Android Programming/JAVA : rotating a Square about its centre.

[lixiang9779]

Hi , new to programming in android/ java, i am wondering is it possible to rotate a square about its centre.
Or even rotate a Bitmap about its centre.




c.drawRect(left, top, right, bottom, paint);



I tried googling but the solutions are rather alien to me, can anyone explain the concept of rotation?

Thanks!

 

[Yowe555 Wannabe]

Hi , new to programming in android/ java, i am wondering is it possible to rotate a square about its centre.
Or even rotate a Bitmap about its centre.




c.drawRect(left, top, right, bottom, paint);



I tried googling but the solutions are rather alien to me, can anyone explain the concept of rotation?

Thanks!

Dear lixiang9779,

Google has plenty of answers.
java - Rotate a saved bitmap in android - Stack Overflow

Basically, you would need to translate the Bitmap into a matrix, which you will then provide the angle of rotation.

More good years ahead,
Thank you

 

[lixiang9779]

Didnt really thought of using a bitmap.

i was thinking of a canvas drawn rectangle using canvas.drawRect method.

But, cool at least i know it rotates, will try that in the next weekend!

 

[davidktw]

Dear lixiang9779,

Google has plenty of answers.
java - Rotate a saved bitmap in android - Stack Overflow

Basically, you would need to translate the Bitmap into a matrix, which you will then provide the angle of rotation.

More good years ahead,
Thank you

Generally, if the objective is to draw anything rotated, one doesn't need to save the bitmap rotated first. Just apply affine transformation on the Graphics Context first and draw the rectangle. Transformation will be applied on the fly during rasterisation.