c++ - Direct2D：将文本转换为路径

Question

我对 Direct2D 和 DirectWrite 非常陌生，并且仍在研究这些 API 提供的可能性。对于潜在的图形应用程序，我想知道是否可以将文本渲染为路径，以便可以像在矢量图形编辑器中一样修改各个点。是否可以直接在 Direct2D 和 DirectWrite 中执行类似的操作，或者至少有办法检索必要的信息并手动构建类似于文本的路径对象？

Answer 1

您在评论中引用的文章是正确的。关键就是IDWriteFontFace::GetGlyphRunOutline。更多关于用法的信息可以在这里找到。他们的示例代码中的 CustomTextRenderer 文章中描述的功能如下（虽然丑陋）：

//  Gets GlyphRun outlines via IDWriteFontFace::GetGlyphRunOutline
//  and then draws and fills them using Direct2D path geometries
IFACEMETHODIMP CustomTextRenderer::DrawGlyphRun(
    _In_opt_ void* clientDrawingContext,
    FLOAT baselineOriginX,
    FLOAT baselineOriginY,
    DWRITE_MEASURING_MODE measuringMode,
    _In_ DWRITE_GLYPH_RUN const* glyphRun,
    _In_ DWRITE_GLYPH_RUN_DESCRIPTION const* glyphRunDescription,
    IUnknown* clientDrawingEffect)
{
    HRESULT hr = S_OK;

    // Create the path geometry.
    Microsoft::WRL::ComPtr<ID2D1PathGeometry> pathGeometry;
    hr = D2DFactory->CreatePathGeometry(&pathGeometry);

    // Write to the path geometry using the geometry sink.
    Microsoft::WRL::ComPtr<ID2D1GeometrySink> sink;
    if (SUCCEEDED(hr))
    {
        hr = pathGeometry->Open(&sink);
    }

    // Get the glyph run outline geometries back from DirectWrite 
    // and place them within the geometry sink.
    if (SUCCEEDED(hr))
    {
        hr = glyphRun->fontFace->GetGlyphRunOutline(
            glyphRun->fontEmSize,
            glyphRun->glyphIndices,
            glyphRun->glyphAdvances,
            glyphRun->glyphOffsets,
            glyphRun->glyphCount,
            glyphRun->isSideways,
            glyphRun->bidiLevel % 2,
            sink.Get());
    }

    // Close the geometry sink
    if (SUCCEEDED(hr))
    {
        hr = sink.Get()->Close();
    }

    // Initialize a matrix to translate the origin of the glyph run.
    D2D1::Matrix3x2F const matrix = D2D1::Matrix3x2F(
        1.0f, 0.0f,
        0.0f, 1.0f,
        baselineOriginX, baselineOriginY);

    // Create the transformed geometry
    Microsoft::WRL::ComPtr<ID2D1TransformedGeometry> transformedGeometry;
    if (SUCCEEDED(hr))
    {
        hr = D2DFactory.Get()->CreateTransformedGeometry(
            pathGeometry.Get(),
            &matrix,
            &transformedGeometry);
    }

    // Draw the outline of the glyph run
    D2DDeviceContext->DrawGeometry(
        transformedGeometry.Get(),
        outlineBrush.Get());

    // Fill in the glyph run
    D2DDeviceContext->FillGeometry(
        transformedGeometry.Get(),
        fillBrush.Get());

    return hr;
}

在该示例中，在从文本创建路径几何图形后，它们只是移动到 x 和 y 参数中指定的位置，然后跟踪和填充几何图形。由于逻辑原因，我称代码丑陋，特别是如果大纲调用失败，接收器可能不会关闭。但这只是示例代码。祝你好运。