Windows程序设计-输出文字

WM_PAINT消息

窗口消息处理程序会接收到一个WM_PAINT消息的事件：

在使用者移动窗口或显示窗口时，窗口中先前被隐藏的区域重新可见。

使用者改变窗口的大小（如果窗口类别样式有着CS_HREDRAW和CS_VREDRAW位旗标的设定）。

程序使用ScrollWindow或ScrollDC函数滚动显示区域的一部分。

程序使用InvalidateRect或InvalidateRgn函数刻意产生WM_PAINT消息。

Windows可能发送WM_PAINT消息的事件：

Windows擦除覆盖了部分窗口的对话框或消息框。

菜单下拉出来，然后被释放。

显示工具提示消息。

Windows总是保存它所覆盖的显示区域，然后恢复它的事件：

鼠标光标穿越显示区域。

图标拖过显示区域。

有效矩形和无效矩形

需要重新渲染的区域就是无效矩阵。渲染之后，要设置为有效矩阵。

可以通过调用Windows函数InvalidateRect使显示区域中的矩形失效。

取得设备内容句柄

方法一

PAINTSTRUCT ps ;
HDC hdc ;

caseWM_PAINT:
hdc = BeginPaint (hwnd, &ps) ;
// 使用GDI函数
EndPaint (hwnd, &ps) ;
return 0 ;

// 绘图结构
typedef struct tagPAINTSTRUCT {
HDC         hdc;
BOOL        fErase; // False表示Windows已经擦除了无效矩形的背景
// RECT结构定义了一个矩形，其四个字段为left、top、right和bottom。 是无效矩形，还是一个剪取矩形
RECT        rcPaint;
BOOL        fRestore;
BOOL        fIncUpdate;
BYTE        rgbReserved[32];
} PAINTSTRUCT, *PPAINTSTRUCT, *NPPAINTSTRUCT, *LPPAINTSTRUCT;

方法二

ReleaseDC：
hdc = GetDC (hwnd) ;
// 使用GDI函数

ReleaseDC (hwnd, hdc) ;

与BeginPaint和EndPaint一样，GetDC和ReleaseDC函数必须成对地使用。

ValidateRect (hwnd, NULL) ; //使整个显示区域有效

TextOut：细节

TextOut (
hdc,  // 设备内容句柄 设备内容的属性控制了被显示的字符串的特征。
x,  // 显示区域内字符串的开始位置，x是水平位置，y是垂直位置
y,
psText,  // 指向字符串的指针
iLength  // 字符串中字符的个数
) ;

字符大小

TEXTMETRIC tm;  // GetTextMetrics传回设备内容中目前选取的字体信息
hdc = GetDC (hwnd) ;
GetTextMetrics (hdc, &tm) ;  // 可以查看文字尺寸结构中的值
ReleaseDC (hwnd, hdc) ;

滚动条信息函数

SetScrollInfo和GetScrollInfo函数的语法是

SCROLLINFO si ;
SetScrollInfo (hwnd, iBar, &si, bRedraw) ;
GetScrollInfo (hwnd, iBar, &si) ;

综合使用

sysmets.h

#define NUMLINES ((int) (sizeof sysmetrics / sizeof sysmetrics [0]))
struct
{
int iIndex;
TCHAR * szLabel;
TCHAR * szDesc;
}
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")
};

