是否可以有一个支持水平和垂直平移/拖动的视图。最重要的是，我希望能够捏缩放和双击缩放。 这个视图是否存在于 Android 上，或者有人知道有一个项目吗？
为了让它变得更加困难，需要将另一个视图（Button、TextView、VideoView、...）添加到视图中。当第一个/父视图放大或移动时，子视图（按钮）需要随着父视图移动。
我尝试了多种解决方案，但没有一个具有我正在寻找的所有选项。
【问题讨论】：
我认为有可能实现您想要的，但据我所知，有内置解决方案。从你问题的第二部分，我猜你不想要一个可缩放的View，而是一个ViewGroup，它是所有可以包含其他视图（例如布局）的视图的超类。下面是一些代码，您可以从构建自己的 ViewGroup 开始，其中大部分来自 this 博客文章：
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.graphics.Rect;
import android.view.*;
public class ZoomableViewGroup extends ViewGroup {
private static final int INVALID_POINTER_ID = 1;
private int mActivePointerId = INVALID_POINTER_ID;
private float mScaleFactor = 1;
private ScaleGestureDetector mScaleDetector;
private Matrix mScaleMatrix = new Matrix();
private Matrix mScaleMatrixInverse = new Matrix();
private float mPosX;
private float mPosY;
private Matrix mTranslateMatrix = new Matrix();
private Matrix mTranslateMatrixInverse = new Matrix();
private float mLastTouchX;
private float mLastTouchY;
private float mFocusY;
private float mFocusX;
private float[] mInvalidateWorkingArray = new float[6];
private float[] mDispatchTouchEventWorkingArray = new float[2];
private float[] mOnTouchEventWorkingArray = new float[2];
public ZoomableViewGroup(Context context) {
super(context);
mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());
mTranslateMatrix.setTranslate(0, 0);
mScaleMatrix.setScale(1, 1);
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
int childCount = getChildCount();
for (int i = 0; i < childCount; i++) {
View child = getChildAt(i);
if (child.getVisibility() != GONE) {
child.layout(l, t, l+child.getMeasuredWidth(), t + child.getMeasuredHeight());
}
}
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int childCount = getChildCount();
for (int i = 0; i < childCount; i++) {
View child = getChildAt(i);
if (child.getVisibility() != GONE) {
measureChild(child, widthMeasureSpec, heightMeasureSpec);
}
}
}
@Override
protected void dispatchDraw(Canvas canvas) {
canvas.save();
canvas.translate(mPosX, mPosY);
canvas.scale(mScaleFactor, mScaleFactor, mFocusX, mFocusY);
super.dispatchDraw(canvas);
canvas.restore();
}
@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
mDispatchTouchEventWorkingArray[0] = ev.getX();
mDispatchTouchEventWorkingArray[1] = ev.getY();
mDispatchTouchEventWorkingArray = screenPointsToScaledPoints(mDispatchTouchEventWorkingArray);
ev.setLocation(mDispatchTouchEventWorkingArray[0],
mDispatchTouchEventWorkingArray[1]);
return super.dispatchTouchEvent(ev);
}
/**
* Although the docs say that you shouldn't override this, I decided to do
* so because it offers me an easy way to change the invalidated area to my
* likening.
*/
@Override
public ViewParent invalidateChildInParent(int[] location, Rect dirty) {
mInvalidateWorkingArray[0] = dirty.left;
mInvalidateWorkingArray[1] = dirty.top;
mInvalidateWorkingArray[2] = dirty.right;
mInvalidateWorkingArray[3] = dirty.bottom;
mInvalidateWorkingArray = scaledPointsToScreenPoints(mInvalidateWorkingArray);
dirty.set(Math.round(mInvalidateWorkingArray[0]), Math.round(mInvalidateWorkingArray[1]),
Math.round(mInvalidateWorkingArray[2]), Math.round(mInvalidateWorkingArray[3]));
location[0] *= mScaleFactor;
location[1] *= mScaleFactor;
return super.invalidateChildInParent(location, dirty);
}
private float[] scaledPointsToScreenPoints(float[] a) {
mScaleMatrix.mapPoints(a);
mTranslateMatrix.mapPoints(a);
return a;
}
private float[] screenPointsToScaledPoints(float[] a){
mTranslateMatrixInverse.mapPoints(a);
mScaleMatrixInverse.mapPoints(a);
return a;
}
@Override
public boolean onTouchEvent(MotionEvent ev) {
mOnTouchEventWorkingArray[0] = ev.getX();
mOnTouchEventWorkingArray[1] = ev.getY();
mOnTouchEventWorkingArray = scaledPointsToScreenPoints(mOnTouchEventWorkingArray);
ev.setLocation(mOnTouchEventWorkingArray[0], mOnTouchEventWorkingArray[1]);
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;
// Save the ID of this pointer
mActivePointerId = ev.getPointerId(0);
break;
