Android实现图片放大缩小

package com.min.Test_Gallery; import android.app.Activity; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.graphics.Color; import android.graphics.Matrix; import android.os.Bundle; import android.util.DisplayMetrics; import android.util.Log; import android.view.GestureDetector; import android.view.KeyEvent; import android.view.MotionEvent; import android.view.View; import android.view.GestureDetector.OnGestureListener; import android.view.View.OnTouchListener; import android.widget.Button; import android.widget.FrameLayout; import android.widget.ImageView; import android.widget.LinearLayout; import android.widget.Toast; public class DisplayImage extends Activity implements OnTouchListener, OnGestureListener { private static final String TAG = "DisplayImage"; private static final int FLING_MIN_DISTANCE = 100; private static final int FLING_MIN_VELOCITY = 200; /* 相关变量声明 */ private ImageView mImageView; private Button mButton01; private Button mButton02; private FrameLayout layout1; private LinearLayout layoutImage; private Bitmap bmp; private int id=0; private int displayWidth; private int displayHeight; private float scaleWidth=1; private float scaleHeight=1; private GestureDetector mGestureDetector; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); /* 加载display.xml Layout */ setContentView(R.layout.display); /* 取得屏幕分辨率大小 */ DisplayMetrics dm=new DisplayMetrics(); getWindowManager().getDefaultDisplay().getMetrics(dm); displayWidth=dm.widthPixels; displayHeight=dm.heightPixels; /* 初始化相关变量 */ Bundle bundle = this.getIntent().getExtras(); Integer imageId = bundle.getInt("imageId"); Log.i(TAG, "onCreate, imageId = " + imageId); bmp=BitmapFactory.decodeResource(getResources(), imageId); mImageView = (ImageView)findViewById(R.id.myImageView); mImageView.setImageBitmap(bmp); mImageView.setOnTouchListener(this); mImageView.setLongClickable(true); layout1 = (FrameLayout)findViewById(R.id.layout1); layoutImage = (LinearLayout)findViewById(R.id.layoutImage); mButton01 = (Button)findViewById(R.id.myButton1); mButton02 = (Button)findViewById(R.id.myButton2); /* 缩小按钮onClickListener */ mButton01.setOnClickListener(new Button.OnClickListener() { @Override public void onClick(View v) { small(); } }); /* 放大按钮onClickListener */ mButton02.setOnClickListener(new Button.OnClickListener() { @Override public void onClick(View v) { big(); } }); } // 用户轻触触摸屏，由1个MotionEvent ACTION_DOWN触发 @Override public boolean onDown(MotionEvent e) { // TODO Auto-generated method stub // Toast.makeText(this, "onDown", Toast.LENGTH_SHORT).show(); Log.i(TAG, "onDown..."); return false; } /* 用户按下触摸屏、快速移动后松开，由1个MotionEvent ACTION_DOWN, * 多个ACTION_MOVE, 1个ACTION_UP触发 * 参数解释： * e1：第1个ACTION_DOWN MotionEvent * e2：最后一个ACTION_MOVE MotionEvent * velocityX：X轴上的移动速度，像素/秒 * velocityY：Y轴上的移动速度，像素/秒 * 触发条件： * X轴的坐标位移大于FLING_MIN_DISTANCE，且移动速度大于FLING_MIN_VELOCITY个像素/秒 * @see android.view.GestureDetector$OnGestureListener#onFling(android.view.MotionEvent, android.view.MotionEvent, float, float) */ @Override public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) { // TODO Auto-generated method stub Log.i(TAG, "onFling..."); if (e1.getX() - e2.getX() > FLING_MIN_DISTANCE && Math.abs(velocityX) > FLING_MIN_VELOCITY) { // Fling left Toast.makeText(this, "Fling Left", Toast.LENGTH_SHORT).show(); } else if (e2.getX() - e1.getX() > FLING_MIN_DISTANCE && Math.abs(velocityX) > FLING_MIN_VELOCITY) { // Fling right Toast.makeText(this, "Fling Right", Toast.LENGTH_SHORT).show(); } return false; } // 用户长按触摸屏，由多个MotionEvent ACTION_DOWN触发 @Override public void onLongPress(MotionEvent e) { // TODO Auto-generated method stub Log.i(TAG, "onLongPress..."); } // 用户按下触摸屏，并拖动，由1个MotionEvent ACTION_DOWN, 多个ACTION_MOVE触发 @Override public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) { // TODO Auto-generated method stub Log.i(TAG, "onScroll..."); return false; } // 用户轻触触摸屏，尚未松开或拖动，由一个1个MotionEvent ACTION_DOWN触发 // 注意和onDown()的区别，强调的是没有松开或者拖动的状态 @Override public void onShowPress(MotionEvent e) { // TODO Auto-generated method stub Log.i(TAG, "onShowPress..."); } // 用户（轻触触摸屏后）松开，由一个1个MotionEvent ACTION_UP触发 @Override public boolean onSingleTapUp(MotionEvent e) { // TODO Auto-generated method stub Log.i(TAG, "onSingleTapUp..."); return false; } @Override public boolean onTouch(View v, MotionEvent event) { // TODO Auto-generated method stub Log.i(TAG, "onTouch..."); // Set button visible