step1:新建一個項目DragAndZoom，并準(zhǔn)備一張照片放在res/drawable-hdpi目錄下，如下圖所示：

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step2: 設(shè)置應(yīng)用的UI界面，在main.xml中設(shè)置：

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[html]?view plain?copy

<?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"?????

????/>??<!--?指定為matrix類型?-->??

</LinearLayout>??

step3:MainActivity.java中實(shí)現(xiàn)具體的需求

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[java]?view plain?copy

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?{??

??????????

????????/**?記錄是拖拉照片模式還是放大縮小照片模式?*/??

????????private?int?mode?=?0;//?初始狀態(tài)????

????????/**?拖拉照片模式?*/??

????????private?static?final?int?MODE_DRAG?=?1;??

????????/**?放大縮小照片模式?*/??

????????private?static?final?int?MODE_ZOOM?=?2;??

??????????

????????/**?用于記錄開始時候的坐標(biāo)位置?*/??

????????private?PointF?startPoint?=?new?PointF();??

????????/**?用于記錄拖拉圖片移動的坐標(biāo)位置?*/??

????????private?Matrix?matrix?=?new?Matrix();??

????????/**?用于記錄圖片要進(jìn)行拖拉時候的坐標(biāo)位置?*/??

????????private?Matrix?currentMatrix?=?new?Matrix();??

??????

????????/**?兩個手指的開始距離?*/??

????????private?float?startDis;??

????????/**?兩個手指的中間點(diǎn)?*/??

????????private?PointF?midPoint;??

??

????????@Override??

????????public?boolean?onTouch(View?v,?MotionEvent?event)?{??

????????????/**?通過與運(yùn)算保留最后八位?MotionEvent.ACTION_MASK?=?255?*/??

????????????switch?(event.getAction()?&?MotionEvent.ACTION_MASK)?{??

????????????//?手指壓下屏幕??

????????????case?MotionEvent.ACTION_DOWN:??

????????????????mode?=?MODE_DRAG;??

????????????????//?記錄ImageView當(dāng)前的移動位置??

????????????????currentMatrix.set(imageView.getImageMatrix());??

????????????????startPoint.set(event.getX(),?event.getY());??

????????????????break;??

????????????//?手指在屏幕上移動，改事件會被不斷觸發(fā)??

????????????case?MotionEvent.ACTION_MOVE:??

????????????????//?拖拉圖片??

????????????????if?(mode?==?MODE_DRAG)?{??

????????????????????float?dx?=?event.getX()?-?startPoint.x;?//?得到x軸的移動距離??

????????????????????float?dy?=?event.getY()?-?startPoint.y;?//?得到x軸的移動距離??

????????????????????//?在沒有移動之前的位置上進(jìn)行移動??

????????????????????matrix.set(currentMatrix);??

????????????????????matrix.postTranslate(dx,?dy);??

????????????????}??

????????????????//?放大縮小圖片??

????????????????else?if?(mode?==?MODE_ZOOM)?{??

????????????????????float?endDis?=?distance(event);//?結(jié)束距離??

????????????????????if?(endDis?>?10f)?{?//?兩個手指并攏在一起的時候像素大于10??

????????????????????????float?scale?=?endDis?/?startDis;//?得到縮放倍數(shù)??

????????????????????????matrix.set(currentMatrix);??

????????????????????????matrix.postScale(scale,?scale,midPoint.x,midPoint.y);??

????????????????????}??

????????????????}??

????????????????break;??

????????????//?手指離開屏幕??

????????????case?MotionEvent.ACTION_UP:??

????????????????//?當(dāng)觸點(diǎn)離開屏幕，但是屏幕上還有觸點(diǎn)(手指)??

????????????case?MotionEvent.ACTION_POINTER_UP:??

????????????????mode?=?0;??

????????????????break;??

????????????//?當(dāng)屏幕上已經(jīng)有觸點(diǎn)(手指)，再有一個觸點(diǎn)壓下屏幕??

????????????case?MotionEvent.ACTION_POINTER_DOWN:??

????????????????mode?=?MODE_ZOOM;??

????????????????/**?計算兩個手指間的距離?*/??

????????????????startDis?=?distance(event);??

????????????????/**?計算兩個手指間的中間點(diǎn)?*/??

????????????????if?(startDis?>?10f)?{?//?兩個手指并攏在一起的時候像素大于10??

????????????????????midPoint?=?mid(event);??

????????????????????//記錄當(dāng)前ImageView的縮放倍數(shù)??

????????????????????currentMatrix.set(imageView.getImageMatrix());??

????????????????}??

????????????????break;??

????????????}??

????????????imageView.setImageMatrix(matrix);??

????????????return?true;??

????????}??

??

????????/**?計算兩個手指間的距離?*/??

????????private?float?distance(MotionEvent?event)?{??

????????????float?dx?=?event.getX(1)?-?event.getX(0);??

????????????float?dy?=?event.getY(1)?-?event.getY(0);??

????????????/**?使用勾股定理返回兩點(diǎn)之間的距離?*/??

????????????return?FloatMath.sqrt(dx?*?dx?+?dy?*?dy);??

????????}??

??

????????/**?計算兩個手指間的中間點(diǎn)?*/??

????????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);??

????????}??

??

????}??

??

}??

step4:AndroidMainfest.xml

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?