}
case MotionEvent.ACTION_MOVE: {
// Find the index of the active pointer and fetch its position
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;
mTranslateMatrix.preTranslate(dx, dy);
mTranslateMatrix.invert(mTranslateMatrixInverse);
mLastTouchX = x;
mLastTouchY = y;
invalidate();
break;
}
case MotionEvent.ACTION_UP: {
mActivePointerId = INVALID_POINTER_ID;
break;
}
case MotionEvent.ACTION_CANCEL: {
mActivePointerId = INVALID_POINTER_ID;
break;
}
case MotionEvent.ACTION_POINTER_UP: {
// Extract the index of the pointer that left the touch sensor
final int pointerIndex = (action & 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();
if (detector.isInProgress()) {
mFocusX = detector.getFocusX();
mFocusY = detector.getFocusY();
}
mScaleFactor = Math.max(0.1f, Math.min(mScaleFactor, 5.0f));
mScaleMatrix.setScale(mScaleFactor, mScaleFactor,
mFocusX, mFocusY);
mScaleMatrix.invert(mScaleMatrixInverse);
invalidate();
requestLayout();
return true;
}
}
}
这个类应该能够做的是拖动内容并允许捏缩放，双击缩放现在是不可能的，但它应该很容易在onTouchEvent方法中实现。
如果您对如何在 ViewGroup 中布局子元素有任何疑问，我发现此 video 非常有帮助，或者如果您对单个方法的工作方式有任何疑问，或者有任何其他问题，请随时在 cmets 中提问。
【讨论】：
此自定义视图是 Android 标准 imageView 的子类，并向其添加（多点）触控平移和缩放（以及双击缩放）：
https://github.com/sephiroth74/ImageViewZoom
http://blog.sephiroth.it/2011/04/04/imageview-zoom-and-scroll/
它类似于您已经知道的 MikeOrtiz 的 TouchImageView，但增加了一些功能。
您可以在视图“堆栈”（Android FrameLayout 或类似的东西）中使用它以及您需要的其他 textView。 （我的意思是“一堆”视图，比如一堆盘子或一堆卡片。换句话说，一堆视图在 Z 轴上一个接一个。）
将所有视图一起移动需要您控制 Android 手势（多点触控）机制并编写所需的代码。对于您的（相当复杂的）需求，没有任何现成的解决方案。看看这篇文章：
http://android-developers.blogspot.it/2010/06/making-sense-of-multitouch.html
【讨论】：
重新发布@Artjom 答案并修复了小错误，即大括号、导入和扩展 ViewGroup。
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.graphics.Rect;
import android.view.*;
public class ZoomableViewGroup extends ViewGroup {
private static final int INVALID_POINTER_ID = 1;
private int mActivePointerId = INVALID_POINTER_ID;
private float mScaleFactor = 1;
private ScaleGestureDetector mScaleDetector;
private Matrix mScaleMatrix = new Matrix();
private Matrix mScaleMatrixInverse = new Matrix();
private float mPosX;
private float mPosY;
private Matrix mTranslateMatrix = new Matrix();
private Matrix mTranslateMatrixInverse = new Matrix();
private float mLastTouchX;
private float mLastTouchY;
private float mFocusY;
private float mFocusX;
private float[] mInvalidateWorkingArray = new float[6];
private float[] mDispatchTouchEventWorkingArray = new float[2];
private float[] mOnTouchEventWorkingArray = new float[2];
public ZoomableViewGroup(Context context) {
super(context);
mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());
mTranslateMatrix.setTranslate(0, 0);
mScaleMatrix.setScale(1, 1);
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
int childCount = getChildCount();
for (int i = 0; i < childCount; i++) {
View child = getChildAt(i);
if (child.getVisibility() != GONE) {
child.layout(l, t, l+child.getMeasuredWidth(), t + child.getMeasuredHeight());
}
}
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int childCount = getChildCount();
for (int i = 0; i < childCount; i++) {
View child = getChildAt(i);
if (child.getVisibility() != GONE) {
measureChild(child, widthMeasureSpec, heightMeasureSpec);
}
}
}
@Override
protected void dispatchDraw(Canvas canvas) {
canvas.save();
canvas.translate(mPosX, mPosY);
canvas.scale(mScaleFactor, mScaleFactor, mFocusX, mFocusY);
super.dispatchDraw(canvas);
canvas.restore();
}
@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
mDispatchTouchEventWorkingArray[0] = ev.getX();
mDispatchTouchEventWorkingArray[1] = ev.getY();
mDispatchTouchEventWorkingArray = screenPointsToScaledPoints(mDispatchTouchEventWorkingArray);
ev.setLocation(mDispatchTouchEventWorkingArray[0],
mDispatchTouchEventWorkingArray[1]);
return super.dispatchTouchEvent(ev);
}
/**
* Although the docs say that you shouldn't override this, I decided to do
* so because it offers me an easy way to change the invalidated area to my
* likening.
