import android.content.Context;
import android.graphics.Matrix;
import android.graphics.PointF;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.widget.ImageView;
/**
* ImageView手势/双击可缩放
* Created on 2019/11/4.
*/
public class GestureImageView extends ImageView implements View.OnTouchListener {
public class ZoomMode{
public final static int Ordinary = 0;
public final static int ZoomIn = 1;
public final static int DoubleZoomIn = 2;
}
private int curMode=0;
private Matrix matrix;
private PointF viewSize;
private PointF imageSize;
private PointF scaleSize;
//记录图片当前坐标
private PointF curPoint;
private PointF originScale;
//0:宽度适应 1:高度适应
private int fitMode=0;
private PointF start;
private PointF center;
private float scaleDoubleZoom=0;
private PointF relativePoint;
private float doubleFingerDistance=0;
long doubleClickTimeSpan=280;
long lastClickTime=0;
int rationZoomIn=2;
public void GestureImageViewInit(){
this.setOnTouchListener(this);
this.setScaleType(ScaleType.MATRIX);
matrix = new Matrix();
originScale = new PointF();
scaleSize = new PointF();
start = new PointF();
center = new PointF();
curPoint = new PointF();
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int width = MeasureSpec.getSize(widthMeasureSpec);
int height = MeasureSpec.getSize(heightMeasureSpec);
viewSize = new PointF(width, height);
//获取当前Drawable的大小
Drawable drawable = getDrawable();
if (drawable == null) {
Log.e("no drawable","drawable is nullPtr");
imageSize = new PointF(width, height/2);
}else {
imageSize = new PointF(drawable.getMinimumWidth(),drawable.getMinimumHeight());
}
FitCenter();
}
/**
* 使图片保存在中央
*/
public void FitCenter(){
float scaleH = viewSize.y/imageSize.y;
float scaleW = viewSize.x/imageSize.x;
//选择小的缩放因子确保图片全部显示在视野内
float scale = scaleH<scaleW?scaleH:scaleW;
//根据view适应大小
setImageScale(new PointF(scale, scale));
originScale.set(scale, scale);
//根据缩放因子大小来将图片中心调整到view 中心
if (scaleH < scaleW) {
setImageTranslation(new PointF(viewSize.x / 2 - scaleSize.x / 2, 0));
fitMode = 1;
} else {
fitMode = 0;
setImageTranslation(new PointF(0, viewSize.y / 2 - scaleSize.y / 2));
}
//记录缩放因子 下次继续从这个比例缩放
scaleDoubleZoom = originScale.x;
}
public GestureImageView(Context context) {
super(context);
GestureImageViewInit();
}
public GestureImageView(Context context, AttributeSet attrs) {
super(context, attrs);
GestureImageViewInit();
}
public GestureImageView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
GestureImageViewInit();
}
@Override
public boolean onTouch(View v, MotionEvent event) {
switch (event.getAction() & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN:
start.set(event.getX(), event.getY());
//手指按下事件
if (event.getPointerCount() == 1) {
if (event.getEventTime()-lastClickTime <= doubleClickTimeSpan) {
//双击事件触发
Log.e("TouchEvent", "DoubleClick");
if (curMode == ZoomMode.Ordinary) {
curMode = ZoomMode.ZoomIn;
relativePoint = new PointF();
//计算归一化坐标
relativePoint.set( (start.x-curPoint.x)/scaleSize.x, (start.y-curPoint.y)/scaleSize.y );
setImageScale(new PointF(originScale.x * rationZoomIn, originScale.y * rationZoomIn));
setImageTranslation(new PointF(start.x - relativePoint.x * scaleSize.x, start.y - relativePoint.y * scaleSize.y));
} else {
curMode = ZoomMode.Ordinary;
FitCenter();
}
} else {
lastClickTime = event.getEventTime();
}
}
break;
case MotionEvent.ACTION_POINTER_DOWN:
//屏幕上已经有一个点按住 再按下一点时触发该事件
doubleFingerDistance = getDoubleFingerDistance(event);
break;
case MotionEvent.ACTION_POINTER_UP:
//屏幕上已经有两个点按住 再松开一点时触发该事件
curMode = ZoomMode.ZoomIn;
scaleDoubleZoom = scaleSize.x/imageSize.x;
if (scaleSize.x<viewSize.x && scaleSize.y<viewSize.y) {
curMode = ZoomMode.Ordinary;
FitCenter();
}
break;
case MotionEvent.ACTION_MOVE:
//手指移动时触发事件
if (event.getPointerCount() == 1) {
if (curMode == ZoomMode.ZoomIn) {
setImageTranslation(new PointF(event.getX() - start.x, event.getY() - start.y));
start.set(event.getX(),event.getY());
}
} else {
//双指缩放时判断是否满足一定距离
if (Math.abs(getDoubleFingerDistance(event) - doubleFingerDistance) > 50 && curMode != ZoomMode.DoubleZoomIn) {
//获取双指中点
center.set((event.getX(0) + event.getX(1)) / 2, (event.getY(0) + event.getY(1)) / 2);
//设置起点
start.set(center);
curMode = ZoomMode.DoubleZoomIn;
doubleFingerDistance = getDoubleFingerDistance(event);
relativePoint = new PointF();
//根据图片当前坐标值计算归一化坐标
relativePoint.set(( start.x-curPoint.x )/ scaleSize.x,(start.y-curPoint.y)/scaleSize.y);
}
if(curMode==ZoomMode.DoubleZoomIn) {
float scale =scaleDoubleZoom*getDoubleFingerDistance(event)/doubleFingerDistance;
setImageScale(new PointF(scale, scale));
setImageTranslation(new PointF(start.x - relativePoint.x * scaleSize.x, start.y - relativePoint.y * scaleSize.y));
}
}
break;
case MotionEvent.ACTION_UP:
//手指松开时触发事件
break;
}
//注意这里return 的一定要是true 否则只会触发按下事件
return true;
}
/**
* 根据缩放因子缩放图片
* @param scale
*/
public void setImageScale(PointF scale){
matrix.setScale(scale.x, scale.y);
scaleSize.set(scale.x*imageSize.x, scale.y*imageSize.y);
this.setImageMatrix(matrix);
}
/**
* 根据偏移量改变图片位置
* @param offset
*/
public void setImageTranslation (PointF offset) {
matrix.postTranslate(offset.x, offset.y);
curPoint.set(offset);
this.setImageMatrix(matrix);
}
public static float getDoubleFingerDistance (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);
}
}
