IDWriteFactory::CreateTextLayout 方法导致窗口突然关闭

Question

在我使用 Windows API 构建的应用程序中，我目前正在将文本写入屏幕。我正在尝试使用CreateTextLayout 方法，但是使用该特定功能时，我遇到了无法解决的问题。当我刚刚运行我的应用程序时，我开始正常，并且刚刚退出，没有任何类型的错误警告。使用断点，我将问题追溯到该函数。这是我用来调用它的代码：

IDWriteFactory* writeFactory;
IDWriteTextFormat* writeTextFormat;
IDWriteTextLayout* writeTextLayout;

 HRESULT App::CreateDeviceIndependentResources()
{
    HRESULT hr;
// Create a Direct2D factory.
hr = D2D1CreateFactory(
    D2D1_FACTORY_TYPE_SINGLE_THREADED,
    &writeFactory
);


if (SUCCEEDED(hr))
{
    hr = DWriteCreateFactory(
        DWRITE_FACTORY_TYPE_SHARED,
        __uuidof(writeFactory),
        reinterpret_cast<IUnknown**>(&writeFactory)
    );

}

if (writeFactory == NULL)
        OutputDebugStringA("NULL\n");

if (SUCCEEDED(hr))
{
    hr =  writeFactory->CreateTextFormat(
        L"Times New Roman",
        NULL,
        DWRITE_FONT_WEIGHT_NORMAL,
        DWRITE_FONT_STYLE_NORMAL,
        DWRITE_FONT_STRETCH_NORMAL,
        14.0f,
        L"EN-US",
        &writeTextFormat
    );
}
if (SUCCEEDED(hr))
{
    // Create a DirectWrite text format object.
    hr = writeFactory->CreateTextLayout(
        L"Projects",      // The string to be laid out and formatted.
        8,  // The length of the string.
        writeTextFormat,  // The text format to apply to the string (contains font information, etc).
        10.0f,         // The width of the layout box.
        10.0f,        // The height of the layout box.
        &writeTextLayout  // The IDWriteTextLayout interface pointer.
    );
}
}

我觉得这很基本，因为我只是按照 Microsoft.com 上的教程进行操作；但是，有些地方显然是错误的。我的猜测是它可能与writeTextFormat 有关。它是一个IDWriteTextFormat 对象。此外，所有这些对象都在 CreateDeviceIndependentResources() 函数中初始化。我应该在其他地方初始化它们吗？

Answer 1

您混淆了D2D1CreateFactory 和DWriteCreateFactory 的使用。

D2D1CreateFactory用于创建ID2D1Factory接口，用于创建ID2D1HwndRenderTarget和ID2D1SolidColorBrush来渲染文本。

DWriteCreateFactory 用于创建IDWriteFactory 接口，它是所有DirectWrite 对象的根工厂接口。 DirectWrite 对象用于格式化文本。

如：

ID2D1HwndRenderTarget* pRT_;
...

pRT_->DrawText(
    wszText_,        // The string to render.
    cTextLength_,    // The string's length.
    pTextFormat_,    // The text format.
    layoutRect,       // The region of the window where the text will be rendered.
    pBlackBrush_     // The brush used to draw the text.
    );

也许你可以从Part 2: Create Device Independent Resources开始。

一些代码：

IDWriteFactory* pDWriteFactory_;

hr = DWriteCreateFactory(
       DWRITE_FACTORY_TYPE_SHARED,
       __uuidof(IDWriteFactory),
       reinterpret_cast<IUnknown**>(&pDWriteFactory_)
       );
...

if (SUCCEEDED(hr))
{
    // Create a DirectWrite text format object.
    hr = pDWriteFactory_->CreateTextLayout(
        L"Projects",      // The string to be laid out and formatted.
        8,  // The length of the string.
        writeTextFormat,  // The text format to apply to the string (contains font information, etc).
        10.0f,         // The width of the layout box.
        10.0f,        // The height of the layout box.
        &writeTextLayout  // The IDWriteTextLayout interface pointer.
    );
}

官方示例：HelloWorld