android——图片缩放（双击放大、手势缩放）

Android——图片缩放（双击放大、手势缩放）

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent">

<com.ndt.testdemo.com.ZoomImageView
android:id="@+id/zoomView"
android:src="@mipmap/map"
android:layout_width="match_parent"
android:layout_height="match_parent"/>

</android.support.constraint.ConstraintLayout>

public class ZoomImageView extends android.support.v7.widget.AppCompatImageView
implements ViewTreeObserver.OnGlobalLayoutListener,
ScaleGestureDetector.OnScaleGestureListener, View.OnTouchListener {

private boolean mOnce;
//初始化时缩放的值
private float mInitScale;
//双击放大值到达的值
private float mMidScale;
//放大的最大值
private float mMaxScale;

private Matrix mScaleMatrix;

//捕获用户多指触控时缩放的比例
private ScaleGestureDetector mScaleGestureDetector;

//记录上一次多点触控的数量
private int mLastPointerCount;

private float mLastX;
private float mLastY;

private int mTouchSlop;
private boolean isCanDrag;

private boolean isCheckLeftAndRight;
private boolean isCheckTopAndBottom;

/*********双击放大与缩小*********/
private GestureDetector mGestureDetector;

private boolean isAutoScale;

public ZoomImageView(Context context) {
this(context, null);
}

public ZoomImageView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}

public ZoomImageView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
// init
mScaleMatrix = new Matrix();
setScaleType(ScaleType.MATRIX);
setOnTouchListener(this);
mTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop();
mScaleGestureDetector = new ScaleGestureDetector(context, this);
mGestureDetector = new GestureDetector(context,
new GestureDetector.SimpleOnGestureListener() {
@Override
public boolean onDoubleTap(MotionEvent e) {

if (isAutoScale) {
return true;
}

float x = e.getX();
float y = e.getY();

if (getScale() < mMidScale) {
postDelayed(new AutoScaleRunnable(mMidScale, x, y), 16);
isAutoScale = true;
} else {
postDelayed(new AutoScaleRunnable(mInitScale, x, y), 16);
isAutoScale = true;
}
return true;
}
});
}

/**
* 自动放大与缩小
*/
private class AutoScaleRunnable implements Runnable {
/**
* 缩放的目标值
*/
private float mTargetScale;
// 缩放的中心点
private float x;
private float y;

private final float BIGGER = 1.07f;
private final float SMALL = 0.93f;

private float tmpScale;

/**
* @param mTargetScale
* @param x
* @param y
*/
public AutoScaleRunnable(float mTargetScale, float x, float y) {
this.mTargetScale = mTargetScale;
this.x = x;
this.y = y;

if (getScale() < mTargetScale) {
tmpScale = BIGGER;
}
if (getScale() > mTargetScale) {
tmpScale = SMALL;
}
}

@Override
public void run() {
//进行缩放
mScaleMatrix.postScale(tmpScale, tmpScale, x, y);
checkBorderAndCenterWhenScale();
setImageMatrix(mScaleMatrix);

float currentScale = getScale();

if ((tmpScale >1.0f && curre
efc3
ntScale <mTargetScale) ||(tmpScale<1.0f &¤tScale>mTargetScale)) {
//这个方法是重新调用run()方法
postDelayed(this, 16);
}else{
//设置为我们的目标值
float scale = mTargetScale/currentScale;
mScaleMatrix.postScale(scale, scale, x, y);
checkBorderAndCenterWhenScale();
setImageMatrix(mScaleMatrix);

isAutoScale = false;
}
}
}

/**
* 获取ImageView加载完成的图片
*/
@Override
public void onGlobalLayout() {
if (!mOnce) {
// 得到控件的宽和高
int width = getWidth();
int height = getHeight();

// 得到我们的图片，以及宽和高
Drawable drawable = getDrawable();
if (drawable == null) {
return;
}
int dh = drawable.getIntrinsicHeight();
int dw = drawable.getIntrinsicWidth();

float scale = 1.0f;

// 图片的宽度大于控件的宽度，图片的高度小于空间的高度，我们将其缩小
if (dw > width && dh < height) {
scale = width * 1.0f / dw;
}

// 图片的宽度小于控件的宽度，图片的高度大于空间的高度，我们将其缩小
if (dh > height && dw < width) {
scale = height * 1.0f / dh;
}

// 缩小值
if (dw > width && dh > height) {
scale = Math.min(width * 1.0f / dw, height * 1.0f / dh);
}

// 放大值
if (dw < width && dh < height) {
scale = Math.min(width * 1.0f / dw, height * 1.0f / dh);
}

/**
* 得到了初始化时缩放的比例
*/
mInitScale = scale;
mMaxScale = mInitScale * 4;
mMidScale = mInitScale * 2;

// 将图片移动至控件的中间
int dx = getWidth() / 2 - dw / 2;
int dy = getHeight() / 2 - dh / 2;

mScaleMatrix.postTranslate(dx, dy);
mScaleMatrix.postScale(mInitScale, mInitScale, width / 2,
height / 2);
setImageMatrix(mScaleMatrix);

mOnce = true;
}
}

/**
* 注册OnGlobalLayoutListener这个接口
*/
@Override
protected void onAttachedToWindow() {
super.onAttachedToWindow();
getViewTreeObserver().addOnGlobalLayoutListener(this);
}

/**
* 取消OnGlobalLayoutListener这个接口
*/
@SuppressWarnings("deprecation")
@Override
protected void onDetachedFromWindow() {
super.onDetachedFromWindow();
getViewTreeObserver().removeGlobalOnLayoutListener(this);
}

