5.静态控件背景透明化

一、静态控件透明化

　　前面我们介绍过，通过WM_CTLCOLORDLG消息来设置对话框背景，还有消息来设置其他控件得背景：

　　　　WM_CTLCOLORBTN - 按钮

　　　　WM_CTLCOLOREDIT - 编辑框

　　　　WM_CTLCOLORLISTBOX - 列表框

　　　　WM_CTLCOLORSCROLLBAR - 滚动条

　　　　WM_CTLCOLORSTATIC - 静态框

二、具体事例 - 静态框

　　通过在WM_CTLCOLORSTATIC消息中，返回一个空画刷达到背景透明化的要求。

　　设置背景透明：

　　　　int  SetBkMode ( HDC hdc,  int iBkMode );

　　代码：　

 1 #include "stdafx.h"
 2 #include "05静态控件背景透明化.h"
 3
 4 WCHAR szDlgTitle[] = L"静态控件背景透明化";
 5
 6 BOOL CALLBACK DlgProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
 7 {
 8     RECT rcDialog;
 9     HBITMAP hBitmap;
10     static BITMAP s_bm;
11     static HDC s_hdcMem;
12     switch (message)
13     {
14     case WM_INITDIALOG:
15         SetWindowText(hWnd, szDlgTitle);
16         SetWindowLong(hWnd, GWL_STYLE, GetWindowLong(hWnd, GWL_STYLE) | WS_SIZEBOX);
17         // 加载背影图片
18         hBitmap = (HBITMAP)LoadImage(NULL, L"006.bmp", IMAGE_BITMAP, 0, 0, LR_LOADFROMFILE | LR_CREATEDIBSECTION);
19         if (hBitmap == NULL)
20         {
21             MessageBox(hWnd, L"LoadImage failed", L"Error", MB_ICONERROR);
22             exit(0);
23         }
24         else
25         {
26             // 将背影图片放入HDC - s_hdcMem
27             HDC hdc;
28             hdc = GetDC(hWnd);
29             s_hdcMem = CreateCompatibleDC(hdc);
30             SelectObject(s_hdcMem, hBitmap);
31             ReleaseDC(hWnd, hdc);
32             // 得到位图信息
33             GetObject(hBitmap, sizeof(s_bm), &s_bm);
34         }
35         return 0;
36     case WM_COMMAND:
37         if (IDCANCEL == LOWORD(wParam))
38         {
39             DeleteDC(s_hdcMem);
40             EndDialog(hWnd, LOWORD(wParam));
41             return TRUE;
42         }
43         break;
44     case WM_SIZE:
45         InvalidateRect(hWnd, NULL, TRUE);
46         return TRUE;
47     case WM_CTLCOLORSTATIC:
48         SetBkMode((HDC)wParam, TRANSPARENT);
49         return (BOOL)((HBRUSH)GetStockObject(NULL_BRUSH));
50     case WM_CTLCOLORDLG:
51         GetClientRect(hWnd, &rcDialog);
52         //通过SetStretchBltMode的设置能使StretchBlt在缩放图像更加清晰
53         SetStretchBltMode((HDC)wParam, COLORONCOLOR);
54         StretchBlt((HDC)wParam, 0, 0, rcDialog.right, rcDialog.bottom, s_hdcMem, 0, 0, s_bm.bmWidth, s_bm.bmHeight, SRCCOPY);
55         return (BOOL)((HBRUSH)GetStockObject(NULL_BRUSH));
56     }
57     return FALSE;
58 }
59
60 int APIENTRY wWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPWSTR lpCmdLine, int nCmdShow)
61 {
62     DialogBox(hInstance, MAKEINTRESOURCE(IDD_DIALOG1), NULL, DlgProc);
63     return 0;
64 }

　　运行结果：

未处理WM_CTLCOLORSTATIC消息                                                                         处理WM_CTLCOLORSTATIC消息

三、继续优化

　　静态框的背景已经透明化了，但是组合框的文字是被白色得边框划过的，很不美观。要解决这个问题，我们用位图画刷，在WM_CTLCOLORSTATIC消息中返回一个位图画刷。

　　代码：　

 1 #include "stdafx.h"
 2 #include "05静态控件背景透明化.h"
 3
 4 WCHAR szDlgTitle[] = L"静态控件背景透明化";
 5
 6 BOOL CALLBACK DlgProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
 7 {
 8     static HBRUSH s_hBitmapBrush; //位图画刷
 9     switch (message)
10     {
11     case WM_INITDIALOG:
12         SetWindowText(hWnd, szDlgTitle);
13         SetWindowLong(hWnd, GWL_STYLE, GetWindowLong(hWnd, GWL_STYLE) | WS_SIZEBOX);
14         // 加载背影图片
15         HBITMAP hBitmap;
16         hBitmap = (HBITMAP)LoadImage(NULL, L"006.bmp", IMAGE_BITMAP, 0, 0, LR_LOADFROMFILE | LR_CREATEDIBSECTION);
17         if (hBitmap == NULL)
18         {
19             MessageBox(hWnd, L"LoadImage failed", L"Error", MB_ICONERROR);
20             exit(0);
21         }
22         // 创建位图画刷
23         s_hBitmapBrush = CreatePatternBrush(hBitmap);
24         return 0;
25     case WM_COMMAND:
26         if (IDCANCEL == LOWORD(wParam))
27         {
28             DeleteObject(s_hBitmapBrush);
29             EndDialog(hWnd, LOWORD(wParam));
30             return TRUE;
31         }
32         break;
33     case WM_CTLCOLORSTATIC:
34         SetBkMode((HDC)wParam, TRANSPARENT);
35     case WM_CTLCOLORDLG:
36         return (BOOL)s_hBitmapBrush;
37     }
38     return FALSE;
39 }
40 int APIENTRY wWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPWSTR lpCmdLine, int nCmdShow)
41 {
42     DialogBox(hInstance, MAKEINTRESOURCE(IDD_DIALOG1), NULL, DlgProc);
43     return 0;
44 }

　　运行结果：