public class ZoomImageView extends ImageView implements OnTouchListener, OnGlobalLayoutListener {
private static final String TAG = "bqt";
/**一些边界缩放倍数，SCALE_FULL的效果为：第一次双击后将图片宽或高放大到view的宽或高的比例*/
private float SCALE_FULL, SCALE_DOUBLE, SCALE_MAX;
/** 初始化时【屏幕/图片】的大小，也是最后一次双击时使用的缩放比例。如果图片宽高大于屏幕宽高，此值将小于1 */
private float SCALE_INIT;
/**是否限制双指缩放时的缩放倍数*/
private boolean isLimitedScale = true;
private Matrix mScaleMatrix = new Matrix();
private final float[] matrixValues = new float[9];//用于存放矩阵的9个值
/** 缩放的手势检测 */
private ScaleGestureDetector mScaleGestureDetector;
private GestureDetector mGestureDetector;
private boolean isAutoScale;
private int mTouchSlop;
private float mLastX, mLastY;
private boolean isCanDrag;
private int lastPointerCount;
private boolean isCheckTopAndBottom = true, isCheckLeftAndRight = true;
public ZoomImageView(Context context) {
this(context, null);
}
public ZoomImageView(Context context, AttributeSet attrs) {
super(context, attrs);
setScaleType(ScaleType.MATRIX);//用矩阵来绘制
mGestureDetector = new GestureDetector(context, new GestureDetector.SimpleOnGestureListener() {
@Override
public boolean onDoubleTap(MotionEvent e) {//双击时
if (isAutoScale == true) return true;
float x = e.getX();
float y = e.getY();
Log.i(TAG, "双击onDoubleTap，" + "缩放比例：" + getScale() + " , " + SCALE_INIT);
if (getScale() < SCALE_FULL) post(new AutoScaleRunnable(SCALE_FULL, x, y));
else if (getScale() >= SCALE_FULL && getScale() < SCALE_DOUBLE) post(new AutoScaleRunnable(SCALE_DOUBLE, x, y));
else post(new AutoScaleRunnable(SCALE_INIT, x, y));
isAutoScale = true;
return true;
}
});
mScaleGestureDetector = new ScaleGestureDetector(context, new ScaleGestureDetector.SimpleOnScaleGestureListener() {
@Override
public boolean onScale(ScaleGestureDetector detector) {//双指缩放时
if (getDrawable() == null) return true;
float scale = getScale();
float scaleFactor = detector.getScaleFactor();
//缩放的范围控制
if (!isLimitedScale) mScaleMatrix.postScale(scaleFactor, scaleFactor, detector.getFocusX(), detector.getFocusY());
else if ((scale < SCALE_MAX && scaleFactor > 1.0f) || (scale > SCALE_INIT && scaleFactor < 1.0f)) {
//最大值最小值判断
if (scaleFactor * scale < SCALE_INIT) scaleFactor = SCALE_INIT / scale;
if (scaleFactor * scale > SCALE_MAX) scaleFactor = SCALE_MAX / scale;
//设置缩放比例
mScaleMatrix.postScale(scaleFactor, scaleFactor, detector.getFocusX(), detector.getFocusY());
checkBorderAndCenterWhenScale();
setImageMatrix(mScaleMatrix);
}
return true;
}
});
this.setOnTouchListener(this);
}
@Override
protected void onAttachedToWindow() {//在onDraw前调用的。也就是我们写的View在没有绘制出来时调用的
super.onAttachedToWindow();
Log.i(TAG, "onAttachedToWindow");
getViewTreeObserver().addOnGlobalLayoutListener(this);
}
@Override
public void onGlobalLayout() {//根据图片的宽和高以及屏幕的宽和高，对图片进行缩放以及移动至屏幕的中心
if (getDrawable() == null) return;
// 图片的宽高
int dw = getDrawable().getIntrinsicWidth();
int dh = getDrawable().getIntrinsicHeight();
Log.i(TAG, "view大小：" + getWidth() + " * " + getHeight() + " ，图片大小： " + dw + " * " + dh);
