java - 缩小时如何将图像返回到原始位置 - AndroidX
问题描述
当我缩小图像并且图像比例小于第一个初始图像大小时,我想将图像返回到原始位置
@Override
public boolean onTouch(View v, MotionEvent event)
{
ImageView view = (ImageView) v;
view.setScaleType(ImageView.ScaleType.MATRIX);
float scale = 0;
dumpEvent(event);
// Handle touch events here...
switch (event.getAction() & MotionEvent.ACTION_MASK)
{
case MotionEvent.ACTION_DOWN: // first finger down only
savedMatrix.set(matrix);
start.set(event.getX(), event.getY());
Log.d(TAG, "mode=DRAG"); // write to LogCat
mode = DRAG;
break;
/*case MotionEvent.ACTION_UP: // first finger lifted
case MotionEvent.ACTION_POINTER_UP: // second finger lifted
mode = NONE;
Log.d(TAG, "mode=NONE");
break;*/
case MotionEvent.ACTION_UP: // first finger lifted
mode = NONE;
break;
case MotionEvent.ACTION_POINTER_UP:// second finger lifted
/*matrix.set(savedMatrix);*/
/*view.setScaleType(ImageView.ScaleType.CENTER);*/
Log.v("/h/", ""+scale);
mode = ZOOMOUT;
//When release back to position
matrix.set(savedMatrix);
Log.d(TAG, "mode=ZOOMOUT");
break;
case MotionEvent.ACTION_POINTER_DOWN: // first and second finger down
oldDist = spacing(event);
Log.d(TAG, "oldDist=" + oldDist);
if (oldDist > 5f) {
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); // create the transformation in the matrix of points
}
else if (mode == ZOOM)
{
// pinch zooming
float newDist = spacing(event);
Log.d(TAG, "newDist=" + newDist);
if (newDist > 5f)
{
matrix.set(savedMatrix);
scale = newDist / oldDist; // setting the scaling of the
// matrix...if scale > 1 means
// zoom in...if scale < 1 means
// zoom out
if(scale>1) {
//Zoom In
}else if(scale<1) {
//Zoom Out
}
matrix.postScale(scale, scale, mid.x, mid.y);
Log.v("/h/", ""+scale+mode);
}
}
break;
}
view.setImageMatrix(matrix); // display the transformation on screen
return true; // indicate event was handled
}
/*
* --------------------------------------------------------------------------
* Method: spacing Parameters: MotionEvent Returns: float Description:
* checks the spacing between the two fingers on touch
* ----------------------------------------------------
*/
private float spacing(MotionEvent event)
{
float x = event.getX(0) - event.getX(1);
float y = event.getY(0) - event.getY(1);
return (float) Math.sqrt(x * x + y * y);
}
/*
* --------------------------------------------------------------------------
* Method: midPoint Parameters: PointF object, MotionEvent Returns: void
* Description: calculates the midpoint between the two fingers
* ------------------------------------------------------------
*/
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);
}
解决方案
- 将 savedMatrix 设置为
view.getImageMatrix()
on ACTION_DOWN。 - 在单独的矩阵上进行缩放/拖动更改
- 在 ACTION_UP 或 ACTION_POINTER_UP 上将原始矩阵设置回 imageview。
view.setImageMatrix(savedMatrix)
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