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我正在制作一个程序，让我点击两个同心圆的中心，然后通过鼠标移动，改变它的位置，我可以用它的半径做同样的事情。问题是鼠标移动之后是来自画圆的延迟响应，使半径跟随鼠标而不是在移动过程中完全处于同一位置。

你们知道如何让它像这样工作吗？紧随其后的图纸。

一些处理鼠标点击和移动的代码：

void DemoApp::OnLButtonDown(FLOAT pixelX, FLOAT pixelY)
{
    SetCapture(m_hwnd);

    mouseRegion = DPIScale::PixelsToDips(pixelX, pixelY);
    FLOAT xDifference = centerCircles.x - mouseRegion.x;
    FLOAT yDifference = centerCircles.y - mouseRegion.y;
    FLOAT distanceToCenter = sqrtf(xDifference*xDifference + yDifference*yDifference);

    if(distanceToCenter < 10.0f)
    {
        centerMove = true;
        minimumRadiusCircleMove = false;
        maximumRadiusCircleMove = false;
    }
    else if((distanceToCenter > (minimumRadius - 1.0f)) && (distanceToCenter < (minimumRadius + 1.0f)))
    {
        minimumRadiusCircleMove = true;
        centerMove = false;
        maximumRadiusCircleMove = false;
    }
    else if((distanceToCenter > (maximumRadius - 1.0f)) && (distanceToCenter < (maximumRadius + 1.0f)))
    {
        maximumRadiusCircleMove = true;
        centerMove = false;
        minimumRadiusCircleMove = false;
    }
    else
    {
        centerMove = false;
        minimumRadiusCircleMove = false;
        maximumRadiusCircleMove = false;
    }


    InvalidateRect(m_hwnd, NULL, FALSE);
}

void DemoApp::OnMouseMove(int pixelX, int pixelY, DWORD flags)
{
    if (flags & MK_LBUTTON) 
    { 
        if(centerMove)
        {
            centerCircles = DPIScale::PixelsToDips(pixelX, pixelY);

            FLOAT distanceLeftToCenterCircles = abs(centerCircles.x - bitmapTopLeft);
            FLOAT distanceTopToCenterCircles = abs(centerCircles.y - bitmapTopRight);

            percentageFromLeft = distanceLeftToCenterCircles / displaySizeWidth;
            percentageFromTop = distanceTopToCenterCircles / displaySizeHeight;

        }
        else if(minimumRadiusCircleMove)
        {
            radiusSelection = DPIScale::PixelsToDips(pixelX, pixelY);
            FLOAT xDifference = centerCircles.x - radiusSelection.x;
            FLOAT yDifference = centerCircles.y - radiusSelection.y;
            minimumRadius = sqrtf(xDifference*xDifference + yDifference*yDifference);

            minimumRadiusPercentage = minimumRadius/(displaySizeWidth/2);
        }
        else if(maximumRadiusCircleMove)
        {
            radiusSelection = DPIScale::PixelsToDips(pixelX, pixelY);
            FLOAT xDifference = centerCircles.x - radiusSelection.x;
            FLOAT yDifference = centerCircles.y - radiusSelection.y;
            maximumRadius = sqrtf(xDifference*xDifference + yDifference*yDifference);

            maximumRadiusPercentage = maximumRadius/(displaySizeWidth/2);
        }

        InvalidateRect(m_hwnd, NULL, FALSE);
    }
}

void DemoApp::OnLButtonUp()
{
    ReleaseCapture(); 
}
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2 回答 2

2

根据 MSDN ( http://msdn.microsoft.com/en-us/library/dd145002%28v=vs.85%29.aspx ) InvalidateRect 直到下一个 WM_PAINT 和“系统只要窗口的更新区域不为空并且该窗口的应用程序队列中没有其他消息，就会向窗口发送 WM_PAINT 消息。” 所以它不是立即的。

我在 MSDN 上找到了一个可能的解决方案，在没有 WM_PAINT 消息的情况下绘图

于 2012-01-30T15:07:59.017 回答
2

我找到了解决这个问题的方法！

这比预期的要简单，您所要做的就是在创建渲染目标时添加一个标志，这样mousemove 会更快地响应：标志是：D2D1_PRESENT_OPTIONS_IMMEDIATELY。

// Create Direct2d render target.
        hr = m_pD2DFactory->CreateHwndRenderTarget(
            D2D1::RenderTargetProperties(),
            D2D1::HwndRenderTargetProperties(m_hwnd, size, D2D1_PRESENT_OPTIONS_IMMEDIATELY),
            &m_pRenderTarget
            );
于 2012-03-14T15:53:48.733 回答