*/
@Override
public ViewParent invalidateChildInParent(int[] location, Rect dirty) {
mInvalidateWorkingArray[0] = dirty.left;
mInvalidateWorkingArray[1] = dirty.top;
mInvalidateWorkingArray[2] = dirty.right;
mInvalidateWorkingArray[3] = dirty.bottom;
mInvalidateWorkingArray = scaledPointsToScreenPoints(mInvalidateWorkingArray);
dirty.set(Math.round(mInvalidateWorkingArray[0]), Math.round(mInvalidateWorkingArray[1]),
Math.round(mInvalidateWorkingArray[2]), Math.round(mInvalidateWorkingArray[3]));
location[0] *= mScaleFactor;
location[1] *= mScaleFactor;
return super.invalidateChildInParent(location, dirty);
}
private float[] scaledPointsToScreenPoints(float[] a) {
mScaleMatrix.mapPoints(a);
mTranslateMatrix.mapPoints(a);
return a;
}
private float[] screenPointsToScaledPoints(float[] a){
mTranslateMatrixInverse.mapPoints(a);
mScaleMatrixInverse.mapPoints(a);
return a;
}
@Override
public boolean onTouchEvent(MotionEvent ev) {
mOnTouchEventWorkingArray[0] = ev.getX();
mOnTouchEventWorkingArray[1] = ev.getY();
mOnTouchEventWorkingArray = scaledPointsToScreenPoints(mOnTouchEventWorkingArray);
ev.setLocation(mOnTouchEventWorkingArray[0], mOnTouchEventWorkingArray[1]);
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;
// Save the ID of this pointer
mActivePointerId = ev.getPointerId(0);
break;
}
case MotionEvent.ACTION_MOVE: {
// Find the index of the active pointer and fetch its position
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;
mTranslateMatrix.preTranslate(dx, dy);
mTranslateMatrix.invert(mTranslateMatrixInverse);
mLastTouchX = x;
mLastTouchY = y;
invalidate();
break;
}
case MotionEvent.ACTION_UP: {
mActivePointerId = INVALID_POINTER_ID;
break;
}
case MotionEvent.ACTION_CANCEL: {
mActivePointerId = INVALID_POINTER_ID;
break;
}
case MotionEvent.ACTION_POINTER_UP: {
// Extract the index of the pointer that left the touch sensor
final int pointerIndex = (action & 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();
if (detector.isInProgress()) {
mFocusX = detector.getFocusX();
mFocusY = detector.getFocusY();
}
mScaleFactor = Math.max(0.1f, Math.min(mScaleFactor, 5.0f));
mScaleMatrix.setScale(mScaleFactor, mScaleFactor,
mFocusX, mFocusY);
mScaleMatrix.invert(mScaleMatrixInverse);
invalidate();
requestLayout();
return true;
}
}
}
【讨论】：
private float[] screenPointsToScaledPoints(float[] a)改为：private float[] screenPointsToScaledPoints(float[] a) { mScaleMatrixInverse.mapPoints(a); mTranslateMatrixInverse.mapPoints(a); return a; }
根据给定的答案，我使用此代码使平移和缩放功能正常工作。一开始的枢轴点有问题。
public class ZoomableViewGroup extends ViewGroup {
// these matrices will be used to move and zoom image
private Matrix matrix = new Matrix();
private Matrix matrixInverse = new Matrix();
private Matrix savedMatrix = new Matrix();
// we can be in one of these 3 states
private static final int NONE = 0;
private static final int DRAG = 1;
private static final int ZOOM = 2;
private int mode = NONE;
// remember some things for zooming
private PointF start = new PointF();
private PointF mid = new PointF();
private float oldDist = 1f;
private float[] lastEvent = null;
private boolean initZoomApplied=false;
private float[] mDispatchTouchEventWorkingArray = new float[2];
private float[] mOnTouchEventWorkingArray = new float[2];
@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
mDispatchTouchEventWorkingArray[0] = ev.getX();
mDispatchTouchEventWorkingArray[1] = ev.getY();
mDispatchTouchEventWorkingArray = screenPointsToScaledPoints(mDispatchTouchEventWorkingArray);
ev.setLocation(mDispatchTouchEventWorkingArray[0],
mDispatchTouchEventWorkingArray[1]);
return super.dispatchTouchEvent(ev);
}
private float[] scaledPointsToScreenPoints(float[] a) {
matrix.mapPoints(a);
return a;
}
private float[] screenPointsToScaledPoints(float[] a){
matrixInverse.mapPoints(a);
return a;
}
public ZoomableViewGroup(Context context) {
super(context);
init(context);
}
public ZoomableViewGroup(Context context, AttributeSet attrs) {
super(context, attrs);
init(context);
}
public ZoomableViewGroup(Context context, AttributeSet attrs,
int defStyleAttr) {
super(context, attrs, defStyleAttr);
init(context);
}
/**
* 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 (float)Math.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);
}
private void init(Context context){
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
int childCount = getChildCount();
for (int i = 0; i < childCount; i++) {
View child = getChildAt(i);
if (child.getVisibility() != GONE) {
child.layout(l, t, l+child.getMeasuredWidth(), t + child.getMeasuredHeight());
}
}
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int widthSize = MeasureSpec.getSize(widthMeasureSpec);
int heightSize = MeasureSpec.getSize(heightMeasureSpec);
float[] values = new float[9];
matrix.getValues(values);
float container_width = values[Matrix.MSCALE_X]*widthSize;
float container_height = values[Matrix.MSCALE_Y]*heightSize;
//Log.d("zoomToFit", "m width: "+container_width+" m height: "+container_height);
//Log.d("zoomToFit", "m x: "+pan_x+" m y: "+pan_y);
