Drawing scalable shapes in Android

Question

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I need to draw a cross shape in android, i have fixed set of points to draw,

Java

Path path = new Path();
path.moveTo(133.133f, 45.7109f);
path.lineTo(154.307f, 24.5363f);
path.lineTo(175.482f, 45.7109f);
path.lineTo(154.307f, 66.8856f);
path.lineTo(175.482f, 88.0603f);
path.lineTo(154.307f, 109.235f);
path.lineTo(133.133f, 88.0603f);
path.lineTo(111.958f, 109.235f);
path.lineTo(90.7835f, 88.0603f);
path.lineTo(111.958f, 66.8856f);
path.lineTo(90.7835f, 45.7109f);
path.lineTo(111.958f, 24.5363f);
path.lineTo(133.133f, 45.7109f);
canvas.drawPath(path, paint);

Working fine upto this,

My Requirement is to scale this shape to various size, i have tried to scale the whole view, but the other elements which is drew in the same canvas was effected. Could you please suggest me the right way to archive this?

Posted 25-Aug-14 18:58pm

User 1234567

Updated 25-Aug-14 18:59pm

v2

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2 solutions

Solution 1

Don't use fixed points in this way. First calculate the relative distance between each point and then scale up or down as you draw each line.

Posted 25-Aug-14 21:19pm

Richard MacCutchan

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Fredrik Bornander · Accepted Answer · 2014-08-25T21:38:00

Solution 2

Use a scale Transform;

Matrix matrix = new Matrix();
matrixsetScale(2.0f, 2.0f);
// path is your path
path.transform(matrix);

Or, if you want to scale around the center of the path;

Matrix matrix = new Matrix();
RectF boundingBox = new RectF();
path.computeBounds(boundingBox, true);
matrix.setScale(2.0f, 2.0f, boundingBox.centerX(), boundingBox.centerY());
path.transform(matrix);

Hope this helps,
Fredrik

Posted 25-Aug-14 21:38pm

Fredrik Bornander

Comments

User 1234567 26-Aug-14 23:59pm

Works like charm. thanks

Fredrik Bornander 27-Aug-14 3:40am

Glad I could help.
Using matrices will allow you to easily scale, skew, rotate and translate (move) paths.
They're awesome.