调整椭圆大小
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我不明白为什么这行不通。在消息WM_LBUTTONDOWN上，存储了指针的坐标。然后在WM_MOUSEMOVE上，如果按下鼠标左键，我希望它绘制一个包含原始点和鼠标现在所在的新点的椭圆。但是当我调试时什么也没有发生。这是我的WindowProc
LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
PAINTSTRUCT ps;
HDC hdc;
switch (uMsg)
{
case WM_DESTROY:
{
DestroyWindow(hwnd);
PostQuitMessage(0);
break;
}
case WM_PAINT:
{
hdc = BeginPaint(hwnd, &ps);
EndPaint(hwnd, &ps);
break;
}
case WM_LBUTTONDOWN:
{
pnt.x = GET_X_LPARAM(lParam);
pnt.y = GET_Y_LPARAM(lParam);
break;
}
case WM_MOUSEMOVE:
{
if(wParam == MK_LBUTTON)
{
hdc = BeginPaint(hwnd, &ps);
Ellipse(hdc, pnt.x, pnt.y, GET_X_LPARAM(lParam), GET_Y_LPARAM(lParam)); // nothing happens
EndPaint(hwnd, &ps);
}
break;
}
return 0;
}
return DefWindowProc(hwnd, uMsg, wParam, lParam);
}
没有找到相关结果
已邀请:
2 个回复
窝头菊
static POINT begin, end; static BOOL drawing = false; // ... case WM_PAINT: hdc = BeginPaint(hWnd, &ps); if (drawing) Ellipse(hdc, begin.x, begin.y, end.x, end.y); EndPaint(hWnd, &ps); break; case WM_LBUTTONDOWN: begin.x = GET_X_LPARAM(lParam); begin.y = GET_Y_LPARAM(lParam); SetCapture(hWnd); drawing = true; break; case WM_LBUTTONUP: ReleaseCapture(); drawing = false; break; case WM_MOUSEMOVE: end.x = GET_X_LPARAM(lParam); end.y = GET_Y_LPARAM(lParam); { RECT invalid = {begin.x, begin.y, end.x, end.y}; InvalidateRect(hWnd, &invalid, true); } break;骨酚柯
不会做任何事情。您应该将点存储在WM_MOUSEMOVE（与in3ѭ类似的结构）中，然后调用InvalidateRect（）。然后，在WM_PAINT中进行绘画。有关更多信息，请参见此链接。