Android開發學習之路--Camera之初體驗

Android開發學習之路--Camera之初體驗

顧名思義Camera就是拍照和錄影的功能，像裡面，我們想拍照傳一下照片，就可以通過camera來拍照，然後儲存照片，發送給好友。那麼的app裡面是不會直接通過camera api來實現的，因為系統一般都會有camera這個程式，那麼直接調用camera app來實現拍照的功能不是很方便嘛，這裡我們學習下。其實最終camera調用到android底層的是v4l2的介面，關於v4l2，還有android的camera的架構以後有機會再好好研究研究。

調用系統內建的camera需要用到intent，通過MediaStore擷取照片路徑，下面來試一下，建立工程CameraPictureTest，為layout添加代碼如下：

 

編寫代碼如下：

 

 

package com.example.jared.camerapicturetest;import android.content.Intent;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.net.Uri;import android.os.Bundle;import android.os.Environment;import android.provider.MediaStore;import android.support.v7.app.AppCompatActivity;import android.view.View;import android.widget.Button;import android.widget.ImageView;import java.io.File;import java.io.FileNotFoundException;import java.io.IOException;public class MainActivity extends AppCompatActivity {    public static final int TAKE_PHOTO = 1;    public static final int CROP_PICTURE = 2;    private Button takePhoto;    private ImageView picture;    private Uri imageUri;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        takePhoto = (Button)findViewById(R.id.take_photo);        takePhoto.setOnClickListener(new myOnClickListener());        picture = (ImageView)findViewById(R.id.picture);        picture.setOnClickListener(new myOnClickListener());    }    private class myOnClickListener implements View.OnClickListener {        @Override        public void onClick(View view) {            switch (view.getId()) {                case R.id.take_photo:                    setTakePhoto();                    break;                default:                    break;            }        }    }    public void setTakePhoto() {        File outputImage = new File(Environment.getExternalStorageDirectory(), "test.jpg");        try {            if(outputImage.exists()) {                outputImage.delete();            }            outputImage.createNewFile();        } catch (IOException e) {            e.printStackTrace();        }        imageUri = Uri.fromFile(outputImage);        Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);        intent.putExtra(MediaStore.EXTRA_OUTPUT, imageUri);        startActivityForResult(intent, TAKE_PHOTO);    }    @Override    protected void onActivityResult(int requestCode, int resultCode, Intent data) {        super.onActivityResult(requestCode, resultCode, data);        switch (requestCode) {            case TAKE_PHOTO:                if(resultCode == RESULT_OK) {                    Intent intent1 = new Intent("com.android.camera.action.CROP");                    intent1.setDataAndType(imageUri, "image/*");                    intent1.putExtra("scale", true);                    intent1.putExtra(MediaStore.EXTRA_OUTPUT, imageUri);                    startActivityForResult(intent1, CROP_PICTURE);                }                break;            case CROP_PICTURE:                if(resultCode == RESULT_OK) {                    try {                        Bitmap bitmap = BitmapFactory.decodeStream(getContentResolver()                                .openInputStream(imageUri));                        picture.setImageBitmap(bitmap);                    } catch (FileNotFoundException e) {                        e.printStackTrace();                    }                }                break;            default:                break;        }    }}

這裡首先確定了儲存的路徑為根目錄下的test.jpg，然後通過intent，傳入這個路徑的Uri，開啟相機進行拍照，這裡有對拍照的返回，如果返回成功，那麼就調用CROP的功能對照片進行裁剪，進入到裁減後返回成功就把圖片顯示在layout建立的ImageView中。

 

具體需要真機顯示，這裡再插播一段關於真機螢幕在mac電腦上的顯示，具體可以參考這篇文章，將你的安卓手機螢幕畫面分享到PC或Mac上。通過一個chrome的Vysor外掛程式來實現，需要android的5.0以上的版本才可以。

