我已经创建了一个ImageView的一个缩放和平移类。
特点我想创建。 - 这平底锅上的单手指触摸和移动 - 它放大，并在两个手指触摸和移动盘
在大多数情况下这工作得非常好。 它有一个轻微的错误，当我做到以下几点： - 我平移用一个手指（状态：没问题） - 我放下第二根手指，缩放和平移（状态：没问题） - 我释放我的第二个手指（状态：图像跳一点点）
希望有人能帮助我解决这个问题。
我想，它必须与复位mLastTouchX和mLastTouchY在“案例MotionEvent.ACTION_POINTER_UP”做
任何帮助将大大感激！
import android.content.Context;
import android.graphics.Canvas;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.ScaleGestureDetector;
import android.widget.ImageView;
public class MyImageView extends ImageView {
private static final int INVALID_POINTER_ID = -1;
private float mPosX;
private float mPosY;
private float mLastTouchX;
private float mLastTouchY;
private float mLastGestureX;
private float mLastGestureY;
private int mActivePointerId = INVALID_POINTER_ID;
private ScaleGestureDetector mScaleDetector;
private float mScaleFactor = 1.f;
public MyImageView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
mScaleDetector = new ScaleGestureDetector(getContext(), new ScaleListener());
}
public MyImageView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());
}
@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: {
if (!mScaleDetector.isInProgress()) {
final float x = ev.getX();
final float y = ev.getY();
mLastTouchX = x;
mLastTouchY = y;
mActivePointerId = ev.getPointerId(0);
}
break;
}
case MotionEvent.ACTION_POINTER_1_DOWN: {
if (mScaleDetector.isInProgress()) {
final float gx = mScaleDetector.getFocusX();
final float gy = mScaleDetector.getFocusY();
mLastGestureX = gx;
mLastGestureY = gy;
}
break;
}
case MotionEvent.ACTION_MOVE: {
// Only move if the ScaleGestureDetector isn't processing a gesture.
if (!mScaleDetector.isInProgress()) {
final int pointerIndex = ev.findPointerIndex(mActivePointerId);
final float x = ev.getX(pointerIndex);
final float y = ev.getY(pointerIndex);
final float dx = x - mLastTouchX;
final float dy = y - mLastTouchY;
mPosX += dx;
mPosY += dy;
invalidate();
mLastTouchX = x;
mLastTouchY = y;
}
else{
final float gx = mScaleDetector.getFocusX();
final float gy = mScaleDetector.getFocusY();
final float gdx = gx - mLastGestureX;
final float gdy = gy - mLastGestureY;
mPosX += gdx;
mPosY += gdy;
invalidate();
mLastGestureX = gx;
mLastGestureY = gy;
}
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) {
Log.d("DEBUG", "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;
}
@Override
public void onDraw(Canvas canvas) {
canvas.save();
canvas.translate(mPosX, mPosY);
if (mScaleDetector.isInProgress()) {
canvas.scale(mScaleFactor, mScaleFactor, mScaleDetector.getFocusX(), mScaleDetector.getFocusY());
}
else{
canvas.scale(mScaleFactor, mScaleFactor);
}
super.onDraw(canvas);
canvas.restore();
}
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, 10.0f));
invalidate();
return true;
}
}
}
看来canvas.scale（）在“的onDraw”方法的“其他”语句所需的mLastGestureX和mLastGestureY停止跳动。 我也刷新mLastTouchX和mLastTouchY要回单指当平移“的情况下MotionEvent.ACTION_POINTER_UP”
这里是最后的，可能不适合所有人都导致它不限制平移过去的图像边界但应该是很容易实现，也有很多讨论，在那里上的话题。
import android.content.Context;
import android.graphics.Canvas;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.ScaleGestureDetector;
import android.widget.ImageView;
public class MyImageView extends ImageView {
private static final int INVALID_POINTER_ID = -1;
private float mPosX;
private float mPosY;
private float mLastTouchX;
private float mLastTouchY;
private float mLastGestureX;
private float mLastGestureY;
private int mActivePointerId = INVALID_POINTER_ID;
private ScaleGestureDetector mScaleDetector;
private float mScaleFactor = 1.f;
public MyImageView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
mScaleDetector = new ScaleGestureDetector(getContext(), new ScaleListener());
}
public MyImageView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());
}
@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: {
if (!mScaleDetector.isInProgress()) {
final float x = ev.getX();
final float y = ev.getY();
mLastTouchX = x;
mLastTouchY = y;
mActivePointerId = ev.getPointerId(0);
}
break;
}
case MotionEvent.ACTION_POINTER_1_DOWN: {
if (mScaleDetector.isInProgress()) {
final float gx = mScaleDetector.getFocusX();
final float gy = mScaleDetector.getFocusY();
mLastGestureX = gx;
mLastGestureY = gy;
}
break;
}
case MotionEvent.ACTION_MOVE: {
// Only move if the ScaleGestureDetector isn't processing a gesture.
