Bitmap source effect

Use the bitmap source effect to generate an ID2D1Image from a IWICBitmapSource for use as an input in an effect graph. This effect performs scaling and rotation on the CPU. It can also optionally generate a system memory mipmap, which can be a performance optimization for actively scaling very large images at various reduced resolutions.

The CLSID for this effect is CLSID_D2D1BitmapSource.

• Effect properties
• Interpolation modes
• Orientation
• Alpha modes
• Remarks
• Requirements
• Related topics

Effect properties

Interpolation modes

The effect interpolates using this mode when it scales an image or when it corrects the DPI. The interpolation modes this effect uses are calculated by the CPU, not the GPU.

Orientation

The Orientation property can be used to apply an EXIF orientation flag that is embedded within an image.

This code snippet demonstrates how to convert from EXIF orientation values (defined in propkey.h) to D2D1_BITMAPSOURCE_ORIENTATION values.

#include <propkey.h>
#include <d2d1effects.h>

D2D1_BITMAPSOURCE_ORIENTATION GetBitmapSourceOrientation(unsigned short PhotoOrientation)
{
       switch (PhotoOrientation)
       {
       case PHOTO_ORIENTATION_NORMAL:
              return D2D1_BITMAPSOURCE_ORIENTATION_DEFAULT;
       case PHOTO_ORIENTATION_FLIPHORIZONTAL:
              return D2D1_BITMAPSOURCE_ORIENTATION_FLIP_HORIZONTAL;
       case PHOTO_ORIENTATION_ROTATE180:
              return D2D1_BITMAPSOURCE_ORIENTATION_ROTATE_CLOCKWISE180;
       case PHOTO_ORIENTATION_FLIPVERTICAL:
              return D2D1_BITMAPSOURCE_ORIENTATION_ROTATE_CLOCKWISE180_FLIP_HORIZONTAL;
       case PHOTO_ORIENTATION_TRANSPOSE: 
              return D2D1_BITMAPSOURCE_ORIENTATION_ROTATE_CLOCKWISE90_FLIP_HORIZONTAL;
       case PHOTO_ORIENTATION_ROTATE270:
              return D2D1_BITMAPSOURCE_ORIENTATION_ROTATE_CLOCKWISE90;
       case PHOTO_ORIENTATION_TRANSVERSE:
              return D2D1_BITMAPSOURCE_ORIENTATION_ROTATE_CLOCKWISE270_FLIP_HORIZONTAL;
       case PHOTO_ORIENTATION_ROTATE90:
              return D2D1_BITMAPSOURCE_ORIENTATION_ROTATE_CLOCKWISE270;
       default:
              return D2D1_BITMAPSOURCE_ORIENTATION_DEFAULT;
       }
}

Alpha modes

Remarks

To optimize performance when using WIC and Direct2D together, you should use IWICFormatConverter to convert to an appropriate pixel format based your app s scenario and the image s native precision.

In most cases, either your app s Direct2D pipeline only requires 8 bits per channel (bpc) of precision, or the image only provides 8 bpc precision, and therefore you should convert to GUID_WICPixelFormat32bppPBGRA. However, if you want to take advantage of extra precision provided by an image (for example, a JPEG-XR or TIFF stored with greater than 8 bpc precision), you should use an RGBA-based pixel format. The below table provides more details.

Because many image formats support multiple levels of precision, you should use IWICBitmapSource::GetPixelFormat to obtain the image s native pixel format, and then use IWICPixelFormatInfo to determine how many bits per channel of precision are available for that format. Also, note that not all hardware supports high precision pixel formats. In those cases your app may need to fall back to the WARP device to support high precision.

Requirements

Related topics

ID2D1Effect