private void RenderImage(DrawArgs args)
{
if (args.DrawMode == DrawMode.Refresh)
{
RefreshImage(args);
return;
}
if (_firstRender)
{
// the first time we try to render a freshly cloned image, we need to draw it twice
// this is to make sure the client rectangle is updated when we try to compute the correct point of interest
_firstRender = false;
RenderImage(args);
}
try
{
var sourceTransform = (ImageSpatialTransform)((ISpatialTransformProvider)SelectedPresentationImage).SpatialTransform;
var transform = (ImageSpatialTransform)((ISpatialTransformProvider)_magnificationImage).SpatialTransform;
float scale = sourceTransform.Scale * ToolSettings.DefaultInstance.MagnificationFactor;
transform.ScaleToFit = false;
transform.Scale = scale;
transform.TranslationX = 0;
transform.TranslationY = 0;
var midPoint = new PointF(args.RenderingSurface.ClientRectangle.Width / 2f, args.RenderingSurface.ClientRectangle.Height / 2f);
var sourcePointOfInterest = sourceTransform.ConvertToSource(_tileLocation);
// compute translation required to move the point of interest on the magnified image to the centre of the client area
var translation = transform.ConvertToSource(midPoint) - new SizeF(sourcePointOfInterest);
transform.TranslationX = translation.X;
transform.TranslationY = translation.Y;
_magnificationImage.Draw(args);
// clear the rendering exception message
_lastRenderExceptionMessage = null;
}
catch (Exception ex)
{
Platform.Log(LogLevel.Error, ex,
"An error has occured while rendering the magnified contents of the tile.");
// a rendering exception was encountered, so set the message field
_lastRenderExceptionMessage = ex is RenderingException
? ((RenderingException)ex).UserMessage
: ex.Message;
// we cannot simply pass the existing Graphics because we haven't released its hDC yet
// if we do, we'll get a "Object is currently in use elsewhere" exception
DrawErrorMessage(_lastRenderExceptionMessage, args.RenderingSurface.ContextID, args.RenderingSurface.ClientRectangle);
}
}
private void RefreshImage(System.Drawing.Graphics graphics)
{
if (!Visible)
{
return;
}
_renderingSurface.WindowID = Handle;
_renderingSurface.ContextID = graphics.GetHdc();
_renderingSurface.ClientRectangle = ClientRectangle;
_renderingSurface.ClipRectangle = ClientRectangle;
try
{
// if there was an exception the last time we rendered the buffer, don't refresh from the buffer and instead redraw the error message
if (string.IsNullOrEmpty(_lastRenderExceptionMessage))
{
WinFormsScreenProxy screen = new WinFormsScreenProxy(Screen.FromControl(this));
DrawArgs args = new DrawArgs(_renderingSurface, screen, DrawMode.Refresh);
_magnificationImage.Draw(args);
}
else
{
// we cannot simply pass the existing Graphics because we haven't released its hDC yet
// if we do, we'll get a "Object is currently in use elsewhere" exception
DrawErrorMessage(_lastRenderExceptionMessage, _renderingSurface.ContextID, ClientRectangle);
}
}
catch (Exception ex)
{
Platform.Log(LogLevel.Error, ex, "An error has occured while refreshing the magnified contents of the tile.");
var exceptionMessage = ex is RenderingException ? ((RenderingException)ex).UserMessage : ex.Message;
// we cannot simply pass the Graphics because we haven't released its hDC yet
// if we do, we'll get a "Object is currently in use elsewhere" exception
DrawErrorMessage(exceptionMessage, _renderingSurface.ContextID, ClientRectangle);
}
finally
{
graphics.ReleaseHdc(_renderingSurface.ContextID);
}
}