if (!mScaleDetector.isInProgress()) {
final int pointerIndex = ev.findPointerIndex(mActivePointerId);
final float x = ev.getX(pointerIndex);
final float y = ev.getY(pointerIndex);
final float dx = x - mLastTouchX;
final float dy = y - mLastTouchY;
mPosX += dx;
mPosY += dy;
invalidate();
mLastTouchX = x;
mLastTouchY = y;
}
else{
final float gx = mScaleDetector.getFocusX();
final float gy = mScaleDetector.getFocusY();
final float gdx = gx - mLastGestureX;
final float gdy = gy - mLastGestureY;
mPosX += gdx;
mPosY += gdy;
invalidate();
mLastGestureX = gx;
mLastGestureY = gy;
}
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);
}
else{
final int tempPointerIndex = ev.findPointerIndex(mActivePointerId);
mLastTouchX = ev.getX(tempPointerIndex);
mLastTouchY = ev.getY(tempPointerIndex);
}
break;
}
}
return true;
}
@Override
public void onDraw(Canvas canvas) {
canvas.save();
canvas.translate(mPosX, mPosY);
if (mScaleDetector.isInProgress()) {
canvas.scale(mScaleFactor, mScaleFactor, mScaleDetector.getFocusX(), mScaleDetector.getFocusY());
}
else{
canvas.scale(mScaleFactor, mScaleFactor, mLastGestureX, mLastGestureY);
}
super.onDraw(canvas);
canvas.restore();
}
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, 10.0f));
invalidate();
return true;
}
}
}
我一直在玩弄了一个多星期了解决这个问题，和它给了我一吨的问题。 我已经收窄的问题倒显著，虽然。 您的解决方案上面并没有为我工作，但我下面的解决方法是关闭。 问题是，每当第二手指按下或抬起它跳跃。 我发现，这是因为mPosX和mPosY并不总是真正的变量应该代表什么。 这里就是我的意思是：
当ACTION_MOVE被调用，代码进入“其他”的声明（处理缩放事件），mPosX和mPosY根据对焦的变化 ，而不是 在变焦的变化只改变。 这意味着，用两个手指平移工作，并用两个手指缩放工作，但mPosX和mPosY不是对于不断变化的变焦适当改变。
我一直在试图找出方法来解决这个问题使用变焦差变化（mScaleDetector.getScaleFactor（）），并在对焦差的变化，但我似乎无法通过逻辑不够好，找到的东西，工作的人。
另一种解决方案是把所有缩放操作成OnTouchListener，并完全摆脱ScaleListener的。 这意味着更多的数学，但它肯定会是一个解决办法。
这里onDraw有：
@Override
public void onDraw(Canvas c) {
c.save();
if (mScaleDetector.isInProgress()) {
c.scale(mScaleFactor, mScaleFactor, mLastGestureX - mPosX,
mLastGestureY - mPosY);
} else {
c.scale(mScaleFactor, mScaleFactor, mLastGestureX, mLastGestureY);
}
c.translate(mPosX / mScaleFactor, mPosY / mScaleFactor);
// drawing instruction here
c.restore();
}
下面是代码如何反应手指按压：
@Override
public boolean onTouchEvent(MotionEvent ev) {
mScaleDetector.onTouchEvent(ev);
final int action = ev.getAction();
switch (action & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN: {
if (!mScaleDetector.isInProgress()) {
final float x = ev.getX();
final float y = ev.getY();
mLastTouchX = x;
mLastTouchY = y;
mActivePointerId = ev.getPointerId(0);
}
break;
}
case MotionEvent.ACTION_POINTER_DOWN: {
if (!mScaleDetector.isInProgress()) {
final float gx = mScaleDetector.getFocusX();
final float gy = mScaleDetector.getFocusY();
mLastGestureX = gx;
mLastGestureY = gy;
}
break;
}
case MotionEvent.ACTION_MOVE: {
if (!mScaleDetector.isInProgress()) {
Log.i("hi", "SD not in progress");
final int pointerIndex = ev.findPointerIndex(mActivePointerId);
final float x = ev.getX(pointerIndex);
final float y = ev.getY(pointerIndex);
final float dx = x - mLastTouchX;
final float dy = y - mLastTouchY;
mPosX += dx;
mPosY += dy;
invalidate();
mLastTouchX = x;
mLastTouchY = y;
} else {
Log.i("hi", "SD in progress");
final float gx = mScaleDetector.getFocusX();
final float gy = mScaleDetector.getFocusY();
final float gdx = gx - mLastGestureX;
final float gdy = gy - mLastGestureY;
mPosX += gdx;
mPosY += gdy;
// SOMETHING NEEDS TO HAPPEN RIGHT HERE.
invalidate();
mLastGestureX = gx;
mLastGestureY = gy;
}
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);
} else {
final int tempPointerIndex = ev.findPointerIndex(mActivePointerId);
mLastTouchX = ev.getX(tempPointerIndex);
mLastTouchY = ev.getY(tempPointerIndex);
}
break;
}
}
return true;
}
虽然它主要是无关的，这里的ScaleListener：
private class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener {
@Override
public boolean onScale(ScaleGestureDetector detector) {
mScaleFactor *= detector.getScaleFactor();
invalidate();
return true;
}
}
同样，这段代码是不是完美的工作，但它是非常密切的。 我已经解释确切的问题上面，现在还在遇到麻烦它的工作。 我不知道这是否会在您的通知，汉克弹出，但希望有人会看到它，并帮助我。
汉克的解决方案对我的作品。 我添加了一个复位功能以便后续图像可以被正常地显示。
public void ResetView() {
mScaleFactor = 1.f;
mPosX = 0.f;
mPosY = 0.f;
}
W / O看代码我会假设你正在做基于2个手指的位置计算时有2个手指。 您总能获得在这种情况下一跳。
