Tag Archives: Direct2D

MFC Support for Direct2D – Part 6: Composite Effects

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

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);
}

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 (106)
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

MFC Support for DirectWrite – Part 11: About Trimming Again

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In a previous article, I showed how to trim a text which overflows the layout box. In the example presented there, the ellipsis is added at the end of truncated text. But if, let’s say, we have to show a long path and file name, it is not meaningful if the file name is not displayed. No problem, this can be easily resolved if have a look at DWRITE_TRIMMING structure which passed to IDWriteTextFormat::SetTrimming. The second parameter is a character code used as delimiter and the third one is the delimiter count. The text is preserved from the end until is found the delimiter which coresponds to delimiter count. For example, if the delimiter is backslash and the delimiter count is 2, a text like “e:\Articles\MFC Support for DirectWrite\DirectWrite Trimming Demo\D2DStaticCtrl.cpp” may be displayed as follows “e:\Articles…\DirectWrite Trimming Demo\D2DStaticCtrl.cpp”.

An example of trimming by using a delimiter

LRESULT CD2DStaticCtrl::OnAfxDraw2D(WPARAM wParam, LPARAM lParam)
{
    // ...

    // Set text trimming
    CComPtr<IDWriteInlineObject> spInlineObject;
    IDWriteFactory* pDirectWriteFactory = AfxGetD2DState()->GetWriteFactory();
    hr = pDirectWriteFactory->CreateEllipsisTrimmingSign(textFormat.Get(), 
        &spInlineObject);
    if (FAILED(hr))
        return FALSE;

    DWRITE_TRIMMING trimming = { DWRITE_TRIMMING_GRANULARITY_CHARACTER, '\\', 2 };

    hr = textFormat.Get()->SetTrimming(&trimming, spInlineObject);
    if (FAILED(hr))
        return FALSE;

    // ...

    return TRUE;
}

LRESULT CD2DStaticCtrl::OnAfxDraw2D(WPARAM wParam, LPARAM lParam)

{

// ...

// Set text trimming

CComPtr<IDWriteInlineObject> spInlineObject;

IDWriteFactory* pDirectWriteFactory = AfxGetD2DState()->GetWriteFactory();

hr = pDirectWriteFactory->CreateEllipsisTrimmingSign(textFormat.Get(),

&spInlineObject);

if (FAILED(hr))

return FALSE;

DWRITE_TRIMMING trimming = { DWRITE_TRIMMING_GRANULARITY_CHARACTER, '\\', 2 };

hr = textFormat.Get()->SetTrimming(&trimming, spInlineObject);

if (FAILED(hr))

return FALSE;

// ...

return TRUE;

}

Demo project

Download: DirectWrite Trimming Demo.zip (120)
The demo project is a simple MFC application which demonstrate how to trim text rendered with DirectWrite. You can choose the granularity, the delimiter and the delimiter count and see what is displayed.

DirectWrite Trimming Demo

Resources and related articles

MSDN: DWRITE_TRIMMING structure
Codexpert: MFC Support for DirectWrite – Part 8: Trimming

MFC Support for Direct2D – Part 5: Interoperability with GDI

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There are two ways to combine Direct2D with Windows GDI API in the same application:

Drawing Direct2D content to a GDI device context
Drawing GDI content to a Direct2D GDI-compatible render target

Let’s see each one!

Drawing Direct2D content to a GDI device context

For this purpose, use ID2D1DCRenderTarget instead of ID2D1HwndRenderTarget interface. If using MFC shipped with Visual Studio 2015 or newer, then CDCRenderTarget wrapper class makes the programmer life easier. Here are the steps:

In the WM_CREATE message handler call CWnd::EnableD2DSupport passing TRUE as second parameter. This way, the MFC framework creates a CDCRenderTarget instead of a CHwndRenderTarget object.

int CChildView::OnCreate(LPCREATESTRUCT lpCreateStruct)
{
    if (__super::OnCreate(lpCreateStruct) == -1)
        return -1;

    // Note: need Visual Studio 2015 or newer (_MFC_VER >= 0x0E00)
    BOOL bUseDCRenderTarget = TRUE;
    EnableD2DSupport(TRUE, bUseDCRenderTarget);

    if (!IsD2DSupportEnabled())
        return -1;

    return 0;
}

int CChildView::OnCreate(LPCREATESTRUCT lpCreateStruct)

{

if (__super::OnCreate(lpCreateStruct) == -1)

return -1;

// Note: need Visual Studio 2015 or newer (_MFC_VER >= 0x0E00)

BOOL bUseDCRenderTarget = TRUE;

EnableD2DSupport(TRUE, bUseDCRenderTarget);

if (!IsD2DSupportEnabled())

return -1;

return 0;

}

Map AFX_WM_DRAW2D registered messge.