mButton01.setVisibility(View.VISIBLE); mButton02.setVisibility(View.VISIBLE); return mGestureDetector.onTouchEvent(event); } // @Override // public boolean onTouchEvent(MotionEvent event) { // // TODO Auto-generated method stub // super.onTouchEvent(event); // // Log.i(TAG, "onTouchEvent"); // // Set button visible // mButton01.setVisibility(View.VISIBLE); // mButton02.setVisibility(View.VISIBLE); // // return true; // } @Override public boolean onKeyDown(int keyCode, KeyEvent event) { // TODO Auto-generated method stub super.onKeyDown(keyCode, event); Log.i(TAG, "onKeyDown..."); // Set button visible mButton01.setVisibility(View.VISIBLE); mButton02.setVisibility(View.VISIBLE); return true; } /* 图片缩小的method */ private void small() { int bmpWidth=bmp.getWidth(); int bmpHeight=bmp.getHeight(); Log.i(TAG, "bmpWidth = " + bmpWidth + ", bmpHeight = " + bmpHeight); /* 设置图片缩小的比例 */ double scale=0.8; /* 计算出这次要缩小的比例 */ scaleWidth=(float) (scaleWidth*scale); scaleHeight=(float) (scaleHeight*scale); /* 产生reSize后的Bitmap对象 */ Matrix matrix = new Matrix(); matrix.postScale(scaleWidth, scaleHeight); Bitmap resizeBmp = Bitmap.createBitmap(bmp,0,0,bmpWidth, bmpHeight,matrix,true); if(id==0) { /* 如果是第一次按，就删除原来默认的ImageView */ layoutImage.removeView(mImageView); } else { /* 如果不是第一次按，就删除上次放大缩小所产生的ImageView */ layoutImage.removeView((ImageView)findViewById(id)); } /* 产生新的ImageView，放入reSize的Bitmap对象，再放入Layout中 */ id++; ImageView imageView = new ImageView(this); imageView.setId(id); imageView.setImageBitmap(resizeBmp); layoutImage.addView(imageView); Log.i(TAG, "imageView.getWidth() = " + imageView.getWidth() + ", imageView.getHeight() = " + imageView.getHeight()); setContentView(layout1); /* 因为图片放到最大时放大按钮会disable，所以在缩小时把它重设为enable */ mButton02.setEnabled(true); mButton02.setTextColor(Color.MAGENTA); } /* 图片放大的method */ private void big() { int bmpWidth=bmp.getWidth(); int bmpHeight=bmp.getHeight(); Log.i(TAG, "bmpWidth = " + bmpWidth + ", bmpHeight = " + bmpHeight); /* 设置图片放大的比例 */ double scale=1.25; /* 计算这次要放大的比例 */ scaleWidth=(float)(scaleWidth*scale); scaleHeight=(float)(scaleHeight*scale); /* 产生reSize后的Bitmap对象 */ Matrix matrix = new Matrix(); matrix.postScale(scaleWidth, scaleHeight); Bitmap resizeBmp = Bitmap.createBitmap(bmp,0,0,bmpWidth, bmpHeight,matrix,true); if(id==0) { /* 如果是第一次按，就删除原来设置的ImageView */ layoutImage.removeView(mImageView); } else { /* 如果不是第一次按，就删除上次放大缩小所产生的ImageView */ layoutImage.removeView((ImageView)findViewById(id)); } /* 产生新的ImageView，放入reSize的Bitmap对象，再放入Layout中 */ id++; ImageView imageView = new ImageView(this); imageView.setId(id); imageView.setImageBitmap(resizeBmp); layoutImage.addView(imageView); setContentView(layout1); /* 如果再放大会超过屏幕大小，就把Button disable */ if( scaleWidth * scale * bmpWidth > bmpWidth * 3 || scaleHeight * scale * bmpHeight > bmpWidth * 3 || scaleWidth * scale * bmpWidth > displayWidth * 5 || scaleHeight * scale * bmpHeight > displayHeight * 5) { mButton02.setEnabled(false); mButton02.setTextColor(Color.GRAY); } else { mButton02.setEnabled(true); mButton02.setTextColor(Color.MAGENTA); } } }

display.xml文件

<?xml version="1.0" encoding="utf-8"?> <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent" android:id="@+id/layout1" > <ScrollView xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_weight="19" android:scrollbars="vertical" android:fadingEdge="vertical"> <HorizontalScrollView android:layout_height="fill_parent" android:layout_width="wrap_content"> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="horizontal" android:layout_width="fill_parent" android:layout_height="wrap_content" android:gravity="center" android:id="@+id/layoutImage" > <ImageView android:id="@+id/myImageView" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_weight="19" android:paddingTop="5dip" android:paddingBottom="5dip" /> </LinearLayout> </HorizontalScrollView > </ScrollView> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="wrap_content" > <Button android:id="@+id/myButton1" android:layout_width="45dip" android:layout_height="30dip" android:layout_alignParentLeft="true" android:gravity="left" style="@style/my_style_button" android:visibility="gone" android:text="缩小" /> <Button android:id="@+id/myButton2" android:layout_width="45dip" android:layout_height="30dip" android:layout_alignParentRight="true" android:gravity="right" style="@style/my_style_button" android:visibility="gone" android:text="放大" /> </RelativeLayout> </FrameLayout>

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