21
我們可以在Android中使用縮放手勢檢測器進行縮放嗎？我們可以在Android中使用縮放手勢檢測器進行縮放嗎？
A
回答
22
您可以使用此
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.drawable.BitmapDrawable;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.ScaleGestureDetector;
import android.view.View;
public class MyImageView extends View {
private static final int INVALID_POINTER_ID = -1;
private Drawable mImage;
private float mPosX;
private float mPosY;
private float mLastTouchX;
private float mLastTouchY;
private int mActivePointerId = INVALID_POINTER_ID;
private ScaleGestureDetector mScaleDetector;
private float mScaleFactor = 1.f;
public MyImageView(Context context) {
this(context, null, 0);
mImage=act.getResources().getDrawable(context.getResources().getIdentifier("imagename", "drawable", "packagename"));
mImage.setBounds(0, 0, mImage.getIntrinsicWidth(), mImage.getIntrinsicHeight());
}
public MyImageView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public MyImageView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());
}
@Override
public boolean onTouchEvent(MotionEvent ev) {
// Let the ScaleGestureDetector inspect all events.
mScaleDetector.onTouchEvent(ev);
final int action = ev.getAction();
switch (action & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN: {
final float x = ev.getX();
final float y = ev.getY();
mLastTouchX = x;
mLastTouchY = y;
mActivePointerId = ev.getPointerId(0);
break;
}
case MotionEvent.ACTION_MOVE: {
final int pointerIndex = ev.findPointerIndex(mActivePointerId);
final float x = ev.getX(pointerIndex);
final float y = ev.getY(pointerIndex);
// Only move if the ScaleGestureDetector isn't processing a gesture.
if (!mScaleDetector.isInProgress()) {
final float dx = x - mLastTouchX;
final float dy = y - mLastTouchY;
mPosX += dx;
mPosY += dy;
invalidate();
}
mLastTouchX = x;
mLastTouchY = y;
break;
}
case MotionEvent.ACTION_UP: {
mActivePointerId = INVALID_POINTER_ID;
break;
}
case MotionEvent.ACTION_CANCEL: {
mActivePointerId = INVALID_POINTER_ID;
break;
}
case MotionEvent.ACTION_POINTER_UP: {
final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK)
>> MotionEvent.ACTION_POINTER_INDEX_SHIFT;
final int pointerId = ev.getPointerId(pointerIndex);
if (pointerId == mActivePointerId) {
// This was our active pointer going up. Choose a new
// active pointer and adjust accordingly.
final int newPointerIndex = pointerIndex == 0 ? 1 : 0;
mLastTouchX = ev.getX(newPointerIndex);
mLastTouchY = ev.getY(newPointerIndex);
mActivePointerId = ev.getPointerId(newPointerIndex);
}
break;
}
}
return true;
}
@Override
public void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.save();
Log.d("DEBUG", "X: "+mPosX+" Y: "+mPosY);
canvas.translate(mPosX, mPosY);
canvas.scale(mScaleFactor, mScaleFactor);
mImage.draw(canvas);
canvas.restore();
}
private class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener {
@Override
public boolean onScale(ScaleGestureDetector detector) {
mScaleFactor *= detector.getScaleFactor();
// Don't let the object get too small or too large.
mScaleFactor = Math.max(0.1f, Math.min(mScaleFactor, 10.0f));
invalidate();
return true;
}
}
}
在activity.setContentView(new MyImageView(this));
10
ScaleGestureDetector調用，這是在現有的Android 2.2（Froyo的又名，API 8級）開始。請參閱：http://android-developers.blogspot.com/2010/06/making-sense-of-multitouch.html
在2.0/2.1，你沒有ScaleGestureDetector，但您可以提供雙指縮放使用由Ed伯內特在ZDNet的博客條目Pieter888連接到上面：http://www.zdnet.com/blog/burnette/how-to-use-multi-touch-in-android-2-part-6-implementing-the-pinch-zoom-gesture/1847
1
是的，我們能這裏是示例代碼，其中onPinch（）和onZoom（）是要在落實行動，自己
public class simpleOnScaleGestureListener extends
SimpleOnScaleGestureListener {
@Override
public boolean onScale(ScaleGestureDetector detector) {
startScale = detector.getScaleFactor();
return true;
}
@Override
public boolean onScaleBegin(ScaleGestureDetector detector) {
return true;
}
@Override
public void onScaleEnd(ScaleGestureDetector detector) {
endScale = detector.getScaleFactor();
// if ((startScale - endScale) > 0.0100
