如何在android中放大/缩小ImageView（不使用Canvas）

Question

我正在开发应用程序，我必须在其中旋转、拖放和放大/缩小图像（较小的图像）而不是另一图像（较大的图像）。我完成了旋转和拖放，但无法实现放大/缩小。我知道如何在画布上做到这一点但在我的应用程序中我没有使用画布。 任何帮助将不胜感激............

谢谢 达文德

Answer 1

查看以下代码，如果有帮助请告诉我。

public class Touch extends Activity implements OnTouchListener {

private static final String TAG = "Touch" ;
// These matrices will be used to move and zoom image
Matrix matrix = new Matrix();
Matrix savedMatrix = new Matrix();
PointF start = new  PointF();
public static PointF mid = new PointF();

// We can be in one of these 3 states
public static final int NONE = 0;
public static final int DRAG = 1;
public static final int ZOOM = 2;
public static int mode = NONE;

float oldDist;

private float[] matrixValues = new float[9];

@Override
public void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    ImageView view = (ImageView) findViewById(R.id.imageView);
    view.setOnTouchListener(this);
}

@Override
public boolean onTouch(View v, MotionEvent event) {

    ImageView view = (ImageView) v;

    switch (event.getAction() & MotionEvent.ACTION_MASK) {

    case MotionEvent.ACTION_DOWN:

        savedMatrix.set(matrix);
        start.set(event.getX(), event.getY());
        Log.d(TAG, "mode=DRAG" );
        mode = DRAG;
        break;

    case MotionEvent.ACTION_POINTER_DOWN:

        oldDist = spacing(event);
        Log.d(TAG, "oldDist=" + oldDist);
        if (oldDist > 10f) {

            savedMatrix.set(matrix);
            midPoint(mid, event);
            mode = ZOOM;
            Log.d(TAG, "mode=ZOOM" );
        }
        break;

    case MotionEvent.ACTION_MOVE:

        if (mode == DRAG) {

            matrix.set(savedMatrix);
            matrix.postTranslate(event.getX() - start.x, event.getY() - start.y);
        }
        else if (mode == ZOOM) {

            float newDist = spacing(event);
            Log.d(TAG, "newDist=" + newDist);
            if (newDist > 10f) {

                matrix.set(savedMatrix);
                float scale = newDist / oldDist;
                matrix.postScale(scale, scale, mid.x, mid.y);
            }
        }
        break;

    case MotionEvent.ACTION_UP:
    case MotionEvent.ACTION_POINTER_UP:

        mode = NONE;
        Log.d(TAG, "mode=NONE" );
        break;
    }

    // Perform the transformation
    view.setImageMatrix(matrix);

    return true; // indicate event was handled
}

  private float spacing(MotionEvent event) {
    float x = event.getX(0) - event.getX(1);
    float y = event.getY(0) - event.getY(1);
    return FloatMath.sqrt(x * x + y * y);
}

private void midPoint(PointF point, MotionEvent event) {

    float x = event.getX(0) + event.getX(1);
    float y = event.getY(0) + event.getY(1);
    point.set(x / 2, y / 2);
}

}

下面是main.xml文件

<?xml version="1.0" encoding="utf-8"?>
    <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="fill_parent" 
        android:layout_height="fill_parent">
    <ImageView 
            android:id="@+id/imageView"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:src="@drawable/yourimage"
            android:scaleType="matrix">
    </ImageView>
    </FrameLayout>

将 imageview (yourimage) 的 src 属性的值替换为您在项目中拥有的图像的名称。