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<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:layout_gravity="center" >

    <ImageView
        android:id="@+id/imag"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:layout_gravity="center"
        android:scaleType="matrix" >
    </ImageView>

</FrameLayout>

View Code

　　　　　　Android 图片的浏览、缩放、拖动和自动居中 

转载地址：http://www.cnblogs.com/dwinter/archive/2012/01/12/2321082.html

• Touch.java

/**
 * 图片浏览、缩放、拖动、自动居中
 */
public class Touch extends Activity implements OnTouchListener {

    Matrix matrix = new Matrix();
    Matrix savedMatrix = new Matrix();
    DisplayMetrics dm;
    ImageView imgView;
    Bitmap bitmap;

    float minScaleR;// 最小缩放比例
    static final float MAX_SCALE = 4f;// 最大缩放比例

    static final int NONE = 0;// 初始状态
    static final int DRAG = 1;// 拖动
    static final int ZOOM = 2;// 缩放
    int mode = NONE;

    PointF prev = new PointF();
    PointF mid = new PointF();
    float dist = 1f;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.scale);
        imgView = (ImageView) findViewById(R.id.imag);// 获取控件
        bitmap = BitmapFactory.decodeResource(getResources(), this.getIntent()
                .getExtras().getInt("IMG"));// 获取图片资源
        imgView.setImageBitmap(bitmap);// 填充控件
        imgView.setOnTouchListener(this);// 设置触屏监听
        dm = new DisplayMetrics();
        getWindowManager().getDefaultDisplay().getMetrics(dm);// 获取分辨率
        minZoom();
        center();
        imgView.setImageMatrix(matrix);
    }

    /**
     * 触屏监听
     */
    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:
        case MotionEvent.ACTION_POINTER_UP:
            mode = NONE;
            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;
        }
        imgView.setImageMatrix(matrix);
        CheckView();
        return true;
    }

    /**
     * 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) {
                matrix.setScale(minScaleR, minScaleR);
            }
            if (p[0] > MAX_SCALE) {
                matrix.set(savedMatrix);
            }
        }
        center();
    }

    /**
     * 最小缩放比例，最大为100%
     */
    private void minZoom() {
        minScaleR = Math.min(
                (float) dm.widthPixels / (float) bitmap.getWidth(),
                (float) dm.heightPixels / (float) bitmap.getHeight());
        if (minScaleR < 1.0) {
            matrix.postScale(minScaleR, minScaleR);
        }
    }

    private void center() {
        center(true, 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 = imgView.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);
    }

    /**
     * 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);
    }
}

View Code

• scale.xml

android Matrix图片随意的放大缩小,拖动

转载地址：http://www.bdqn.cn/news/201304/8794.shtml

step1:新建一个项目DragAndZoom，并准备一张照片放在res/drawable-hdpi目录下，如下图所示：

（图片略）

step2: 设置应用的UI界面，在main.xml中设置：

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

    android:orientation="vertical"

    android:layout_width="fill_parent"

    android:layout_height="fill_parent"

    >

<ImageView 

    android:layout_width="fill_parent"

    android:layout_height="wrap_content"

    android:src="@drawable/wall"

    android:id="@+id/imageView"

    android:scaleType="matrix" 

    />  <!-- 指定为matrix类型 -->

</LinearLayout>

View Code

step3:MainActivity.java中实现具体的需求

package cn.roco.drag;
  
import android.app.Activity;
import android.graphics.Matrix;
import android.graphics.PointF;
import android.os.Bundle;
import android.util.FloatMath;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.widget.ImageView;
  
public class MainActivity extends Activity {
  
    private ImageView imageView;
  
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
  
        imageView = (ImageView) this.findViewById(R.id.imageView);
        imageView.setOnTouchListener(new TouchListener());
    }
  
    private final class TouchListener implements OnTouchListener {
          
        /** 记录是拖拉照片模式还是放大缩小照片模式 */
        private int mode = 0;// 初始状态 
        /** 拖拉照片模式 */
        private static final int MODE_DRAG = 1;
        /** 放大缩小照片模式 */
        private static final int MODE_ZOOM = 2;
          
        /** 用于记录开始时候的坐标位置 */
        private PointF startPoint = new PointF();
        /** 用于记录拖拉图片移动的坐标位置 */
        private Matrix matrix = new Matrix();
        /** 用于记录图片要进行拖拉时候的坐标位置 */
        private Matrix currentMatrix = new Matrix();
      
        /** 两个手指的开始距离 */
        private float startDis;
        /** 两个手指的中间点 */
        private PointF midPoint;
  
        @Override
        public boolean onTouch(View v, MotionEvent event) {
            /** 通过与运算保留最后八位 MotionEvent.ACTION_MASK = 255 */
            switch (event.getAction() & MotionEvent.ACTION_MASK) {
            // 手指压下屏幕
            case MotionEvent.ACTION_DOWN:
                mode = MODE_DRAG;
                // 记录ImageView当前的移动位置
                currentMatrix.set(imageView.getImageMatrix());
                startPoint.set(event.getX(), event.getY());
                break;
            // 手指在屏幕上移动，改事件会被不断触发
            case MotionEvent.ACTION_MOVE:
                // 拖拉图片
                if (mode == MODE_DRAG) {
                    float dx = event.getX() - startPoint.x; // 得到x轴的移动距离
                    float dy = event.getY() - startPoint.y; // 得到x轴的移动距离
                    // 在没有移动之前的位置上进行移动
                    matrix.set(currentMatrix);
                    matrix.postTranslate(dx, dy);
                }
                // 放大缩小图片
                else if (mode == MODE_ZOOM) {
                    float endDis = distance(event);// 结束距离
                    if (endDis > 10f) { // 两个手指并拢在一起的时候像素大于10
                        float scale = endDis / startDis;// 得到缩放倍数
                        matrix.set(currentMatrix);
                        matrix.postScale(scale, scale,midPoint.x,midPoint.y);
                    }
                }
                break;
            // 手指离开屏幕
            case MotionEvent.ACTION_UP:
                // 当触点离开屏幕，但是屏幕上还有触点(手指)
            case MotionEvent.ACTION_POINTER_UP:
                mode = 0;
                break;
            // 当屏幕上已经有触点(手指)，再有一个触点压下屏幕
            case MotionEvent.ACTION_POINTER_DOWN:
                mode = MODE_ZOOM;
                /** 计算两个手指间的距离 */
                startDis = distance(event);
                /** 计算两个手指间的中间点 */
                if (startDis > 10f) { // 两个手指并拢在一起的时候像素大于10
                    midPoint = mid(event);
                    //记录当前ImageView的缩放倍数
                    currentMatrix.set(imageView.getImageMatrix());
                }
                break;
            }
            imageView.setImageMatrix(matrix);
            return true;
        }
  
        /** 计算两个手指间的距离 */
        private float distance(MotionEvent event) {
            float dx = event.getX(1) - event.getX(0);
            float dy = event.getY(1) - event.getY(0);
            /** 使用勾股定理返回两点之间的距离 */
            return FloatMath.sqrt(dx * dx + dy * dy);
        }
  
        /** 计算两个手指间的中间点 */
        private PointF mid(MotionEvent event) {
            float midX = (event.getX(1) + event.getX(0)) / 2;
            float midY = (event.getY(1) + event.getY(0)) / 2;
            return new PointF(midX, midY);
        }
  
    }
  
}

View Code

step4:AndroidMainfest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="cn.roco.drag"
      android:versionCode="1"
      android:versionName="1.0">
    <uses-sdk android:minSdkVersion="8" />
  
    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".MainActivity"
                  android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
  
    </application>
</manifest>

View Code