int childCount = getChildCount();
for (int i = 0; i < childCount; i++) {
View child = getChildAt(i);
if (child.getVisibility() != GONE) {
measureChild(child, widthMeasureSpec, heightMeasureSpec);
if(i==0 && !initZoomApplied && child.getWidth()>0){
int c_w = child.getWidth();
int c_h = child.getHeight();
//zoomToFit(c_w, c_h, container_width, container_height);
}
}
}
}
private void zoomToFit(int c_w, int c_h, float container_width, float container_height){
float proportion_firstChild = (float)c_w/(float)c_h;
float proportion_container = container_width/container_height;
//Log.d("zoomToFit", "firstChildW: "+c_w+" firstChildH: "+c_h);
//Log.d("zoomToFit", "proportion-container: "+proportion_container);
//Log.d("zoomToFit", "proportion_firstChild: "+proportion_firstChild);
if(proportion_container<proportion_firstChild){
float initZoom = container_height/c_h;
//Log.d("zoomToFit", "adjust height with initZoom: "+initZoom);
matrix.postScale(initZoom, initZoom);
matrix.postTranslate(-1*(c_w*initZoom-container_width)/2, 0);
matrix.invert(matrixInverse);
}else {
float initZoom = container_width/c_w;
//Log.d("zoomToFit", "adjust width with initZoom: "+initZoom);
matrix.postScale(initZoom, initZoom);
matrix.postTranslate(0, -1*(c_h*initZoom-container_height)/2);
matrix.invert(matrixInverse);
}
initZoomApplied=true;
invalidate();
}
@Override
protected void dispatchDraw(Canvas canvas) {
canvas.save();
canvas.setMatrix(matrix);
super.dispatchDraw(canvas);
canvas.restore();
}
@Override
public boolean onTouchEvent(MotionEvent event) {
// handle touch events here
mOnTouchEventWorkingArray[0] = event.getX();
mOnTouchEventWorkingArray[1] = event.getY();
mOnTouchEventWorkingArray = scaledPointsToScreenPoints(mOnTouchEventWorkingArray);
event.setLocation(mOnTouchEventWorkingArray[0], mOnTouchEventWorkingArray[1]);
switch (event.getAction() & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN:
savedMatrix.set(matrix);
start.set(event.getX(), event.getY());
mode = DRAG;
lastEvent = null;
break;
case MotionEvent.ACTION_POINTER_DOWN:
oldDist = spacing(event);
if (oldDist > 10f) {
savedMatrix.set(matrix);
midPoint(mid, event);
mode = ZOOM;
}
lastEvent = new float[4];
lastEvent[0] = event.getX(0);
lastEvent[1] = event.getX(1);
lastEvent[2] = event.getY(0);
lastEvent[3] = event.getY(1);
//d = rotation(event);
break;
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_POINTER_UP:
mode = NONE;
lastEvent = null;
break;
case MotionEvent.ACTION_MOVE:
if (mode == DRAG) {
matrix.set(savedMatrix);
float dx = event.getX() - start.x;
float dy = event.getY() - start.y;
matrix.postTranslate(dx, dy);
matrix.invert(matrixInverse);
} else if (mode == ZOOM) {
float newDist = spacing(event);
if (newDist > 10f) {
matrix.set(savedMatrix);
float scale = (newDist / oldDist);
matrix.postScale(scale, scale, mid.x, mid.y);
matrix.invert(matrixInverse);
}
}
break;
}
invalidate();
return true;
}
}
onTouch 函数的功劳转到：http://judepereira.com/blog/multi-touch-in-android-translate-scale-and-rotate/ 感谢 Artjom 处理触摸事件的方法。
我添加了一个 zoomToFit 方法，此时对其进行了注释，因为大多数人不需要它。它使孩子适合容器的大小，并将第一个孩子作为比例因子的参考。
【讨论】：
int MAX_ZOOM = 4;，然后在发布比例之前添加此行（matrix.postScale）：float[] values = new float[9]; matrix.getValues(values); if(scale*values[Matrix.MSCALE_X] >= MAX_ZOOM){ scale = MAX_ZOOM/values[Matrix.MSCALE_X]; }
ZoomableViewGroup 在状态栏下方开始。如果在dispatchDraw 中我将canvas.setMatrix(matrix); 替换为：float[] values = new float[9]; matrix.getValues(values); canvas.translate(values[Matrix.MTRANS_X], values[Matrix.MTRANS_Y]); canvas.scale(values[Matrix.MSCALE_X], values[Matrix.MSCALE_Y]);，则效果很好...
onLayout 中的行更改为child.layout(child.getLeft(), child.getTop(), child.getLeft() + child.getMeasuredWidth(), child.getTop() + child.getMeasuredHeight());。此外，将super.onLayout(changed, l, t, r, b) 添加到方法的开头。
为了在 Alex 的代码中获得更好的 Zooming 性能，请添加以下更改
private class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener {
@Override
public boolean onScale(ScaleGestureDetector detector) {
mScaleFactor *= detector.getScaleFactor();
if (detector.isInProgress()) {
mFocusX = detector.getFocusX();
mFocusY = detector.getFocusY();
}
mFocusX = (mFocusX + mLastTouchX)/2; // get center of touch
mFocusY = (mFocusY + mLastTouchY)/2; // get center of touch
mScaleFactor = Math.max(1f, Math.min(mScaleFactor, 2.0f));
mScaleMatrix.setScale(mScaleFactor, mScaleFactor,mFocusX, mFocusY);
mScaleMatrix.invert(mScaleMatrixInverse);
invalidate();
requestLayout();
return true;
}
}
【讨论】：
Thomas 答案几乎是最好的（我的手机上有一个位置错误）：缩放立即开始（Alex 的代码不是这种情况），并且缩放是在正确的枢轴上进行的-点。
但是，与Alex 的代码相反，无法使用“双击-拖动”手势进行缩放（不是众所周知的手势，但仅用一根手指进行缩放非常有用，例如谷歌浏览器或谷歌地图应用程序）。所以这里对Thomas的代码进行了修改，使其成为可能（并修复了子视图位置错误）：
public class ZoomableView extends ViewGroup {
// States.
private static final byte NONE = 0;
private static final byte DRAG = 1;
private static final byte ZOOM = 2;
private byte mode = NONE;
// Matrices used to move and zoom image.
private Matrix matrix = new Matrix();
private Matrix matrixInverse = new Matrix();
private Matrix savedMatrix = new Matrix();
// Parameters for zooming.
