how to create shadow effect using direct2d?

Question

how to create shadow effect using direct2d to line or rectangle?

I know I can create shadow on ID2D1Image.but Can I create it on line or rectangle?

when I fill rectangle can I create its shaodow? or when I Draw Rectangle can I draw it's shadow?

Answer 1

You can add a Shadow effect on anything you draw .

For example on a blue Rectangle :

pDeviceContext->BeginDraw();
pDeviceContext->Clear(D2D1::ColorF(D2D1::ColorF::White, 1.0f));

D2D1_SIZE_F renderTargetSize = pDeviceContext->GetSize();
ID2D1BitmapRenderTarget* pCompatibleRenderTarget = NULL;
HRESULT hr = pDeviceContext->CreateCompatibleRenderTarget(renderTargetSize, &pCompatibleRenderTarget);
if (SUCCEEDED(hr))
{
	pCompatibleRenderTarget->BeginDraw();
	//pCompatibleRenderTarget->Clear(D2D1::ColorF(D2D1::ColorF::White, 1.0f));
	pCompatibleRenderTarget->Clear(NULL);
	ID2D1SolidColorBrush* pBlackBrush = NULL;
	pCompatibleRenderTarget->CreateSolidColorBrush(D2D1::ColorF(D2D1::ColorF::Black), &pBlackBrush);
	pCompatibleRenderTarget->FillRectangle(D2D1::RectF(50.f, 50.f, 250.f, 250.f), pBlackBrush);
	SafeRelease(&pBlackBrush);
	pCompatibleRenderTarget->EndDraw();

	ID2D1Bitmap* pCompatibleBitmap = NULL;
	hr = pCompatibleRenderTarget->GetBitmap(&pCompatibleBitmap);
	if (SUCCEEDED(hr))
	{
		ID2D1Effect* pShadowEffect = NULL;
		hr = pDeviceContext->CreateEffect(CLSID_D2D1Shadow, &pShadowEffect);
		if (SUCCEEDED(hr))
		{
			pShadowEffect->SetValue(D2D1_SHADOW_PROP_BLUR_STANDARD_DEVIATION, 5.f);
			pShadowEffect->SetInput(0, pCompatibleBitmap);
			pDeviceContext->DrawImage(pShadowEffect,
					D2D1::Point2F(10, 10),
					D2D1::RectF(0, 0, renderTargetSize.width, renderTargetSize.height),
					D2D1_INTERPOLATION_MODE_LINEAR,
					D2D1_COMPOSITE_MODE_SOURCE_OVER
				);
			SafeRelease(&pShadowEffect);
		}
		SafeRelease(&pCompatibleBitmap);
	}
	SafeRelease(&pCompatibleRenderTarget);

	ID2D1SolidColorBrush* pBlueBrush = NULL;
	pDeviceContext->CreateSolidColorBrush(D2D1::ColorF(D2D1::ColorF::Blue), &pBlueBrush);
	pDeviceContext->FillRectangle(D2D1::RectF(50.f, 50.f, 250.f, 250.f), pBlueBrush);
	SafeRelease(&pBlueBrush);
}

pDeviceContext->EndDraw();