使用Polyline()
函数绘制形状。
相关代码在这里:
void DoDrawing(HWND hwnd) {
LOGBRUSH brush;
COLORREF col = RGB(0, 0, 0);
DWORD pen_style = PS_SOLID | PS_JOIN_MITER | PS_GEOMETRIC;
brush.lbStyle = BS_SOLID;
brush.lbColor = col;
brush.lbHatch = 0;
PAINTSTRUCT ps;
HDC hdc = BeginPaint(hwnd, &ps);
HPEN hPen1 = ExtCreatePen(pen_style, 8, &brush, 0, NULL);
HPEN holdPen = SelectObject(hdc, hPen1);
POINT points[5] = { { 10, 30 }, { 100, 30 }, { 100, 100 }, { 10, 100 }, {10, 30}};
Polyline(hdc, points, 5);
DeleteObject(hPen1);
SelectObject(hdc, holdPen);
EndPaint(hwnd, &ps);
}
PS_JOIN_MITER
应用于三个角但不在左上角。在该角落,使用默认的PS_JOIN_ROUND
。如何解决这个问题?
以下是一个完整的工作示例:
#include <windows.h>
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
void DoDrawing(HWND);
int WINAPI wWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
PWSTR lpCmdLine, int nCmdShow) {
MSG msg;
WNDCLASSW wc = {0};
wc.style = CS_HREDRAW | CS_VREDRAW;
wc.lpszClassName = L"Pens";
wc.hInstance = hInstance;
wc.hbrBackground = (HBRUSH) GetStockObject(WHITE_BRUSH);
wc.lpfnWndProc = WndProc;
wc.hCursor = LoadCursor(0, IDC_ARROW);
RegisterClassW(&wc);
CreateWindowW(wc.lpszClassName, L"Line joins",
WS_OVERLAPPEDWINDOW | WS_VISIBLE,
100, 100, 250, 180, NULL, NULL, hInstance, NULL);
while (GetMessage(&msg, NULL, 0, 0)) {
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return (int) msg.wParam;
}
LRESULT CALLBACK WndProc(HWND hwnd, UINT msg,
WPARAM wParam, LPARAM lParam) {
switch(msg) {
case WM_PAINT:
DoDrawing(hwnd);
break;
case WM_DESTROY:
PostQuitMessage(0);
return 0;
}
return DefWindowProcW(hwnd, msg, wParam, lParam);
}
void DoDrawing(HWND hwnd) {
LOGBRUSH brush;
COLORREF col = RGB(0, 0, 0);
DWORD pen_style = PS_SOLID | PS_JOIN_MITER | PS_GEOMETRIC;
brush.lbStyle = BS_SOLID;
brush.lbColor = col;
brush.lbHatch = 0;
PAINTSTRUCT ps;
HDC hdc = BeginPaint(hwnd, &ps);
HPEN hPen1 = ExtCreatePen(pen_style, 8, &brush, 0, NULL);
HPEN holdPen = SelectObject(hdc, hPen1);
POINT points[5] = { { 10, 30 }, { 100, 30 }, { 100, 100 }, { 10, 100 }, {10, 30}};
Polyline(hdc, points, 5);
DeleteObject(hPen1);
SelectObject(hdc, holdPen);
EndPaint(hwnd, &ps);
}
答案 0 :(得分:1)
Polyline
没有加入第一点和最后一点。
使用Polygon(hdc, points, 5)
代替Polyline
此外,在删除现有笔之前,请按以下顺序选择oldPen到DC:
SelectObject(hdc, holdPen);
DeleteObject(hPen1);
(如果你不按正确的顺序执行,Windows会原谅你)