C# Cairo.Context.SetSourceSurface方法代码示例

		public void Start (BaseEffect effect)
		{			
			if (live_preview_enabled)
				throw new InvalidOperationException ("LivePreviewManager.Start() called while live preview is already enabled.");
			
			// Create live preview surface.
			// Start rendering.
			// Listen for changes to effectConfiguration object, and restart render if needed.
			
			live_preview_enabled = true;
			apply_live_preview_flag = false;
			cancel_live_preview_flag = false;
			
			layer = PintaCore.Layers.CurrentLayer;
			this.effect = effect;
			
			// Handle selection path.
			PintaCore.Tools.Commit ();
			selection_path = (PintaCore.Layers.ShowSelection) ? PintaCore.Workspace.ActiveDocument.Selection.SelectionPath : null;
			render_bounds = selection_path.GetBounds ();
			render_bounds = PintaCore.Workspace.ClampToImageSize (render_bounds);			
									
			//TODO Use the current tool layer instead.
			live_preview_surface = new Cairo.ImageSurface (Cairo.Format.Argb32,
			                                  PintaCore.Workspace.ImageSize.Width,
			                                  PintaCore.Workspace.ImageSize.Height);
			
			// Paint the pre-effect layer surface into into the working surface.
			using (var ctx = new Cairo.Context (live_preview_surface)) {
				ctx.SetSourceSurface (layer.Surface, (int) layer.Offset.X, (int) layer.Offset.Y);
				ctx.Paint ();
			}
			
			if (effect.EffectData != null)
				effect.EffectData.PropertyChanged += EffectData_PropertyChanged;
			
			if (Started != null) {
				Started (this, new LivePreviewStartedEventArgs());
			}
			
			var settings = new AsyncEffectRenderer.Settings () {
				ThreadCount = PintaCore.System.RenderThreads,
				TileWidth = render_bounds.Width,
				TileHeight = 1,
				ThreadPriority = ThreadPriority.BelowNormal
			};
			
			Debug.WriteLine (DateTime.Now.ToString("HH:mm:ss:ffff") + "Start Live preview.");
			
			renderer = new Renderer (this, settings);
			renderer.Start (effect, layer.Surface, live_preview_surface, render_bounds);
			
			if (effect.IsConfigurable) {		
				if (!effect.LaunchConfiguration ()) {
					PintaCore.Chrome.MainWindowBusy = true;
					Cancel ();
				} else {
					PintaCore.Chrome.MainWindowBusy = true;
					Apply ();
				}
			} else {
				PintaCore.Chrome.MainWindowBusy = true;
				Apply ();
			}
		}

        private Layer CreateOffsetLayer(Layer original)
        {
            var offset = OffsetLayer;
            offset.Surface.Clear ();

            using (var g = new Cairo.Context (offset.Surface)) {
                g.SetSourceSurface (original.Surface, (int)original.Offset.X, (int)original.Offset.Y);
                g.Paint ();
            }

            offset.BlendMode = original.BlendMode;
            offset.Offset = original.Offset;
            offset.Opacity = original.Opacity;

            return offset;
        }

		// Called from asynchronously from Renderer.OnCompletion ()
		void HandleApply ()
		{
			Debug.WriteLine ("LivePreviewManager.HandleApply()");

			var item = new SimpleHistoryItem (effect.Icon, effect.Name);
			item.TakeSnapshotOfLayer (PintaCore.Layers.CurrentLayerIndex);			
			
			using (var ctx = new Cairo.Context (layer.Surface)) {
				
				ctx.Save ();
				ctx.AppendPath (PintaCore.Workspace.ActiveDocument.Selection.SelectionPath);
				ctx.FillRule = Cairo.FillRule.EvenOdd;
				ctx.Clip ();				
			
				ctx.Operator = Cairo.Operator.Source;
				
				ctx.SetSourceSurface (live_preview_surface, (int)layer.Offset.X, (int)layer.Offset.Y);
				ctx.Paint ();
				ctx.Restore ();
			}
			
			PintaCore.History.PushNewItem (item);
			
			FireLivePreviewEndedEvent(RenderStatus.Completed, null);
			
			live_preview_enabled = false;
			
			PintaCore.Workspace.Invalidate (); //TODO keep track of dirty bounds.
			CleanUp ();
		}

        private void UpdateThumbnail()
        {
            double scalex = (double)Allocation.Width / (double)PintaCore.Workspace.ImageSize.Width;
            double scaley = (double)Allocation.Height / (double)PintaCore.Workspace.ImageSize.Height;

            thumbnail = new Cairo.ImageSurface (Cairo.Format.Argb32, Allocation.Width, Allocation.Height);

            using (Cairo.Context g = new Cairo.Context (thumbnail)) {
                g.Scale (scalex, scaley);
                foreach (Layer layer in PintaCore.Layers.GetLayersToPaint ()) {
                    g.SetSourceSurface (layer.Surface, (int)layer.Offset.X, (int)layer.Offset.Y);
                    g.PaintWithAlpha (layer.Opacity);
                }
            }
        }