Android绘制进阶之六：触摸轨迹的绘制及图片的保存

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

<Button
android:id="@+id/pickImageBtn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="pickImage" />

<ImageView
android:id="@+id/pickedImage"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="@drawable/ic_launcher" />

<Button
android:id="@+id/saveBtn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Save" />

</LinearLayout>

public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

Button pickImageBtn = (Button) findViewById(R.id.pickImageBtn);
Button saveBtn = (Button) findViewById(R.id.saveBtn);
mImageView = (ImageView) findViewById(R.id.pickedImage);

pickImageBtn.setOnClickListener(this);
saveBtn.setOnClickListener(this);

}

public void onClick(View v) {
// TODO Auto-generated method stub
Log.d("bitmap", "has onClick");
switch (v.getId()) {
case R.id.pickImageBtn:
Intent intent = new Intent(Intent.ACTION_PICK, android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
startActivityForResult(intent, REQUEST_CODE);
break;

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent intent) {
// TODO Auto-generated method stub
super.onActivityResult(requestCode, resultCode, intent);
Log.d("bitmap", "requestCode is :" + requestCode);
if (resultCode == RESULT_OK) {
Log.d("bitmap", "has result ok");
Uri uri = intent.getData();

int dw = getWindowManager().getDefaultDisplay().getWidth();
int dh = getWindowManager().getDefaultDisplay().getHeight();

try {
BitmapFactory.Options opts = new BitmapFactory.Options();
opts.inJustDecodeBounds = true;//如果设置为true，本身不会返回
Bitmap chooseBitmap = BitmapFactory.decodeStream(getContentResolver().openInputStream(uri), null, opts);
int bw = opts.outWidth;//此时，chooseBitmap的值为null，但opts仍然获得其config
int bh = opts.outHeight;

int widthRatio = (int) Math.ceil(bw / (float) dw);
int heightRatio = (int) Math.ceil(bh / (float) dh);

if (widthRatio > 1 || heightRatio >1) {
if (widthRatio > heightRatio) {
opts.inSampleSize = widthRatio;//设置比例
} else {
opts.inSampleSize = heightRatio;
}
}
opts.inJustDecodeBounds = false;
chooseBitmap = BitmapFactory.decodeStream(getContentResolver().openInputStream(uri), null, opts);
Log.d("bitmap", "chooseBitmap is :" + chooseBitmap);

alteredBitmap = Bitmap.createBitmap(chooseBitmap.getWidth(), chooseBitmap.getHeight(), chooseBitmap.getConfig());
canvas = new Canvas(alteredBitmap);//画布
paint = new Paint();
paint.setColor(Color.WHITE);
paint.setStyle(Style.STROKE);
Matrix matrix = new Matrix();
canvas.drawBitmap(chooseBitmap, matrix , paint);

mImageView.setImageBitmap(alteredBitmap);
mImageView.setOnTouchListener(this);//设置监听

} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

}

}

public boolean onTouch(View v, MotionEvent event) {
// TODO Auto-generated method stub
Log.d("touch_draw", "ontouch()");

switch (event.getAction()) {
case MotionEvent.ACTION_UP:
//          upX = event.getX();
//          upY = event.getY();//画直线的相关代码，可自己测试。同理，画圆椭圆都可在相关方法里设置
//          canvas.drawLine(downX, downY, upX, upY, paint);
//          mImageView.invalidate();
//          break;
case MotionEvent.ACTION_DOWN:
downX = event.getX();
downY = event.getY();
break;
case MotionEvent.ACTION_MOVE:
upX = event.getX();
upY = event.getY();
canvas.drawLine(downX, downY, upX, upY, paint);
mImageView.invalidate();
downX = upX;
downY = upY;
break;
case MotionEvent.ACTION_CANCEL:
break;

}

return true;
}

public void onClick(View v) {
// TODO Auto-generated method stub
Log.d("bitmap", "has onClick");
switch (v.getId()) {
case R.id.pickImageBtn:
Intent intent = new Intent(Intent.ACTION_PICK, android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
startActivityForResult(intent, REQUEST_CODE);
break;case R.id.saveBtn://保存已经涂鸦过的图片

/*
* PNG :非常适合艺术线条和图形：始终保持所有数据
* JPEG:非常适合带渐变的全彩图像，例如照片。是“有损的”编解码器，可设置质量
*/

if (null != alteredBitmap) {
Uri imageFileUri = getContentResolver().insert(Media.EXTERNAL_CONTENT_URI, new ContentValues());//创建一个新的uri

try {
OutputStream imageFileOS = getContentResolver().openOutputStream(imageFileUri);//输出流

alteredBitmap.compress(CompressFormat.JPEG, 90, imageFileOS);//生成图片

Toast.makeText(this, "has saved", Toast.LENGTH_SHORT).show();

} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
break;
}
}