我正在尝试缩放下面的ImageView是xml，代码和错误报告....它工作正常..它也可以放大和缩小但是两三次后它会崩溃...它给出了间距函数event.get（X）中的错误...说指针索引超出范围...
这是xml
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
<ImageView android:id="@+id/imageView"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:src="@drawable/gm01"
android:scaleType="matrix" >
</ImageView>
</FrameLayout>
这是活动
package com.imageviewzoomactivity;
import android.app.Activity;
import android.graphics.Matrix;
import android.graphics.PointF;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.util.FloatMath;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.widget.ImageView;
public class ImageViewZoomActivityActivity 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();
Matrix savedMatrix2 = new Matrix();
private static final int WIDTH = 0;
private static final int HEIGHT = 1;
// 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 start = new PointF();
PointF mid = new PointF();
float oldDist = 1f;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
ImageView view = (ImageView) findViewById(R.id.imageView);
view.setOnTouchListener(this);
}
@Override
public boolean onTouch(View v, MotionEvent event) {
ImageView view = (ImageView) v;
int rotation = 25;
// 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:
mode = NONE;
Log.d(TAG, "mode=NONE");
savedMatrix.set(matrix);
// matrix.postRotate(90);
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;
}
fixing(v);
view.setImageMatrix(savedMatrix2);
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);
}
public void fixing(View v)
{
float[] value = new float[9];
matrix.getValues(value);
float[] savedValue = new float[9];
savedMatrix2.getValues(savedValue);
int width = v.getWidth();
int height = v.getHeight();
Drawable d = getResources().getDrawable(v.getId());
if (d == null) return;
int imageWidth = d.getIntrinsicWidth();
int imageHeight = d.getIntrinsicHeight();
int scaleWidth = (int) (imageWidth * value[0]);
int scaleHeight = (int) (imageHeight * value[4]);
// don't let the image go outside
if (value[2] > width-1)
value[2] = width-10;
else if (value[5] > height - 1)
value[5] = height - 10;
else if (value[2] < -(scaleWidth-1))
value[2] = -(scaleWidth-10);
else if (value[5] < -(scaleHeight-1))
value[5] = -(scaleHeight-10);
float MAX_ZOOM=2;
// maximum zoom ratio: MAx
if (value[0] > MAX_ZOOM || value[4] > MAX_ZOOM){
value[0] = MAX_ZOOM;
value[4] = MAX_ZOOM;
//value[2] = savedValue[2];
//value[5] = savedValue[5];
}
// don't let the image become smaller than the screen
if (imageWidth > width || imageHeight > height){
if (scaleWidth < width && scaleHeight < height){
int target = WIDTH;
if (imageWidth < imageHeight) target = HEIGHT;
if (target == WIDTH) value[0] = value[4] = (float)width / imageWidth;
if (target == HEIGHT) value[0] = value[4] = (float)height / imageHeight;
scaleWidth = (int) (imageWidth * value[0]);
scaleHeight = (int) (imageHeight * value[4]);
if (scaleWidth > width) value[0] = value[4] = (float)width / imageWidth;
if (scaleHeight > height) value[0] = value[4] = (float)height / imageHeight;
}
}
// don't allow scale down under its size
else{
if (value[0] < 1) value[0] = 1;
if (value[4] < 1) value[4] = 1;
}
// center the image
scaleWidth = (int) (imageWidth * value[0]);
scaleHeight = (int) (imageHeight * value[4]);
if (scaleWidth < width){
value[2] = (float) width / 2 - (float)scaleWidth / 2;
}
if (scaleHeight < height){
value[5] = (float) height / 2 - (float)scaleHeight / 2;
}
matrix.setValues(value);
savedMatrix2.set(matrix);
}
}
差不多已经完成了，但是经过一段时间它会崩溃....在它的方法中将它的方法与event.getX（0）间隔开来？这是Logcat报告
03-06 16:33:17.960: E/AndroidRuntime(6534): FATAL EXCEPTION: main
03-06 16:33:17.960: E/AndroidRuntime(6534): java.lang.IllegalArgumentException: pointerIndex out of range
03-06 16:33:17.960: E/AndroidRuntime(6534): at android.view.MotionEvent.nativeGetAxisValue(Native Method)
03-06 16:33:17.960: E/AndroidRuntime(6534): at android.view.MotionEvent.getX(MotionEvent.java:1549)
03-06 16:33:17.960: E/AndroidRuntime(6534): at com.imageviewzoomactivity.ImageViewZoomActivityActivity.spacing(ImageViewZoomActivityActivity.java:136)
03-06 16:33:17.960: E/AndroidRuntime(6534): at com.imageviewzoomactivity.ImageViewZoomActivityActivity.onTouch(ImageViewZoomActivityActivity.java:89)
03-06 16:33:17.960: E/AndroidRuntime(6534): at android.view.View.dispatchTouchEvent(View.java:4622)
03-06 16:33:17.960: E/AndroidRuntime(6534): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1560)
03-06 16:33:17.960: E/AndroidRuntime(6534): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1333)
03-06 16:33:17.960: E/AndroidRuntime(6534): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1560)
03-06 16:33:17.960: E/AndroidRuntime(6534): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1333)
03-06 16:33:17.960: E/AndroidRuntime(6534): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1560)
03-06 16:33:17.960: E/AndroidRuntime(6534): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1333)
03-06 16:33:17.960: E/AndroidRuntime(6534): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1560)
03-06 16:33:17.960: E/AndroidRuntime(6534): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1333)
03-06 16:33:17.960: E/AndroidRuntime(6534): at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1862)
03-06 16:33:17.960: E/AndroidRuntime(6534): at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1286)
03-06 16:33:17.960: E/AndroidRuntime(6534): at android.app.Activity.dispatchTouchEvent(Activity.java:2315)
03-06 16:33:17.960: E/AndroidRuntime(6534): at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1835)
03-06 16:33:17.960: E/AndroidRuntime(6534): at android.view.View.dispatchPointerEvent(View.java:4694)
03-06 16:33:17.960: E/AndroidRuntime(6534): at android.view.ViewRoot.deliverPointerEvent(ViewRoot.java:2419)
03-06 16:33:17.960: E/AndroidRuntime(6534): at android.view.ViewRoot.handleMessage(ViewRoot.java:2080)
03-06 16:33:17.960: E/AndroidRuntime(6534): at android.os.Handler.dispatchMessage(Handler.java:99)
03-06 16:33:17.960: E/AndroidRuntime(6534): at android.os.Looper.loop(Looper.java:132)
03-06 16:33:17.960: E/AndroidRuntime(6534): at android.app.ActivityThread.main(ActivityThread.java:4126)
03-06 16:33:17.960: E/AndroidRuntime(6534): at java.lang.reflect.Method.invokeNative(Native Method)
03-06 16:33:17.960: E/AndroidRuntime(6534): at java.lang.reflect.Method.invoke(Method.java:491)
03-06 16:33:17.960: E/AndroidRuntime(6534): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:844)
03-06 16:33:17.960: E/AndroidRuntime(6534): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:602)
03-06 16:33:17.960: E/AndroidRuntime(6534): at dalvik.system.NativeStart.main(Native Method)
答案 0 :(得分：1)
尝试更改间距功能
private float spacing(MotionEvent event) {
if(event.getPointerCount() == 2){
float x = event.getX(0) - event.getX(1);
float y = event.getY(0) - event.getY(1);
return FloatMath.sqrt(x * x + y * y);
}
return 0;
}