问题
I have an imageview that can be zoomed. I have a code that works well, but my problem is that I want to add a limit for maximum and minimum zooming levels.
import android.annotation.TargetApi;
import android.app.ActionBar;
import android.app.Activity;
import android.graphics.Matrix;
import android.graphics.PointF;
import android.os.Build;
import android.os.Bundle;
import android.util.FloatMath;
import android.util.Log;
import android.view.MenuItem;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.widget.ImageView;
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
public class Reach extends Activity implements OnTouchListener
{
private static final String TAG = "Touch";
@SuppressWarnings("unused")
private static final float MIN_ZOOM = 1f,MAX_ZOOM = 1f;
// These matrices will be used to scale points of the image
Matrix matrix = new Matrix();
Matrix savedMatrix = new Matrix();
// The 3 states (events) which the user is trying to perform
static final int NONE = 0;
static final int DRAG = 1;
static final int ZOOM = 2;
int mode = NONE;
// these PointF objects are used to record the point(s) the user is touching
PointF start = new PointF();
PointF mid = new PointF();
float oldDist = 1f;
@Override
protected void onCreate(Bundle savedInstanceState)
{
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.reach_us);
int currentAPIVersion = android.os.Build.VERSION.SDK_INT;
if (currentAPIVersion >= android.os.Build.VERSION_CODES.HONEYCOMB)
{
// RUN THE CODE SPECIFIC TO THE API LEVELS ABOVE HONEYCOMB (API 11+)
ActionBar actionBar = getActionBar();
actionBar.setDisplayHomeAsUpEnabled(true);
}
ImageView view=(ImageView)findViewById(R.id.map);
view.setOnTouchListener(this);
}
@Override
public boolean onOptionsItemSelected(MenuItem item)
{
switch (item.getItemId()) {
case android.R.id.home: {
this.finish();
return true;
}
default:
return super.onOptionsItemSelected(item);
}
}
@Override
public boolean onTouch(View v, MotionEvent event)
{
ImageView view = (ImageView) v;
view.setScaleType(ImageView.ScaleType.MATRIX);
float scale;
dumpEvent(event);
// Handle touch events here...
switch (event.getAction() & MotionEvent.ACTION_MASK)
{
case MotionEvent.ACTION_DOWN: // first finger down only
savedMatrix.set(matrix);
start.set(event.getX(), event.getY());
Log.d(TAG, "mode=DRAG"); // write to LogCat
mode = DRAG;
break;
case MotionEvent.ACTION_UP: // first finger lifted
case MotionEvent.ACTION_POINTER_UP: // second finger lifted
mode = NONE;
Log.d(TAG, "mode=NONE");
break;
case MotionEvent.ACTION_POINTER_DOWN: // first and second finger down
oldDist = spacing(event);
Log.d(TAG, "oldDist=" + oldDist);
if (oldDist > 5f) {
savedMatrix.set(matrix);
midPoint(mid, event);
mode = ZOOM;
Log.d(TAG, "mode=ZOOM");
}
break;
case MotionEvent.ACTION_MOVE:
if (mode == DRAG)
{
matrix.set(savedMatrix);
matrix.postTranslate(event.getX() - start.x, event.getY() - start.y); // create the transformation in the matrix of points
}
else if (mode == ZOOM)
{
// pinch zooming
float newDist = spacing(event);
Log.d(TAG, "newDist=" + newDist);
if (newDist > 5f)
{
matrix.set(savedMatrix);
scale = newDist / oldDist; // setting the scaling of the
// matrix...if scale > 1 means
// zoom in...if scale < 1 means
// zoom out
matrix.postScale(scale, scale, mid.x, mid.y);
}
}
break;
}
view.setImageMatrix(matrix); // display the transformation on screen
return true; // indicate event was handled
}
/*
* --------------------------------------------------------------------------
* Method: spacing Parameters: MotionEvent Returns: float Description:
* checks the spacing between the two fingers on touch
* ----------------------------------------------------
*/
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);
