在android游戏开发中进行缩放，如何正确执行？

Question

So, recently me and my two teammates started on our exam project. Which is a basic 2D skijumping game.

We've done programming on android before but never in relation to games and we have the basic techniques down for creating animations using a thread and all that. But we seem to have a scaling issue.

Currently we have a background image in the drawable folder in the resolution 1920x1080, we are using BitmapFactory to scale the background image to the users screen size, which seems to be working fine it fits perfectly on all our 3 different smartphones.

Were creating an animation of the player sprite skiing down the hill and jumping off the edge, which looks very funny and works perfectly. For this I simply divided the screen width and height by 100 and used that percentage of either 1% screen width to move him at certain speeds on the x-axis and likewise on the y-axis with the 1% of the screen height.

It works on most phones but, for some reason it won't work on all of them? I don't understand why not? I mean the math should always work shouldn't it? On some phones he skies outside of the hill in the air and not on the proper trajectory. I don't get what I'm missing but I'm suspecting it has something to do with the screen format or something?

Can anyone enlighten me on this? Please keep in mind this is our first android game so were new at game dev.

And thanks for all your input if you have any in advance.

Answer 1

try this:

class V extends View implements Callback {

    private Bitmap mBitmap;
    private Matrix mMatrix;
    private Handler mHandler;
    private float mX;
    private Paint mPaint;

    public V(Context context) {
        super(context);
        Resources res = getResources();
        mBitmap = BitmapFactory.decodeResource(res, R.drawable.layer0);
        mMatrix = new Matrix();
        mHandler = new Handler(this);
        mHandler.obtainMessage(0).sendToTarget();
        mPaint = new Paint();
        mPaint.setColor(0xff00ff00);
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        RectF src = new RectF(0, 0, mBitmap.getWidth(), mBitmap.getHeight());
        RectF dst = new RectF(0, 0, w, h);
        mMatrix.setRectToRect(src, dst, ScaleToFit.CENTER);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        canvas.concat(mMatrix);
        canvas.drawBitmap(mBitmap,  0,  0, null);
        canvas.drawRect(mX, 20, mX + 20, 40, mPaint);
    }

    @Override
    public boolean handleMessage(Message msg) {
        msg = mHandler.obtainMessage(0);
        if (mX < mBitmap.getWidth()) {
            mX += 1.5f;
            mHandler.sendMessageDelayed(msg, 50);
        } else {
            Log.d(TAG, "handleMessage stop");
        }
        invalidate();
        return true;
    }
}