SM_CYMINTRACK"), TEXT("Minimum window tracking height"),
	SM_CXDOUBLECLK, TEXT("SM_CXDOUBLECLK"), TEXT("Double click x tolerance"),
	SM_CYDOUBLECLK, TEXT("SM_CYDOUBLECLK"), TEXT("Double click y tolerance"),
	SM_CXICONSPACING, TEXT("SM_CXICONSPACING"), TEXT("Horizontal icon spacing"),
	SM_CYICONSPACING, TEXT("SM_CYICONSPACING"), TEXT("Vertical icon spacing"),
	SM_MENUDROPALIGNMENT, TEXT("SM_MENUDROPALIGNMENT"), TEXT("Left or right menu drop"),
	SM_PENWINDOWS, TEXT("SM_PENWINDOWS"), TEXT("Pen extensions installed"),
	SM_DBCSENABLED, TEXT("SM_DBCSENABLED"), TEXT("Double-Byte Char Set enabled"),
	SM_CMOUSEBUTTONS, TEXT("SM_CMOUSEBUTTONS"), TEXT("Number of mouse buttons"), 
	SM_SECURE, TEXT("SM_SECURE"), TEXT("Security present flag"),
	SM_CXEDGE, TEXT("SM_CXEDGE"), TEXT("3-D border width"),
	SM_CYEDGE, TEXT("SM_CYEDGE"), TEXT("3-D border height"),
	SM_CXMINSPACING, TEXT("SM_CXMINSPACING"), TEXT("Minimized window spacing width"),
	SM_CYMINSPACING, TEXT("SM_CYMINSPACING"), TEXT("Minimized window spacing height"),
	SM_CXSMICON, TEXT("SM_CXSMICON"), TEXT("Small icon width"),
	SM_CYSMICON, TEXT("SM_CYSMICON"), TEXT("Small icon height"),
	SM_CYSMCAPTION, TEXT("SM_CYSMCAPTION"), TEXT("Small caption height"),
	SM_CXSMSIZE, TEXT("SM_CXSMSIZE"), TEXT("Small caption button width"),
	SM_CYSMSIZE, TEXT("SM_CYSMSIZE"), TEXT("Small caption button height"),
	SM_CXMENUSIZE, TEXT("SM_CXMENUSIZE"), TEXT("Menu bar button width"),
	SM_CYMENUSIZE, TEXT("SM_CYMENUSIZE"), TEXT("Menu bar button height"),
	SM_ARRANGE, TEXT("SM_ARRANGE"), TEXT("How minimized windows arranged"),
	SM_CXMINIMIZED, TEXT("SM_CXMINIMIZED"), TEXT("Minimized window width"),
	SM_CYMINIMIZED, TEXT("SM_CYMINIMIZED"), TEXT("Minimized window height"),
	SM_CXMAXTRACK, TEXT("SM_CXMAXTRACK"), TEXT("Maximum draggable width"),
	SM_CYMAXTRACK, TEXT("SM_CYMAXTRACK"), TEXT("Maximum draggable height"),
	SM_CXMAXIMIZED, TEXT("SM_CXMAXIMIZED"), TEXT("Width of maximized window"),
	SM_CYMAXIMIZED, TEXT("SM_CYMAXIMIZED"), TEXT("Height of maximized window"),
	SM_NETWORK, TEXT("SM_NETWORK"), TEXT("Network present flag"),
	SM_CLEANBOOT, TEXT("SM_CLEANBOOT"), TEXT("How system was booted"),
	SM_CXDRAG, TEXT("SM_CXDRAG"), TEXT("Avoid drag x tolerance"),
	SM_CYDRAG, TEXT("SM_CYDRAG"), TEXT("Avoid drag y tolerance"),
	SM_SHOWSOUNDS, TEXT("SM_SHOWSOUNDS"), TEXT("Present sounds visually"),
	SM_CXMENUCHECK, TEXT("SM_CXMENUCHECK"), TEXT("Menu check-mark width"),
	SM_CYMENUCHECK, TEXT("SM_CYMENUCHECK"), TEXT("Menu check-mark height"),
	SM_SLOWMACHINE, TEXT("SM_SLOWMACHINE"), TEXT("Slow processor flag"),
	SM_MIDEASTENABLED, TEXT("SM_MIDEASTENABLED"), TEXT("Hebrew and Arabic enabled flag"),
	SM_MOUSEWHEELPRESENT, TEXT("SM_MOUSEWHEELPRESENT"), TEXT("Mouse wheel present flag"),
	SM_XVIRTUALSCREEN, TEXT("SM_XVIRTUALSCREEN"), TEXT("Virtual screen x origin"),
	SM_YVIRTUALSCREEN, TEXT("SM_YVIRTUALSCREEN"), TEXT("Virtual screen y origin"),
	SM_CXVIRTUALSCREEN, TEXT("SM_CXVIRTUALSCREEN"), TEXT("Virtual screen width"),
	SM_CYVIRTUALSCREEN, TEXT("SM_CYVIRTUALSCREEN"), TEXT("Virtual screen height"),
	SM_CMONITORS, TEXT("SM_CMONITORS"), TEXT("Number of monitors"),
	SM_SAMEDISPLAYFORMAT, TEXT("SM_SAMEDISPLAYFORMAT"), TEXT("Same color format flag")
};

