如何在DirectWrite上为所有字体大小强制启用Y轴抗锯齿

Question

我正在使用DirectWrite渲染文本。DirectWrite仅在字体大小较大时才启用y轴抗锯齿，这会使CJK字体看起来很糟糕。

如何对所有字体大小强制启用Y-Axis Antialiasing？

Answer 1

在渲染目标上，将IDWriteRenderingParams设置为使用DWRITE_RENDERING_MODE_NATURAL_SYMMETRIC，然后调用ID2D1RenderTarget::SetTextRenderingParams。

ComPtr<IDWriteRenderingParams> textRenderingParams;
dwriteFactory->CreateCustomRenderingParams(
    gamma,
    contrast,
    clearTypeLevel,
    pixelGeometry,
    DWRITE_RENDERING_MODE_NATURAL_SYMMETRIC,
    OUT &textRenderingParams
    );
d2dRenderTarget->SetTextRenderingParams(textRenderingParams);

如果要从默认渲染参数检查现有设置，可以先调用ID2D1RenderTarget::GetTextRenderingParams，然后创建自己的以替换默认设置。

// Get defaults for gamma, contrast, CT level, pixel geometry...
ComPtr<IDWriteRenderingParams> defaultRenderingParams;
RETURN_IF_FAILED(dwriteFactory->CreateRenderingParams(OUT &defaultRenderingParams));

// Alternately create suitable rendering params for your monitor:
//     dwriteFactory->CreateMonitorRenderingParams(...)
//
// Or retrieve the existing rendering params if one was already set:
//     d2dRenderTarget->GetTextRenderingParams(OUT &defaultRenderingParams);

auto gamma = defaultRenderingParams->GetGamma(); // default=1.8f
auto contrast = defaultRenderingParams->GetEnhancedContrast(); // default=0.5f
auto clearTypeLevel = defaultRenderingParams->GetClearTypeLevel(); // default=0.5f
auto pixelGeometry = defaultRenderingParams->GetPixelGeometry(); // default=RGB for most monitors

“这会使CJK字体看起来很糟。”但是请小心，因为使用6x5或8x8可能会丢失茎的精细细节。