initial commit

Signed-off-by: Peter Siegmund <mars3142@noreply.mars3142.dev>

libs/wxWidgets-3.3.1/interface/wx/dcmemory.h

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+/////////////////////////////////////////////////////////////////////////////
+// Name:        dcmemory.h
+// Purpose:     interface of wxMemoryDC
+// Author:      wxWidgets team
+// Licence:     wxWindows licence
+/////////////////////////////////////////////////////////////////////////////
+
+/**
+    @class wxMemoryDC
+
+    A memory device context provides a means to draw graphics onto a bitmap.
+    When drawing in to a mono-bitmap, using @c wxWHITE, @c wxWHITE_PEN and
+    @c wxWHITE_BRUSH will draw the background colour (i.e. 0) whereas all other
+    colours will draw the foreground colour (i.e. 1).
+
+    A bitmap must be selected into the new memory DC before it may be used for
+    anything. Typical usage is as follows:
+
+    @code
+    // Create a memory DC
+    wxMemoryDC temp_dc;
+    temp_dc.SelectObject(test_bitmap);
+
+    // We can now draw into the memory DC...
+    // Copy from this DC to another DC.
+    old_dc.Blit(250, 50, BITMAP_WIDTH, BITMAP_HEIGHT, temp_dc, 0, 0);
+    @endcode
+
+    Note that the memory DC must be deleted (or the bitmap selected out of it)
+    before a bitmap can be reselected into another memory DC.
+
+    And, before performing any other operations on the bitmap data, the bitmap
+    must be selected out of the memory DC:
+
+    @code
+    temp_dc.SelectObject(wxNullBitmap);
+    @endcode
+
+    This happens automatically when wxMemoryDC object goes out of scope.
+
+    Note that the scaling factor of the bitmap determines the scaling factor
+    used by this device context, so when using a memory device context as a
+    back buffer for a window, you should typically create the bitmap using the
+    same scale factor as used by the window, e.g.
+    @code
+    void MyWindow::OnPaint(wxPaintEvent&)
+    {
+        wxBitmap bmp;
+        bmp.CreateWithDIPSize(GetClientSize(), GetDPIScaleFactor());
+        {
+            wxMemoryDC memdc(bmp);
+            ... use memdc to draw on the bitmap ...
+        }
+
+        wxPaintDC dc(this);
+        dc.DrawBitmap(bmp, wxPoint(0, 0));
+    }
+    @endcode
+
+    @library{wxcore}
+    @category{dc}
+
+    @see wxBitmap, wxDC
+*/
+class wxMemoryDC : public wxDC
+{
+public:
+    /**
+        Constructs a new memory device context.
+
+        Use the wxDC::IsOk() member to test whether the constructor was
+        successful in creating a usable device context. Don't forget to select
+        a bitmap into the DC before drawing on it.
+    */
+    wxMemoryDC();
+
+    /**
+        Constructs a new memory device context having the same characteristics
+        as the given existing device context.
+
+        This constructor creates a memory device context @e compatible with @a
+        dc in wxMSW, the argument is ignored in the other ports. If @a dc is
+        @NULL, a device context compatible with the screen is created, just as
+        with the default constructor.
+
+        Note that the DPI scaling factor is @e not inherited from @a dc, but
+        is determined by the scaling factor of the bitmap selected into this
+        device context later.
+     */
+    wxMemoryDC(wxDC *dc);
+
+    /**
+        Constructs a new memory device context and calls SelectObject() with
+        the given bitmap.
+
+        Use the wxDC::IsOk() member to test whether the constructor was
+        successful in creating a usable device context.
+    */
+    wxMemoryDC(wxBitmap& bitmap);
+
+    /**
+        Allow using this device context object to modify the given bitmap
+        contents.
+
+        Note that if you need to only use the existing bitmap contents instead
+        of modifying it, you should use SelectObjectAsSource() instead.
+
+        Before using the updated bitmap data, make sure to select it out of
+        context first either by selecting ::wxNullBitmap into the device
+        context or destroying the device context entirely.
+
+        If the bitmap is already selected in this device context, nothing is
+        done. If it is selected in another context, the function asserts and
+        drawing on the bitmap won't work correctly.
+
+        Note that this function changes the scale factor of this device context
+        (as returned by wxDC::GetContentScaleFactor()) to be the same as the
+        bitmap scale factor (as returned by wxBitmap::GetScaleFactor()).
+    */
+    void SelectObject(wxBitmap& bitmap);
+
+    /**
+        Selects the given bitmap into the device context, to use as the memory
+        bitmap.
+
+        Selecting the bitmap as source into a memory DC allows you to copy its
+        contents to another device context using wxDC::Blit(). Note that using
+        wxDC::DrawBitmap() or wxDC::DrawIcon() is a simpler way to do the same
+        thing.
+
+        @note Modifying a bitmap selected only as a source may not work
+        correctly and can notably modify the other bitmaps sharing the same
+        data due to the use of reference counting (see @ref overview_refcount).
+
+        If the argument is ::wxNullBitmap (or some other uninitialised wxBitmap)
+        the current bitmap is selected out of the device context, allowing the
+        current bitmap to be destroyed safely.
+    */
+    void SelectObjectAsSource(const wxBitmap& bitmap);
+
+    /**
+       Get the selected bitmap.
+    */
+    const wxBitmap& GetSelectedBitmap() const;
+    wxBitmap& GetSelectedBitmap();
+
+};
+