我尝试创建一个缩放视图，其中的图像始终按其中心缩放。但是，如果我更改图像的初始位置并捏合图像移动到窗口的右下角。作为参考，我使用了Android Developer的pinch zoom视图并更改了一些参数。你有什么想法来解决这个问题吗？
package android.oli.com.fitnessapp;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.ScaleGestureDetector;
import android.view.View;
public class ZoomView extends View{
private Drawable mIcon;
private float mPosX;
private float mPosY;
private float mLastTouchX;
private float mLastTouchY;
private ScaleGestureDetector mScaleDetector;
private float mScaleFactor = 1.f;
private static final int INVALID_POINTER_ID = -1;
// The ‘active pointer’ is the one currently moving our object.
private int mActivePointerId = INVALID_POINTER_ID;
Context context;
public ZoomView(Context context) {
super(context);
mIcon = context.getResources().getDrawable(R.drawable.image_1);
this.context = context;
init();
}
public ZoomView(Context context, AttributeSet attrs) {
super(context, attrs);
mIcon = context.getResources().getDrawable(R.drawable.image_1);
this.context = context;
init();
}
public ZoomView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
mIcon = context.getResources().getDrawable(R.drawable.image_1);
this.context = context;
init();
}
public void init(){
mIcon.setBounds(0, 0, mIcon.getIntrinsicWidth(), mIcon.getIntrinsicHeight());
mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());
}
@Override
public void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.save();
canvas.translate(mPosX - ((mIcon.getIntrinsicWidth()) * mScaleFactor) / 2, mPosY - ((mIcon.getIntrinsicWidth()) * mScaleFactor) / 2);
canvas.scale(mScaleFactor, mScaleFactor);
mIcon.draw(canvas);
//rectMid.set(0, 0, canvas.getWidth(), canvas.getHeight()/2);
//canvas.drawRect(rectMid, blue);
canvas.restore();
}
@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;
}
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, 5.0f));
invalidate();
return true;
}
}
}
XML：
<android.oli.com.fitnessapp.ZoomView
android:layout_width="match_parent"
android:layout_height="match_parent" />
答案 0 :(得分：0)
好的，我明白了：D
import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.view.MotionEvent;
import android.view.ScaleGestureDetector;
import android.view.View;
public class ZoomView extends View{
private Drawable mIcon;
private float mPosX;
private float mPosY;
private float mLastTouchX;
private float mLastTouchY;
private ScaleGestureDetector mScaleDetector;
private float mScaleFactor = 1.f;
private static final int INVALID_POINTER_ID = -1;
// The ‘active pointer’ is the one currently moving our object.
private int mActivePointerId = INVALID_POINTER_ID;
Context context;
int height, width;
public ZoomView(Context context) {
super(context);
mIcon = context.getResources().getDrawable(R.drawable.image_1);
this.context = context;
init();
}
public ZoomView(Context context, AttributeSet attrs) {
super(context, attrs);
mIcon = context.getResources().getDrawable(R.drawable.image_1);
this.context = context;
init();
}
public ZoomView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
mIcon = context.getResources().getDrawable(R.drawable.image_1);
this.context = context;
init();
}
public void init(){
DisplayMetrics displaymetrics = new DisplayMetrics();
((Activity) getContext()).getWindowManager().getDefaultDisplay().getMetrics(displaymetrics);
height = displaymetrics.heightPixels;
width = displaymetrics.widthPixels;
mIcon.setBounds(0, 0, 0 + mIcon.getIntrinsicWidth(), 0 + mIcon.getIntrinsicHeight());
mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());
}
@Override
public void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.save();
canvas.translate(width/2 + mPosX - (mIcon.getIntrinsicWidth() * mScaleFactor) / 2, height/2 + mPosY - (mIcon.getIntrinsicWidth() * mScaleFactor) / 2);
canvas.scale(mScaleFactor, mScaleFactor);
mIcon.draw(canvas);
//rectMid.set(0, 0, canvas.getWidth(), canvas.getHeight()/2);
//canvas.drawRect(rectMid, blue);
canvas.restore();
}
@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;
}
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, 5.0f));
invalidate();
return true;
}
}
}