Android如何更新视图以包括自定义图形？

Question

I found this really useful code that allows me to scale and move a bitmap and I've been trying to find a way to use this code in my app. I don't really understand the way the class is being used (self taught java coder, so I may be missing some basics here). I basically want to be able to open up gallery and pick a file which can be used by this code. I can do all this with a standard ImageView but with an ImageView I'm unable to scale/move.

The main class, and it simply uses the touchexampleview class to place the image on screen, and the touchexampleview class contains a line which loads a default image.

mIcon = context.getResources().getDrawable(R.drawable.ic_launcher);

I could work out how to change this in the class but I want to be able to do this dynamically and be user driven.

Here is the main class.

public class TouchExampleActivity extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        TouchExampleView view = new TouchExampleView(this);

        view.setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,
                ViewGroup.LayoutParams.MATCH_PARENT));

        setContentView(view);

    }
}

and the touchexampleview class

public class TouchExampleView extends View {
    private Drawable mIcon;
    private float mPosX;
    private float mPosY;

    private VersionedGestureDetector mDetector;
    private float mScaleFactor = 1.f;

    public TouchExampleView(Context context) {
        this(context, null, 0);
    }

    public TouchExampleView(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public TouchExampleView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);

        mIcon = context.getResources().getDrawable(R.drawable.ic_launcher);
        mIcon.setBounds(0, 0, mIcon.getIntrinsicWidth(), mIcon.getIntrinsicHeight());

        mDetector = VersionedGestureDetector.newInstance(context, new GestureCallback());
    }

    @Override
    public boolean onTouchEvent(MotionEvent ev) {
        mDetector.onTouchEvent(ev);
        return true;
    }

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

        canvas.save();
        canvas.translate(mPosX, mPosY);
        canvas.scale(mScaleFactor, mScaleFactor);
        mIcon.draw(canvas);
        canvas.restore();
    }

    private class GestureCallback implements VersionedGestureDetector.OnGestureListener {
        public void onDrag(float dx, float dy) {
            mPosX += dx;
            mPosY += dy;
            invalidate();
        }

        public void onScale(float scaleFactor) {
            mScaleFactor *= scaleFactor;

            // Don't let the object get too small or too large.
            mScaleFactor = Math.max(0.1f, Math.min(mScaleFactor, 5.0f));

            invalidate();
        }
    }
}

Answer 1

我不确定，但这是您要寻找的吗？

imageSpot.setImageResource(R.drawable.myImage);