问题
My layout contains buttons, textviews, etc. Is it possible to implement pinch zoom in my layout?
回答1:
** Answer Outdated **
Check out the following links which may help you
Best examples are provided in the below links, which you can refactor to meet your requirements.
implementing-the-pinch-zoom-gestur
Android-pinch
GestureDetector.SimpleOnGestureListener
回答2:
For android 2.2+ (api level8), you can use ScaleGestureDetector.
you need a member:
private ScaleGestureDetector mScaleDetector;
in your constructor (or onCreate()) you add:
mScaleDetector = new ScaleGestureDetector(context, new OnScaleGestureListener() {
@Override
public void onScaleEnd(ScaleGestureDetector detector) {
}
@Override
public boolean onScaleBegin(ScaleGestureDetector detector) {
return true;
}
@Override
public boolean onScale(ScaleGestureDetector detector) {
Log.d(LOG_KEY, "zoom ongoing, scale: " + detector.getScaleFactor());
return false;
}
});
You override onTouchEvent:
@Override
public boolean onTouchEvent(MotionEvent event) {
mScaleDetector.onTouchEvent(event);
return true;
}
If you draw your View by hand, in the onScale() you probably do store the scale factor in a member, then call invalidate() and use the scale factor when drawing in your onDraw(). Otherwise you can directly modify font sizes or things like that in the onScale().
回答3:
I implemented a pinch zoom for my TextView
, using this tutorial. The resulting code is this:
private GestureDetector gestureDetector;
private View.OnTouchListener gestureListener;
and in onCreate():
// Zoom handlers
gestureDetector = new GestureDetector(new MyGestureDetector());
gestureListener = new View.OnTouchListener() {
// We can be in one of these 2 states
static final int NONE = 0;
static final int ZOOM = 1;
int mode = NONE;
static final int MIN_FONT_SIZE = 10;
static final int MAX_FONT_SIZE = 50;
float oldDist = 1f;
@Override
public boolean onTouch(View v, MotionEvent event) {
TextView textView = (TextView) findViewById(R.id.text);
switch (event.getAction() & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_POINTER_DOWN:
oldDist = spacing(event);
Log.d(TAG, "oldDist=" + oldDist);
if (oldDist > 10f) {
mode = ZOOM;
Log.d(TAG, "mode=ZOOM" );
}
break;
case MotionEvent.ACTION_POINTER_UP:
mode = NONE;
break;
case MotionEvent.ACTION_MOVE:
if (mode == ZOOM) {
float newDist = spacing(event);
// If you want to tweak font scaling, this is the place to go.
if (newDist > 10f) {
float scale = newDist / oldDist;
if (scale > 1) {
scale = 1.1f;
} else if (scale < 1) {
scale = 0.95f;
}
float currentSize = textView.getTextSize() * scale;
if ((currentSize < MAX_FONT_SIZE && currentSize > MIN_FONT_SIZE)
||(currentSize >= MAX_FONT_SIZE && scale < 1)
|| (currentSize <= MIN_FONT_SIZE && scale > 1)) {
textView.setTextSize(TypedValue.COMPLEX_UNIT_PX, currentSize);
}
}
}
break;
}
return false;
}
Magic constants 1.1 and 0.95 were chosen empirically (using scale
variable for this purpose made my TextView
behave kind of weird).
回答4:
There is also this project that does the job and worked perfectly for me: https://github.com/chrisbanes/PhotoView
回答5:
In honeycomb, API level 11, it is possible, We can use setScalaX and setScaleY with pivot point
I have explained it here
Zooming a view completely
Pinch Zoom to view completely
回答6:
I have created a project for basic pinch-zoom that supports Android 2.1+
Available here
回答7:
I have an open source library that does this very well. It's a four gesture library that comes with an out-of-the-box pan zoom setting. You can find it here: https://bitbucket.org/warwick/hacergestov3 Or you can download the demo app here: https://play.google.com/store/apps/details?id=com.WarwickWestonWright.HacerGestoV3Demo This is a pure canvas library so it can be used in pretty any scenario. Hope this helps.
来源:https://stackoverflow.com/questions/5375817/android-pinch-zoom