// || (endScale - startScale) > 0.0100) {
if (startScale > endScale) {
Log.i("onScaleEnd", "Pinch Dection");
onPinch();
} else if (startScale < endScale) {
Log.i("onScaleEnd", "Zoom Dection");
onZoom();
}
// }
}
}
1
實際上有一個使用這個類只是圖像的縮放庫。
這就是所謂的「TouchImageView」
11
您可以創建一個實現OnTouchListener做到這一點可重複使用的類。
public class MyScaleGestures implements OnTouchListener, OnScaleGestureListener {
private View view;
private ScaleGestureDetector gestureScale;
private float scaleFactor = 1;
public StandardGestures(Context c){ gestureScale = new ScaleGestureDetector(c, this); }
@Override
public boolean onTouch(View view, MotionEvent event) {
this.view = view;
gestureScale.onTouchEvent(event);
return true;
}
@Override
public boolean onScale(ScaleGestureDetector detector) {
scaleFactor *= detector.getScaleFactor();
scaleFactor = (scaleFactor < 1 ? 1 : scaleFactor); // prevent our view from becoming too small //
scaleFactor = ((float)((int)(scaleFactor * 100)))/100; // Change precision to help with jitter when user just rests their fingers //
view.setScaleX(scaleFactor);
view.setScaleY(scaleFactor);
return true;
}
@Override
public boolean onScaleBegin(ScaleGestureDetector detector) {
inScale = true;
return true;
}
@Override
public void onScaleEnd(ScaleGestureDetector detector) { inScale = false; }
}
然後將其指派爲您View的OnTouchListener像這樣。
myView.setOnTouchListener(new MyScaleGestures(context));
如果你想添加一個滾動能力的View，你將需要實現onScroll。您可以將此覆蓋添加到MyScaleGestures類來完成此操作。
@Override
public boolean onScroll(MotionEvent event1, MotionEvent event2, float x, float y) {
float newX = view.getX();
float newY = view.getY();
if(!inScale){
newX -= x;
newY -= y;
}
WindowManager wm = (WindowManager) view.getContext().getSystemService(Context.WINDOW_SERVICE);
Display d = wm.getDefaultDisplay();
Point p = new Point();
d.getSize(p);
if (newX > (view.getWidth() * scaleFactor - p.x)/2){
newX = (view.getWidth() * scaleFactor - p.x)/2;
} else if (newX < -((view.getWidth() * scaleFactor - p.x)/2)){
newX = -((view.getWidth() * scaleFactor - p.x)/2);
}
if (newY > (view.getHeight() * scaleFactor - p.y)/2){
newY = (view.getHeight() * scaleFactor - p.y)/2;
} else if (newY < -((view.getHeight() * scaleFactor - p.y)/2)){
newY = -((view.getHeight() * scaleFactor - p.y)/2);
}
view.setX(newX);
view.setY(newY);
return true;
}
+0
縮放後，我無法移動圖像以閱讀由於比例而不在屏幕上的內容。 – 2016-05-10 14:47:42
+0
@shriduttkothari更正，此代碼不會偵聽滾動手勢。你將需要實現'onScroll'移動到查看。 – ChrisStillwell 2016-05-10 14:53:50
+0
請你舉例嗎？ – 2016-05-11 07:00:24
1
TouchImageView
public class TouchImageView extends ImageView {
Matrix matrix;
// We can be in one of these 3 states
static final int NONE = 0;
static final int DRAG = 1;
static final int ZOOM = 2;
int mode = NONE;
// Remember some things for zooming
PointF last = new PointF();
PointF start = new PointF();
float minScale = 1f;
float maxScale = 3f;
float[] m;
int viewWidth, viewHeight;
static final int CLICK = 3;
float saveScale = 1f;
protected float origWidth, origHeight;
int oldMeasuredWidth, oldMeasuredHeight;
ScaleGestureDetector mScaleDetector;
Context context;
public TouchImageView(Context context) {
super(context);
sharedConstructing(context);
}
public TouchImageView(Context context, AttributeSet attrs) {
super(context, attrs);
sharedConstructing(context);
}
private void sharedConstructing(Context context) {
super.setClickable(true);
this.context = context;
mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());
matrix = new Matrix();
m = new float[9];
setImageMatrix(matrix);
setScaleType(ScaleType.MATRIX);
setOnTouchListener(new OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
mScaleDetector.onTouchEvent(event);
PointF curr = new PointF(event.getX(), event.getY());
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
last.set(curr);
start.set(last);
mode = DRAG;
break;
case MotionEvent.ACTION_MOVE:
if (mode == DRAG) {
float deltaX = curr.x - last.x;
float deltaY = curr.y - last.y;
float fixTransX = getFixDragTrans(deltaX, viewWidth, origWidth * saveScale);