main.cpp

#include <windows.h>
#include "sysmets.h"
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName[] = TEXT("SysMets3");
HWND hwnd;
MSG msg;
WNDCLASS wndclass;
wndclass.style = CS_HREDRAW | CS_VREDRAW;
wndclass.lpfnWndProc = WndProc;
wndclass.cbClsExtra = 0;
wndclass.cbWndExtra = 0;
wndclass.hInstance = hInstance;
wndclass.hIcon = LoadIcon(NULL, IDI_APPLICATION);
wndclass.hCursor = LoadCursor(NULL, IDC_ARROW);
wndclass.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
wndclass.lpszMenuName = NULL;
wndclass.lpszClassName = szAppName;
if (!RegisterClass(&wndclass))
{
MessageBox(NULL, TEXT("Program requires Windows NT!"),
szAppName, MB_ICONERROR);
return 0;
}
hwnd = CreateWindow(szAppName, TEXT("Get System Metrics No. 3"),
WS_OVERLAPPEDWINDOW | WS_VSCROLL |
WS_HSCROLL,
CW_USEDEFAULT, CW_USEDEFAULT,
CW_USEDEFAULT, CW_USEDEFAULT,
NULL, NULL, hInstance, NULL);
ShowWindow(hwnd, iCmdShow);
UpdateWindow(hwnd);
while (GetMessage(&msg, NULL, 0, 0))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return msg.wParam;
}
LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam,
LPARAM lParam)
{
static int cxChar, cxCaps, cyChar, cxClient, cyClient, iMaxWidth;
HDC hdc;
int i, x, y, iVertPos, iHorzPos, iPaintBeg, iPaintEnd;
PAINTSTRUCT ps;
SCROLLINFO si;
TCHAR szBuffer[10];
TEXTMETRIC tm;
switch (message)
{
case WM_CREATE:
hdc = GetDC(hwnd);
GetTextMetrics(hdc, &tm);
cxChar = tm.tmAveCharWidth;
cxCaps = (tm.tmPitchAndFamily & 1 ? 3 : 2) * cxChar / 2;
cyChar = tm.tmHeight + tm.tmExternalLeading;
ReleaseDC(hwnd, hdc);
// Save the width of the three columns
iMaxWidth = 40 * cxChar + 22 * cxCaps;
return 0;
case WM_SIZE:
cxClient = LOWORD(lParam);
cyClient = HIWORD(lParam);
// Set vertical scroll bar range and page size
si.cbSize = sizeof(si);
si.fMask = SIF_RANGE | SIF_PAGE;
si.nMin = 0;
si.nMax = NUMLINES - 1;
si.nPage = cyClient / cyChar;
SetScrollInfo(hwnd, SB_VERT, &si, TRUE);
// Set horizontal scroll bar range and page size
si.cbSize = sizeof(si);
si.fMask = SIF_RANGE | SIF_PAGE;
si.nMin = 0;
si.nMax = 2 + iMaxWidth / cxChar;
si.nPage = cxClient / cxChar;
SetScrollInfo(hwnd, SB_HORZ, &si, TRUE);
return 0;
case WM_VSCROLL:
// Get all the vertical scroll bar information
si.cbSize = sizeof(si);
si.fMask = SIF_ALL;
GetScrollInfo(hwnd, SB_VERT, &si);
// Save the position for comparison later on
iVertPos = si.nPos;
switch (LOWORD(wParam))
{
case SB_TOP:
si.nPos = si.nMin;
break;
case SB_BOTTOM:
si.nPos = si.nMax;
break;
case SB_LINEUP:
si.nPos -= 1;
break;
case SB_LINEDOWN:
si.nPos += 1;
break;
case SB_PAGEUP:
si.nPos -= si.nPage;
break;
case SB_PAGEDOWN:
si.nPos += si.nPage;
break;
case SB_THUMBTRACK:
si.nPos = si.nTrackPos;
break;
default:
break;
}
// Set the position and then retrieve it. Due to adjustments
// by Windows it may not be the same as the value set.
si.fMask = SIF_POS;
SetScrollInfo(hwnd, SB_VERT, &si, TRUE);
GetScrollInfo(hwnd, SB_VERT, &si);
// If the position has changed, scroll the window and update it
if (si.nPos != iVertPos)
{
ScrollWindow(hwnd, 0, cyChar * (iVertPos - si.nPos),
NULL, NULL);
UpdateWindow(hwnd);
}
return 0;
case WM_HSCROLL:
// Get all the vertical scroll bar information
si.cbSize = sizeof(si);
si.fMask = SIF_ALL;
// Save the position for comparison later on
GetScrollInfo(hwnd, SB_HORZ, &si);
iHorzPos = si.nPos;
switch (LOWORD(wParam))
{
case SB_LINELEFT:
si.nPos -= 1;
break;
case SB_LINERIGHT:
si.nPos += 1;
break;
case SB_PAGELEFT:
si.nPos -= si.nPage;
break;
case SB_PAGERIGHT:
si.nPos += si.nPage;
break;
case SB_THUMBPOSITION:
si.nPos = si.nTrackPos;
break;
default:
break;
}
// Set the position and then retrieve it. Due to adjustments
// by Windows it may not be the same as the value set.
si.fMask = SIF_POS;
SetScrollInfo(hwnd, SB_HORZ, &si, TRUE);
GetScrollInfo(hwnd, SB_HORZ, &si);
// If the position has changed, scroll the window
if (si.nPos != iHorzPos)
{
ScrollWindow(hwnd, cxChar * (iHorzPos - si.nPos), 0,
NULL, NULL);
}
return 0;
case WM_PAINT:
hdc = BeginPaint(hwnd, &ps);
// Get vertical scroll bar position
si.cbSize = sizeof(si);
si.fMask = SIF_POS;
GetScrollInfo(hwnd, SB_VERT, &si);
iVertPos = si.nPos;
// Get horizontal scroll bar position
GetScrollInfo(hwnd, SB_HORZ, &si);
iHorzPos = si.nPos;
// Find painting limits
iPaintBeg = max(0, iVertPos + ps.rcPaint.top / cyChar);
iPaintEnd = min(NUMLINES - 1,
iVertPos + ps.rcPaint.bottom / cyChar);
for (i = iPaintBeg; i <= iPaintEnd; i++)
{
x = cxChar * (1 - iHorzPos);
y = cyChar * (i - iVertPos);
TextOut(hdc, x, y,
sysmetrics[i].szLabel,
lstrlen(sysmetrics[i].szLabel));
TextOut(hdc, x + 22 * cxCaps, y,
sysmetrics[i].szDesc,
lstrlen(sysmetrics[i].szDesc));
SetTextAlign(hdc, TA_RIGHT | TA_TOP);
TextOut(hdc, x + 22 * cxCaps + 40 * cxChar, y, szBuffer,
wsprintf(szBuffer, TEXT("%5d"),
GetSystemMetrics(sysmetrics[i].iIndex)));
SetTextAlign(hdc, TA_LEFT | TA_TOP);
}
EndPaint(hwnd, &ps);
return 0;
case WM_DESTROY:
PostQuitMessage(0);
return 0;
}
return DefWindowProc(hwnd, message, wParam, lParam);
}