//初始化缩放比例
if (dw >= getWidth() && dh >= getHeight()) {// 如果图片的宽【和】高都大于view，则让其按按比例适应屏幕大小
SCALE_INIT = Math.min(getWidth() * 1.0f / dw, getHeight() * 1.0f / dh);
SCALE_FULL = Math.max(getWidth() * 1.0f / dw, getHeight() * 1.0f / dh);
} else if (dw >= getWidth()) { // 如果图片的宽【或】高大于view，则缩放至屏幕的宽或者高
SCALE_INIT = getWidth() * 1.0f / dw;
SCALE_FULL = getHeight() * 1.0f / dh;
} else if (dh >= getHeight()) {
SCALE_INIT = getHeight() * 1.0f / dh;
SCALE_FULL = getWidth() * 1.0f / dw;
} else {//其他情况，也即小图片时，默认不进行缩放
SCALE_INIT = 1.0f;
SCALE_FULL = Math.min(getWidth() * 1.0f / dw, getHeight() * 1.0f / dh);
}
SCALE_DOUBLE = 1.5f * SCALE_FULL;//第二次双击时的缩放比例
SCALE_MAX = 3.5f * SCALE_FULL;//最大缩放比例
Log.i(TAG, "缩放比例SCALE_INIT = " + SCALE_INIT + "--双击缩放比例：" + SCALE_FULL);
// 将图片移动至屏幕中心，以SCALE_INIT为比例进行缩放
mScaleMatrix.postTranslate((getWidth() - dw) / 2, (getHeight() - dh) / 2);
mScaleMatrix.postScale(SCALE_INIT, SCALE_INIT, getWidth() / 2, getHeight() / 2);
setImageMatrix(mScaleMatrix);
getViewTreeObserver().removeOnGlobalLayoutListener(this);
}
@Override
public boolean onTouch(View v, MotionEvent event) {
if (mGestureDetector.onTouchEvent(event)) return true;//双击时，不再响应其他操作
mScaleGestureDetector.onTouchEvent(event);
float x = 0, y = 0;
// 拿到触摸点的个数
final int pointerCount = event.getPointerCount();
// 得到多个触摸点的x与y均值
for (int i = 0; i < pointerCount; i++) {
x += event.getX(i);
y += event.getY(i);
}
x = x / pointerCount;
y = y / pointerCount;
/** 每当触摸点发生变化时，重置mLasX , mLastY */
if (pointerCount != lastPointerCount) {
isCanDrag = false;
mLastX = x;
mLastY = y;
}
lastPointerCount = pointerCount;
RectF rectF = getMatrixRectF();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
if (rectF.width() > getWidth() || rectF.height() > getHeight()) getParent().requestDisallowInterceptTouchEvent(true);
break;
case MotionEvent.ACTION_MOVE:
if (rectF.width() > getWidth() || rectF.height() > getHeight()) getParent().requestDisallowInterceptTouchEvent(true);
Log.i(TAG, "ACTION_MOVE");
float dx = x - mLastX;
float dy = y - mLastY;
if (!isCanDrag) isCanDrag = isCanDrag(dx, dy);
if (isCanDrag) {
if (getDrawable() != null) {
isCheckLeftAndRight = isCheckTopAndBottom = true;
// 如果宽度小于屏幕宽度，则禁止左右移动
if (rectF.width() < getWidth()) {
dx = 0;
isCheckLeftAndRight = false;
}
// 如果高度小雨屏幕高度，则禁止上下移动
if (rectF.height() < getHeight()) {
dy = 0;
isCheckTopAndBottom = false;
}
/**移动时的缩放比例*/
float translateScale = getScale();
if (translateScale > 2.0f) translateScale = 2.0f;
if (translateScale < 0.5f) translateScale = 0.5f;
mScaleMatrix.postTranslate(dx * translateScale, dy * translateScale);//非常有用的设置，当放大很多倍时可以快速的滑动
checkMatrixBounds();
setImageMatrix(mScaleMatrix);
}
}
mLastX = x;
mLastY = y;
break;
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_CANCEL:
Log.i(TAG, "ACTION_UP");
lastPointerCount = 0;
break;
}
return true;
}
//**************************************************************************************************************************
