我使用以下代码来获取在ImageView上运行的图像缩放功能：
@Override
public boolean onTouch(View v, MotionEvent event) {
ImageView view = (ImageView) v;
// Dump touch event to log
dumpEvent(event);
// Handle touch events here...
switch (event.getAction() & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN:
savedMatrix.set(matrix);
start.set(event.getX(), event.getY());
mode = DRAG;
break;
case MotionEvent.ACTION_POINTER_DOWN:
oldDist = spacing(event);
if (oldDist > 10f) {
savedMatrix.set(matrix);
midPoint(mid, event);
mode = ZOOM;
}
break;
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_POINTER_UP:
mode = NONE;
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[] f = new float[9];
matrix.getValues(f);
float scaleX = f[Matrix.MSCALE_X];
float scaleY = f[Matrix.MSCALE_Y];
if (scaleX > MAX_ZOOM || scaleY > MAX_ZOOM || scaleX < MIN_ZOOM
|| scaleY < MIN_ZOOM) {
System.out.println("@@@ true!!!");
} else {
System.out.println("@@@ false!!!");
float newDist = spacing(event);
if (newDist > 10f) {
matrix.set(savedMatrix);
float scale = newDist / oldDist;
matrix.postScale(scale, scale, mid.x, mid.y);
}
}
}
break;
}
view.setImageMatrix(matrix);
return true; // indicate event was handled
}
/** Show an event in the LogCat view, for debugging */
private void dumpEvent(MotionEvent event) {
String names[] = { "DOWN", "UP", "MOVE", "CANCEL", "OUTSIDE",
"POINTER_DOWN", "POINTER_UP", "7?", "8?", "9?" };
StringBuilder sb = new StringBuilder();
int action = event.getAction();
int actionCode = action & MotionEvent.ACTION_MASK;
sb.append("event ACTION_").append(names[actionCode]);
if (actionCode == MotionEvent.ACTION_POINTER_DOWN
|| actionCode == MotionEvent.ACTION_POINTER_UP) {
sb.append("(pid ").append(
action >> MotionEvent.ACTION_POINTER_ID_SHIFT);
sb.append(")");
}
sb.append("[");
for (int i = 0; i < event.getPointerCount(); i++) {
sb.append("#").append(i);
sb.append("(pid ").append(event.getPointerId(i));
sb.append(")=").append((int) event.getX(i));
sb.append(",").append((int) event.getY(i));
if (i + 1 < event.getPointerCount())
sb.append(";");
}
sb.append("]");
}
/** Determine the space between the first two fingers */
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);
}
/** Calculate the mid point of the first 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);
}
我在这里遇到了问题。我修改了代码以设置最大放大和缩小限制。我在这里面临的问题是，一旦达到任何限制，因为我在“if”块中没有任何内容，图像会卡住。我应该在这里放什么？
答案 0 :(得分：0)
如果您使用ScaleGestureDetector.SimpleOnScaleGestureListener类，事情会变得更容易......
class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener {
public boolean onScale(ScaleGestureDetector detector) {
//update the current scale
scaleFactor *= detector.getScaleFactor();
if(scaleFactor < MIN_SCALE_FACTOR || scaleFactor > MAX_SCALE_FACTOR){
scaleFactor = Math.max(MIN_SCALE_FACTOR,
Math.min(scaleFactor, MAX_SCALE_FACTOR));
transformMatrix.setScale(scaleFactor, scaleFactor);
}
}
transformMatrix是imageview的图像矩阵;您可以拨打imageView.getImageMatrix()来保存副本，然后像我使用transformMatrix.setScale(scaleFactor, scaleFactor)一样重新申请
如果达到最大/最小缩放级别，这种方式不会冻结
答案 1 :(得分：-1)
希望这可以帮助遇到同样问题的人，这个链接上的库帮助我轻松实现缩放功能：
答案 2 :(得分：-2)
试试这段代码。请在使用前进行编辑。
public class GuessImageView extends ImageView {
Matrix matrix = new 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;
public GuessImageActivity guessImage/* =new GuessImageActivity() */;
public GuessImageView(Context context) {
super(context);
sharedConstructing(context);
}
public GuessImageView(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.setTranslate(1f, 1f);
m = new float[9];
setImageMatrix(matrix);
setScaleType(ScaleType.MATRIX);
setOnTouchListener(new OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
mScaleDetector.onTouchEvent(event);
matrix.getValues(m);
Log.e("Touch Count","Touch Count"+event.getPointerCount());
// checkTouchEvent=event.getPointerCount();
float x = m[Matrix.MTRANS_X];
float y = m[Matrix.MTRANS_Y];
PointF curr = new PointF(event.getX(), event.getY());
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
last.set(event.getX(), event.getY());
start.set(last);
mode = DRAG;
isDrag=false;
// isDraw=false;
break;
case MotionEvent.ACTION_MOVE:
// Log.i("onTouch", "origWidth : " + origWidth +
// " origHeight : " + origHeight);
if (mode == DRAG) {
