GDI 画刷（10）

创建画刷

调用 CreateSoildBrush、CreateHatchBrush、CreateBrushIndirect 函数可以创建画刷。

CreateSoildBrush：创建实心画刷；

CreateHatchBrush：创建阴影画刷；

CreateBrushIndirect：根据 LOGBRUSH 结构的内容创建画刷；

Windows 使用被选入设备环境的画笔来描绘边线，使用被选入设备环境的画刷来填充图形。

画刷使用的示例代码：

// 定义画刷句柄（HBRUSH）

HBRUSH hBrush;

// 获取 GRAY_BRUSH 的句柄

hBrush = GetStockObject(GRAY_BRUSH);

// 将画刷选入当前的设备环境

SelectObject(hdc, hBrush);

将 NULL_PEN 画笔选入当前的设备环境，可以绘制不含边线的图形：

SelectObject(hdc, GetStockObject(NULL_PEN));

同样地，将 NULL_BRUSH 画刷选入当前的设备环境，可以绘制不填充内容的图形：

SelectObject(hdc, GetStockObject(NULL_BRUSH));

多边形填充（Polygon）

调用 Polygon 函数可以绘制一个带边框线且带填充效果的多边形，它的参数与 Polyline 函数类似：

BOOL Polygon(

    HDC hdc,                // 设备环境句柄

    CONST POINT *lpPoints,  // 端点的集合（POINT 类型数组）

    int nCount              // 端点的数量

);

调用 PolyPolygon 函数可以绘制多个待边框线且带填充效果的的多边形，它的参数与 PolyPolyline 函数类似：

BOOL PolyPolygon(

    HDC hdc,                  // 设备环境句柄

    CONST POINT *lpPoints,    // 所有端点的集合

    CONST INT *lpPolyCounts,  // 整型数组，每个元素是每个多边形各自的端点个数

    int nCount                // 多边形的数量

);

填充颜色取决于当前选入设备环境的画刷，填充模式可以调用 SetPolyFillMode 函数来设置：

• ALTERNATE 模式（扫描线碰到奇数边则填充，偶数边则不填充）
• WINDING 模式（能够一笔完成的图形则填充，否则不填充）

int SetPolyFillMode(

    HDC hdc,            // 设备环境句柄

    int iPolyFillMode   // 多边形填充模式，可选 ALTERNATE（交替）或 WINDING（螺旋）

);

五角星 Polygon 示例程序

#include <windows.h>

#include <math.h>

#define TIMES 200

#define PI 3.1415926535897932384626433832795

LRESULT CALLBACK WindowProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam) {

    HDC hdc;

    PAINTSTRUCT ps;

    POINT ptCenter;

    POINT apt[5];

    HBRUSH hBrush, hOldBrush;

    static int cxClient, cyClient;

    switch (message) {

    case WM_SIZE:

        cxClient = LOWORD(lParam);

        cyClient = HIWORD(lParam);

        return 0;

    case WM_PAINT:

        hdc = BeginPaint(hwnd, &ps);

        ptCenter.x = cxClient / 2;

        ptCenter.y = cyClient / 2;

        apt[3].x = ptCenter.x;

        apt[3].y = ptCenter.y - TIMES;

        apt[1].x = (LONG)(ptCenter.x + cos(PI / 10) * TIMES);

        apt[1].y = (LONG)(ptCenter.y - sin(PI / 10) * TIMES);

        apt[4].x = (LONG)(ptCenter.x + cos(3 * PI / 10) * TIMES);

        apt[4].y = (LONG)(ptCenter.y + sin(3 * PI / 10) * TIMES);

        apt[2].x = (LONG)(ptCenter.x - cos(3 * PI / 10) * TIMES);

        apt[2].y = (LONG)(ptCenter.y + sin(3 * PI / 10) * TIMES);

        apt[0].x = (LONG)(ptCenter.x - cos(PI / 10) * TIMES);

        apt[0].y = (LONG)(ptCenter.y - sin(PI / 10) * TIMES);

        hBrush = CreateSolidBrush(RGB(255, 255, 0));

        hOldBrush = (HBRUSH)SelectObject(hdc, hBrush);

        Polygon(hdc, apt, 5);

        DeleteObject(SelectObject(hdc, hOldBrush));

        EndPaint(hwnd, &ps);

        return 0;

    case WM_DESTROY:

        PostQuitMessage(0);

        return 0;

    }

    return DefWindowProc(hwnd, message, wParam, lParam);

}

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow) {

    LPCTSTR lpszClassName = TEXT("PolygonDemo");

    LPCTSTR lpszWindowName = TEXT("Polygon Demo Program");

    WNDCLASS wndclass;

    wndclass.cbClsExtra = 0;

    wndclass.cbWndExtra = 0;

    wndclass.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);

    wndclass.hCursor = LoadCursor(NULL, IDC_ARROW);

    wndclass.hIcon = LoadIcon(NULL, IDI_APPLICATION);

    wndclass.hInstance = hInstance;

    wndclass.lpfnWndProc = WindowProc;

    wndclass.lpszClassName = lpszClassName;

    wndclass.lpszMenuName = NULL;

    wndclass.style = CS_HREDRAW | CS_VREDRAW;

    if (!RegisterClass(&wndclass)) {

        MessageBox(NULL, TEXT("This program requires Windows NT!"), lpszWindowName, MB_ICONERROR);

        return 0;

    }

    HWND hwnd = CreateWindow(

        lpszClassName,

        lpszWindowName,

        WS_OVERLAPPEDWINDOW,

        CW_USEDEFAULT,

        CW_USEDEFAULT,

        CW_USEDEFAULT,

        CW_USEDEFAULT,

        NULL,

        NULL,

        hInstance,

        NULL

    );

    ShowWindow(hwnd, nCmdShow);

    UpdateWindow(hwnd);

    MSG msg;

    while (GetMessage(&msg, NULL, 0, 0)) {

        TranslateMessage(&msg);

        DispatchMessage(&msg);

    }

    return msg.wParam;

}