android - Android：停止图像缩小

Question

我正在尝试在视图中绘制图像，但在尝试保持原始图像的比例时遇到问题。基本上，我有一个小视图，我想在视图中显示部分图像。然后，目的是对图像执行转换，以便视图中出现不同的部分。

无论我尝试什么，图像都会自动缩小以适合视图，或者整个图像都是可见的。我尝试过使用 BitmapDrawable、ImageView 和 Layout 的设置，但无济于事。

有谁知道实现这一目标的好方法？

Answer 1

希望这段代码有帮助。我一个月前用谷歌搜索过。较大图像的滚动性能。此处将整个显示尺寸设置为视图的高度和宽度。你可以改变你知道的。并且也可以保持缩放控制。

public class LargeImageScroller extends Activity {

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

/** Called when the activity is first created. */
@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.testlargeimage);
     }

     @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;

     }
}
}

Answer 2

这可能不是最有效的方法，但如果你不打算移动它太多，它就可以了。将其视为精灵表，使用 Bitmap.createBitmap(Bitmap source, int x, int y, int width, int height) 从原始位图中获取您想要的部分作为自己的位图，然后将其传入。然后将其传入而不是整个位图，它只会与您希望它显示的部分一起使用。

Answer 3

听起来你想在一个较小的 View （就像一个窗口）中有一个大的 ImageView 控件，然后在里面移动 ImageView 控件，所以一次只有一部分是可见的。

虽然不完全确定你会如何做到这一点，但很确定 AbsoluteLayout 和一些修补是可能的。