标签:android android-imageview imageview image-zoom
如何实现这个功能,PullToZoom只有一个ImageView(样本中没有ListView)?
相似的question,但没有答案:(
解决方法:
使用Gesture Detector怎么样?您可以在以下代码中找到并实现您需要的内容(我认为):
public class MainActivity extends AppCompatActivity {
private static final String DEBUG_TAG = "Gestures";
private GestureDetectorCompat mDetector;
private ImageView imageView;
private MyGestureListener myGestureListener;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
imageView = (ImageView) findViewById(R.id.image);
myGestureListener = new MyGestureListener();
mDetector = new GestureDetectorCompat(this, myGestureListener);
imageView.setOnTouchListener(new View.OnTouchListener() {
public boolean onTouch(View v, MotionEvent event) {
int action = MotionEventCompat.getActionMasked(event);
if (action == MotionEvent.ACTION_UP) {
myGestureListener.upDetected();
}
return mDetector.onTouchEvent(event);
}
});
imageView.setImageDrawable(ContextCompat.getDrawable(this, R.drawable.test));
}
class MyGestureListener extends GestureDetector.SimpleOnGestureListener {
private static final float MAX_ZOOM = 0.5f;
private static final float PCT = 300f;
private float delta;
private ValueAnimator valueAnimator;
@Override
public boolean onDown(MotionEvent event) {
return true;
}
@Override
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
if (valueAnimator != null) {
valueAnimator.cancel();
}
delta += distanceY;
float pct = getPct(delta);
imageView.setScaleX(1.0f + pct);
imageView.setScaleY(1.0f + pct);
return false;
}
void upDetected() {
float pct = getPct(delta);
valueAnimator = new ValueAnimator();
valueAnimator.setFloatValues(pct, 0.0f);
valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
@Override
public void onAnimationUpdate(ValueAnimator animation) {
imageView.setScaleX(1.0f + (float) animation.getAnimatedValue());
imageView.setScaleY(1.0f + (float) animation.getAnimatedValue());
}
});
valueAnimator.addListener(new Animator.AnimatorListener() {
@Override
public void onAnimationStart(Animator animation) {
}
@Override
public void onAnimationEnd(Animator animation) {
delta = 0f;
imageView.setScaleX(1.0f);
imageView.setScaleY(1.0f);
}
@Override
public void onAnimationCancel(Animator animation) {
}
@Override
public void onAnimationRepeat(Animator animation) {
}
});
valueAnimator.start();
}
private float getPct(float delta) {
float pct = delta / PCT;
if (pct >= MAX_ZOOM) {
pct = MAX_ZOOM;
}
else if (pct <= -MAX_ZOOM) {
pct = -MAX_ZOOM;
}
return pct;
}
}
}
MainActivity有一个简单的ImageView.当您在其中“滚动”时,会检测到手势并缩放图像(向上或向下).从屏幕上移除手指时,图像将通过简单的动画缩放回原始大小.如果你想避免缩小,你只需要使用getPct()方法.
编辑
例如,getPtc可能是这样的(如果你只是对放大感兴趣)
private float getPct(float delta) {
float pct = -delta / PCT;
if (pct >= MAX_ZOOM) {
pct = MAX_ZOOM;
}
else if (pct <= 0) {
pct = 0;
}
return pct;
}
编辑#2
似乎手势检测器的第一个滚动事件很宽.我添加了一些代码来忽略它
class MyGestureListener extends GestureDetector.SimpleOnGestureListener {
private static final float MAX_ZOOM = 0.8f;
private static final float PCT = 300f;
private float delta;
private ValueAnimator valueAnimator;
private boolean mFirstEvent = true;
@Override
public boolean onDown(MotionEvent event) {
return true;
}
@Override
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
if (valueAnimator != null) {
valueAnimator.cancel();
}
if (mFirstEvent) {
mFirstEvent = false;
return false;
}
delta += distanceY;
float pct = getPct(delta);
imageView.setScaleX(1.0f + pct);
imageView.setScaleY(1.0f + pct);
textView.setScaleY(1.0f - pct);
return false;
}
void upDetected() {
mFirstEvent = true;
float pct = getPct(delta);
valueAnimator = new ValueAnimator();
valueAnimator.setFloatValues(pct, 0.0f);
valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
@Override
public void onAnimationUpdate(ValueAnimator animation) {
imageView.setScaleX(1.0f + (Float) animation.getAnimatedValue());
imageView.setScaleY(1.0f + (Float) animation.getAnimatedValue());
textView.setScaleY(1.0f - (Float) animation.getAnimatedValue());
}
});
valueAnimator.addListener(new Animator.AnimatorListener() {
@Override
public void onAnimationStart(Animator animation) {
}
@Override
public void onAnimationEnd(Animator animation) {
delta = 0f;
imageView.setScaleX(1.0f);
imageView.setScaleY(1.0f);
textView.setScaleY(1.0f);
}
@Override
public void onAnimationCancel(Animator animation) {
}
@Override
public void onAnimationRepeat(Animator animation) {
}
});
valueAnimator.start();
}
private float getPct(float delta) {
float pct = -delta / PCT;
if (pct >= MAX_ZOOM) {
pct = MAX_ZOOM;
}
else if (pct <= 0) {
pct = 0;
}
return pct;
}
/*private float getPct(float delta) {
float pct = delta / PCT;
if (pct >= MAX_ZOOM) {
pct = MAX_ZOOM;
}
else if (pct <= -MAX_ZOOM) {
pct = -MAX_ZOOM;
}
return pct;
}*/
}
标签:android,android-imageview,imageview,image-zoom 来源: https://codeday.me/bug/20190702/1358701.html
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