private PointF start = new PointF();
private PointF mid = new PointF();
private float oldDist = 1f;
private float[] lastEvent = null;
private long lastDownTime = 0l;
private float[] mDispatchTouchEventWorkingArray = new float[2];
private float[] mOnTouchEventWorkingArray = new float[2];
@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
mDispatchTouchEventWorkingArray[0] = ev.getX();
mDispatchTouchEventWorkingArray[1] = ev.getY();
mDispatchTouchEventWorkingArray = screenPointsToScaledPoints(mDispatchTouchEventWorkingArray);
ev.setLocation(mDispatchTouchEventWorkingArray[0], mDispatchTouchEventWorkingArray[1]);
return super.dispatchTouchEvent(ev);
}
public ZoomableView(Context context) {
super(context);
init(context);
}
public ZoomableView(Context context, AttributeSet attrs) {
super(context, attrs);
init(context);
}
public ZoomableView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init(context);
}
private void init(Context context) {
}
/**
* 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 (float) Math.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);
}
private float[] scaledPointsToScreenPoints(float[] a) {
matrix.mapPoints(a);
return a;
}
private float[] screenPointsToScaledPoints(float[] a) {
matrixInverse.mapPoints(a);
return a;
}
@Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
int childCount = getChildCount();
for (int i = 0; i < childCount; i++) {
View child = getChildAt(i);
if (child.getVisibility() != GONE) {
child.layout(left, top, left + child.getMeasuredWidth(), top + child.getMeasuredHeight());
}
}
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int childCount = getChildCount();
for (int i = 0; i < childCount; i++) {
View child = getChildAt(i);
if (child.getVisibility() != GONE) {
measureChild(child, widthMeasureSpec, heightMeasureSpec);
}
}
}
@Override
protected void dispatchDraw(Canvas canvas) {
float[] values = new float[9];
matrix.getValues(values);
canvas.save();
canvas.translate(values[Matrix.MTRANS_X], values[Matrix.MTRANS_Y]);
canvas.scale(values[Matrix.MSCALE_X], values[Matrix.MSCALE_Y]);
super.dispatchDraw(canvas);
canvas.restore();
}
@Override
public boolean onTouchEvent(MotionEvent event) {
// handle touch events here
mOnTouchEventWorkingArray[0] = event.getX();
mOnTouchEventWorkingArray[1] = event.getY();
mOnTouchEventWorkingArray = scaledPointsToScreenPoints(mOnTouchEventWorkingArray);
event.setLocation(mOnTouchEventWorkingArray[0], mOnTouchEventWorkingArray[1]);
switch (event.getAction() & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN:
savedMatrix.set(matrix);
mode = DRAG;
lastEvent = null;
long downTime = event.getDownTime();
if (downTime - lastDownTime < 300l) {
float density = getResources().getDisplayMetrics().density;
if (Math.max(Math.abs(start.x - event.getX()), Math.abs(start.y - event.getY())) < 40.f * density) {
savedMatrix.set(matrix);
mid.set(event.getX(), event.getY());
mode = ZOOM;
lastEvent = new float[4];
lastEvent[0] = lastEvent[1] = event.getX();
lastEvent[2] = lastEvent[3] = event.getY();
}
lastDownTime = 0l;
} else {
lastDownTime = downTime;
}
start.set(event.getX(), event.getY());
break;
case MotionEvent.ACTION_POINTER_DOWN:
oldDist = spacing(event);
if (oldDist > 10f) {
savedMatrix.set(matrix);
midPoint(mid, event);
mode = ZOOM;
}
lastEvent = new float[4];
lastEvent[0] = event.getX(0);
lastEvent[1] = event.getX(1);
lastEvent[2] = event.getY(0);
lastEvent[3] = event.getY(1);
break;
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_POINTER_UP:
mode = NONE;
lastEvent = null;
break;
case MotionEvent.ACTION_MOVE:
final float density = getResources().getDisplayMetrics().density;
if (mode == DRAG) {
matrix.set(savedMatrix);
float dx = event.getX() - start.x;
float dy = event.getY() - start.y;
matrix.postTranslate(dx, dy);
matrix.invert(matrixInverse);
if (Math.max(Math.abs(start.x - event.getX()), Math.abs(start.y - event.getY())) > 20.f * density) {
lastDownTime = 0l;
}
} else if (mode == ZOOM) {
if (event.getPointerCount() > 1) {
float newDist = spacing(event);
if (newDist > 10f * density) {
matrix.set(savedMatrix);
float scale = (newDist / oldDist);
matrix.postScale(scale, scale, mid.x, mid.y);
matrix.invert(matrixInverse);
}
} else {
matrix.set(savedMatrix);
float scale = event.getY() / start.y;
matrix.postScale(scale, scale, mid.x, mid.y);
matrix.invert(matrixInverse);
}
}
break;
}
invalidate();
return true;
}
}
【讨论】：
onTouchEvent 上获得转换后的 x,y 坐标？
对于那些对缩放/平移 LinearLayout 感兴趣的人，我修改了 Alex 发布的版本以垂直布局并将平移限制为可见视图。我将它用于 PDFRenderer 中的位图。我已经对此进行了测试，但如果您发现任何错误，请发布，因为我也想了解它们！
注意：我选择不实现双击，因为 QuickScale 有效。