#endif /*_METICS_H__*/

• ScrollTest.cpp

• #include "Metrics.h"
  
  LRESULT CALLBACK pfnWndProc(HWND, UINT, WPARAM, LPARAM);
  
  int WINAPI WinMain(HINSTANCE hInstance,		
  	HINSTANCE hPrevInstance,	
  	PSTR szCmdLine,			
  	int iCmdShow)		
  {
  	MSG stMsg;
  	memset(&stMsg, 0, sizeof (stMsg));
  	HWND stHwnd;
  	memset(&stHwnd, 0, sizeof (stHwnd));
  	WNDCLASS stWndClass;
  	memset(&stWndClass, 0, sizeof (stWndClass));
  	const TCHAR szAppName[] = TEXT("SCROLL TEST");
  
  	stWndClass.style = CS_HREDRAW | CS_VREDRAW;	
  	stWndClass.lpfnWndProc = pfnWndProc;
  	stWndClass.cbClsExtra = 0;
  	stWndClass.cbWndExtra = 0;
  
  	stWndClass.hInstance = hInstance;
  	stWndClass.hIcon = LoadIcon(NULL, IDI_APPLICATION);
  	stWndClass.hCursor = LoadCursor(NULL, IDC_ARROW);
  	stWndClass.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
  	stWndClass.lpszMenuName = NULL;
  	stWndClass.lpszClassName = szAppName;
  
  	if (!RegisterClass(&stWndClass))
  	{
  		MessageBox(NULL, TEXT("Regiester failure"), szAppName, MB_ICONERROR);
  		return 0;
  	}
  
  	stHwnd = CreateWindow(szAppName,			
  						  TEXT("SCROLL TEST"),		
  						  WS_OVERLAPPEDWINDOW | WS_VSCROLL /*| WS_HSCROLL*/,  
  						  CW_USEDEFAULT,		
  						  CW_USEDEFAULT,		
  						  CW_USEDEFAULT,		
  						  CW_USEDEFAULT,		
  						  NULL,					
  						  NULL,					
  						  hInstance,			
  						  NULL);			
  
  	ShowWindow(stHwnd, iCmdShow);				
  	UpdateWindow(stHwnd);						
  
  	while (GetMessage(&stMsg, NULL, 0, 0))
  	{
  		TranslateMessage(&stMsg);
  		DispatchMessage(&stMsg);
  	}
  
  	return stMsg.wParam;
  }
  
  LRESULT CALLBACK pfnWndProc(HWND stHwnd, UINT uiMsg, WPARAM wParam, LPARAM lParam)
  {
  	HDC stHdc;
  	memset(&stHdc, 0, sizeof (stHdc));
  	PAINTSTRUCT stPs;
  	memset(&stPs, 0, sizeof (stPs));
  	RECT stRect;
  	memset(&stRect, 0, sizeof (stRect));
  	TEXTMETRIC stTextMetric;
  	memset(&stTextMetric, 0, sizeof (stTextMetric));
  	SCROLLINFO stScrollInfo;
  	memset(&stScrollInfo, 0, sizeof (stScrollInfo));
  
  	int iYpos = 0;
  	int iSavePos = 0;
  