C++

class CChildView : public CWnd { // ... afx_msg LRESULT OnAfxDraw2D(WPARAM wParam, LPARAM lParam); };

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class CChildView : public CWnd
{
    // ...
    afx_msg LRESULT OnAfxDraw2D(WPARAM wParam, LPARAM lParam);
};

C++

BEGIN_MESSAGE_MAP(CChildView, CWnd) // ... ON_REGISTERED_MESSAGE(AFX_WM_DRAW2D, &CChildView::OnAfxDraw2D) END_MESSAGE_MAP()

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BEGIN_MESSAGE_MAP(CChildView, CWnd)
    // ...
    ON_REGISTERED_MESSAGE(AFX_WM_DRAW2D, &CChildView::OnAfxDraw2D)
END_MESSAGE_MAP()

Finally, get the CDCRenderTarget* passed by MFC framework in LPARAM and enjoy.

LRESULT CChildView::OnAfxDraw2D(WPARAM wParam, LPARAM lParam)
{
    CDCRenderTarget* pDCRenderTarget = (CDCRenderTarget*)lParam;
    ASSERT_KINDOF(CDCRenderTarget, pDCRenderTarget);

    // Draw Direct2D content in GDI device context
    _DrawDirect2DContent(pDCRenderTarget);

    pDCRenderTarget->EndDraw();

    // Draw using GDI
    CWindowDC dc(this);
    _DrawGDIContent(&dc);

    return TRUE;
}

LRESULT CChildView::OnAfxDraw2D(WPARAM wParam, LPARAM lParam)

{

CDCRenderTarget* pDCRenderTarget = (CDCRenderTarget*)lParam;

ASSERT_KINDOF(CDCRenderTarget, pDCRenderTarget);

// Draw Direct2D content in GDI device context

_DrawDirect2DContent(pDCRenderTarget);

pDCRenderTarget->EndDraw();

// Draw using GDI

CWindowDC dc(this);

_DrawGDIContent(&dc);

return TRUE;

}

Drawing GDI content to a Direct2D GDI-compatible render target

So far, MFC has not a wrapper class for ID2D1GdiInteropRenderTarget interface. Also, CWnd::EnableD2DSupport creates a CHwndRenderTarget which is not GDI-compatible. So, we must do it ourselves. Here is the sample code:

class CChildView : public CWnd
{
    // ...
    CComQIPtr<ID2D1GdiInteropRenderTarget> m_spGdiInteropRenderTarget;
    // ...
    afx_msg LRESULT OnAfxDraw2D(WPARAM wParam, LPARAM lParam);
};

class CChildView : public CWnd

{

// ...

CComQIPtr<ID2D1GdiInteropRenderTarget> m_spGdiInteropRenderTarget;

// ...

afx_msg LRESULT OnAfxDraw2D(WPARAM wParam, LPARAM lParam);

};

int CChildView::OnCreate(LPCREATESTRUCT lpCreateStruct)
{
    if (__super::OnCreate(lpCreateStruct) == -1)
        return -1;

    // get global Direct2D factory
    ID2D1Factory* pDirect2DFactory = AfxGetD2DState()->GetDirect2dFactory();

    // create GDI-compatible window render target
    D2D1_RENDER_TARGET_PROPERTIES rtProps = D2D1::RenderTargetProperties();
    rtProps.usage = D2D1_RENDER_TARGET_USAGE_GDI_COMPATIBLE;
    rtProps.pixelFormat.format = DXGI_FORMAT_B8G8R8A8_UNORM;
    rtProps.pixelFormat.alphaMode = D2D1_ALPHA_MODE_PREMULTIPLIED;

    ID2D1HwndRenderTarget* pHwndRenderTarget = NULL;
    HRESULT hr = pDirect2DFactory->CreateHwndRenderTarget(
        &rtProps,
        &D2D1::HwndRenderTargetProperties(m_hWnd, CD2DSizeU()),
        &pHwndRenderTarget);
    if (FAILED(hr))
        return -1;

    // instantiate new CHwndRenderTarget and attach the GDI-compatible render target
    m_pRenderTarget = new CHwndRenderTarget;
    GetRenderTarget()->Attach(pHwndRenderTarget);

    // create ID2D1GdiInteropRenderTarget instance
    m_spGdiInteropRenderTarget = pHwndRenderTarget;
    if (!m_spGdiInteropRenderTarget)
        return -1;

    return 0;
}

int CChildView::OnCreate(LPCREATESTRUCT lpCreateStruct)

{

if (__super::OnCreate(lpCreateStruct) == -1)

return -1;

// get global Direct2D factory

ID2D1Factory* pDirect2DFactory = AfxGetD2DState()->GetDirect2dFactory();

