|Scripting Samurai: Getting Started with the MapBasic window |
|Are you an inquisitive type of person? Do you sometimes lift the hood of your car and gaze at the engine in wonder, curious to know what all the components are and how they almost magically combine together to safely deliver you from A to B? Well this article will show you how can lift the hood on MapInfo Professional, understand some of the magic that is happening, and even jump in and take control of the MapInfo engine providing a powerful way to control and manipulate the application, all without getting a spot of grease on your hands!|
For most Users, the MapBasic Window is a seldom used component of MapInfo Professional interface hidden away out of sight, you can find it under Options >> Show MapBasic Window.
Once opened up, you'll see commands and strings of instructions reflected within the window as you execute different commands, tools and menu options in the MapInfo Professional environment. Each of the actions within the User Interface (UI) will result in a command or multiple commands being shown in the MapBasic Window - tracking the commands and relating them to the action in the User Interface provides an insight on the logic within the MapInfo Engine used to undertake common tasks such as opening and manipulating a series of datasets.
By undertaking a number of consecutive activities then reviewing the generated script in the MapBasic Window we will be able to gain a greater understanding into how the magic of the MapInfo engine executes the requests from the User Interface. For example, open the MapBasic window but leave it minimized in the work session, now try some simple actions such as:
Now restore the MapBasic window and look at the contents, the exact commands may vary however you should see something similar to:
- Open a table or a workspace
- Run a simple SQL Select statement
- Close all the tables
If we look at the syntax of the commands we can see that they reflect the three steps executed via the UI listed above; open a table, execute a query (& then open the results in a new browser), finally close all tables. This is a simple example however it gives us a sense of the level of information that can be revealed via the MapBasic window.
We can also interact with the MapInfo Professional engine via the MapBasic Window, this can be a real time saver to help automate repetitive tasks and functions. For example click in the MapBasic Window from the earlier exercise and place the cursor at the end of the first line ("Run Application..."), with the cursor in place press the [Enter] key to execute this command. You should see the workspace (or table) reopened. By chaining together multiple commands in this manner we can create basic scripts to automate tasks without use of the GUI components of the application.
Here are 3 things you can do within the MapBasic window that will help you understand the power that comes from working directly with the MapInfo Professional engine:
1. Create a table of rectangles from a table of coordinates
Requires an open, mappable table "tablename" with four fields that represent two opposite corners of the rectangle object. Open the MapBasic window and type:
Update tablename set obj = mbr(createline(x1,y1,x2,y2))
2. Set or Update the name of an open Map window
This command allows you to set or modify the name for an open Map window. Click on the title bar of the map window (to ensure it is the active or front window), then click in the MapBasic window and use the following command:
Set Window FrontWindow() Title "Place the new window title here"
3. Need to open a TAB file with an alias (a temporary name assigned just for the session whilst the file is open)? Here's how you can go about it, open the MapBasic window and use the following command:
Open table "TableName" as "Alias name" interactive
What else? Many of the 100's of MapBasic functions available can be executed in the MapBasic Window. To check if a particular function is accessible via the MapBasic window, look up the function in theMapBasic reference guide and look for the following statement under the Purpose description:
"You can call this function from the MapBasic window in MapInfo Professional."
If you see this statement then you're able to use the function within the MapBasic window. Hopefully this article shows how easy it is to get started with the MapBasic window, keep a look out for a future article to explore how we can take advantage of this capability to help automate repetitive tasks and cut down on processing time.
So go ahead, lift the hood, watch the magic happen and then jump in to try it out for yourself!
Article by Ashley Crane
When not writing articles for the MapInfo Professional journal, Ashley enjoys hearing about how Pitney Bowes customers are using our solutions to solve real world business problems and is on a journey to make & consume the perfect cup of coffee.