By Graham K. Rogers

Most of us are familiar with bitmap images, even if we do not recognise the term. The computer is given a set of coordinates (like a map) and color information, which then places the data on a screen at the right place. The position of a cursor on a screen is described as a bit-map. We see bitmap images daily, for example on Facebook and other websites. In most cases, they look fine.

A problem occurs, however, when we try to make the image bigger. As long as the image we are viewing is not over-enlarged, the display will be acceptable. Eventually, depending on how large the image is made, we will see tiny squares of colours on the screen and the full image may become indistinct. This blockiness means bitmap images are not scalable.

Bitmap image: normal size and enlarged

Scalability limits are not acceptable to industry where relatively small plans drawn on a computer screen may need to be enlarged many times with no loss of resolution. Parts need to be formed, buildings constructed, aircraft assembled. Engineering drawings are most often produced using vector graphics: drawing instructions that are not affected by how many times the image is enlarged.

Autodesk, who are no strangers to engineering drawing (AutoCAD) or iOS apps have an app available that can edit and produce vector graphics images. The app has the simple name, Graphic. It was formerly known as iDraw and Autodesk have taken over Indeeo who originally developed it and its sister desktop application.

I downloaded the version for the iPhone at $2.99 but there is also a separate iPad version at $8.99. When first opened the user is offered the option of using iCloud and then the app displays a list of contents containing a sample design item and a sample floorplan.

To the left of this basic screen is a + for a new drawing: create new or import options. Beside this is an export icon that opens a menu with a large range of options (see below). To the right are a Settings icon with some basic controls and Edit (the user needs to select a document first).

When creating or editing a diagram, a good range of tools options is available, including Properties, Shape Libraries and Layers, with drawing tools like line, curve, arrow, shapes (including square, oval, circle), text and color options.

As I saved the test drawing (more a doodle to be honest), it appeared almost immediately in the iCloud folder on the Mac, with files in the .idraw format: a vector graphics type developed by Indeeo. I was able to open this in Graphic Converter on the Mac, but not AutoDesk's 123 Design. None of the other graphics applications I have currently could handle this file type.

To be fair, if a user were skilled at working with vector graphics and intended to make proper use of this app, it is probable that the desktop version of Graphic ($29.99) would be available on the hard disk. The file type is not shown as one supported by AutoCAD (surprisingly), or by SolidWork. Instead, the app offers export options.

Saving the test image to Photos gave me a PNG image, although this was quite small. More options were found with the Dropbox export: Graphic (IDRAW), PDF, SVG, PSD, PNG and JPG.

For those who are required to produce quality vector output, Graphic is a relatively easy to use app with a number of useful tools. With current limitations with the idraw file type, the export options compensate somewhat and I was able to open the image on the Mac.

I did not try the $8.99 iPad version of Graphic, but it would seem to be a perfect fit for the iPad Pro that has just been released.

Graham K. Rogers teaches at the Faculty of Engineering, Mahidol University in Thailand. He wrote in the Bangkok Post, Database supplement on IT subjects. For the last seven years of Database he wrote a column on Apple and Macs. He is now continuing that in the Bangkok Post supplement, Life.