// create GDI-compatible window render target

D2D1_RENDER_TARGET_PROPERTIES rtProps = D2D1::RenderTargetProperties();

rtProps.usage = D2D1_RENDER_TARGET_USAGE_GDI_COMPATIBLE;

rtProps.pixelFormat.format = DXGI_FORMAT_B8G8R8A8_UNORM;

rtProps.pixelFormat.alphaMode = D2D1_ALPHA_MODE_PREMULTIPLIED;

ID2D1HwndRenderTarget* pHwndRenderTarget = NULL;

HRESULT hr = pDirect2DFactory->CreateHwndRenderTarget(

&rtProps,

&D2D1::HwndRenderTargetProperties(m_hWnd, CD2DSizeU()),

&pHwndRenderTarget);

if (FAILED(hr))

return -1;

// instantiate new CHwndRenderTarget and attach the GDI-compatible render target

m_pRenderTarget = new CHwndRenderTarget;

GetRenderTarget()->Attach(pHwndRenderTarget);

// create ID2D1GdiInteropRenderTarget instance

m_spGdiInteropRenderTarget = pHwndRenderTarget;

if (!m_spGdiInteropRenderTarget)

return -1;

return 0;

}

LRESULT CChildView::OnAfxDraw2D(WPARAM wParam, LPARAM lParam)
{
    CHwndRenderTarget* pHwndRenderTarget = (CHwndRenderTarget*)lParam;
    ASSERT_VALID(pHwndRenderTarget);

    // draw using Direct2D
    _DrawDirect2DContent(pHwndRenderTarget);

    HDC hDC = NULL;
    HRESULT hr = m_spGdiInteropRenderTarget->GetDC(
        D2D1_DC_INITIALIZE_MODE_COPY, &hDC);

    if (FAILED(hr) || (NULL == hDC))
        return FALSE;

    // draw GDI content in a GDI-compatible window render target
    _DrawGDIContent(CDC::FromHandle(hDC));

    CRect rcClient;
    GetClientRect(rcClient);
    hr = m_spGdiInteropRenderTarget->ReleaseDC(rcClient);
    if (FAILED(hr))
        return FALSE;

    return TRUE;
}

LRESULT CChildView::OnAfxDraw2D(WPARAM wParam, LPARAM lParam)

{

CHwndRenderTarget* pHwndRenderTarget = (CHwndRenderTarget*)lParam;

ASSERT_VALID(pHwndRenderTarget);

// draw using Direct2D

_DrawDirect2DContent(pHwndRenderTarget);

HDC hDC = NULL;

HRESULT hr = m_spGdiInteropRenderTarget->GetDC(

D2D1_DC_INITIALIZE_MODE_COPY, &hDC);

if (FAILED(hr) || (NULL == hDC))

return FALSE;

// draw GDI content in a GDI-compatible window render target

_DrawGDIContent(CDC::FromHandle(hDC));

CRect rcClient;

GetClientRect(rcClient);

hr = m_spGdiInteropRenderTarget->ReleaseDC(rcClient);

if (FAILED(hr))

return FALSE;

return TRUE;

}

Demo projects

Download: Direct2D and GDI Interop Demo.zip (256)

The Visual C++ solution attached here has two simple projects showing the both Direct2D and GDI interoperatibily methods listed above.

Direct2D and GDI Interop – Demo Application

Notes

can be observed that Direct2D drawing quality is higher than GDI drawing, because Direct2D is capable of rendering with antialiasing;
given the first note, my opinion is that GDI drawing has no much sense once using Direct2D but never know…

Resources and related articles

MSDN: Direct2D and GDI Interoperability Overview
MSDN: CDCRenderTarget Class
MSDN: ID2D1GdiInteropRenderTarget interface

MFC Support for Direct2D – Part 4: Built-in Effects

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Direct2D has built-in support for image processing like changing brightness or contrast, blurring, creating drop shadows, and so on. Basically, we can use for this purpose the CreateEffect and DrawImage methods of ID2D1DeviceContext interface. So far, there is no MFC wrapper class for ID2D1DeviceContext but that’s not so big issue. Once having a valid ID2D1RenderTarget instance (wrapped in CRenderTarget class) we can easily get the ID2D1DeviceContext interface by calling QueryInterface. No sweat!

Getting ID2D1DeviceContext interface in an MFC application

    CComPtr<ID2D1DeviceContext> spDeviceContext;
    pRenderTarget->GetRenderTarget()->QueryInterface(__uuidof(ID2D1DeviceContext), 
        reinterpret_cast<void**>(&spDeviceContext));
    // ...

CComPtr<ID2D1DeviceContext> spDeviceContext;

pRenderTarget->GetRenderTarget()->QueryInterface(__uuidof(ID2D1DeviceContext),

reinterpret_cast<void**>(&spDeviceContext));

// ...

Or, a little bit easier, use CComQIPtr which calls QueryInterface for you.

    CComQIPtr<ID2D1DeviceContext> spDeviceContext = pRenderTarget->GetRenderTarget();
    // ...