float fixTransY = getFixDragTrans(deltaY, viewHeight, origHeight * saveScale);
matrix.postTranslate(fixTransX, fixTransY);
fixTrans();
last.set(curr.x, curr.y);
}
break;
case MotionEvent.ACTION_UP:
mode = NONE;
int xDiff = (int) Math.abs(curr.x - start.x);
int yDiff = (int) Math.abs(curr.y - start.y);
if (xDiff < CLICK && yDiff < CLICK)
performClick();
break;
case MotionEvent.ACTION_POINTER_UP:
mode = NONE;
break;
}
setImageMatrix(matrix);
invalidate();
return true; // indicate event was handled
}
});
}
public void setMaxZoom(float x) {
maxScale = x;
}
private class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener {
@Override
public boolean onScaleBegin(ScaleGestureDetector detector) {
mode = ZOOM;
return true;
}
@Override
public boolean onScale(ScaleGestureDetector detector) {
float mScaleFactor = detector.getScaleFactor();
float origScale = saveScale;
saveScale *= mScaleFactor;
if (saveScale > maxScale) {
saveScale = maxScale;
mScaleFactor = maxScale/origScale;
} else if (saveScale < minScale) {
saveScale = minScale;
mScaleFactor = minScale/origScale;
}
if (origWidth * saveScale <= viewWidth || origHeight * saveScale <= viewHeight)
matrix.postScale(mScaleFactor, mScaleFactor, viewWidth/2, viewHeight/2);
else
matrix.postScale(mScaleFactor, mScaleFactor, detector.getFocusX(), detector.getFocusY());
fixTrans();
return true;
}
}
void fixTrans() {
matrix.getValues(m);
float transX = m[Matrix.MTRANS_X];
float transY = m[Matrix.MTRANS_Y];
float fixTransX = getFixTrans(transX, viewWidth, origWidth * saveScale);
float fixTransY = getFixTrans(transY, viewHeight, origHeight * saveScale);
if (fixTransX != 0 || fixTransY != 0)
matrix.postTranslate(fixTransX, fixTransY);
}
float getFixTrans(float trans, float viewSize, float contentSize) {
float minTrans, maxTrans;
if (contentSize <= viewSize) {
minTrans = 0;
maxTrans = viewSize - contentSize;
} else {
minTrans = viewSize - contentSize;
maxTrans = 0;
}
if (trans < minTrans)
return -trans + minTrans;
if (trans > maxTrans)
return -trans + maxTrans;
return 0;
}
float getFixDragTrans(float delta, float viewSize, float contentSize) {
if (contentSize <= viewSize) {
return 0;
}
return delta;
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
viewWidth = MeasureSpec.getSize(widthMeasureSpec);
viewHeight = MeasureSpec.getSize(heightMeasureSpec);
//
// Rescales image on rotation
//
if (oldMeasuredHeight == viewWidth && oldMeasuredHeight == viewHeight
|| viewWidth == 0 || viewHeight == 0)
return;
oldMeasuredHeight = viewHeight;
oldMeasuredWidth = viewWidth;
if (saveScale == 1) {
//Fit to screen.
float scale;
Drawable drawable = getDrawable();
if (drawable == null || drawable.getIntrinsicWidth() == 0 || drawable.getIntrinsicHeight() == 0)
return;
int bmWidth = drawable.getIntrinsicWidth();
int bmHeight = drawable.getIntrinsicHeight();
Log.e("bmSize", "bmWidth: " + bmWidth + " bmHeight : " + bmHeight);
float scaleX = (float) viewWidth/(float) bmWidth;
float scaleY = (float) viewHeight/(float) bmHeight;
scale = Math.min(scaleX, scaleY);
matrix.setScale(scale, scale);
// Center the image
float redundantYSpace = (float) viewHeight - (scale * (float) bmHeight);
float redundantXSpace = (float) viewWidth - (scale * (float) bmWidth);
redundantYSpace /= (float) 2;
redundantXSpace /= (float) 2;
matrix.postTranslate(redundantXSpace, redundantYSpace);
origWidth = viewWidth - 2 * redundantXSpace;
origHeight = viewHeight - 2 * redundantYSpace;
setImageMatrix(matrix);
}
fixTrans();
}
}
MainActivity.java
public class SecondActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_second);
TouchImageView img = new TouchImageView(this);
img.setImageResource(R.drawable.ic_launcher);
img.setMaxZoom(4f);
setContentView(img);
}
}
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在縮小它把你給點0,0。它不會放大手指的初始點。爲什麼？ – sajjoo 2012-01-09 13:31:55
sajjoo：我認爲你可以使用'ScaleGestureDetector.getFocusX，Y（）' – Timmmm 2012-07-28 15:19:11
這樣做，但縮放非常無反應和不連貫（我正在畫布上以編程方式繪製線條）。任何想法爲什麼？ – Rookatu 2013-05-29 06:07:22