android中的图片处理

大图片处理

大图片处理是将原来像素高的转换为像素低的图片,比如原来图片是1024*768的，而手机屏幕是800*600的，这时候就需要进行转换。转换的方式很简单就是等比例缩放。

package xidian.dy.com.chujia;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.os.Environment;
import android.support.v7.app.AppCompatActivity;
import android.view.Display;
import android.view.View;
import android.widget.ImageView;

import java.io.File;

public class MainActivity extends AppCompatActivity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}

public void load(View v){
BitmapFactory.Options options = new BitmapFactory.Options();
File file = new File(Environment.getExternalStorageDirectory(), "a.dog");
options.inJustDecodeBounds = true;
BitmapFactory.decodeFile(file.toString(), options);
//获取图片宽高
int imgWidth = options.outWidth;
int imgHeight = options.outHeight;
//获取屏幕宽高
Display dsp = getWindowManager().getDefaultDisplay();
int screanWidth = dsp.getWidth();
int screanHeight = dsp.getHeight();
//计算缩放比例
int scaleWidth = imgWidth / screanWidth;
int scaleHeight = imgHeight / screanHeight;
int scale = scaleHeight >= scaleWidth ? scaleHeight:scaleWidth;
if(scale < 1)
scale = 1;
//设置缩放比例(scale应大于1缩放才能其作用)
options.inSampleSize = scale;
options.inJustDecodeBounds = false;
Bitmap bm = BitmapFactory.decodeFile(file.toString(), options);

ImageView img = (ImageView) findViewById(R.id.iv);
if(img != null)
img.setImageBitmap(bm);
}
}

图片副本

创建图片副本是为了对图片进行修改,下面的代码将图片进行了水平反转

package xidian.dy.com.chujia;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.ImageView;

public class MainActivity extends AppCompatActivity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Bitmap bm = BitmapFactory.decodeFile("/sdcard/a.dog");
//创建一个与原图等宽高的bitmap对象,可以看作是画纸
Bitmap bmcpy = Bitmap.createBitmap(bm.getWidth(), bm.getHeight(),bm.getConfig());

//创建画笔对象
Paint paint = new Paint();
//创建画板对象,将画纸铺在画板上
Canvas canvas = new Canvas(bmcpy);
//开始作画
//将图片水平翻转
Matrix mt = new Matrix();
mt.setScale(-1, 1);
mt.postTranslate(bmcpy.getWidth(), 0);
canvas.drawBitmap(bm, mt, paint);
ImageView iv = (ImageView) findViewById(R.id.iv2);
iv.setImageBitmap(bmcpy);
ImageView iv1 = (ImageView) findViewById(R.id.iv1);
iv1.setImageBitmap(bm);
}
}

画画

让用户在画板上作画

package xidian.dy.com.chujia;

import android.content.Intent;
import android.graphics.Bitmap;
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.os.Environment;
import android.support.v7.app.AppCompatActivity;
import android.view.MotionEvent;
import android.view.View;
import android.widget.ImageView;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;

public class MainActivity extends AppCompatActivity {
int preX,preY;
Bitmap bmcpy;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Bitmap bm = BitmapFactory.decodeResource(getResources(), R.drawable.bg);
bmcpy = Bitmap.createBitmap(bm.getWidth(), bm.getHeight(), bm.getConfig());
final Paint paint = new Paint();
final Canvas canvas = new Canvas(bmcpy);
//设置画笔的颜色为红色
paint.setColor(Color.RED);
canvas.drawBitmap(bm, new Matrix(), paint);
final ImageView iv = (ImageView) findViewById(R.id.iv);
iv.setImageBitmap(bmcpy);
if(iv != null)
iv.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
int action = event.getAction();
switch (action) {
case MotionEvent.ACTION_DOWN:
preX = (int) event.getX();
preY = (int) event.getY();
break;
case MotionEvent.ACTION_UP:
break;
case MotionEvent.ACTION_MOVE:
int x = (int) event.getX();
int y = (int) event.getY();
canvas.drawLine(preX, preY, x, y, paint);
iv.setImageBitmap(bmcpy);
preX = x;
preY = y;
break;
}
return true;
}
});
}

//将画好的图片进行保存
public void save(){
File file = new File("/sdcard/tmp.png");
try {
FileOutputStream fos = new FileOutputStream(file);
bmcpy.compress(Bitmap.CompressFormat.PNG,10,fos);
Intent intent = new Intent();
//发出SDcard挂载广播来刷新MediaStore数据库
intent.setAction(Intent.ACTION_MEDIA_MOUNTED);
intent.setData(Uri.fromFile(Environment.getExternalStorageDirectory()));
startActivity(intent);
} catch (FileNotFoundException e) {
e.printStackTrace();
}
}
}