IDWriteBitmapRenderTarget interface

Encapsulates a 32-bit device independent bitmap and device context, which can be used for rendering glyphs.

Members

The IDWriteBitmapRenderTarget interface inherits from the IUnknown interface. IDWriteBitmapRenderTarget also has these types of members:

• Methods

Methods

The IDWriteBitmapRenderTarget interface has these methods.

Remarks

You create an IDWriteBitmapRenderTarget by using the IDWriteGdiInterop::CreateBitmapRenderTarget method, as shown in the following code.

if (SUCCEEDED(hr))
{
    hr = g_pGdiInterop->CreateBitmapRenderTarget(hdc, r.right, r.bottom, &g_pBitmapRenderTarget);
}

IDWriteGdiInterop::CreateBitmapRenderTarget takes a handle to a DC and the desired width and height. In the above example, the width and height given are the size of the window rect.

Rendering

One way to use a IDWriteBitmapRenderTarget, for rendering to a bitmap, is to implement a custom renderer interface derived from the IDWriteTextRenderer interface. In your implementation of the DrawGlyphRun method of your custom renderer, call the IDWriteBitmapRenderTarget::DrawGlyphRun method to draw the glyphs as shown in the following code.

STDMETHODIMP GdiTextRenderer::DrawGlyphRun(
    __maybenull 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;

    // Pass on the drawing call to the render target to do the real work.
    RECT dirtyRect = {0};

    hr = pRenderTarget_->DrawGlyphRun(
        baselineOriginX,
        baselineOriginY,
        measuringMode,
        glyphRun,
        pRenderingParams_,
        RGB(0,200,255),
        &dirtyRect
        );
    

    return hr;
}

The IDWriteBitmapRenderTarget encapsulates and renders to a bitmap in memory. The GetMemoryDC function returns a handle to the device context of this bitmap.

Requirements

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Build date: 11/22/2012