Highlight a region in a PDF or an image in C#
This example shows how to draw highlighted regions on top of a document. A highlighted region is a special feature that’s modifiable by mouse. It can be used to specify areas and highlight them, and it’s especially useful in anchor and OMR applications.
//We assume that GdPicture has been correctly installed and unlocked.//We assume the GdViewer object called GdViewer1 has been created and painted on the form.GdPictureImaging oGdPictureImaging = new GdPictureImaging();//Loading the image from a file.int imageId = oGdPictureImaging.CreateGdPictureImageFromFile("C:\\Image.tif");//Checking if the image resource has been loaded correctly.if (oGdPictureImaging.GetStat() != GdPictureStatus.OK){ MessageBox.Show("The image can't be loaded. Error: " + oGdPictureImaging.GetStat().ToString(), "Drawing regions Example", MessageBoxButtons.OK, MessageBoxIcon.Error);}else{ //Displaying the image in the GdViewer. GdViewer1.DisplayFromGdPictureImage(imageId);}oGdPictureImaging.Dispose();
//On the Mouse UP event on the GdViewer, create a highlighted region based on the rectangle of selection of the GdViewer.//If no rectangle of selection is painted on the GdViewer, this event will do nothing.public void Mouse_UP_Draw_Region(System.Object eventSender, System.EventArgs eventArgs){ //Initializing variables to hold the position of the rectangle of selection on the document. int leftArea = 0; int topArea = 0; int widthArea = 0; int heightArea = 0; //Checking if a rectangle of selection has been painted on the GdViewer. if (GdViewer1.IsRect()) { //Getting the location of the selection on the document. GdViewer1.GetRectCoordinatesOnDocument(ref leftArea, ref topArea, ref widthArea, ref heightArea); //Setting the ROI on the document: //Adding a region in place of the rectangle of selection. int regionId = GdViewer1.AddRegion("Region", leftArea, topArea, widthArea, heightArea, GdPicture14.ForegroundMixMode.ForegroundMixModeMASKPEN, Color.Green); //Setting region border width. GdViewer1.SetRegionBorderWidth(regionId, 1); //Setting region border color. GdViewer1.SetRegionBorderColor(regionId, Color.Blue); //Redrawing the whole image. GdViewer1.ClearRect(); GdViewer1.Redraw(); }}
This code sample is an example that illustrates how to use our SDK. Please adapt it to your specific use case.