Android编程权威指南（第2版）--第16章 使用intent拍照 挑战练习

时间：2023-01-04 17:57:55

Android编程权威指南（第2版）--第16章 使用intent拍照 挑战练习

16.7挑战练习：优化照片显示

新建dialog_photo.xml

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

    <ImageView
 android:id="@ id/crime_photo_detail"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 />

</LinearLayout>

新建PhotoDetailFragment.java

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public class extends DialogFragment {

    private static final String ARG_File = "file";
    private ImageView mPhotoView;

    public static PhotoDetailFragment newInstance(File file) {
        Bundle args = new Bundle();
        args.putSerializable(ARG_File, file);

        PhotoDetailFragment fragment = new PhotoDetailFragment();
        fragment.setArguments(args);
        return fragment;
    }

    
    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        File file = (File) getArguments().getSerializable(ARG_File);

        View v = LayoutInflater.from(getActivity())
                .inflate(R.layout.dialog_photo, null);
        mPhotoView = (ImageView) v.findViewById(R.id.crime_photo_detail);

        Bitmap bitmap = PictureUtils.getScaledBitmap(
                file.getPath(), getActivity());
        mPhotoView.setImageBitmap(bitmap);

        return new AlertDialog.Builder(getActivity())
                .setView(v)
                
                .setPositiveButton(android.R.string.ok, null)
                .create();

    }
}

修改CrimeFragment.java

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private static final int REQUEST_PHOTO = 3;
private static final String DIALOG_PHOTO = "DialogPhoto";

onCreateView增加处理

大专栏  Android编程权威指南（第2版）--第16章 使用intent拍照 挑战练习r">
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mPhotoView = (ImageView) v.findViewById(R.id.crime_photo);
mPhotoView.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View view) {
        if (mPhotoFile == null || !mPhotoFile.exists()) {
            mPhotoView.setImageDrawable(null);
        } else {

            FragmentManager manager = getFragmentManager();
            PhotoDetailFragment dialog = PhotoDetailFragment.newInstance(mPhotoFile);
            dialog.setTargetFragment(CrimeFragment.this, REQUEST_PHOTO);
            dialog.show(manager, DIALOG_PHOTO);

        }

    }
});
updatePhotoView();

演示结果：



Android编程权威指南（第2版）--第16章 使用intent拍照 挑战练习

16.8 挑战练习：优化缩略图加载

修改CrimeFragment.java

updatePhotoView,调用带宽高参数的getScaledBitmap

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private void updatePhotoView(int width, int height) {
    if (mPhotoFile == null || !mPhotoFile.exists()) {
        mPhotoView.setImageDrawable(null);
    } else {
        Bitmap bitmap = PictureUtils.getScaledBitmap(
                mPhotoFile.getPath(), width, height); // change this one
        mPhotoView.setImageBitmap(bitmap);
    }
}

onCreateView加上

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mPhotoObserver = mPhotoView.getViewTreeObserver();
mPhotoObserver.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
            @Override
            public void onGlobalLayout() {
                updatePhotoView(mPhotoView.getWidth(), mPhotoView.getHeight());
            }
        });
return v;

修改onActivityResult，不然返回拍完照片返回CrimeFragment的时候会显示不出略缩图

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else if (requestCode == REQUEST_PHOTO) {
    updatePhotoView(mPhotoView.getWidth(), mPhotoView.getHeight());
}

上述代码运行无误，可以达到效果，虽然可以通过OnGlobalLayoutListener这个方式获取视图的宽和高，但是还没搞清楚，待日后补充吧

参考：点击打开链接

Github具体代码：hyyyrwang.github.io

我的简书：https://www.jianshu.com/p/1b9785db93a6

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