some problems

[LinXiaoTao]

Matrix multiplication is not commutative law,How can I guarantee the changes as expected?
for example, the first call postTranslate, then call postRotate. If reversed, the result is completely different.
thanks

[van048]

In your example, it will execute in this order: translate->rotate. Remember that rotation is based on the origin, not the center point of itself. Thus the result (the final coordinate of each point) is different in most cases. You should first make sure your transform is right before coding.

[LinXiaoTao]

For example, these two codes have different results:
1.mMatrix.postTranslate (100, 100);
    mMatrix.postRotate (30);
2.mMatrix.postRotate (30);
    mMatrix.postTranslate (100, 100);
know I can to get the desired effect?
thanks

[van048]

@LinXiaoTao It depends on what you desire....

[LinXiaoTao]

I just think that reversing the order will produce different results,Intuitive difficult to achieve