package com.example.myimageview;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Matrix;
import android.graphics.PointF;
import android.graphics.RectF;
import android.graphics.drawable.BitmapDrawable;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.util.FloatMath;
import android.view.MotionEvent;
import android.view.View;
import android.widget.ImageView;
public class MyImageView extends ImageView{
Matrix matrix = new Matrix();
Matrix savedMatrix = new Matrix();
/**位图对象*/
private Bitmap bitmap = null;
/** 屏幕的分辨率*/
private DisplayMetrics dm;
/** 最小缩放比例*/
float minScaleR = 1.0f;
/** 最大缩放比例*/
static final float MAX_SCALE = 15f;
/** 初始状态*/
static final int NONE = 0;
/** 拖动*/
static final int DRAG = 1;
/** 缩放*/
static final int ZOOM = 2;
/** 当前模式*/
int mode = NONE;
/** 存储float类型的x，y值，就是你点下的坐标的X和Y*/
PointF prev = new PointF();
PointF mid = new PointF();
float dist = 1f;
public MyImageView(Context context) {
super(context);
setupView();
}
public MyImageView(Context context, AttributeSet attrs) {
super(context, attrs);
setupView();
}
public void setupView(){
Context context = getContext();
//获取屏幕分辨率,需要根据分辨率来使用图片居中
dm = context.getResources().getDisplayMetrics();
//根据MyImageView来获取bitmap对象
BitmapDrawable bd = (BitmapDrawable)this.getDrawable();
if(bd != null){
bitmap = bd.getBitmap();
}
//设置ScaleType为ScaleType.MATRIX，这一步很重要
this.setScaleType(ScaleType.MATRIX);
this.setImageBitmap(bitmap);
//bitmap为空就不调用center函数
if(bitmap != null){
center(true, true);
}
this.setImageMatrix(matrix);
this.setOnTouchListener(new OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
switch (event.getAction() & MotionEvent.ACTION_MASK) {
// 主点按下
case MotionEvent.ACTION_DOWN:
savedMatrix.set(matrix);
prev.set(event.getX(), event.getY());
mode = DRAG;
break;
// 副点按下
case MotionEvent.ACTION_POINTER_DOWN:
dist = spacing(event);
// 如果连续两点距离大于10，则判定为多点模式
if (spacing(event) > 10f) {
savedMatrix.set(matrix);
midPoint(mid, event);
mode = ZOOM;
}
break;
case MotionEvent.ACTION_UP:{
break;
}
case MotionEvent.ACTION_POINTER_UP:
mode = NONE;
//savedMatrix.set(matrix);
break;
case MotionEvent.ACTION_MOVE:
if (mode == DRAG) {
matrix.set(savedMatrix);
matrix.postTranslate(event.getX() - prev.x, event.getY()
- prev.y);
} else if (mode == ZOOM) {
float newDist = spacing(event);
if (newDist > 10f) {
matrix.set(savedMatrix);
float tScale = newDist / dist;
matrix.postScale(tScale, tScale, mid.x, mid.y);
}
}
break;
}
MyImageView.this.setImageMatrix(matrix);
CheckView();
return true;
}
});
}
/**
* 横向、纵向居中
*/
protected void center(boolean horizontal, boolean vertical) {
Matrix m = new Matrix();
m.set(matrix);
RectF rect = new RectF(0, 0, bitmap.getWidth(), bitmap.getHeight());
m.mapRect(rect);
float height = rect.height();
float width = rect.width();
float deltaX = 0, deltaY = 0;
if (vertical) {
// 图片小于屏幕大小，则居中显示。大于屏幕，上方留空则往上移，下方留空则往下移
int screenHeight = dm.heightPixels;
if (height < screenHeight) {
deltaY = (screenHeight - height) / 2 - rect.top;
} else if (rect.top > 0) {
deltaY = -rect.top;
} else if (rect.bottom < screenHeight) {
deltaY = this.getHeight() - rect.bottom;
}
}
if (horizontal) {
int screenWidth = dm.widthPixels;
if (width < screenWidth) {
deltaX = (screenWidth - width) / 2 - rect.left;
} else if (rect.left > 0) {
deltaX = -rect.left;
} else if (rect.right < screenWidth) {
deltaX = screenWidth - rect.right;
}
}
matrix.postTranslate(deltaX, deltaY);
}
/**
* 限制最大最小缩放比例，自动居中
*/
private void CheckView() {
float p[] = new float[9];
matrix.getValues(p);
if (mode == ZOOM) {
if (p[0] < minScaleR) {
//Log.d("", "当前缩放级别:"+p[0]+",最小缩放级别:"+minScaleR);
matrix.setScale(minScaleR, minScaleR);
}
if (p[0] > MAX_SCALE) {
//Log.d("", "当前缩放级别:"+p[0]+",最大缩放级别:"+MAX_SCALE);
matrix.set(savedMatrix);
}
}
center(true, true);
}
/**
* 两点的距离
*/
private float spacing(MotionEvent event) {
float x = event.getX(0) - event.getX(1);
float y = event.getY(0) - event.getY(1);
return FloatMath.sqrt(x * x + y * y);
}
/**
* 两点的中点
*/
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);
}
}