我在我的应用程序中有图像缩放和拖动我的要求是图像设置最大和最小缩放级别。我使用了以下代码。
public class Touch extends Activity implements OnTouchListener {
private static final String TAG = "Touch";
// These matrices will be used to move and zoom image
Matrix matrix = new Matrix();
Matrix savedMatrix = 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;
int mode = NONE;
static final float MAX_ZOOM = 5.0f;
static final float MIN_ZOOM = 1.0f;
// Remember some things for zooming
PointF start = new PointF();
PointF mid = new PointF();
float oldDist = 1f;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.findstation);
ImageView view = (ImageView) findViewById(R.id.imageView);
view.setOnTouchListener(this);
}
@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());
Log.d(TAG, "mode=DRAG");
mode = DRAG;
break;
case MotionEvent.ACTION_POINTER_DOWN:
oldDist = spacing(event);
Log.d(TAG, "oldDist=" + oldDist);
if (oldDist > 10f) {
savedMatrix.set(matrix);
midPoint(mid, event);
mode = ZOOM;
Log.d(TAG, "mode=ZOOM");
}
break;
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_POINTER_UP:
mode = NONE;
Log.d(TAG, "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 newDist = spacing(event);
Log.d(TAG, "newDist=" + newDist);
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("]");
Log.d(TAG, sb.toString());
}
/** 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);
}
}
您能否告诉我如何设置缩放的最大和最小级别？
答案 0 :(得分：1)
您好需要定义最大缩放级别
private static final float MIN_ZOOM = 1.0f;
private static final float MAX_ZOOM = //set Maximum zooming level
float scale = Math.max(MIN_ZOOM, Math.min(scale, MAX_ZOOM));
答案 1 :(得分：0)
该解决方案不起作用，因为比例是相对值，但MIN_ZOOM和MAX_ZOOM是绝对的。 我已经解决了这个问题：
public class GestureImageView extends ImageView {
private static final float MIN_DISTANCE_FOR_ZOOM = 5f;
private static final float MAX_SCALE_RATIO = 5f;
private static final int SCALE_X_INDEX = 0;
private static final int MATRIX_SIZE = 9;
private static final int NONE = 0;
private static final int DRAG = 1;
private static final int ZOOM = 2;
private int mode = NONE;
private GestureDetector gestureDetector;
private Matrix fitScreenMatrix = new Matrix();
private Matrix defaultMatrix = new Matrix();
private Matrix matrix = new Matrix();
private Matrix savedMatrix = new Matrix();
private PointF start = new PointF(0, 0);
private PointF mid = new PointF(0, 0);
private float oldDist = 1f;
private float minScale;
private float maxScale;
public GestureImageView(Context context) {
super(context);
gestureDetector = new GestureDetector(context, new DoubleTapListener());
setOnTouchListener(new ZoomDragListener());
setScaleType(AsyncGestureImageView.ScaleType.MATRIX);
}
private void calculateDefaultValues(Drawable drawable) {
float imgWidth = drawable.getIntrinsicWidth();
float imgHeight = drawable.getIntrinsicHeight();
float width = getWidth();
float height = getHeight();
float widthRatio = width / imgWidth;
float heightRatio = height / imgHeight;
float values[] = new float[MATRIX_SIZE];
float ratio;
PointF fitScreenPosition;
PointF defaultPosition = new PointF((width - imgWidth)/2f, (height - imgHeight)/2f);
if ( widthRatio < heightRatio ) {
ratio = widthRatio;
fitScreenPosition = new PointF(0f, (height/ratio-imgHeight)/2f);
} else {
ratio = heightRatio;
fitScreenPosition = new PointF((width/ratio - imgWidth)/2f, 0f);
}
fitScreenMatrix.postTranslate(fitScreenPosition.x, fitScreenPosition.y);
fitScreenMatrix.postScale(ratio, ratio, 0, 0);
fitScreenMatrix.getValues(values);
defaultMatrix.postTranslate(defaultPosition.x, defaultPosition.y);
maxScale = values[SCALE_X_INDEX] * MAX_SCALE_RATIO;
minScale = values[SCALE_X_INDEX];
}
private void fitScreen() {
matrix.set(fitScreenMatrix);
setImageMatrix(matrix);
}
private void defaultScreen() {
matrix.set(defaultMatrix);
setImageMatrix(matrix);
}
private class DoubleTapListener extends GestureDetector.SimpleOnGestureListener {
@Override
public boolean onDoubleTap(MotionEvent e) {
if ( isFitScreen() ) {
defaultScreen();
return true;
}
fitScreen();
return true;
}
}
public boolean isFitScreen() {
return matrix.equals(fitScreenMatrix);
}
private class ZoomDragListener implements OnTouchListener {
@Override
public boolean onTouch(View v, MotionEvent event) {
gestureDetector.onTouchEvent(event);
AsyncGestureImageView i = (AsyncGestureImageView) v;
dragAndZoom(i, event);
return true;
}
private void dragAndZoom(View v, MotionEvent event) {
AsyncGestureImageView view = (AsyncGestureImageView) v;
switch (event.getAction() & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN:
savedMatrix.set(matrix);
start.x = event.getX();
start.y = event.getY();
if (isFitScreen()) {
return;
}
mode = DRAG;
break;
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_POINTER_UP:
mode = NONE;
break;
case MotionEvent.ACTION_POINTER_DOWN:
oldDist = gestureDistance(event);
if (oldDist > MIN_DISTANCE_FOR_ZOOM) {
savedMatrix.set(matrix);
midPoint(mid, event);
mode = ZOOM;
}
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 newDist = gestureDistance(event);
if (newDist > MIN_DISTANCE_FOR_ZOOM) {
matrix.set(savedMatrix);
float scale = newDist / oldDist;
float values[] = new float[MATRIX_SIZE];
matrix.getValues(values);
float currentScale = values[SCALE_X_INDEX];
float newScale = currentScale * scale;
if ( newScale > maxScale ) {
scale = maxScale / currentScale;
}
if ( newScale < minScale ) {
scale = minScale / currentScale;
}
matrix.postScale(scale, scale, mid.x, mid.y);
}
}
break;
}
view.setImageMatrix(matrix);
}
private float gestureDistance(MotionEvent event) {
if ( event.getPointerCount() != 2 ) {
return 0;
}
float x = event.getX(0) - event.getX(1);
float y = event.getY(0) - event.getY(1);
return FloatMath.sqrt(x * x + y * y);
}
private void midPoint(PointF point, MotionEvent event) {
point.x = event.getX(0) / 2 + event.getX(1) / 2;
point.y = event.getY(0) / 2 + event.getY(1) / 2;
}
}
@Override
public void setImageDrawable(Drawable drawable) {
if ( drawable != null ) {
calculateDefaultValues(drawable);
fitScreen();
}
super.setImageDrawable(drawable);
}