예제 #1
0
        public static WindowsGraphics FromGraphics(Graphics g, ApplyGraphicsProperties properties)
        {
            Debug.Assert(g != null, "null Graphics object.");
            //Debug.Assert( properties != ApplyGraphicsProperties.None, "Consider using other WindowsGraphics constructor if not preserving Graphics properties." );

            WindowsRegion wr = null;

            float[] elements = null;

            Region clipRgn     = null;
            Matrix worldTransf = null;

            if ((properties & ApplyGraphicsProperties.TranslateTransform) != 0 || (properties & ApplyGraphicsProperties.Clipping) != 0)
            {
                if (g.GetContextInfo() is object[] data && data.Length == 2)
                {
                    clipRgn     = data[0] as Region;
                    worldTransf = data[1] as Matrix;
                }

                if (worldTransf != null)
                {
                    if ((properties & ApplyGraphicsProperties.TranslateTransform) != 0)
                    {
                        elements = worldTransf.Elements;
                    }
                    worldTransf.Dispose();
                }

                if (clipRgn != null)
                {
                    if ((properties & ApplyGraphicsProperties.Clipping) != 0)
                    {
                        // We have to create the WindowsRegion and dipose the Region object before locking the Graphics object,
                        // in case of an unlikely exception before releasing the WindowsRegion, the finalizer will do it for us.
                        // (no try-finally block since this method is used frequently - perf).
                        // If the Graphics.Clip has not been set (Region.IsInfinite) we don't need to apply it to the DC.
                        if (!clipRgn.IsInfinite(g))
                        {
                            wr = WindowsRegion.FromRegion(clipRgn, g); // WindowsRegion will take ownership of the hRegion.
                        }
                    }
                    clipRgn.Dispose(); // Disposing the Region object doesn't destroy the hRegion.
                }
            }

            WindowsGraphics wg = WindowsGraphics.FromHdc(g.GetHdc()); // This locks the Graphics object.

            wg.graphics = g;

            // Apply transform and clip
            if (wr != null)
            {
                using (wr)
                {
                    // If the Graphics object was created from a native DC the actual clipping region is the intersection
                    // beteween the original DC clip region and the GDI+ one - for display Graphics it is the same as
                    // Graphics.VisibleClipBounds.
                    wg.DeviceContext.IntersectClip(wr);
                }
            }

            if (elements != null)
            {
                // elements (XFORM) = [eM11, eM12, eM21, eM22, eDx, eDy], eDx/eDy specify the translation offset.
                wg.DeviceContext.TranslateTransform((int)elements[4], (int)elements[5]);
            }

            return(wg);
        }