1 2	CComQIPtr<ID2D1DeviceContext> spDeviceContext = pRenderTarget->GetRenderTarget(); // ...

Drawing an image using the Gaussian Blur built-in effect

Here is an example:

void CChildView::_DrawBlurredImage(CRenderTarget* pRenderTarget)
{
    // ...
    // get ID2D1DeviceContext interface
    CComQIPtr<ID2D1DeviceContext> spDeviceContext = 
        pRenderTarget->GetRenderTarget();

    // create Gaussian Blur effect
    CComPtr<ID2D1Effect> spEffect;
    HRESULT hr = spDeviceContext->CreateEffect(CLSID_D2D1GaussianBlur, &spEffect);
    ATLASSERT(SUCCEEDED(hr));
    // ...

    // set the input image
    spEffect->SetInput(0, m_pBitmap->Get());

    // finally, call ID2D1DeviceContext::DrawImage
    spDeviceContext->DrawImage(spEffect);
    //
    // if it doesn't blew up until here, means that it works. :)
    // ...  
}

void CChildView::_DrawBlurredImage(CRenderTarget* pRenderTarget)

{

// ...

// get ID2D1DeviceContext interface

CComQIPtr<ID2D1DeviceContext> spDeviceContext =

pRenderTarget->GetRenderTarget();

// create Gaussian Blur effect

CComPtr<ID2D1Effect> spEffect;

HRESULT hr = spDeviceContext->CreateEffect(CLSID_D2D1GaussianBlur, &spEffect);

ATLASSERT(SUCCEEDED(hr));

// ...

// set the input image

spEffect->SetInput(0, m_pBitmap->Get());

// finally, call ID2D1DeviceContext::DrawImage

spDeviceContext->DrawImage(spEffect);

// if it doesn't blew up until here, means that it works. :)

// ...

}

Just note that you should additionally include d2d1_1.h header and link your project to dxguid.lib. More details can be found in the attached demo project.

The demo project

Download: Gaussian Blur Effect demo.zip (237)

Notes

Picture used in the demo application is taken from http://www.icondrawer.com/gift-icons.php
I have to apologize for blurring the little cute dog.

Resources and related articles

MFC Support for DirectWrite – Part 9: Hit-Test

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DirectWrite has hit-testing support that can be useful for showing a caret, making a selection, doing some action if the user chicks in a given text range, and so on. The hit-test methods of IDWriteTextLayout interface are HitTestPoint, HitTestTextPosition and HitTestTextRange. Let me show a simple example for each one.

Hit-testing a point

This example calls IDWriteTextLayout::HitTestPoint in the WM_LBUTTONDOWN message handler and keeps in mind the text position in which the user has clicked.

void CChildView::OnLButtonDown(UINT nFlags, CPoint point)
{
    // ...
    // Get  IDWriteTextLayout interface from CD2DTextLayout object
    IDWriteTextLayout* pTextLayout = m_pTextLayout->Get();

    // pixel location X to hit-test, 
    // relative to the top-left location of the layout box. 
    FLOAT fPointX = static_cast<FLOAT>(point.x);
    // pixel location Y to hit-test, 
    // relative to the top-left location of the layout box.
    FLOAT fPointY = static_cast<FLOAT>(point.y);
    // an output flag that indicates whether the hit-test location 
    // is at the leading or the trailing side of the character.
    BOOL bIsTrailingHit = FALSE;
    // an output flag that indicates whether the hit-test location 
    // is inside the text string
    BOOL bIsInside = FALSE;
    // output geometry fully enclosing the hit-test location
    DWRITE_HIT_TEST_METRICS hitTestMetrics = { 0 };

    HRESULT hr = pTextLayout->HitTestPoint(IN fPointX, IN fPointY,
        OUT &bIsTrailingHit, OUT &bIsInside, OUT &hitTestMetrics);

    if (SUCCEEDED(hr))
    {
        // keep in mind the hit-test text position
        m_nCaretPosition = hitTestMetrics.textPosition;
        Invalidate();
    }

    CWnd::OnLButtonDown(nFlags, point);
}

void CChildView::OnLButtonDown(UINT nFlags, CPoint point)

{

// ...

// Get IDWriteTextLayout interface from CD2DTextLayout object

IDWriteTextLayout* pTextLayout = m_pTextLayout->Get();

// pixel location X to hit-test,

// relative to the top-left location of the layout box.

FLOAT fPointX = static_cast<FLOAT>(point.x);

// pixel location Y to hit-test,

// relative to the top-left location of the layout box.

FLOAT fPointY = static_cast<FLOAT>(point.y);

// an output flag that indicates whether the hit-test location

// is at the leading or the trailing side of the character.