/**
* 获取当前图片的缩放值
*
* @return
*/
public float getScale() {
float[] values = new float[9];
mScaleMatrix.getValues(values);
return values[Matrix.MSCALE_X];
}

// 缩放区间时initScale maxScale
@Override
public boolean onScale(ScaleGestureDetector detector) {
float scale = getScale();
float scaleFactor = detector.getScaleFactor();

if (getDrawable() == null) {
return true;
}

// 缩放范围的控制
if ((scale < mMaxScale && scaleFactor > 1.0f)
|| (scale > mInitScale && scaleFactor < 1.0f)) {
if (scale * scaleFactor < mInitScale) {
scaleFactor = mInitScale / scale;
}

if (scale * scaleFactor > mMaxScale) {
scale = mMaxScale / scale;
}

// 缩放
mScaleMatrix.postScale(scaleFactor, scaleFactor,
detector.getFocusX(), detector.getFocusY());

checkBorderAndCenterWhenScale();

setImageMatrix(mScaleMatrix);
}

return true;
}

/**
* 获得图片放大缩小以后的宽和高，以及left，right，top，bottom
*
* @return
*/
private RectF getMatrixRectF() {
Matrix matrix = mScaleMatrix;
RectF rectF = new RectF();
Drawable d = getDrawable();
if (d != null) {
rectF.set(0, 0, d.getIntrinsicWidth(), d.getIntrinsicHeight());
matrix.mapRect(rectF);
}
return rectF;
}

/**
* 在缩放的时候进行边界以及我们的位置的控制
*/
private void checkBorderAndCenterWhenScale() {
RectF rectF = getMatrixRectF();
float deltaX = 0;
float deltaY = 0;

int width = getWidth();
int height = getHeight();

// 缩放时进行边界检测，防止出现白边
if (rectF.width() >= width) {
if (rectF.left > 0) {
deltaX = -rectF.left;
}
if (rectF.right < width) {
deltaX = width - rectF.right;
}
}

if (rectF.height() >= height) {
if (rectF.top > 0) {
deltaY = -rectF.top;
}
if (rectF.bottom < height) {
deltaY = height - rectF.bottom;
}
}

/**
* 如果宽度或高度小于空间的宽或者高，则让其居中
*/
if (rectF.width() < width) {
deltaX = width / 2f - rectF.right + rectF.width() / 2f;
}

if (rectF.height() < height) {
deltaY = height / 2f - rectF.bottom + rectF.height() / 2f;
}

mScaleMatrix.postTranslate(deltaX, deltaY);
}

@Override
public boolean onScaleBegin(ScaleGestureDetector detector) {
return true;
}

@Override
public void onScaleEnd(ScaleGestureDetector detector) {

}

@Override
public boolean onTouch(View v, MotionEvent event) {

if (mGestureDetector.onTouchEvent(event)) {
return true;
}

mScaleGestureDetector.onTouchEvent(event);

float x = 0;
float y = 0;
// 拿到多点触控的数量
int pointerCount = event.getPointerCount();
for (int i = 0; i < pointerCount; i++) {
x += event.getX(i);
y += event.getY(i);
}

x /= pointerCount;
y /= pointerCount;

if (mLastPointerCount != pointerCount) {
isCanDrag = false;
mLastX = x;
mLastY = y;
}
mLastPointerCount = pointerCount;
RectF rectF = getMatrixRectF();
switch (event.getAction()) {

case MotionEvent.ACTION_DOWN:
if (rectF.width()>getWidth() +0.01|| rectF.height()>getHeight()+0.01) {
if(getParent() instanceof ViewPager)
getParent().requestDisallowInterceptTouchEvent(true);
}
break;

case MotionEvent.ACTION_MOVE:
if (rectF.width()>getWidth()+0.01 || rectF.height()>getHeight()+0.01) {
if(getParent() instanceof ViewPager)
getParent().requestDisallowInterceptTouchEvent(true);
}
float dx = x - mLastX;
float dy = y - mLastY;

if (!isCanDrag) {
isCanDrag = isMoveAction(dx, dy);
}

if (isCanDrag) {
if (getDrawable() != null) {
isCheckLeftAndRight = isCheckTopAndBottom = true;
// 如果宽度小于控件宽度，不允许横向移动
if (rectF.width() < getWidth()) {
isCheckLeftAndRight = false;
dx = 0;
}
// 如果高度小于控件高度，不允许纵向移动
if (rectF.height() < getHeight()) {
isCheckTopAndBottom = false;
dy = 0;
}
mScaleMatrix.postTranslate(dx, dy);

checkBorderWhenTranslate();

setImageMatrix(mScaleMatrix);
}
}
mLastX = x;
mLastY = y;
break;
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_CANCEL:
mLastPointerCount = 0;
break;

default:
break;
}

return true;
}

/**
* 当移动时进行边界检查
*/
private void checkBorderWhenTranslate() {
RectF rectF = getMatrixRectF();
float deltaX = 0;
float deltaY = 0;

int width = getWidth();
int heigth = getHeight();

if (rectF.top > 0 && isCheckTopAndBottom) {
deltaY = -rectF.top;
}
if (rectF.bottom < heigth && isCheckTopAndBottom) {
deltaY = heigth - rectF.bottom;
}
if (rectF.left > 0 && isCheckLeftAndRight) {
deltaX = -rectF.left;
}
if (rectF.right < width && isCheckLeftAndRight) {
deltaX = width - rectF.right;
}
mScaleMatrix.postTranslate(deltaX, deltaY);

}

/**
* 判断是否是move
*
* @param dx
* @param dy
* @return
*/
private boolean isMoveAction(float dx, float dy) {
return Math.sqrt(dx * dx + dy * dy) > mTouchSlop;
}

}

public class ZoomActivity extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_zoom);
}
}