public class ZoomableLinearLayout extends ViewGroup {
private static final int INVALID_POINTER_ID = 1;
private int mActivePointerId = INVALID_POINTER_ID;
private float mScaleFactor = 1;
private ScaleGestureDetector mScaleDetector;
private Matrix mScaleMatrix = new Matrix();
private Matrix mScaleMatrixInverse = new Matrix();
private float mPosX;
private float mPosY;
private Matrix mTranslateMatrix = new Matrix();
private Matrix mTranslateMatrixInverse = new Matrix();
private float mLastTouchX;
private float mLastTouchY;
private float mFocusY;
private float mFocusX;
private int mCanvasWidth;
private int mCanvasHeight;
private float[] mInvalidateWorkingArray = new float[6];
private float[] mDispatchTouchEventWorkingArray = new float[2];
private float[] mOnTouchEventWorkingArray = new float[2];
private boolean mIsScaling;
public ZoomableLinearLayout(Context context) {
super(context);
mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());
mTranslateMatrix.setTranslate(0, 0);
mScaleMatrix.setScale(1, 1);
}
public ZoomableLinearLayout(Context context, AttributeSet attributeSet) {
super(context, attributeSet);
mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());
mTranslateMatrix.setTranslate(0, 0);
mScaleMatrix.setScale(1, 1);
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
int childCount = getChildCount();
for (int i = 0; i < childCount; i++) {
View child = getChildAt(i);
if (child.getVisibility() != GONE) {
child.layout(l, t, l+child.getMeasuredWidth(), t += child.getMeasuredHeight());
}
}
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int height = 0;
int width = 0;
int childCount = getChildCount();
for (int i = 0; i < childCount; i++) {
View child = getChildAt(i);
if (child.getVisibility() != GONE) {
measureChild(child, widthMeasureSpec, heightMeasureSpec);
height += child.getMeasuredHeight();
width = Math.max(width, child.getMeasuredWidth());
}
}
mCanvasWidth = width;
mCanvasHeight = height;
}
@Override
protected void dispatchDraw(Canvas canvas) {
canvas.save();
canvas.translate(mPosX, mPosY);
canvas.scale(mScaleFactor, mScaleFactor, mFocusX, mFocusY);
super.dispatchDraw(canvas);
canvas.restore();
}
@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
mDispatchTouchEventWorkingArray[0] = ev.getX();
mDispatchTouchEventWorkingArray[1] = ev.getY();
mDispatchTouchEventWorkingArray = screenPointsToScaledPoints(mDispatchTouchEventWorkingArray);
ev.setLocation(mDispatchTouchEventWorkingArray[0],
mDispatchTouchEventWorkingArray[1]);
return super.dispatchTouchEvent(ev);
}
/**
* Although the docs say that you shouldn't override this, I decided to do
* so because it offers me an easy way to change the invalidated area to my
* likening.
*/
@Override
public ViewParent invalidateChildInParent(int[] location, Rect dirty) {
mInvalidateWorkingArray[0] = dirty.left;
mInvalidateWorkingArray[1] = dirty.top;
mInvalidateWorkingArray[2] = dirty.right;
mInvalidateWorkingArray[3] = dirty.bottom;
mInvalidateWorkingArray = scaledPointsToScreenPoints(mInvalidateWorkingArray);
dirty.set(Math.round(mInvalidateWorkingArray[0]), Math.round(mInvalidateWorkingArray[1]),
Math.round(mInvalidateWorkingArray[2]), Math.round(mInvalidateWorkingArray[3]));
location[0] *= mScaleFactor;
location[1] *= mScaleFactor;
return super.invalidateChildInParent(location, dirty);
}
private float[] scaledPointsToScreenPoints(float[] a) {
mScaleMatrix.mapPoints(a);
mTranslateMatrix.mapPoints(a);
return a;
}
private float[] screenPointsToScaledPoints(float[] a){
mTranslateMatrixInverse.mapPoints(a);
mScaleMatrixInverse.mapPoints(a);
return a;
}
@Override
public boolean onTouchEvent(MotionEvent ev) {
mOnTouchEventWorkingArray[0] = ev.getX();
mOnTouchEventWorkingArray[1] = ev.getY();
mOnTouchEventWorkingArray = scaledPointsToScreenPoints(mOnTouchEventWorkingArray);
ev.setLocation(mOnTouchEventWorkingArray[0], mOnTouchEventWorkingArray[1]);
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;
// Save the ID of this pointer
mActivePointerId = ev.getPointerId(0);
break;
}
case MotionEvent.ACTION_MOVE: {
// Find the index of the active pointer and fetch its position
final int pointerIndex = ev.findPointerIndex(mActivePointerId);
final float x = ev.getX(pointerIndex);
final float y = ev.getY(pointerIndex);
if (mIsScaling && ev.getPointerCount() == 1) {
// Don't move during a QuickScale.
mLastTouchX = x;
mLastTouchY = y;
break;
}
float dx = x - mLastTouchX;
float dy = y - mLastTouchY;
float[] topLeft = {0f, 0f};
float[] bottomRight = {getWidth(), getHeight()};
/*
* Corners of the view in screen coordinates, so dx/dy should not be allowed to
* push these beyond the canvas bounds.