BOOL bIsTrailingHit = FALSE;

// an output flag that indicates whether the hit-test location

// is inside the text string

BOOL bIsInside = FALSE;

// output geometry fully enclosing the hit-test location

DWRITE_HIT_TEST_METRICS hitTestMetrics = { 0 };

HRESULT hr = pTextLayout->HitTestPoint(IN fPointX, IN fPointY,

OUT &bIsTrailingHit, OUT &bIsInside, OUT &hitTestMetrics);

if (SUCCEEDED(hr))

{

// keep in mind the hit-test text position

m_nCaretPosition = hitTestMetrics.textPosition;

Invalidate();

}

CWnd::OnLButtonDown(nFlags, point);

}

Hit-testing a text position

Further, use the previousy kept in mind text position and call IDWriteTextLayout::HitTestTextPosition when need to draw the caret.

void CChildView::_DrawCaret(CHwndRenderTarget* pRenderTarget)
{
    ASSERT_VALID(m_pTextLayout);
    ASSERT(m_pTextLayout->IsValid());

    // Get  IDWriteTextLayout interface from CD2DTextLayout object
    IDWriteTextLayout* pTextLayout = m_pTextLayout->Get();

    // flag that indicates whether the pixel location is of the 
    // leading or the trailing side of the specified text position
    BOOL bIsTrailingHit = FALSE;
    FLOAT fPointX = 0.0f, fPointY = 0.0f;
    DWRITE_HIT_TEST_METRICS hitTestMetrics = { 0 };
    HRESULT hr = pTextLayout->HitTestTextPosition(
        IN m_nCaretPosition,
        IN bIsTrailingHit,
        OUT &fPointX,
        OUT &fPointY,
        OUT &hitTestMetrics);

    if (SUCCEEDED(hr))
    {
        // Draw the caret
        // Note: this is just for demo purpose and
        // you may want to make something more elaborated here
        CD2DRectF rcCaret(fPointX + TEXT_MARGIN, fPointY + TEXT_MARGIN,
            fPointX + TEXT_MARGIN + 2, fPointY + TEXT_MARGIN + hitTestMetrics.height);
        pRenderTarget->FillRectangle(&rcCaret,
            &CD2DSolidColorBrush(pRenderTarget, CARET_COLOR));
    }
}

void CChildView::_DrawCaret(CHwndRenderTarget* pRenderTarget)

{

ASSERT_VALID(m_pTextLayout);

ASSERT(m_pTextLayout->IsValid());

// Get IDWriteTextLayout interface from CD2DTextLayout object

IDWriteTextLayout* pTextLayout = m_pTextLayout->Get();

// flag that indicates whether the pixel location is of the

// leading or the trailing side of the specified text position

BOOL bIsTrailingHit = FALSE;

FLOAT fPointX = 0.0f, fPointY = 0.0f;

DWRITE_HIT_TEST_METRICS hitTestMetrics = { 0 };

HRESULT hr = pTextLayout->HitTestTextPosition(

IN m_nCaretPosition,

IN bIsTrailingHit,

OUT &fPointX,

OUT &fPointY,

OUT &hitTestMetrics);

if (SUCCEEDED(hr))

{

// Draw the caret

// Note: this is just for demo purpose and

// you may want to make something more elaborated here

CD2DRectF rcCaret(fPointX + TEXT_MARGIN, fPointY + TEXT_MARGIN,

fPointX + TEXT_MARGIN + 2, fPointY + TEXT_MARGIN + hitTestMetrics.height);

pRenderTarget->FillRectangle(&rcCaret,

&CD2DSolidColorBrush(pRenderTarget, CARET_COLOR));

}

Hit-testing a text range

And finally, here is an example of using IDWriteTextLayout::HitTestTextRange

BOOL CChildView::_TextRangeHitTest(const CPoint& point, const DWRITE_TEXT_RANGE& textRange)
{
    ASSERT_VALID(m_pTextLayout);
    ASSERT(m_pTextLayout->IsValid());

    // Get  IDWriteTextLayout interface from CD2DTextLayout object
    IDWriteTextLayout* pTextLayout = m_pTextLayout->Get();

    FLOAT nOriginX = 0.0f, nOriginY = 0.0f;
    UINT32 nActualHitTestMetricsCount = 0;
    // Call once IDWriteTextLayout::HitTestTextRange in order to find out
    // the place required for DWRITE_HIT_TEST_METRICS structures
    // See MSDN documentation:
    // https://msdn.microsoft.com/en-us/library/windows/desktop/dd371473(v=vs.85).aspx
    HRESULT hr = pTextLayout->HitTestTextRange(textRange.startPosition, textRange.length,
        nOriginX, nOriginY, NULL, 0, &nActualHitTestMetricsCount);

    if (HRESULT_FROM_WIN32(ERROR_INSUFFICIENT_BUFFER) != hr)
        return FALSE;