  	static int s_iCharWidth = 0;
  	static int s_iCharHeight = 0;
  	static int s_iClientHeight = 0;
  	static int s_iVScrollPos = 0;
  	static int s_iCapitalCharWidth = 0;
  
  	switch (uiMsg)
  	{
  	case WM_CREATE:
  		stHdc = GetDC(stHwnd);//GDI函式入口
  
  		GetTextMetrics(stHdc, &stTextMetric);//獲取系統文字字元結構
  		s_iCharWidth = stTextMetric.tmAveCharWidth;//字元寬度
  		s_iCapitalCharWidth = (stTextMetric.tmPitchAndFamily & 1 ? 3 : 2) * s_iCharWidth / 2;//大字字元寬度
  		s_iCharHeight = stTextMetric.tmHeight + stTextMetric.tmExternalLeading;//字元高度
  
  		ReleaseDC(stHwnd, stHdc);
  
  		return 0;
  
  	case WM_SIZE:
  		s_iClientHeight = HIWORD(lParam);
  
  		stScrollInfo.cbSize = sizeof (stScrollInfo);
  		stScrollInfo.fMask = SIF_RANGE | SIF_PAGE;
  		stScrollInfo.nMin = 0;
  		stScrollInfo.nMax = NUMLINES - 1;
  		stScrollInfo.nPage = s_iClientHeight / s_iCharHeight;
  
  		SetScrollInfo(stHwnd, SB_VERT, &stScrollInfo, TRUE);
  
  		return 0;
  
  	case WM_VSCROLL:
  		stScrollInfo.cbSize = sizeof (stScrollInfo);
  		stScrollInfo.fMask = SIF_ALL;
  		GetScrollInfo(stHwnd, SB_VERT, &stScrollInfo);//獲取
  		iSavePos = stScrollInfo.nPos;
  
  		switch (LOWORD(wParam))
  		{
  		case SB_TOP:
  			stScrollInfo.nPos = stScrollInfo.nMin;
  			break;
  		case SB_BOTTOM:
  			stScrollInfo.nPos = stScrollInfo.nMax;
  			break;
  		case SB_LINEUP:
  			stScrollInfo.nPos -= 1;
  			break;
  		case SB_LINEDOWN:
  			stScrollInfo.nPos += 1;
  			break;
  		case SB_PAGEUP:
  			stScrollInfo.nPos -= stScrollInfo.nPage;
  			break;
  		case SB_PAGEDOWN:
  			stScrollInfo.nPos += stScrollInfo.nPage;
  			break;
  		case SB_THUMBTRACK:
  			stScrollInfo.nPos = stScrollInfo.nTrackPos;
  			break;
  		default:
  			break;
  		}
  		
  		//檢查是否需要更新滑塊位置
  		if ((iSavePos != stScrollInfo.nPos) && (stScrollInfo.nPos < NUMLINES))
  		{
  			stScrollInfo.fMask = SIF_POS;
  			SetScrollInfo(stHwnd, SB_VERT, &stScrollInfo, TRUE);
  			InvalidateRect(stHwnd, NULL, TRUE);
  			UpdateWindow(stHwnd);
  		}
  
  		return 0;
  
  	case WM_PAINT:
  		stHdc = BeginPaint(stHwnd, &stPs);
  
  		stScrollInfo.cbSize = sizeof (stScrollInfo);
  		stScrollInfo.fMask = SIF_POS;
  		GetScrollInfo(stHwnd, SB_VERT, &stScrollInfo);
  		iSavePos = stScrollInfo.nPos;
  
  		for (int iNum = 0; iNum < NUMLINES; iNum++)
  		{
  			iYpos = s_iCharHeight * (iNum - iSavePos);
  			TextOut(stHdc, 0, iYpos, sysmetrics[iNum].szLabel, lstrlen(sysmetrics[iNum].szLabel));
  			TextOut(stHdc, 40 * s_iCapitalCharWidth, iYpos, sysmetrics[iNum].szDesc, lstrlen(sysmetrics[iNum].szDesc));
  		}
  
  		EndPaint(stHwnd, &stPs);
  		return 0;
  
  	case WM_DESTROY:
  		PostQuitMessage(0);
  		return 0;
  
  	default:
  		return DefWindowProc(stHwnd, uiMsg, wParam, lParam);
  	}
  }