Sunday, July 3, 2011

[android-developers] Points and Zooming

still trying to complete my Image class
On a Bitmap I can draw a line
and the starting point is oldX,oldY is 242.5 , 389.0

I then zoom only the image no panning
where the oldX ,oldY is still visible but obviously in another location of the screen because it is zoomed in.

Now I start to draw a line over the exact same points as before

newX , newY is 41 , 293.5 the Zoom factor is 2.8225315
The matrix is Matrix{[2.8225315, 0.0, -640.6198][0.0, 2.8225315, -801.00256][0.0, 0.0, 1.0]}

However I can't find a mathematical relationship between oldX and newX, that is the same as oldY and newY

Currently I'm using the event.getX which gives the X position on the screen,
1) Is there anyway to get the X position of the bitmap itself ?

2) Does anyone have an Idea to relate the oldX,oldY with the newX,newY that would apply to all all zoom factors ?


thanks in advance

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