    // Allocate enough room for all hit-test metrics.
    std::vector<DWRITE_HIT_TEST_METRICS> vHitTestMetrics(nActualHitTestMetricsCount);

    // Call IDWriteTextLayout::HitTestTextRange again to effectively 
    // get the DWRITE_HIT_TEST_METRICS structures
    hr = pTextLayout->HitTestTextRange(textRange.startPosition, textRange.length,
        nOriginX, nOriginY,
        &vHitTestMetrics[0],
        static_cast(vHitTestMetrics.size()),
        &nActualHitTestMetricsCount);

    if (FAILED(hr))
        return FALSE;

    for (UINT32 nIndex = 0; nIndex < nActualHitTestMetricsCount; nIndex++)
    {
        DWRITE_HIT_TEST_METRICS& hitTestMetrics = vHitTestMetrics[nIndex];
        CRect rcHit((int)hitTestMetrics.left, (int)hitTestMetrics.top,
            (int)hitTestMetrics.left + (int)hitTestMetrics.width,
            (int)hitTestMetrics.top + (int)hitTestMetrics.height);

        if (rcHit.PtInRect(point))
            return TRUE;
    }
    return FALSE;
}

BOOL CChildView::_TextRangeHitTest(const CPoint& point, const DWRITE_TEXT_RANGE& textRange)

{

ASSERT_VALID(m_pTextLayout);

ASSERT(m_pTextLayout->IsValid());

// Get IDWriteTextLayout interface from CD2DTextLayout object

IDWriteTextLayout* pTextLayout = m_pTextLayout->Get();

FLOAT nOriginX = 0.0f, nOriginY = 0.0f;

UINT32 nActualHitTestMetricsCount = 0;

// Call once IDWriteTextLayout::HitTestTextRange in order to find out

// the place required for DWRITE_HIT_TEST_METRICS structures

// See MSDN documentation:

// https://msdn.microsoft.com/en-us/library/windows/desktop/dd371473(v=vs.85).aspx

HRESULT hr = pTextLayout->HitTestTextRange(textRange.startPosition, textRange.length,

nOriginX, nOriginY, NULL, 0, &nActualHitTestMetricsCount);

if (HRESULT_FROM_WIN32(ERROR_INSUFFICIENT_BUFFER) != hr)

return FALSE;

// Allocate enough room for all hit-test metrics.

std::vector<DWRITE_HIT_TEST_METRICS> vHitTestMetrics(nActualHitTestMetricsCount);

// Call IDWriteTextLayout::HitTestTextRange again to effectively

// get the DWRITE_HIT_TEST_METRICS structures

hr = pTextLayout->HitTestTextRange(textRange.startPosition, textRange.length,

nOriginX, nOriginY,

&vHitTestMetrics[0],

static_cast(vHitTestMetrics.size()),

&nActualHitTestMetricsCount);

if (FAILED(hr))

return FALSE;

for (UINT32 nIndex = 0; nIndex < nActualHitTestMetricsCount; nIndex++)

{

DWRITE_HIT_TEST_METRICS& hitTestMetrics = vHitTestMetrics[nIndex];

CRect rcHit((int)hitTestMetrics.left, (int)hitTestMetrics.top,

(int)hitTestMetrics.left + (int)hitTestMetrics.width,

(int)hitTestMetrics.top + (int)hitTestMetrics.height);

if (rcHit.PtInRect(point))

return TRUE;

}

return FALSE;

}

It can be used, for example, to set the hand cursor when the mouse is moved over the given text range:

void CChildView::OnMouseMove(UINT nFlags, CPoint point)
{
    DWRITE_TEXT_RANGE textRange = _GetHyperlinkTextRange();

    if (_TextRangeHitTest(point, textRange))
        ::SetCursor(m_hCursorHand);
    else
        ::SetCursor(m_hCursorArrow);

    CWnd::OnMouseMove(nFlags, point);
}

void CChildView::OnMouseMove(UINT nFlags, CPoint point)

{

DWRITE_TEXT_RANGE textRange = _GetHyperlinkTextRange();

if (_TextRangeHitTest(point, textRange))

::SetCursor(m_hCursorHand);

else

::SetCursor(m_hCursorArrow);

CWnd::OnMouseMove(nFlags, point);

}

or can show some internet page when te user clicks on a “hyperlink”.

void CChildView::OnLButtonUp(UINT nFlags, CPoint point)
{
    DWRITE_TEXT_RANGE textRange = _GetHyperlinkTextRange();

    if (_TextRangeHitTest(point, textRange))
    {
        ::ShellExecute(m_hWnd, _T("open"), TEXT_URL, NULL, NULL, SW_SHOWNORMAL);
    }

    CWnd::OnLButtonUp(nFlags, point);
}

void CChildView::OnLButtonUp(UINT nFlags, CPoint point)

{

DWRITE_TEXT_RANGE textRange = _GetHyperlinkTextRange();

if (_TextRangeHitTest(point, textRange))

{

::ShellExecute(m_hWnd, _T("open"), TEXT_URL, NULL, NULL, SW_SHOWNORMAL);

}

CWnd::OnLButtonUp(nFlags, point);

}

More details can be found in the demo examples attached to this article.

