映射大于屏幕的图像

Question

我有一个带有pannable（可滚动）图像的Android应用程序。 用户应该能够在屏幕上按下大理石，但只有在按下棕色大理石时才会启动某个动作。 因为图像是可滚动的，所以当用户移动图像时，棕色大理石将在屏幕上具有其他位置，因此我想知道我应该如何做到这一点。 补充：截图和平移图像的代码。

public class Map1 extends Activity {

// Physical display width and height.
    private static int displayWidth = 0;
    private static int displayHeight = 0;

    /** Called when the activity is first created. */
    @SuppressWarnings("deprecation")
    @Override
    public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);

            // displayWidth and displayHeight will change depending on screen
        // orientation. To get these dynamically, we should hook onSizeChanged().
        // This simple example uses only landscape mode, so it's ok to get them
        // once on startup and use those values throughout.
            Display display = ((WindowManager)
                    getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay();
            displayWidth = display.getWidth();             
            displayHeight = display.getHeight();    

            // SampleView constructor must be constructed last as it needs the
        // displayWidth and displayHeight we just got.
        setContentView(new SampleView(this));
}

private static class SampleView extends View {
        private static Bitmap bmLargeImage; //bitmap large enough to be scrolled
        private static Rect displayRect = null; //rect we display to
        private Rect scrollRect = null; //rect we scroll over our bitmap with
        private int scrollRectX = 0; //current left location of scroll rect
        private int scrollRectY = 0; //current top location of scroll rect
        private float scrollByX = 0; //x amount to scroll by
        private float scrollByY = 0; //y amount to scroll by
        private float startX = 0; //track x from one ACTION_MOVE to the next
        private float startY = 0; //track y from one ACTION_MOVE to the next

            public SampleView(Context context) {
                    super(context);

                    // Destination rect for our main canvas draw. It never changes.
                displayRect = new Rect(0, 0, displayWidth, displayHeight);
                // Scroll rect: this will be used to 'scroll around' over the
                // bitmap in memory. Initialize as above.
                    scrollRect = new Rect(0, 0, displayWidth, displayHeight);

                    // Load a large bitmap into an offscreen area of memory.
                    bmLargeImage = BitmapFactory.decodeResource(getResources(),
                            R.drawable.marbles);
            }

            @Override
            public boolean onTouchEvent(MotionEvent event) {

                    switch (event.getAction()) {
                            case MotionEvent.ACTION_DOWN:
                                    // Remember our initial down event location.
                                    startX = event.getRawX();
                                    startY = event.getRawY();
                                    break;

                            case MotionEvent.ACTION_MOVE:
                                    float x = event.getRawX();
                                    float y = event.getRawY();
                                    // Calculate move update. This will happen many times
                                // during the course of a single movement gesture.
                                scrollByX = x - startX; //move update x increment
                                scrollByY = y - startY; //move update y increment
                                startX = x; //reset initial values to latest
                                startY = y;
                                invalidate(); //force a redraw
                                break;
                }
                return true; //done with this event so consume it
            }

            @Override
            protected void onDraw(Canvas canvas) {

                    // Our move updates are calculated in ACTION_MOVE in the opposite direction
                // from how we want to move the scroll rect. Think of this as dragging to
                // the left being the same as sliding the scroll rect to the right.
                    int newScrollRectX = scrollRectX - (int)scrollByX;
                    int newScrollRectY = scrollRectY - (int)scrollByY;

                    // Don't scroll off the left or right edges of the bitmap.
                    if (newScrollRectX < 0)
                            newScrollRectX = 0;
                    else if (newScrollRectX > (bmLargeImage.getWidth() - displayWidth))
                            newScrollRectX = (bmLargeImage.getWidth() - displayWidth);

                    // Don't scroll off the top or bottom edges of the bitmap.
                    if (newScrollRectY < 0)
                            newScrollRectY = 0;
                    else if (newScrollRectY > (bmLargeImage.getHeight() - displayHeight))
                            newScrollRectY = (bmLargeImage.getHeight() - displayHeight);

                    // We have our updated scroll rect coordinates, set them and draw.
                    scrollRect.set(newScrollRectX, newScrollRectY,
                            newScrollRectX + displayWidth, newScrollRectY + displayHeight);
                    Paint paint = new Paint();
                    canvas.drawBitmap(bmLargeImage, scrollRect, displayRect, paint);

                    // Reset current scroll coordinates to reflect the latest updates,
                // so we can repeat this update process.
                scrollRectX = newScrollRectX;
                scrollRectY = newScrollRectY;
        }
}

}