*/
float[] scaledTopLeft = screenPointsToScaledPoints(topLeft);
float[] scaledBottomRight = screenPointsToScaledPoints(bottomRight);
dx = Math.min(Math.max(dx, scaledBottomRight[0] - mCanvasWidth), scaledTopLeft[0]);
dy = Math.min(Math.max(dy, scaledBottomRight[1] - mCanvasHeight), scaledTopLeft[1]);
mPosX += dx;
mPosY += dy;
mTranslateMatrix.preTranslate(dx, dy);
mTranslateMatrix.invert(mTranslateMatrixInverse);
mLastTouchX = x;
mLastTouchY = y;
invalidate();
break;
}
case MotionEvent.ACTION_UP: {
mActivePointerId = INVALID_POINTER_ID;
break;
}
case MotionEvent.ACTION_CANCEL: {
mActivePointerId = INVALID_POINTER_ID;
break;
}
case MotionEvent.ACTION_POINTER_UP: {
// Extract the index of the pointer that left the touch sensor
final int pointerIndex = (action & 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 float getMaxScale() {
return 2f;
}
private float getMinScale() {
return 1f;
}
private class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener {
@Override
public boolean onScaleBegin(ScaleGestureDetector detector) {
mIsScaling = true;
mFocusX = detector.getFocusX();
mFocusY = detector.getFocusY();
float[] foci = {mFocusX, mFocusY};
float[] scaledFoci = screenPointsToScaledPoints(foci);
mFocusX = scaledFoci[0];
mFocusY = scaledFoci[1];
return true;
}
@Override
public void onScaleEnd(ScaleGestureDetector detector) {
mIsScaling = false;
}
@Override
public boolean onScale(ScaleGestureDetector detector) {
mScaleFactor *= detector.getScaleFactor();
mScaleFactor = Math.max(getMinScale(), Math.min(mScaleFactor, getMaxScale()));
mScaleMatrix.setScale(mScaleFactor, mScaleFactor, mFocusX, mFocusY);
mScaleMatrix.invert(mScaleMatrixInverse);
invalidate();
return true;
}
}
}
【讨论】：
我正在使用此处发布的代码的一些修改版本。此 ZoomLayout 使用 Android 手势识别器进行滚动和缩放。它还在缩放或平移时保留枢轴和边界。
保留平移边界：
if (contentSize != null)
{
float[] values = new float[9];
matrix.getValues(values);
float totX = values[Matrix.MTRANS_X] + distanceX;
float totY = values[Matrix.MTRANS_Y] + distanceY;
float sx = values[Matrix.MSCALE_X];
Rect viewableRect = new Rect();
ZoomLayout.this.getDrawingRect(viewableRect);
float offscreenWidth = contentSize.width() - (viewableRect.right - viewableRect.left);
float offscreenHeight = contentSize.height() - (viewableRect.bottom - viewableRect.top);
float maxDx = (contentSize.width() - (contentSize.width() / sx)) * sx;
float maxDy = (contentSize.height() - (contentSize.height() / sx)) * sx;
if (totX > 0 && distanceX > 0)
{
distanceX = 0;
}
if (totY > 0 && distanceY > 0)
{
distanceY = 0;
}
if(totX*-1 > offscreenWidth+maxDx && distanceX < 0)
{
distanceX = 0;
}
if(totY*-1 > offscreenHeight+maxDy && distanceY < 0)
{
distanceY = 0;
}
}
【讨论】：
我带来了这个解决方案（你的代码和我的一些想法的混合）：
它没有动画，但可以正常工作。享受
用法：
<com.yourapppath.ZoomableViewGroup
android:id="@+id/zoomControl"
android:layout_width="match_parent"
android:layout_height="match_parent">
<FrameLayout
android:id="@+id/frameLayoutZoom"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageView
android:id="@+id/planImageView"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:src="@drawable/yourdrawable"
android:scaleType="center" />
</FrameLayout>
</com.yourapppath.ZoomableViewGroup>
这里是 zoomableViewGroup Java 文件，复制使用即可：
public class ZoomableViewGroup extends ViewGroup {
private boolean doubleTap = false;
private float MIN_ZOOM = 1f;
private float MAX_ZOOM = 2.5f;
private float[] topLeftCorner = {0, 0};
private float scaleFactor;
// States.
private static final byte NONE = 0;
private static final byte DRAG = 1;
private static final byte ZOOM = 2;
private byte mode = NONE;
// Matrices used to move and zoom image.
private Matrix matrix = new Matrix();
private Matrix matrixInverse = new Matrix();
private Matrix savedMatrix = new Matrix();
// Parameters for zooming.
private PointF start = new PointF();
private PointF mid = new PointF();
private float oldDist = 1f;
private float[] lastEvent = null;
private long lastDownTime = 0l;
private long downTime = 0l;
private float[] mDispatchTouchEventWorkingArray = new float[2];
private float[] mOnTouchEventWorkingArray = new float[2];
@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
mDispatchTouchEventWorkingArray[0] = ev.getX();
mDispatchTouchEventWorkingArray[1] = ev.getY();
mDispatchTouchEventWorkingArray = screenPointsToScaledPoints(mDispatchTouchEventWorkingArray);
ev.setLocation(mDispatchTouchEventWorkingArray[0], mDispatchTouchEventWorkingArray[1]);
return super.dispatchTouchEvent(ev);
}
public ZoomableViewGroup(Context context) {
super(context);
}
public ZoomableViewGroup(Context context, AttributeSet attrs) {
super(context, attrs);
}
public ZoomableViewGroup(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
/**
* 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 (float) Math.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);
}
private float[] scaledPointsToScreenPoints(float[] a) {
matrix.mapPoints(a);