好了，下面看下顯示的效果：

效果基本上出來了，很不錯的外掛程式。裡面很多不是直接拍照發送的，還有通過選擇相簿的圖片，已經拍好的照片來發送圖片的，那麼接著我們來實現這個功能，首先layout添加了choosephoto：

 

接著修改MainActivity代碼如下：

 

 

package com.example.jared.camerapicturetest;import android.content.Intent;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.net.Uri;import android.os.Bundle;import android.os.Environment;import android.provider.MediaStore;import android.support.v7.app.AppCompatActivity;import android.view.View;import android.widget.Button;import android.widget.ImageView;import java.io.File;import java.io.FileNotFoundException;import java.io.IOException;public class MainActivity extends AppCompatActivity {    public static final int TAKE_PHOTO = 1;    public static final int CROP_PICTURE = 2;    private Button takePhoto;    private Button choosePhoto;    private ImageView picture;    private Uri imageUri;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        takePhoto = (Button)findViewById(R.id.take_photo);        takePhoto.setOnClickListener(new myOnClickListener());        choosePhoto = (Button)findViewById(R.id.choose_photo);        choosePhoto.setOnClickListener(new myOnClickListener());        picture = (ImageView)findViewById(R.id.picture);        picture.setOnClickListener(new myOnClickListener());    }    private class myOnClickListener implements View.OnClickListener {        @Override        public void onClick(View view) {            switch (view.getId()) {                case R.id.take_photo:                    setTakePhoto();                    break;                case R.id.choose_photo:                    setChoosePhoto();                default:                    break;            }        }    }    public void setChoosePhoto() {        File outputImage1 = new File(Environment.getExternalStorageDirectory(), "test1.jpg");        try {            if(outputImage1.exists()) {                outputImage1.delete();            }            outputImage1.createNewFile();        } catch (IOException e) {            e.printStackTrace();        }        imageUri = Uri.fromFile(outputImage1);        Intent intent1 = new Intent("android.intent.action.GET_CONTENT");        intent1.setType("image/*");        intent1.putExtra("crop", true);        intent1.putExtra("scale", true);        intent1.putExtra(MediaStore.EXTRA_OUTPUT, imageUri);        startActivityForResult(intent1, CROP_PICTURE);    }    public void setTakePhoto() {        File outputImage = new File(Environment.getExternalStorageDirectory(), "test.jpg");        try {            if(outputImage.exists()) {                outputImage.delete();            }            outputImage.createNewFile();        } catch (IOException e) {            e.printStackTrace();        }        imageUri = Uri.fromFile(outputImage);        Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);        intent.putExtra(MediaStore.EXTRA_OUTPUT, imageUri);        startActivityForResult(intent, TAKE_PHOTO);    }    @Override    protected void onActivityResult(int requestCode, int resultCode, Intent data) {        super.onActivityResult(requestCode, resultCode, data);        switch (requestCode) {            case TAKE_PHOTO:                if(resultCode == RESULT_OK) {                    Intent intent1 = new Intent("com.android.camera.action.CROP");                    intent1.setDataAndType(imageUri, "image/*");                    intent1.putExtra("scale", true);                    intent1.putExtra(MediaStore.EXTRA_OUTPUT, imageUri);                    startActivityForResult(intent1, CROP_PICTURE);                }                break;            case CROP_PICTURE:                if(resultCode == RESULT_OK) {                    try {                        Bitmap bitmap = BitmapFactory.decodeStream(getContentResolver()                                .openInputStream(imageUri));                        picture.setImageBitmap(bitmap);                    } catch (FileNotFoundException e) {                        e.printStackTrace();                    }                }                break;            default:                break;        }    }}

基本上和拍照也差不多，然後我們運行下看看效果：

 

點擊選擇照片按鈕，我們會進入到相簿的app裡面，然後選擇一張照片，然後裁剪後儲存，如所示。

 

 

附：參考《第一行代碼》