Question

I created a drawing using different paths, but how can I move the entire drawing? How can I selected and move it around? Here is the main part of my onDraw method:

Path theSymbol = new Path();

theSymbol.moveTo(0.0F, 0.0F);
theSymbol.lineTo(0.0F, 50.0F);
theSymbol.lineTo(16.666666F, 58.333332F);
theSymbol.lineTo(-16.666666F, 75.0F);
theSymbol.lineTo(16.666666F, 91.666664F);
theSymbol.lineTo(-16.666666F, 108.33333F);
theSymbol.lineTo(16.666666F, 124.99999F);
theSymbol.lineTo(-16.666666F, 141.66666F);
theSymbol.lineTo(0.0F, 150.0F);
theSymbol.lineTo(0.0F, 200.0F);
theSymbol.offset(100.0F, 20.0F);

canvas.drawPath(theSymbol, paint);

That’s how I draw a resistor to the screen (It works). Now I want some way of making all those paths be an object, something that I can select and move.

I have been looking at some projects like Sriracha, but I can’t find how they are doing their element drawings.

I have also searched countless times, but all I get is “moving something on a path”. Maibe I am searching for the wrong thing or this is not the way to do this kind of things.

I wold really appreciate if someone can point me in the right direction.

Answer 1

Put this drawing code into the onDraw() method of a custom View subclass. Then you can place your drawings around the screen however you like using layouts, animations, and other transformations just like any other view in the framework. Something like:

public class ResistorView extends View {
    private Path mSymbol;
    private Paint mPaint;

    //...Override Constructors...
    public ResistorView(Context context) {
        super(context);
        init();
    }

    public ResistorView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    private void init() {
        mSymbol = new Path();
        mPaint = new Paint();
        //...Your code here to set up the path,
        //...allocate objects here, never in the drawing code.
    }

    //...Override onMeasure()...
    @Override
    public void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        //Use this method to tell Android how big your view is
        setMeasuredDimension(width, height);
    }

    //...Override onDraw()...
    @Override
    public void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        canvas.drawPath(mSymbol, mPaint);
    }        

}

For more information about creating custom views, check out the SDK docs.

HTH