Log.d("GuessImage","MODE:Drag");
// isDraw=false;
float deltaX = curr.x - last.x;
float deltaY = curr.y - last.y;
scaleWidth = Math.round(origWidth * saveScale);
scaleHeight = Math.round(origHeight * saveScale);
if (scaleWidth < width) {
deltaX = 0;
if (y + deltaY > 0)
deltaY = -y;
else if (y + deltaY < -bottom)
deltaY = -(y + bottom);
} else if (scaleHeight < height) {
deltaY = 0;
if (x + deltaX > 0)
deltaX = -x;
else if (x + deltaX < -right)
deltaX = -(x + right);
} else {
if (x + deltaX > 0)
deltaX = -x;
else if (x + deltaX < -right)
deltaX = -(x + right);
if (y + deltaY > 0)
deltaY = -y;
else if (y + deltaY < -bottom)
deltaY = -(y + bottom);
}
matrix.postTranslate(deltaX, deltaY);
last.set(curr.x, curr.y);
}
isDrag=true;
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) {
// isDraw=false;
Log.v("ACTION_UP", "ACTION_UP");
mPosX = curr.x;
mPosY = curr.y;
performClick();
// if (guessImage.guess_mode) {
checkTouchEvent=event.getAction();
Log.d("checkTouchEvent",checkTouchEvent+"checkTouchEvent");
lastTouchEvent = event.getAction();
isDrag=false;
// }
// else {
//
// lastTouchEvent = -1;
//
// }
// invalidate();
}
break;
}
case MotionEvent.ACTION_POINTER_UP:
mode = NONE;
break;
}
setImageMatrix(matrix);
scaleWidth = Math.round(origWidth * saveScale);
scaleHeight = Math.round(origHeight * saveScale);
invalidate();
return true; // indicate event was handled
}
});
}
@Override
public void setImageBitmap(Bitmap bm) {
super.setImageBitmap(bm);
if (bm != null) {
bmWidth = bm.getWidth();
bmHeight = bm.getHeight();
}
}
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;
}
right = width * saveScale - width
- (2 * redundantXSpace * saveScale);
bottom = height * saveScale - height
- (2 * redundantYSpace * saveScale);
// mPosX = mPosX + right / saveScale;
// mPosY = mPosY + bottom / saveScale;
if (origWidth * saveScale <= width
|| origHeight * saveScale <= height) {
float xMove = 0, yMove = 0;
matrix.postScale(mScaleFactor, mScaleFactor, width / 2,
height / 2);
if (mScaleFactor < 1) {
matrix.getValues(m);
float x = m[Matrix.MTRANS_X];
float y = m[Matrix.MTRANS_Y];
if (mScaleFactor < 1) {
if (Math.round(origWidth * saveScale) < width) {
if (y < -bottom) {
matrix.postTranslate(0, -(y + bottom));
xMove = 0;
yMove = -(y + bottom);
} else if (y > 0) {
matrix.postTranslate(0, -y);
xMove = 0;
yMove = -y;
}
} else {
if (x < -right) {
matrix.postTranslate(-(x + right), 0);
xMove = -(x + right);
yMove = 0;
} else if (x > 0) {
matrix.postTranslate(-x, 0);
xMove = -(x + right);
yMove = 0;
}
}
Log.i("onScale", "mPosX " + mPosX + " mPosX " + mPosX);
}
}
} else {
float xMove = 0, yMove = 0;
matrix.postScale(mScaleFactor, mScaleFactor,
detector.getFocusX(), detector.getFocusY());
matrix.getValues(m);
float x = m[Matrix.MTRANS_X];
float y = m[Matrix.MTRANS_Y];
if (mScaleFactor < 1) {
if (x < -right) {
matrix.postTranslate(-(x + right), 0);
xMove = -(x + right);
yMove = 0;
} else if (x > 0) {
matrix.postTranslate(-x, 0);
xMove = -x;
yMove = 0;
}
if (y < -bottom) {
matrix.postTranslate(0, -(y + bottom));
xMove = 0;
yMove = -(y + bottom);
} else if (y > 0) {
matrix.postTranslate(0, -y);
xMove = 0;
yMove = -y;
}
}
Log.i("onScale", "mPosX " + mPosX + " mPosX " + mPosX);
}
return true;
}
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
if (!isCheckLoadImage) {
width = MeasureSpec.getSize(widthMeasureSpec);
height = MeasureSpec.getSize(heightMeasureSpec);
// Fit to screen.
float scale;
float scaleX = (float) width / (float) bmWidth;
float scaleY = (float) height / (float) bmHeight;
scale = Math.min(scaleX, scaleY);
matrix.setScale(scale, scale);
setImageMatrix(matrix);
saveScale = 1f;
// Center the image
redundantYSpace = (float) height - (scale * (float) bmHeight);
redundantXSpace = (float) width - (scale * (float) bmWidth);
redundantYSpace /= (float) 2;
redundantXSpace /= (float) 2;
matrix.postTranslate(redundantXSpace, redundantYSpace);
origWidth = width - 2 * redundantXSpace;
origHeight = height - 2 * redundantYSpace;
right = width * saveScale - width
- (2 * redundantXSpace * saveScale);
bottom = height * saveScale - height
- (2 * redundantYSpace * saveScale);
setImageMatrix(matrix);
}
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
}