Demo projects

I’ve added the hit-test features to DirectWrite Static Control.
Download: Download: MFC Support for DirectWrite Demo (Part 9).zip (268)

MFC DirectWrite – Hit-Test Demo

Also here can be found a simpler application, only showing the DirectWrite hit-test features, to be easier understand: Simple DirectWrite Hit-Test Demo.zip (292)

Resources and related articles

MSDN: IDWriteTextLayout::HitTestPoint method
MSDN: IDWriteTextLayout::HitTestTextPosition method
MSDN: IDWriteTextLayout::HitTestTextRange method
MSDN: How to Perform Hit Testing on a Text Layout
pauldotknopf/WindowsSDK7-Samples: PadWrite

MFC Support for Direct2D – Part 3: Multithreading

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As shown in previous articles, we can enable MFC Direct2D support for a window by a call of CWnd::EnableD2DSupport.
Example:

int CSlideShowWnd::OnCreate(LPCREATESTRUCT lpCreateStruct)
{
    if (CWnd::OnCreate(lpCreateStruct) == -1)
        return -1;

    // Enable MFC Direct2D support
    EnableD2DSupport();
    // ...

    return 0;
}

int CSlideShowWnd::OnCreate(LPCREATESTRUCT lpCreateStruct)

{

if (CWnd::OnCreate(lpCreateStruct) == -1)

return -1;

// Enable MFC Direct2D support

EnableD2DSupport();

// ...

return 0;

}

So far so good as long as all windows which use Direct2D are running in the same thread (usually the application main thread). But let’s say we have more than one window with intensive rendering (e.g. some images slide show). In this case we would like to create each window in a separate thread. But this could cause the drawing to freeze or even application to crash. So, what should we do?

Create multi-threaded Direct2D factory

If step into MFC code starting with CWnd::EnableD2DSupport, we can notice the following:

check if Direct2D and DirectWrite (kept in a global object of type _AFX_D2D_STATE) are already created;
if not, call _AFX_D2D_STATE::InitD2D with default parameters D2D1_FACTORY_TYPE_SINGLE_THREADED and DWRITE_FACTORY_TYPE_SHARED.

Now, lets see the comments from D2D1_FACTORY_TYPE enumeration.

typedef enum D2D1_FACTORY_TYPE
{
    //
    // The resulting factory and derived resources may only be invoked serially.
    // Reference counts on resources are interlocked, however, resource and render
    // target state is not protected from multi-threaded access.
    //
    D2D1_FACTORY_TYPE_SINGLE_THREADED = 0,

    //
    // The resulting factory may be invoked from multiple threads. Returned resources
    // use interlocked reference counting and their state is protected.
    //
    D2D1_FACTORY_TYPE_MULTI_THREADED = 1,
    D2D1_FACTORY_TYPE_FORCE_DWORD = 0xffffffff

} D2D1_FACTORY_TYPE;

typedef enum D2D1_FACTORY_TYPE

{

// The resulting factory and derived resources may only be invoked serially.

// Reference counts on resources are interlocked, however, resource and render

// target state is not protected from multi-threaded access.

D2D1_FACTORY_TYPE_SINGLE_THREADED = 0,

// The resulting factory may be invoked from multiple threads. Returned resources

// use interlocked reference counting and their state is protected.

D2D1_FACTORY_TYPE_MULTI_THREADED = 1,

D2D1_FACTORY_TYPE_FORCE_DWORD = 0xffffffff

} D2D1_FACTORY_TYPE;

Also, let’s see what MSDN documentation states:

D2D1_FACTORY_TYPE_SINGLE_THREADED
No synchronization is provided for accessing or writing to the factory or the objects it creates. If the factory or the objects are called from multiple threads, it is up to the application to provide access locking.
D2D1_FACTORY_TYPE_MULTI_THREADED
Direct2D provides synchronization for accessing and writing to the factory and the objects it creates, enabling safe access from multiple threads.

Making the synchronization is not so handy so we have to find a way to create a Direct2D factory that uses multi-threaded model. Fortunately, that’s very easy by a single call of CWinApp::EnableD2DSupport.

BOOL CDemoApp::InitInstance()
{
    // NOTE: Just for testing purpose, comment the below line of code
    //       then open more than one slide-show windows which are running 
    //       in different threads. See what happens.
    VERIFY(EnableD2DSupport(D2D1_FACTORY_TYPE_MULTI_THREADED));
    // ...

    return FALSE;
}

BOOL CDemoApp::InitInstance()

{

// NOTE: Just for testing purpose, comment the below line of code

// then open more than one slide-show windows which are running

// in different threads. See what happens.