}
/*
* --------------------------------------------------------------------------
* Method: midPoint Parameters: PointF object, MotionEvent Returns: void
* Description: calculates the midpoint between the 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);
}
/** 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("Touch Events ---------", sb.toString());
}
}
I have seen lot of question & answers linked with this, but no one really helps me. Please give me a solution. Thanks in advance
回答1:
I got a solution for this. But its not seems to be perfect one. Just add the methods given below after the switch cases and just before the view.setImageMatrix(matrix);
here is the methods:
private void limitZoom(Matrix m) {
float[] values = new float[9];
m.getValues(values);
float scaleX = values[Matrix.MSCALE_X];
float scaleY = values[Matrix.MSCALE_Y];
if(scaleX > MAX_ZOOM) {
scaleX = MAX_ZOOM;
} else if(scaleX < MIN_ZOOM) {
scaleX = MIN_ZOOM;
}
if(scaleY > MAX_ZOOM) {
scaleY = MAX_ZOOM;
} else if(scaleY < MIN_ZOOM) {
scaleY = MIN_ZOOM;
}
values[Matrix.MSCALE_X] = scaleX;
values[Matrix.MSCALE_Y] = scaleY;
m.setValues(values);
}
private void limitDrag(Matrix m) {
float[] values = new float[9];
m.getValues(values);
float transX = values[Matrix.MTRANS_X];
float transY = values[Matrix.MTRANS_Y];
float scaleX = values[Matrix.MSCALE_X];
float scaleY = values[Matrix.MSCALE_Y];
ImageView iv = (ImageView)findViewById(R.id.map);
Rect bounds = iv.getDrawable().getBounds();
int viewWidth = getResources().getDisplayMetrics().widthPixels;
int viewHeight = getResources().getDisplayMetrics().heightPixels;
int width = bounds.right - bounds.left;
int height = bounds.bottom - bounds.top;
float minX = (-width + 20) * scaleX;
float minY = (-height + 20) * scaleY;
if(transX > (viewWidth - 20)) {
transX = viewWidth - 20;
} else if(transX < minX) {
transX = minX;
}
if(transY > (viewHeight - 80)) {
transY = viewHeight - 80;
} else if(transY < minY) {
transY = minY;
}
values[Matrix.MTRANS_X] = transX;
values[Matrix.MTRANS_Y] = transY;
m.setValues(values);
}
Is there is any other solution better than this one?
回答2:
setOnTouchListener on your imageview
imgView.setOnTouchListener(this);
Click here!This works for zoomIn and ZoomOut change only MotionEvent.ACTION_MOVE to set zoomIn Limit
@Override
public boolean onTouch(View v, MotionEvent event)
{
ImageView view = (ImageView) v;
view.setScaleType(ImageView.ScaleType.MATRIX);
float scale;
switch (event.getAction() & MotionEvent.ACTION_MASK){
case MotionEvent.ACTION_POINTER_DOWN: // first and second finger down
oldDist = spacing(event);
Log.d(TAG, "oldDist=" + oldDist);
if (oldDist > 5f) {
savedMatrix.set(matrix);
midPoint(mid, event);
mode = ZOOM;
Log.d(TAG, "mode=ZOOM");
}
break;
// and in your Action_Move Event
case MotionEvent.ACTION_MOVE:
if (mode == DRAG)
{
matrix.set(savedMatrix);
matrix.postTranslate(event.getX() - start.x, event.getY() - start.y); // create the transformation in the matrix of points
view.setImageMatrix(matrix);
}
else if (mode == ZOOM)
{
// pinch zooming
float newDist = spacing(event);
Log.d(TAG, "newDist=" + newDist);
if (newDist > 5f)
{
scale = newDist / oldDist; // setting the scaling of the
//if scale is greater then 1 then its mean user want to
// zoom image
//0.37047964 is the limit of zoomin
float[] values = new float[9]; matrix.getValues(values);
if(values[Matrix.MSCALE_X]>0.37047964) {
matrix.set(savedMatrix);
matrix.postScale(scale, scale, mid.x, mid.y);
view.setImageMatrix(matrix);
}else if (scale>1){
matrix.set(savedMatrix);
matrix.postScale(scale, scale, mid.x, mid.y);
view.setImageMatrix(matrix);
}
}
}
break;
}
}
来源：https://stackoverflow.com/questions/15609845/add-limit-to-zoom-in-and-zoom-out-in-android