Working with underlays

PDF files can be attached as an underlay to a drawing file. Much like raster image files and external references (Xrefs), a PDF underlay is not part of the drawing, but is linked to it. The path to the underlay is saved in the parent drawing. You can edit the path to make sure the correct PDF is found. By default the folder of the parent drawing is searched first. If the PDF underlay is not found there, the saved path folder is searched. If the PDF underlay is not found there either, BricsCAD reports a 'Missing or invalid reference' in the drawing.

The PDFADJUST command allows to adjust the fade, contrast and monochrome settings of a PDF underlay in the Command line.

The PDFATTACH and -PDFATTACH commands insert a PDF file as an underlay into the current drawing.

The PDFLAYERS command allows you to control the display of layers in a PDF underlay.

The PDFCLIP command crops the display of a PDF. You can choose between a polygonal or a rectangular boundary. Each instance of the same PDF underlay file can have a different boundary.

The PDFOSNAP system variable allows to snap to the geometry in the PDF underlay if the system variable is On.

The PDFNOTIFY system variable controls whether warnings for missing or modified PDF underlays are issued.

The XNOTIFYTIME system variable defines the frequency to check for modified externally referenced resources: Xrefs, images and PDF attachments if XREFNOTIFY, IMAGENOTIFY and/or PDFNOTIFY is On.

If the value of the FRAME system variable = 3, the PDFFRAME system variable controls the visibility of PDF frames. The options are:

  • 0: Hide PDF frames.
  • 1: Display and plot PDF frames.
  • 2: Display but do not plot PDF frames.

Controlling the PDF underlay caching

A multi-resolution persistent image cache is used to display attached PDF underlays, enabling (very) fast zoom and pan operations. The highest cached resolution is 5000 x 5000 pixels. Still, when zooming in very close, the display of the PDF underlay will become pixelated. So a hybrid modus can be used which switches to the real-time generation of a crisp PDF underlay display when zooming in very closely. The initial generation of the image cache may take a few seconds, but from then on processing gets (very) fast, and remains just as swift in subsequent sessions.

The PDFCACHE system variable controls how PDF caching is applied.

  • 0 = don't use PDF cache, always use real-time generation of the PDF underlay image. (this mode was the default in previous BricsCAD versions).
  • 1 = use PDF cache, switch to real-time generation when zooming in very close.
  • 2 = always use PDF cache (default).

Attaching a PDF underlay

  1. Do one of the following:
    • Click the Attach PDF tool button () on the Insert toolbar or the Insert / PDFs ribbon panel.
    • Click the New tool button () on the Details toolbar of the Drawing Explorer - PDF Underlays dialog box.
    • Type PDFattach in the Command line, then press Enter.

    The Select PDF Underlay File dialog opens.

  2. Select the file, then double click the file or click the Open button on the Select PDF Underlay File dialog.

    The Attach PDF Underlay dialog box appears.

  3. In case of a multi-page PDF, click the down arrow in the Name field, then select the page of the PDF you want to load.
  4. Click the Path option button, then select either:
    • Full path: The full path will be searched when the drawing is loaded. If the overlay is not found there, the folder of the parent drawing is searched. If the overlay file is not found there either, "Missing or invalid reference" is displayed at the insertion point of the PDF overlay.
    • Relative path: The relative path, with respect to the folder of the parent drawing, will be searched when the drawing is loaded. If the overlay is not found there, the folder of the parent drawing is searched. If the overlay file is not found there either, "Missing or invalid reference" is displayed at the insertion point of the PDF overlay.
    • No path: Only the folder of the parent drawing is searched when the drawing is loaded. If the overlay file is not found there, "Missing or invalid reference" is displayed at the insertion point of the PDF overlay.
  5. Choose whether you want to specify the Insertion Point, Scale and the Rotation angle on-screen or not.
  6. Click the OK button.

    The Attach PDF Underlay dialog closes.

  7. Depending on the insertion options chosen in the previous step, you are prompted to specify the Insertion Point, Scale and/or Rotation angle.

Inserting a PDF underlay

If you want to insert a second instance of a PDF that is already attached or another page of such underlay do the following:

  1. Launch the EXPPDFS command.

    The Drawing Explorer - PDF Underlays dialog box appears.

  2. Select the PDF underlay.
  3. Do one of the following:
    • Right click and choose Insert in the context menu.
    • Choose insert in the Edit menu on the Drawing Explorer - PDF Underlays dialog.

    The Drawing Explorer - PDF Underlays dialog closes.

  4. Continue with steps 3 through 7 of the previous procedure.

Controlling the display of a PDF underlay

  1. Click the frame of the PDF underlay.

    The frame of the selected PDF highlights.

    The properties of the underlay are displayed in the Properties panel.

  2. Under Misc, click Show underlay in the Properties bar, then select Yes or No.

Setting the layer display in a PDF underlay

  1. Launch the PDFLAYERS command.

    You are prompted: Select PDF underlay.

  2. Click the frame of the PDF underlay.

    The frame of the selected PDF highlights.

    The Underlay Layers dialog box appears.

  3. The icon in the On column indicates the current state of the layers; On () or Off ().
  4. Click the icon in the On column to toggle the display of a layer.
  5. (option) Click the Search for layer field, then type a layer name to search for a layer.

    Use wildcard characters (? or *) to limit the number of layers in the list.

  6. (option) Click the Reference name button to select another PDF underlay.
  7. Click the OK button to stop.

Clipping a PDF underlay

  1. Launch the PDFCLIP command.

    You are prompted: Select PDF underlay:

  2. Click the frame of the PDF underlay.

    The frame of the selected PDF highlights.

    You are prompted: Enter PDF clipping option [ON/OFF/Delete/New] <New>:

  3. Press Enter to accept the New default command option.

    You are prompted: Enter PDF clipping type [Polygonal/Rectangular] <Rectangular>:

  4. Do one of the following:
    • Press Enter to accept the Rectangular default command option to define a rectangular clipping boundary.
    • Type P, then press Enter to define a polygonal clipping boundary.
  5. Define the clipping boundary.

    The defining points must lie inside the frame of the PDF underlay. If you click outside the PDF underlay the point is placed on the PDF underlay frame.

Toggling the display of the clipped part of a PDF underlay

  1. Click the frame of the PDF underlay.

    The frame of the selected PDF highlights.

    The properties of the underlay are displayed in the Properties panel.

  2. Under Misc, click Show clipped in the Properties bar, then select Yes or No.

Deleting a clipping boundary

  1. Launch the PDFCLIP command.

    You are prompted: Select PDF underlay.

  2. Click the frame of the PDF underlay.

    The frame of the selected PDF highlights.

    You are prompted: Enter PDF clipping option [ON/OFF/Delete/New] <New>:

  3. Type D in the Command line, then press Enter.

    The clipping boundary is deleted and the complete PDF underlay appears.

Adjusting the display settings of a PDF underlay

The PDFADJUST command allows to adjust the Fade, Contrast and Monochrome settings of a PDF underlay in the Command line.

Select the PDF underlay, then adjust the display settings under Underlay Adjust in the Properties panel.