Android手指绘图(一)

package cn.c;import java.io.OutputStream;import android.app.Activity;import android.content.Intent;import android.graphics.Bitmap;import android.graphics.Bitmap.CompressFormat;import android.graphics.BitmapFactory;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Matrix;import android.graphics.Paint;import android.net.Uri;import android.os.Bundle;import android.view.Display;import android.view.MotionEvent;import android.view.View;import android.view.View.OnClickListener;import android.view.View.OnTouchListener;import android.widget.Button;import android.widget.ImageView;import android.widget.Toast;/** * 注意: * 1 event.getX()和event.getRawX()方法的区别 *   event.getX()是相对于父控件而言 *   event.getRawX()是相对于屏幕左上角而言 * 2 在Activity中处理触摸事件采用的是OnTouchEvent() *   在View中处理触摸事件是实现OnTouchListener{}接口 *   覆写其中的onTouch()方法 * 3 Bug的问题: *   计算options.inSampleSize这里有Bug.有的图片过大在 *   设备图片库中是被旋转处理了的(虽然看上去没有).比如一 *   张大图片在图片库中看上去是竖屏的,但得到后在ImageView *   中显示却是横屏的. *   所以这里方便测试直接: *   options.inSampleSize=8; *   写死了 * 4 调用bitmap.compress()方法的时候注意若设置格式为PNG,那么则无效. *   因为PNG将始终保持所有数据.JPEG是"有损的"编解码器 */public class MainActivity extends Activity implements OnTouchListener{    private ImageView mImageView;    private Button mButton;    private Button mSaveButton;    private Bitmap mRawBitmap;    private Bitmap mAlteredBitmap;    private Paint mPaint;    private Canvas mCanvas;    private Uri mPhotoFileUri;    private final int PICK=88;    float downX=0;    float downY=0;    float upX=0;    float upY=0;        @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);        mImageView=(ImageView) findViewById(R.id.imageView);        mImageView.setOnTouchListener(this);        mButton=(Button) findViewById(R.id.button);        mButton.setOnClickListener(new ButtonOnClickListener());        mSaveButton=(Button) findViewById(R.id.saveButton);        mSaveButton.setOnClickListener(new ButtonOnClickListener());        mPaint=new Paint();        mPaint.setColor(Color.RED);        mPaint.setStrokeWidth(5);    }    @Overrideprotected void onActivityResult(int requestCode, int resultCode, Intent data) {super.onActivityResult(requestCode, resultCode, data);if (requestCode==PICK) {mPhotoFileUri=data.getData();Display display=getWindowManager().getDefaultDisplay();float w=display.getWidth();float h=display.getHeight();try {BitmapFactory.Options  options=new BitmapFactory.Options();options.inJustDecodeBounds=true;mRawBitmap=BitmapFactory.decodeStream    (getContentResolver().openInputStream(mPhotoFileUri), null, options);int widthRation=(int) Math.ceil(options.outHeight/h);int heightRation=(int) Math.ceil(options.outWidth/w);if (heightRation>1&&widthRation>1) {if (heightRation>widthRation) {options.inSampleSize=heightRation;} else {options.inSampleSize=widthRation;}}//Bug所在:options.inSampleSize=8;options.inJustDecodeBounds=false;mRawBitmap=BitmapFactory.decodeStream   (getContentResolver().openInputStream(mPhotoFileUri), null, options);mAlteredBitmap=Bitmap.createBitmap(mRawBitmap.getWidth(), mRawBitmap.getHeight(), mRawBitmap.getConfig());mCanvas=new Canvas(mAlteredBitmap);Matrix matrix=new Matrix();mCanvas.drawBitmap(mRawBitmap, matrix, mPaint);mImageView.setImageBitmap(mAlteredBitmap);} catch (Exception e) {}}}private class ButtonOnClickListener implements OnClickListener {public void onClick(View v) {switch (v.getId()) {case R.id.button:Intent intent = new Intent(Intent.ACTION_PICK,android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);startActivityForResult(intent, PICK);break;case R.id.saveButton:try {if (mPhotoFileUri!=null) {OutputStream fos=getContentResolver().openOutputStream(mPhotoFileUri);mAlteredBitmap.compress(CompressFormat.JPEG, 90, fos);fos.close();Toast.makeText(MainActivity.this, "OK", Toast.LENGTH_SHORT).show();}} catch (Exception e) {// TODO: handle exception}break;default:break;}}}public boolean onTouch(View v, MotionEvent event) {int action = event.getAction();switch (action) {case MotionEvent.ACTION_DOWN:            downX=event.getX();            downY=event.getY();break;case MotionEvent.ACTION_MOVE:upX=event.getX();            upY=event.getY();            mCanvas.drawLine(downX, downY, upX, upY, mPaint);            mImageView.invalidate();            downX=upX;            downY=upY;break;case MotionEvent.ACTION_UP://            upX=event.getX();//            upY=event.getY();//            mCanvas.drawLine(downX, downY, upX, upY, mPaint);//            mImageView.invalidate();break;case MotionEvent.ACTION_CANCEL:break;default:break;}return true;}   }