PurplePen.MapUtil.ValidateMapFile C# (CSharp) Method

        public static bool ValidateMapFile(string mapFileName, out float scale, out float dpi, out Size bitmapSize, out RectangleF mapBounds, out MapType mapType, out string errorMessageText)
        {
            scale = 0; dpi = 0;
            mapType = MapType.None;
            bitmapSize = new Size();
            string fileExtension = Path.GetExtension(mapFileName);

            if (string.Compare(fileExtension, ".pdf", StringComparison.InvariantCultureIgnoreCase) == 0) {
                if (ValidatePdf(mapFileName, out dpi, out bitmapSize, out errorMessageText) != null) {
                    mapType = MapType.PDF;
                    mapBounds = new RectangleF(0, 0, (float)bitmapSize.Width / dpi * 25.4F, (float) bitmapSize.Height / dpi * 25.4F);
                    return true;
                }
                else {
                    mapBounds = new RectangleF();
                    return false;
                }
            }

            Map map = new Map(TextMetricsProvider, new GDIPlus_FileLoader(Path.GetDirectoryName(mapFileName)));

            try {
                InputOutput.ReadFile(mapFileName, map);
            }
            catch (Exception e) {
                // Didn't load as an OCAD file. If it has a non-OCD/OpenMapper extension, try loading as an image.
                if ((string.Compare(fileExtension, ".ocd", StringComparison.InvariantCultureIgnoreCase) != 0) &&
                    (string.Compare(fileExtension, ".omap", StringComparison.InvariantCultureIgnoreCase) != 0) &&
                    (string.Compare(fileExtension, ".xmap", StringComparison.InvariantCultureIgnoreCase) != 0))
                {
                    try {
                        Bitmap bitmap = (Bitmap) Image.FromFile(mapFileName);
                        bitmapSize = bitmap.Size;
                        dpi = bitmap.HorizontalResolution;
                        bitmap.Dispose();
                        mapType = MapType.Bitmap;
                        mapBounds = new RectangleF(0, 0, (float)bitmapSize.Width / dpi * 25.4F, (float)bitmapSize.Height / dpi * 25.4F);
                        errorMessageText = "";
                        return true;
                    }
                    catch {
                        // Wasn't an bitmap file either.
                        errorMessageText = string.Format(MiscText.CannotReadImageFile, mapFileName);
                        mapBounds = new RectangleF();
                        return false;
                    }
                }

                errorMessageText = string.Format(MiscText.CannotReadMap, e.Message);
                mapBounds = new RectangleF();
                return false;
            }

            using (map.Read())
            {
                scale = map.MapScale;
                mapBounds = map.Bounds;
            }

            errorMessageText = "";
            mapType = MapType.OCAD;
            return true;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            if (openFileDialog.ShowDialog() == DialogResult.OK)
            {
                containingWizard.MapFileName = mapFileNameTextBox.Text = openFileDialog.FileName;
                mapFileDisplay.Visible       = true;

                string     errorMessageText;
                float      dpi; // not used here.
                float      mapScale;
                MapType    mapType;
                Size       bitmapSize;
                RectangleF mapBounds;
                if (MapUtil.ValidateMapFile(containingWizard.MapFileName, out mapScale, out dpi, out bitmapSize, out mapBounds, out mapType, out errorMessageText))
                {
                    // map file is OK.
                    containingWizard.MapScale   = mapScale;
                    containingWizard.MapType    = mapType;
                    containingWizard.BitmapSize = bitmapSize;
                    containingWizard.mapBounds  = mapBounds;
                    errorDisplayPanel.Visible   = false;
                    infoDisplayPanel.Visible    = true;
                    ((Control)ParentForm.AcceptButton).Focus();
                }
                else
                {
                    // map file is not OK. Show message.
                    errorMessage.Text         = errorMessageText;
                    infoDisplayPanel.Visible  = false;
                    errorDisplayPanel.Visible = true;
                }
            }
        }