return a;
}
private float[] screenPointsToScaledPoints(float[] a) {
matrixInverse.mapPoints(a);
return a;
}
@Override
public void onLayout(boolean changed, int left, int top, int right, int bottom) {
int childCount = getChildCount();
for (int i = 0; i < childCount; i++) {
View child = getChildAt(i);
if (child.getVisibility() != GONE) {
child.layout(left, top, left + child.getMeasuredWidth(), top + child.getMeasuredHeight());
}
}
}
@Override
public void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int childCount = getChildCount();
for (int i = 0; i < childCount; i++) {
View child = getChildAt(i);
if (child.getVisibility() != GONE) {
measureChild(child, widthMeasureSpec, heightMeasureSpec);
}
}
}
@Override
public void dispatchDraw(Canvas canvas) {
float[] values = new float[9];
matrix.getValues(values);
canvas.save();
canvas.translate(values[Matrix.MTRANS_X], values[Matrix.MTRANS_Y]);
canvas.scale(values[Matrix.MSCALE_X], values[Matrix.MSCALE_Y]);
topLeftCorner[0] = values[Matrix.MTRANS_X];
topLeftCorner[1] = values[Matrix.MTRANS_Y];
scaleFactor = values[Matrix.MSCALE_X];
super.dispatchDraw(canvas);
canvas.restore();
}
@Override
public boolean onTouchEvent(MotionEvent event) {
// handle touch events here
mOnTouchEventWorkingArray[0] = event.getX();
mOnTouchEventWorkingArray[1] = event.getY();
mOnTouchEventWorkingArray = scaledPointsToScreenPoints(mOnTouchEventWorkingArray);
event.setLocation(mOnTouchEventWorkingArray[0], mOnTouchEventWorkingArray[1]);
switch (event.getAction() & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN:
savedMatrix.set(matrix);
mode = DRAG;
lastEvent = null;
downTime = SystemClock.elapsedRealtime();
if (downTime - lastDownTime < 250l) {
doubleTap = true;
float density = getResources().getDisplayMetrics().density;
if (Math.max(Math.abs(start.x - event.getX()), Math.abs(start.y - event.getY())) < 40.f * density) {
savedMatrix.set(matrix); //repetition of savedMatrix.setmatrix
mid.set(event.getX(), event.getY());
mode = ZOOM;
lastEvent = new float[4];
lastEvent[0] = lastEvent[1] = event.getX();
lastEvent[2] = lastEvent[3] = event.getY();
}
lastDownTime = 0l;
} else {
doubleTap = false;
lastDownTime = downTime;
}
start.set(event.getX(), event.getY());
break;
case MotionEvent.ACTION_POINTER_DOWN:
oldDist = spacing(event);
if (oldDist > 10f) {
savedMatrix.set(matrix);
midPoint(mid, event);
mode = ZOOM;
}
lastEvent = new float[4];
lastEvent[0] = event.getX(0);
lastEvent[1] = event.getX(1);
lastEvent[2] = event.getY(0);
lastEvent[3] = event.getY(1);
break;
case MotionEvent.ACTION_UP:
if (doubleTap && scaleFactor < 1.8f){
matrix.postScale(2.5f/scaleFactor, 2.5f/scaleFactor, mid.x, mid.y);
} else if(doubleTap && scaleFactor >= 1.8f){
matrix.postScale(1.0f/scaleFactor, 1.0f/scaleFactor, mid.x, mid.y);
}
Handler handler = new Handler();
handler.postDelayed(new Runnable() {
@Override
public void run() {
if(topLeftCorner[0] >= 0){
matrix.postTranslate(-topLeftCorner[0],0);
} else if (topLeftCorner[0] < -getWidth()*(scaleFactor-1)){
matrix.postTranslate((-topLeftCorner[0]) - getWidth()*(scaleFactor-1) ,0);
}
if(topLeftCorner[1] >= 0){
matrix.postTranslate(0,-topLeftCorner[1]);
} else if (topLeftCorner[1] < -getHeight()*(scaleFactor-1)){
matrix.postTranslate(0,(-topLeftCorner[1]) - getHeight()*(scaleFactor-1));
}
matrix.invert(matrixInverse);
invalidate();
}
}, 1);
break;
case MotionEvent.ACTION_POINTER_UP:
mode = NONE;
lastEvent = null;
break;
case MotionEvent.ACTION_MOVE:
final float density = getResources().getDisplayMetrics().density;
if (mode == DRAG) {
matrix.set(savedMatrix);
float dx = event.getX() - start.x;
float dy = event.getY() - start.y;
matrix.postTranslate(dx, dy);
matrix.invert(matrixInverse);
if (Math.max(Math.abs(start.x - event.getX()), Math.abs(start.y - event.getY())) > 20.f * density) {
lastDownTime = 0l;
}
} else if (mode == ZOOM) {
if (event.getPointerCount() > 1) {
float newDist = spacing(event);
if (newDist > 10f * density) {
matrix.set(savedMatrix);
float scale = (newDist / oldDist);
float[] values = new float[9];
matrix.getValues(values);
if (scale * values[Matrix.MSCALE_X] >= MAX_ZOOM) {
scale = MAX_ZOOM / values[Matrix.MSCALE_X];
}
if (scale * values[Matrix.MSCALE_X] <= MIN_ZOOM) {
scale = MIN_ZOOM / values[Matrix.MSCALE_X];
}
matrix.postScale(scale, scale, mid.x, mid.y);
matrix.invert(matrixInverse);
}
} else {
if ( SystemClock.elapsedRealtime() - downTime > 250l) {
doubleTap = false;
}
matrix.set(savedMatrix);
float scale = event.getY() / start.y;
float[] values = new float[9];
matrix.getValues(values);
if (scale * values[Matrix.MSCALE_X] >= MAX_ZOOM) {
scale = MAX_ZOOM / values[Matrix.MSCALE_X];
}
if (scale * values[Matrix.MSCALE_X] <= MIN_ZOOM) {
scale = MIN_ZOOM / values[Matrix.MSCALE_X];
}
matrix.postScale(scale, scale, mid.x, mid.y);
matrix.invert(matrixInverse);
}
}
break;
}
invalidate();
return true;
}
}
【讨论】：