VERIFY(EnableD2DSupport(D2D1_FACTORY_TYPE_MULTI_THREADED));

// ...

return FALSE;

}

That’s all. Hurray!

Demo application

Download: MFC Direct2D Multithreading Demo.zip (269)

The demo application can create multiple windows that perform image slideshow with Direct2D, each one in its own thread. Just push the button then select a folder containing image files.

MFC Direct2D Multithreading – Demo

Resources and related articles

MSDN: CWinApp::EnableD2DSupport
MSDN: D2D1CreateFactory function
MSDN: D2D1_FACTORY_TYPE enumeration
Codexpert blog: MFC Support for Direct2D articles

MFC Support for DirectWrite – Part 8: Trimming

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When using “classic” GDI functions i.e. CDC::DrawText, it’s no sweat to trim with ellipsis a single-line text when that text does not fit in the drawing rectangle width, by specifying DT_WORDBREAK flag. We cannot find a similar flag for CRenderTarget::DrawText or CRenderTarget::DrawTextLayout. However, trimming a text is also possible with DirectDraw. All we have to do is the following:

call IDWriteFactory::CreateEllipsisTrimmingSign to create an inline object for trimming, using ellipsis as the omission sign;
pass the created inline object to IDWriteTextFormat::SetTrimming.

Here is a simple code example in an MFC-based application:

Direct2D text trimming code sample

    // ...
    CD2DTextFormat textFormat(pRenderTarget, m_strFontFamilyName, m_fFontSize);
    IDWriteTextFormat* pTextFormat = textFormat.Get();

    // Set single-line text
    pTextFormat->SetWordWrapping(DWRITE_WORD_WRAPPING_NO_WRAP);

    // Get IDWriteFactory
    _AFX_D2D_STATE* pD2DState = AfxGetD2DState();
    IDWriteFactory* pDirectWriteFactory = pD2DState->GetWriteFactory();

    // Create an inline object for trimming
    CComPtr<IDWriteInlineObject> spInlineObject;
    pDirectWriteFactory->CreateEllipsisTrimmingSign(textFormat.Get(), &spInlineObject);

    // Call IDWriteTextFormat::SetTrimming to set trimming for text overflowing the layout width.
    // Note: use DWRITE_TRIMMING_GRANULARITY_CHARACTER for trimming at character cluster boundary
    //       or DWRITE_TRIMMING_GRANULARITY_WORD for trimming at word boundary.
    DWRITE_TRIMMING trimming = { DWRITE_TRIMMING_GRANULARITY_CHARACTER, 0, 0 };
    pTextFormat->SetTrimming(&trimming, spInlineObject);
    // ...

    // Draw the text in render target
    pRenderTarget->DrawText(m_strText, rcDraw, m_pTextBrush, &textFormat);

// ...

CD2DTextFormat textFormat(pRenderTarget, m_strFontFamilyName, m_fFontSize);

IDWriteTextFormat* pTextFormat = textFormat.Get();

// Set single-line text

pTextFormat->SetWordWrapping(DWRITE_WORD_WRAPPING_NO_WRAP);

// Get IDWriteFactory

_AFX_D2D_STATE* pD2DState = AfxGetD2DState();

IDWriteFactory* pDirectWriteFactory = pD2DState->GetWriteFactory();

// Create an inline object for trimming

CComPtr<IDWriteInlineObject> spInlineObject;

pDirectWriteFactory->CreateEllipsisTrimmingSign(textFormat.Get(), &spInlineObject);

// Call IDWriteTextFormat::SetTrimming to set trimming for text overflowing the layout width.

// Note: use DWRITE_TRIMMING_GRANULARITY_CHARACTER for trimming at character cluster boundary

// or DWRITE_TRIMMING_GRANULARITY_WORD for trimming at word boundary.

DWRITE_TRIMMING trimming = { DWRITE_TRIMMING_GRANULARITY_CHARACTER, 0, 0 };

pTextFormat->SetTrimming(&trimming, spInlineObject);

// ...

// Draw the text in render target

pRenderTarget->DrawText(m_strText, rcDraw, m_pTextBrush, &textFormat);

Demo project

Download: MFC Support for DirectWrite Demo (Part 8).zip (231)

The demo project contains sample code for all my DirectWrite-related articles. To demonstrate this one, in Trimming granularity combo, select “Character” or “Word”. Also select “No wrap” in Word wrapping combo then have fun.

MFC DirectWrite Demo Project

Resources and related articles

MSDN: IDWriteTextFormat::SetTrimming
MSDN: IDWriteFactory::CreateEllipsisTrimmingSign
Codexpert blog: MFC Support for DirectWrite articles
Codexpert blog: MFC Support for Direct2D articles

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