Tag Archives: mfc

MFC Support for DirectWrite – Part 10: Outlined Text

In a previous article, I showed the basics of custom text rendering with DirectWrite (see MFC Support for DirectWrite – Part 7: A Step to Custom Rendering). So far so good but it just mimics the default text rendering. Let’s now modify the overridden IDWriteTextRenderer::DrawGlyphRun in order to draw outlined text.

Overridden IDWriteTextRenderer::DrawGlyphRun implementation

A method for drawing outlined text

Basically, the steps where the following:

  1. if pClientDrawingContext parameter is null then perform the default drawing;
  2. otherwhise, call _DrawOutlinedGlyphRun pasing an object that contains the brushes for text outline and fill (COutlinedTextEffect);
  3. create a path geometry (CD2DPathGeometry);
  4. instantiate a geometry sink that is used to populate the path geometry (CD2DGeometrySink);
  5. get IDWriteFontFace interface from DWRITE_GLYPH_RUN structure;
  6. call IDWriteFontFace::GetGlyphRunOutline, passing a bunch of parameters, most of them contained in DWRITE_GLYPH_RUN structure plus our geometry sink;
  7. close the geometry sink;
  8. translate the render target according to the glyph run baseline origin (baselineOriginX and baselineOriginY parameters of DrawGlyphRun);
  9. finally, call CRenderTarget::DrawGeometry and CRenderTarget::FillGeometry and…
  10. …do not forget to restore the initial render target transform.

You can find more details in the demo application attached here. Also you can have a look in the related articles mentioned at the bottom of this page.

Demo project

The demo project draws outlined text in order to make it readable over any background image.
DownloadOutlined Text Demo.zip (327)

Outlined Text demo project

Outlined Text demo project

Resources and related articles

MFC Support for DirectWrite – Part 9: Hit-Test

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.

Hit-testing a text position

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

Hit-testing a text range

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

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

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

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 (323)

MFC DirectWrite - Hit-Test Demo

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 (353)

Resources and related articles

MFC Support for Direct2D – Part 3: Multithreading

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

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:

  1. check if Direct2D and DirectWrite (kept in a global object of type _AFX_D2D_STATE) are already created;
  2. 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.

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.

That’s all. Hurray!

Demo application

Download: MFC Direct2D Multithreading Demo.zip (324)

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

MFC Direct2D Multithreading – Demo

 

Resources and related articles

MFC Support for DirectWrite – Part 8: Trimming

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:

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

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

Direct2D text trimming code sample

Demo project

Download: MFC Support for DirectWrite Demo (Part 8).zip (297)

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

MFC DirectWrite Demo Project

 

Resources and related articles

Codexpert – 2016 Articles Summary

C++ Programming Language

Microsoft Libraries

Visual C++

See also

Easy PNG Resource Loading with MFC – Part 2

A previous article demonstrates how easy is to load images from PNG resources, by using Direct2D MFC support. I have found even an easier way: CPngImage class which extends CBitmap with methods that allow loading images from PNG format files and resources.
Here is a brief example:

Using CPngImage class for loading PNG resources

Demo project

It is a simple dialog-based MFC application that loads a bitmap from PNG resource then use the bitmap for setting the image in a static picture control.
Download: PNG Resource Loading (VS 2015).zip (603)

PNG Resource Loading - Demo Application

PNG Resource Loading – Demo Application

Notes

  • of course, we can follow a similar way to set images in other controls, like for example CMFCButton;
  • CPngImage was designed for internal use in the MFC framework, but so far I didn’t see any problem in using it for our own purposes.

Resources and related articles

Read IFD and EXIF Metadata with WIC and MFC

A graphic file can store additional information abaout image (camera model, camera manufacturer, date and time, etc). Windows Imaging Component (WIC) provides interfaces which allow dealing with image metadata. Basically, for reading metadata we need an IWICMetadataQueryReader instance to call its GetMetadataByName method. The first argument of GetMetadataByName is based in Metadata Query Language and is composed by a path in metadata tree and an item name/identifier or a block name/identifier (a block contains itself items and/or other blocks). For more details, please see Metadata Query Language Overview in MSDN library. The second argument is a PROPVARIANT structure that gets the value. If returned value is of type VT_UNKNOWN then we’ve got a block, otherwise we’ve got an item value.

Among other metadata blocks defined in TIFF standard, which are are common to other graphic file formats (e.g. JPEG and raw image file formats like NEF) there are IFD (Image File Directory) and EXIF metadata blocks. I’ll not provide more details here (they can be found in MSDN or in other documents and articles). Just to note that EXIF is nested into IFD block and, while IFD block is placed in the metadata root for TIFF, it is nested/embedded into APP1 block for JPEG file format. For example, to get the ISOSpeed EXIF value, we can call IWICMetadataQueryReader::GetMetadataByName passing “/ifd/exif/{ushort=34867}” in case of TIFF or “/app1/ifd/exif/{ushort=34867}” for JPEG format.

Reading IFD and EXIF metadata from a JPEG file

Here is a brief example:

As can be seen, this example assumes that we have a JPEG file and uses the root metadata query reader by passing the item full path.
Let’s improve it in order to read metadata also from TIFF, NEF and other formats. Let’s also get and use the embedded metadata readers both for IFD and EXIF blocks.

Reading IFD and EXIF metadata from an image file

First, we need a functions which finds out if we are dealing with JPEG or other format.

Next, we can write a function that gets the IFD query reader.

Also we need a function to get the embedded EXIF query reader. Here we can write a generic one, which takes the parent query reader and the block name.

Let’a also write a function that gets the root query reader.

Now, the function which reads the image IFD and EXIF metadata may look like this:

It’s a little bit better than the previous example but still needs to be completed and a lot of code refactoring. I’ll do that in a future article to present a “full featured” IFD/EXIF metadata reader.

References and related articles