我正在尝试使用Direct2D绘制时钟。该程序可以正确获取当前时间,但是错误是Direct2D绘制时钟时出现的,因为时钟似乎与当前时间已过时。要获取当前时间,请使用GetLocalTime()
函数,然后映射这些值以将它们转换为一个角度,以便可以绘制它们。我该如何解决?
...
renderTarget->BeginDraw();
renderTarget->Clear(ColorF(ColorF::Black));
GetLocalTime(&sysTime);
wstring text = L"Hour: " + to_wstring(sysTime.wHour)
+ L"\nMinute: " + to_wstring(sysTime.wMinute)
+ L"\nSecond: " + to_wstring(sysTime.wSecond);
brush->SetColor(ColorF(ColorF::White));
renderTarget->DrawTextW(text.c_str(), text.length(), textFormat, textRect, brush);
D2D1_POINT_2F centerPoint = Point2F(320, 240);
FLOAT hourAngle = map(sysTime.wHour%12, 0, 12, 0, 360);
FLOAT minuteAngle = map(sysTime.wMinute, 0, 60, 0, 360);
FLOAT secondAngle = map(sysTime.wSecond, 0, 60, 0, 360);
brush->SetColor(ColorF(ColorF::DeepPink));
renderTarget->DrawEllipse(D2D1::Ellipse(centerPoint, 150, 150), brush, 5);
renderTarget->SetTransform(Matrix3x2F::Rotation(secondAngle, centerPoint));
brush->SetColor(ColorF(ColorF::Blue));
renderTarget->DrawLine(centerPoint,Point2F(centerPoint.x,centerPoint.y + 150*0.9), brush, 10,lineStrokeStyle);
renderTarget->SetTransform(Matrix3x2F::Rotation(minuteAngle, centerPoint));
brush->SetColor(ColorF(ColorF::White));
renderTarget->DrawLine(centerPoint,Point2F(centerPoint.x,centerPoint.y + 150*0.7), brush, 10, lineStrokeStyle);
renderTarget->SetTransform(Matrix3x2F::Rotation(hourAngle, centerPoint));
brush->SetColor(ColorF(ColorF::GreenYellow));
renderTarget->DrawLine(centerPoint, Point2F(centerPoint.x,centerPoint.y + 150*0.5), brush, 10,lineStrokeStyle);
renderTarget->SetTransform(Matrix3x2F::Identity());
HRESULT hrErr = renderTarget->EndDraw();
if (hrErr != S_OK) {
MessageBox(hWnd, L"Direct2D Error", L"Direct2D Error", MB_OK | MB_ICONERROR);
SafeRelease(&brush);
SafeRelease(&renderTarget);
SafeRelease(&factory);
}
...
是,您可以使用GetLocalTime
获取当前的本地日期和时间。问题可能出在将时间映射到某个角度。
但是这些可以解决,因为MSDN中有非常详细的示例。
代替计算线的坐标,我们可以计算角度,然后应用旋转变换。以下代码显示了绘制一只时针的功能。 fAngle参数提供手的角度,以度为单位。
void Scene::DrawClockHand(float fHandLength, float fAngle, float fStrokeWidth)
{
m_pRenderTarget->SetTransform(
D2D1::Matrix3x2F::Rotation(fAngle, m_ellipse.point)
);
// endPoint defines one end of the hand.
D2D_POINT_2F endPoint = D2D1::Point2F(
m_ellipse.point.x,
m_ellipse.point.y - (m_ellipse.radiusY * fHandLength)
);
// Draw a line from the center of the ellipse to endPoint.
m_pRenderTarget->DrawLine(
m_ellipse.point, endPoint, m_pStroke, fStrokeWidth);
}
此代码绘制一条垂直线,从时钟面的中心开始,到端点endPoint结束。通过应用旋转变换,直线绕椭圆的中心旋转。旋转的中心点是形成钟面的椭圆中心。
void Scene::RenderScene()
{
m_pRenderTarget->Clear(D2D1::ColorF(D2D1::ColorF::SkyBlue));
m_pRenderTarget->FillEllipse(m_ellipse, m_pFill);
m_pRenderTarget->DrawEllipse(m_ellipse, m_pStroke);
// Draw hands
SYSTEMTIME time;
GetLocalTime(&time);
// 60 minutes = 30 degrees, 1 minute = 0.5 degree
const float fHourAngle = (360.0f / 12) * (time.wHour) + (time.wMinute * 0.5f);
const float fMinuteAngle =(360.0f / 60) * (time.wMinute);
DrawClockHand(0.6f, fHourAngle, 6);
DrawClockHand(0.85f, fMinuteAngle, 4);
// Restore the identity transformation.
m_pRenderTarget->SetTransform( D2D1::Matrix3x2F::Identity() );
}
调试:
整个代码示例: