We can combine two or more images and/or effects by using the composite effect. Here is an example.
Drawing shadows using Direct2D composite effects
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void CD2DStaticCtrl::_DrawImageWithShadow(CHwndRenderTarget* pRenderTarget) { ASSERT(pRenderTarget && pRenderTarget->IsValid()); ASSERT(m_pBitmap && m_pBitmap->IsValid()); // get ID2D1DeviceContext interface; note: must include <d2d1_1.h> CComQIPtr<ID2D1DeviceContext> spDeviceContext = pRenderTarget->GetRenderTarget(); // create shadow effect and set the input image CComPtr<ID2D1Effect> spShadowEffect; spDeviceContext->CreateEffect(CLSID_D2D1Shadow, &spShadowEffect); spShadowEffect->SetInput(0, m_pBitmap->Get()); spShadowEffect->SetValue(D2D1_SHADOW_PROP_BLUR_STANDARD_DEVIATION, m_fBlurStandardDeviation); spShadowEffect->SetValue(D2D1_SHADOW_PROP_COLOR, CRenderTarget::COLORREF_TO_D2DCOLOR(m_shadowColor)); // create flood effect CComPtr<ID2D1Effect> spFloodEffect; spDeviceContext->CreateEffect(CLSID_D2D1Flood, &spFloodEffect); // Note: shadow will be composed in the top of a surface having the background color D2D1_COLOR_F color = CRenderTarget::COLORREF_TO_D2DCOLOR(m_backColor); spFloodEffect->SetValue(D2D1_FLOOD_PROP_COLOR, D2D1::Vector4F(color.r, color.g, color.b, color.a)); // create 2D affine transform effect in order to translate the shadow CComPtr<ID2D1Effect> spAffineTransformEffect; spDeviceContext->CreateEffect(CLSID_D2D12DAffineTransform, &spAffineTransformEffect); spAffineTransformEffect->SetInputEffect(0, spShadowEffect); D2D1_MATRIX_3X2_F translation = D2D1::Matrix3x2F::Translation(m_fShadowDistance, m_fShadowDistance); spAffineTransformEffect->SetValue(D2D1_2DAFFINETRANSFORM_PROP_TRANSFORM_MATRIX, translation); // create the composite effect and combine the effects CComPtr<ID2D1Effect> spCompositeEffect; spDeviceContext->CreateEffect(CLSID_D2D1Composite, &spCompositeEffect); // set input effects spCompositeEffect->SetInputEffect(0, spFloodEffect); spCompositeEffect->SetInputEffect(1, spAffineTransformEffect); // set input image; because the default input count is 1, he have to set it to 3 spCompositeEffect->SetInputCount(3); spCompositeEffect->SetInput(2, m_pBitmap->Get()); // finally perform drawing spDeviceContext->DrawImage(spCompositeEffect); } |
Demo project
Download: Composite Effect Demo.zip (1220)
You can set the amount of blur and the color as well as the distance of the shadow.
Composite Effect Demo
Resources and related articles
- MSDN: Composite effect
- MSDN: Shadow effect
- Codexpert: MFC Support for Direct2D topics