android 加载图片并在上面画图

像Ps上的应用一样，我们加载一个图片然后在上面增加各种我们需要的挂件，文字效果等。我们今天完成一个简单的Demo

复制代码

复制代码

package com.example.fingerdraw;

import java.io.FileNotFoundException;

import java.io.OutputStream;

import android.app.Activity;

import android.content.ContentValues;

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.provider.MediaStore.Images.Media;

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;

public class MainActivity extends Activity implements OnTouchListener,

OnClickListener {

private ImageView image;

private Paint paint;

private Canvas canvas;

private Bitmap bitmap;

private Bitmap alterBitmap;

private Button choose;

private Button save;

private final static int RESULT = 0;

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

image = (ImageView) findViewById(R.id.image);

choose = (Button) findViewById(R.id.chooseButton);

save=(Button)findViewById(R.id.saveButton);

/*

* bitmap = Bitmap.createBitmap(getWindowManager().getDefaultDisplay()

* .getWidth(), getWindowManager().getDefaultDisplay().getHeight(),

* Bitmap.Config.ARGB_8888); canvas = new Canvas(bitmap);// 画板 

*paint = new Paint();// 画刷 paint.setColor(Color.BLUE);

* image.setImageBitmap(bitmap);

*/

image.setOnTouchListener(this);

choose.setOnClickListener(this);

save.setOnClickListener(this);

}

private float downx = 0;

private float downy = 0;

private float upx = 0;

private float upy = 0;

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:

// 路径画板

upx = event.getX();

upy = event.getY();

canvas.drawLine(downx, downy, upx, upy, paint);

image.invalidate();

downx = upx;

downy = upy;

break;

case MotionEvent.ACTION_UP:

// 直线画板

upx = event.getX();

upy = event.getY();

canvas.drawLine(downx, downy, upx, upy, paint);

image.invalidate();// 刷新

break;

default:

break;

}

return true;

}

public void onClick(View arg0) {

if(arg0==choose){

Intent intent = new Intent(Intent.ACTION_PICK,

android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);

startActivityForResult(intent, RESULT);

}else if(arg0==save){

//保存画好的图片

if(alterBitmap!=null){

try {

Uri imageUri=getContentResolver().insert(Media.EXTERNAL_CONTENT_URI, new ContentValues());

OutputStream outputStream=getContentResolver().openOutputStream(imageUri);

alterBitmap.compress(CompressFormat.PNG, 90, outputStream);

Toast.makeText(getApplicationContext(), "save!", Toast.LENGTH_SHORT).show();

} catch (FileNotFoundException e) {

e.printStackTrace();

}

}

}

}

@Override

protected void onActivityResult(int requestCode, int resultCode, Intent data) {

// TODO Auto-generated method stub

super.onActivityResult(requestCode, resultCode, data);

if (resultCode == RESULT_OK) {

Uri imageFileUri = data.getData();

Display display = getWindowManager().getDefaultDisplay();

float dw = display.getWidth();

float dh = display.getHeight();

try {

BitmapFactory.Options options = new BitmapFactory.Options();

options.inJustDecodeBounds = true;

bitmap = BitmapFactory.decodeStream(getContentResolver()

.openInputStream(imageFileUri), null, options);

int heightRatio = (int) Math.ceil(options.outHeight / dh);

int widthRatio = (int) Math.ceil(options.outWidth / dw);

if (heightRatio > 1 && widthRatio > 1) {

if (heightRatio > widthRatio) {

options.inSampleSize = heightRatio;

} else {

options.inSampleSize = widthRatio;

}

}

options.inJustDecodeBounds = false;

bitmap = BitmapFactory.decodeStream(getContentResolver()

.openInputStream(imageFileUri), null, options);

alterBitmap = Bitmap.createBitmap(bitmap.getWidth(),

bitmap.getHeight(), bitmap.getConfig());

canvas = new Canvas(alterBitmap);

paint = new Paint();

paint.setColor(Color.GREEN);

paint.setStrokeWidth(10);

Matrix matrix = new Matrix();

canvas.drawBitmap(bitmap, matrix, paint);

image.setImageBitmap(alterBitmap);

image.setOnTouchListener(this);

} catch (FileNotFoundException e) {

e.printStackTrace();

}

}

}

}