Android 自定义ImageView支持缩放，拖拽，方便复用

自定义ImageView实现缩放拖拽方便复用

[java]
view plaincopyprint?





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);  
    }  
}  

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);
}
}

布局文件需要注意了，使用 <com.example.myimageview.MyImageView></com.example.myimageview.MyImageView>标签，怕一些新手不知道，别怪我啰嗦

[html]
view plaincopyprint?





<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"  
    xmlns:tools="http://schemas.android.com/tools"  
    android:layout_width="fill_parent"  
    android:layout_height="fill_parent" >  
    <com.example.myimageview.MyImageView  
        android:id="@+id/imageview"  
        android:layout_width="fill_parent"  
        android:layout_height="fill_parent"  
        android:src="@drawable/item" >  
    </com.example.myimageview.MyImageView>  
</RelativeLayout>  

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
<com.example.myimageview.MyImageView
android:id="@+id/imageview"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:src="@drawable/item" >
</com.example.myimageview.MyImageView>
</RelativeLayout>

新建一个MainActivity咯，

[java]
view plaincopyprint?





package com.example.myimageview;  
  
import android.app.Activity;  
import android.os.Bundle;  
  
public class MainActivity extends Activity {  
  
    @Override  
    protected void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.activity_main);  
        MyImageView myImageView = (MyImageView)findViewById(R.id.imageview);  
        myImageView.setImageDrawable(getResources().getDrawable(R.drawable.item1));  
    }  
}