[html]?view plain?copy

<?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>??

step5：具體的效果圖

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上面兩個是圖片拖拽的效果，而圖片的縮放效果要在真機(jī)中才能夠看得到，請讀者自己在真機(jī)環(huán)境中測試。

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附注：具體的程序源碼在：http://pan.baidu.com/share/link?shareid=397888&uk=805959799

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其實(shí) 通過通過手勢也可以縮放圖片 ? ?左--->右 放大 右 --->左 縮小 速度越快，縮放比例越大

zoom.xml

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[html]?view plain?copy

<?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/show"??

????android:scaleType="matrix"?????

????/>??<!--?指定為matrix類型?-->??

</LinearLayout>??

?

?

GestureZoom.java

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[java]?view plain?copy

package?cn.roco.gesture;??

??

import?android.app.Activity;??

import?android.graphics.Bitmap;??

import?android.graphics.BitmapFactory;??

import?android.graphics.Matrix;??

import?android.graphics.drawable.BitmapDrawable;??

import?android.os.Bundle;??

import?android.view.GestureDetector;??

import?android.view.GestureDetector.OnGestureListener;??

import?android.view.MotionEvent;??

import?android.widget.ImageView;??

??

/**?

?*?通過手勢?縮放圖片?左--->右?放大?右?--->左?縮小?速度越快，縮放比例越大?

?*/??

public?class?GestureZoom?extends?Activity?implements?OnGestureListener?{??

????//?定義手勢檢測器實(shí)例??

????GestureDetector?detector;??

????ImageView?imageView;??

????//?初始化圖片資源??

????Bitmap?bitmap;??

????//?定義圖片的高和寬??

????int?width,?height;??

????//?記錄當(dāng)前的縮放比??

????float?currentScale?=?1;??

????//?控制圖片縮放的Matrix對象??

????Matrix?matrix;??

??

????@Override??

????protected?void?onCreate(Bundle?savedInstanceState)?{??

????????super.onCreate(savedInstanceState);??

????????setContentView(R.layout.zoom);??

????????//?創(chuàng)建手勢檢測器??

????????detector?=?new?GestureDetector(this);??

????????imageView?=?(ImageView)?findViewById(R.id.show);??

????????matrix?=?new?Matrix();??

????????//?獲取被縮放的源圖片??

????????bitmap?=?BitmapFactory.decodeResource(this.getResources(),??

????????????????R.drawable.wall);??

????????//?獲得位圖的寬??

????????width?=?bitmap.getWidth();??

????????//?獲得位圖的高??

????????height?=?bitmap.getHeight();??

????????//?設(shè)置?ImageView初始化顯示的圖片??

????????imageView.setImageBitmap(BitmapFactory.decodeResource(??

????????????????this.getResources(),?R.drawable.wall));??

????}??

??

????@Override??

????public?boolean?onTouchEvent(MotionEvent?event)?{??

????????//?將該Activity上的觸碰時間交個?GestureDetector處理??

????????return?detector.onTouchEvent(event);??

????}??

??

????@Override??

????public?boolean?onDown(MotionEvent?e)?{??

????????//?TODO?Auto-generated?method?stub??

????????return?false;??

????}??

??

????@Override??

????public?void?onShowPress(MotionEvent?e)?{??

????????//?TODO?Auto-generated?method?stub??

??

????}??

??

????@Override??

????public?boolean?onSingleTapUp(MotionEvent?e)?{??

????????return?false;??

????}??

??

????@Override??

????public?boolean?onScroll(MotionEvent?e1,?MotionEvent?e2,?float?distanceX,??

????????????float?distanceY)?{??

????????return?false;??

????}??

??

????@Override??

????public?void?onLongPress(MotionEvent?e)?{??

??

????}??

??

????@Override??

????public?boolean?onFling(MotionEvent?e1,?MotionEvent?e2,?float?velocityX,??

????????????float?velocityY)?{??

????????velocityX?=?velocityX?>?4000???4000?:?velocityX;??

????????velocityY?=?velocityY?<?-4000???-4000?:?velocityY;??

????????//?感覺手勢的速度來計算縮放比，如果?velocityX>0,放大圖像，否則縮小圖像??

????????currentScale?+=?currentScale?*?velocityX?/?4000.0f;??

????????//?保證?currentScale?不會等于0??

????????currentScale?=?currentScale?>?0.01???currentScale?:?0.01f;??

????????//?重置?Matrix??

????????matrix.setScale(currentScale,?currentScale,?160,?200);??

????????BitmapDrawable?tmp?=?(BitmapDrawable)?imageView.getDrawable();??

????????//?如果圖片還未回收，先強(qiáng)制收回該圖片??

????????if?(!tmp.getBitmap().isRecycled())?{??

????????????tmp.getBitmap().recycle();??

????????}??

????????//?根據(jù)原始位圖和?Matrix創(chuàng)建新圖片??

????????Bitmap?bitmap2?=?Bitmap.createBitmap(bitmap,?0,?0,?width,?height,??

????????????????matrix,?true);??

????????//顯示新的位圖??

????????imageView.setImageBitmap(bitmap2);??

????????return?true;??

????}??

??????

}??

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查看一下運(yùn)行的效果

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轉(zhuǎn)載于:https://www.cnblogs.com/gzhnan/articles/5286893.html

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