Rendering to bitmaps

Rendering to bitmaps

UniFEP V3 automatically enables Unicode display in all graphics contexts, including CFbsBitGc. This is not the case in UniFEP V2, where CFbsBitGc is not Unicode-capable.

UniFEP comes with a small library UNIBIT.DLL implementing the class CUnicodeRenderer. An object of this class can be used to render Unicode on a bitmap in UniFEP V2. It is not necessary to do this just to render Unicode on a bitmap in UniFEP V3, but the class has not become useless: By proceeding as described below, a protective layer is created that will correctly render Unicode text even if Unicode characters are split over consecutive calls to DrawText (in principle you could render one byte at a time). This is rarely necessary for newly developed applications, but useful to port legacy applications, or for applications using certain EPOC classes for rendering.

The class CUnicodeRenderer is defined in the header file ufrender.h

Once you have created an object of type CUnicodeRenderer, use SetGc(aGc) to attach a CBitmapContext to it. Use the methods of CUnicodeRenderer instead of the CBitmapContext methods with the same name.

You are free to use the other CBitmapContext methods for other drawing operations. However, there is one restriction: You cannot use SetOrigin between setting a clipping rectangle and drawing text. (In other words, if you have an active clipping region when calling DrawText, you must not have changed the origin between the calls to SetClippingRect and DrawText.)

The same CUnicodeRenderer object can be used for several CBitmapContexts by calling SetGc again.

To obtain a CUnicodeRenderer object, proceed as follows:

  RLibrary dll;
  _LIT(KUniBitDllName, "\\System\\Libs\\UniBit.dll");
  User::LeaveIfError(dll.Load(KUniBitDllName));
  TLibraryFunction entry = dll.Lookup(1);
  CUnicodeRenderer *aUniRenderer = (CUnicodeRenderer *) ((*entry)());
  dll.Close();

(The DLL can indeed be closed immediately, it is no longer necessary. The CUnicodeRenderer methods are not actually in that DLL.)

Rendering to bitmaps