如何让我的图像以随机位置显示？

I have a chicken image that only moves whenever I press my arrow keys, the image always appear at the lower left corner when I start to run the program. My problem is that how can I make the image appear at the top or anywhere on the screen(except on the lower left) and the image still moves when I press the arrow keys . I'm not really sure but I think this problem is coming from my translate(). Is there something wrong with my calculation? Thanks for sharing your ideas... I have a chicken image that only moves whenever