40 lines
1.8 KiB
Markdown
40 lines
1.8 KiB
Markdown
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---
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author: dhananjayishere
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comments: true
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date: 2012-01-09 14:30:00
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layout: post
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slug: arrow-keys-input-in-python
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title: Arrow Keys input in python.
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wordpress_id: 93005403
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categories:
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- Programing
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- Python
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---
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I had an assignment to write an applicaion to control a toy helicopter. It should accept the inputs from the arrow keys and then generate a serial signal. The serial port is connected to the interfacing circutary.
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The major problem I faced was how to take arrow keys as input? Using the technical jargon - implement a non-bufferd input. A code to do it in console can be found [here](http://code.activestate.com/recipes/134892-getch-like-unbuffered-character-reading-from-stdin/). But its dirty and is implemented in a complex way that usage is little bit diffcult. At console level the code becomes more os-specific, as you can see from the above code. It has diffrent defenitions to implement the feature in each os.
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The easy way to do this is using any windowing tool kits around, they all have a key logging abstraction implemented. Like this [code](http://stackoverflow.com/a/4205490). it uses the tkinter toolkit to read input. The way I suggest is using pygame, because it is designed to this stuff. (Which game doesnt have a single use arrow key used?)
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You can get the keys from
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{% codeblock lang:python %}
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pressed_keys = pygame.key.get_pressed()
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{% endcodeblock %}
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and the key name as
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{% codeblock lang:python %}
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for key_constant in pressed_keys:
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key_name = pygame.key.name(key_constant)
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{% endcodeblock %}
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Then its just a matter of comparing them with the key name,( of arrow keys in our case).
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{% codeblock lang:python %}
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if key_constant == 'up':
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port.write(_up_data)
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{% endcodeblock %}
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The complete code is available in [github](https://github.com/dhananjaynav/Scripts/blob/master/castalia/helicontrol.py)
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