如何从使用 GetTextExtentPoint32() 测量的文本大小中删除此边距？

问题描述

我使用 GetTextExtentPoint32() 来测量文本大小并计算组合框的宽度和高度。然而，它似乎增加了与文本量成正比的边距，我想摆脱它。似乎字符串越大，我得到的边距就越大。我如何不添加此边距？小一点是可以接受的，但请看第二张图片，右边的大空间。

对于小字符串，我觉得这个边距是可以接受的：

但是，对于大的，我会在右侧看到这个很大的空白区域，我想摆脱它：

我正在像这样测量文本大小：

              int len = wcslen(s);
              HDC dc = GetDC(hwndCombo);
              SIZE sz;
              assert(GetTextExtentPoint32(dc,s,len,&sz));
              ReleaseDC(hwndCombo,dc);
              int weight = sz.cx + 10;
              int height = sz.cy;
              assert(SetwindowPos(hwndCombo,HWND_TOP,weight,height,SWP_NOMOVE));

完整代码：

#pragma comment(lib,"user32.lib")
#pragma comment(lib,"Comctl32.lib")
#pragma comment(lib,"Gdi32.lib")
#pragma comment(lib,"Comdlg32.lib")

#define WIN32_LEAN_AND_MEAN
#define UNICODE
#define _UNICODE

#include <windows.h>
#include <winuser.h>
#include <assert.h>

#define COUNTOF(a) (sizeof(a)/sizeof(a[0]))

LRESULT CALLBACK WndProc(HWND,UINT,WParaM,LParaM);
int largestIndex();
HFONT getDefaultFont();
void SetDefaultFont(HWND hwnd);

HFONT hDefaultSystemFont;

HINSTANCE g_hinst;

const wchar_t *items[] =
{ 
  L"Windows",L"Mac",L"FreeBSD",L"Arch",L"aaaaaa!!!!!!!aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa#",L"foo",L"baaaa"
};
HWND hwndCombo;

enum
{
  ID_COMBO = 10,ID_BTN1,};

int WINAPI wWinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,PWSTR lpCmdLine,int nCmdshow) {

    HWND hwnd;
    MSG  msg ;    
    WNDCLASSW wc = {0};
    wc.lpszClassName = L"Application";
    wc.hInstance     = hInstance ;
    wc.hbrBackground = GetSysColorBrush(COLOR_3DFACE);
    wc.lpfnWndProc   = WndProc ;
    wc.hCursor       = LoadCursor(0,IDC_ARROW);

    g_hinst = hInstance;
  
    RegisterClassW(&wc);
    hwnd = CreateWindowW(wc.lpszClassName,L"",WS_OVERLAPPEDWINDOW | WS_VISIBLE,100,300,170,hInstance,0);  


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

    return (int) msg.wParam;
}

LRESULT CALLBACK WndProc(HWND hwnd,UINT msg,WParaM wParam,LParaM lParam) {

    switch(msg)
    {
    
        case WM_CREATE:
        {
              hwndCombo = CreateWindowW(L"ComboBox",WS_CHILD | WS_VISIBLE | CBS_DROPDOWN,10,60,110,hwnd,(HMENU) ID_COMBO,g_hinst,NULL);
              for (int i = 0; i < COUNTOF(items); i++ )
              {
                SendMessageW(hwndCombo,CB_ADDSTRING,(LParaM) items[i]);
              }
              SetDefaultFont(hwndCombo);

              HWND btn1 =
              CreateWindowW(L"Button",L"Click me",WS_CHILD | WS_VISIBLE,5,40,90,25,(HMENU) ID_BTN1,NULL); 
              SetDefaultFont(btn1);
        }
        break;

        case WM_COMMAND:
        {
          switch(LOWORD(wParam))
          {
                case ID_BTN1:
                {
                  int i = largestIndex();
                  wchar_t *s = (wchar_t*) items[i];
                  int len = wcslen(s);
                  HDC dc = GetDC(hwndCombo);
                  SIZE sz;
                  assert(GetTextExtentPoint32(dc,&sz));
                  ReleaseDC(hwndCombo,dc);
                  int weight = sz.cx + 10;
                  int height = sz.cy;
                  assert(SetwindowPos(hwndCombo,SWP_NOMOVE));
                }
                break;

                default: 
                  break;
            }

        }
        break;

        case WM_DESTROY:
            DeleteObject(hDefaultSystemFont);
            hDefaultSystemFont = NULL;
            PostQuitMessage(0);
            break; 
    }
  
    return DefWindowProcW(hwnd,msg,wParam,lParam);
}

int largestIndex()
{
  int m = 0;
  int idx = -1;

  for(int i = 0; i < COUNTOF(items); i++) {
    int l = wcslen(items[i]);
    if(l > m) {
      m  = l;
      idx = i;
    }
  }

  return idx;
}



HFONT getDefaultFont()
{
  if(hDefaultSystemFont == NULL) {
    NONCLIENTMETRICS ncm;
    ncm.cbSize = sizeof(NONCLIENTMETRICS);
    SystemParametersInfo(SPI_GETNONCLIENTMETRICS,sizeof(NONCLIENTMETRICS),&ncm,0);
    hDefaultSystemFont = CreateFontIndirect(&ncm.lfMessageFont);
  }
  return hDefaultSystemFont;
}


void SetDefaultFont(HWND hwnd)
{
    SendMessage(hwnd,WM_SETFONT,(LParaM) getDefaultFont(),TRUE);
}

解决方法

您使用不同的字体进行测量。

试试

int len = wcslen(s);
HDC dc = GetDC(hwndCombo);
SIZE sz;
// Set correct font
HFONT old = SelectObject(dc,hDefaultSystemFont);
// or
// HFONT control_font = (HFONT)SendMessage(hwndCombo,WM_GETFONT,0);
// HFONT old = SelectObject(dc,control_font);
assert(GetTextExtentPoint32(dc,s,len,&sz));
// Restore font for cleanup
SelectObject(dc,old);
ReleaseDC(hwndCombo,dc);
int weight = sz.cx + 10;
int height = sz.cy;