/** 在缩放时，进行图片显示范围的控制，防止图片宽高大于view时，图片与控件间出现白边；防止图片小于view时不居中 */
private void checkBorderAndCenterWhenScale() {
RectF rect = getMatrixRectF();
float deltaX = 0;
float deltaY = 0;
int width = getWidth();
int height = getHeight();
// 如果宽或高大于屏幕，则控制范围
if (rect.width() >= width) {
if (rect.left > 0) deltaX = -rect.left;
if (rect.right < width) deltaX = width - rect.right;
}
if (rect.height() >= height) {
if (rect.top > 0) deltaY = -rect.top;
if (rect.bottom < height) deltaY = height - rect.bottom;
}
// 如果宽或高小于屏幕，则让其居中
if (rect.width() < width) deltaX = width * 0.5f - rect.right + 0.5f * rect.width();
if (rect.height() < height) deltaY = height * 0.5f - rect.bottom + 0.5f * rect.height();
Log.i(TAG, "deltaX = " + deltaX + " , deltaY = " + deltaY);
mScaleMatrix.postTranslate(deltaX, deltaY);
}
/** 根据当前图片的Matrix获得图片的范围 */
private RectF getMatrixRectF() {
Matrix matrix = mScaleMatrix;
RectF rect = new RectF();
Drawable d = getDrawable();
if (null != d) {
rect.set(0, 0, d.getIntrinsicWidth(), d.getIntrinsicHeight());
matrix.mapRect(rect);
}
return rect;
}
/** 获得当前的缩放比例 */
public final float getScale() {
mScaleMatrix.getValues(matrixValues);
return matrixValues[Matrix.MSCALE_X];
}
/** 移动时，进行边界判断，主要判断宽或高大于屏幕的 */
private void checkMatrixBounds() {
RectF rect = getMatrixRectF();
float deltaX = 0, deltaY = 0;
final float viewWidth = getWidth();
final float viewHeight = getHeight();
// 判断移动或缩放后，图片显示是否超出屏幕边界
if (rect.top > 0 && isCheckTopAndBottom) deltaY = -rect.top;
if (rect.bottom < viewHeight && isCheckTopAndBottom) deltaY = viewHeight - rect.bottom;
if (rect.left > 0 && isCheckLeftAndRight) deltaX = -rect.left;
if (rect.right < viewWidth && isCheckLeftAndRight) deltaX = viewWidth - rect.right;
mScaleMatrix.postTranslate(deltaX, deltaY);
}
/** 是否是拖动行为 */
private boolean isCanDrag(float dx, float dy) {
return Math.sqrt((dx * dx) + (dy * dy)) >= mTouchSlop;
}
//**************************************************************************************************************************
/** 自动缩放的任务*/
private class AutoScaleRunnable implements Runnable {
private float mTargetScale;
private int TIME = 100;//分几次缩放到指定的的比例
private float tmpScale;//
private float x, y;//缩放的中心
/**传入目标缩放值，根据目标值与当前值，判断应该放大还是缩小 */
public AutoScaleRunnable(float targetScale, float x, float y) {
this.mTargetScale = targetScale;
this.x = x;
this.y = y;
if (getScale() < mTargetScale) tmpScale = 1.0f + (mTargetScale - getScale() / TIME);
else tmpScale = 1.0f - (getScale() - mTargetScale / TIME);
}
@Override
public void run() {
// 进行缩放
mScaleMatrix.postScale(tmpScale, tmpScale, x, y);
checkBorderAndCenterWhenScale();
setImageMatrix(mScaleMatrix);
// 如果值在合法范围内，继续缩放
if ((tmpScale > 1f && getScale() < mTargetScale) || (tmpScale < 1f && getScale() > mTargetScale)) {
post(this);
} else { // 设置为目标的缩放比例
float deltaScale = mTargetScale / getScale();
mScaleMatrix.postScale(deltaScale, deltaScale, x, y);
checkBorderAndCenterWhenScale();
setImageMatrix(mScaleMatrix);
isAutoScale = false;
}
}
}
}