Kee*_*ano 8 android android-fragments
我已经完全重写了问题,以便缩小范围.
我有两个片段像卡片一样翻转(左,右).当前片段消失翻转时,它会显示背面.再次单击该按钮后,它再次翻转到前面,但前面片段上的ImageView消失了.
我尝试过保存所选图像数据的不同方法.
这给了我一个空指针,所以我想我创建后需要一些更恒定的东西.
这个我认为可行,只需检查路径并抓住它,如果它翻转到前面或重新创建活动.
这是一些代码
的onCreate():
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.new_postcard_activity);
//UI call
frontImageView = (ImageView) findViewById(R.id.imageView);
Log.d(tag, "onCreate() Instance:" + savedInstanceState);
//fragment start
if (savedInstanceState == null) {
Log.d(tag,"Instance Null");
getFragmentManager()
.beginTransaction()
.add(R.id.postcardFrame, new CardFrontFragment())
.commit();
if(!mShowingBack){
Log.d(tag,"Not showing back");
if(newPath != null && newPath != ""){
Log.d(tag, "entered new path, not empty");
Drawable drawable = Drawable.createFromPath(newPath);
Log.d(tag, "Should be setting saved image.");
frontImageView.setImageDrawable(drawable);
}
}
}
else
{
mShowingBack = (getFragmentManager().getBackStackEntryCount() > 0);
Log.d(tag, "Instance is not Null");
}
翻转按钮单击"侦听器"
//flip card
final Button cardBackButton = (Button) findViewById(R.id.cardBackButton);
cardBackButton.setOnClickListener(new Button.OnClickListener(){
@Override
public void onClick(View v) {
flipCard();
});
flipCard方法:
private void flipCard()
{
Log.d(tag2, "Log after flipCard:" + mShowingBack);
if(mShowingBack)
{
//Flip to front
flipFront();
return;
}
// Flip to back
flipBack();
}
我从他们的PhotoGallery中设置了Image onActivityResult
protected void onActivityResult(int requestCode, int resultCode,
Intent intent) {
super.onActivityResult(requestCode, resultCode, intent);
if (resultCode == RESULT_OK) {
Uri photoUri = intent.getData();
if (photoUri != null) {
try {
ImageView setImage = (ImageView)findViewById(R.id.imageView);
frontImage = MediaStore.Images.Media.getBitmap(this
.getContentResolver(), photoUri);
imageSet = true;
//save image to SD
if(imageSet == true){
Log.d(tag, "Inside Image Set if Statement");
String path = getExternalCacheDir() + "Postcards.png";
if(path != null && path != ""){
Log.d(tag, "Path is:" + path);
File file = new File(path);
newPath = file.getAbsolutePath();
Log.d(tag, "New Path:" + newPath);
if(file.exists()){
Log.d(tag, "File Exists");
Drawable d = Drawable.createFromPath(newPath);
setImage.setImageDrawable(d);
}else{
try{
Log.d(tag,"File didnt exist");
FileOutputStream out = new FileOutputStream(file);
frontImage.compress(Bitmap.CompressFormat.PNG, 90, out);
if(file.exists()){
Log.d(tag, "file exists now");
newPath = file.getAbsolutePath();
Drawable b = Drawable.createFromPath(newPath);
setImage.setImageDrawable(b);
}
}catch(Exception e){
e.printStackTrace();
}
}
}
}
} catch (Exception e) {
e.printStackTrace();
}
这是我访问图像并尝试在Restart()上将其设置为我的ImageView的方式
if(imageSet == true){
if(newPath != null && newPath != ""){
ImageView view = (ImageView) findViewById(R.id.imageView);
Drawable drawable = Drawable.createFromPath(newPath);
view.setImageDrawable(drawable);
}
}
这似乎是获取图像和设置图像的最佳途径,但它不起作用.什么是最佳实践,如何让它以我需要的方式执行？
非常感谢任何帮助!
savedInstanceState服务于不同的目的。
onSaveInstanceState (Bundle)：在 Activity 被终止之前调用此方法，以便当它在未来某个时间返回时可以恢复其状态
而且，在您的特定情况下，甚至可能不需要。单击按钮时，您正在更改片段，而不是重新启动应用程序。
据我所知，您正在让用户创建一张明信片：一侧是图片（例如 A 面），另一面是一条消息（例如 B 面）。当应用程序启动时，A 面就在视图中。以某种方式，您可以让用户从图库中选择图像。我假设它onActivityResult(int, int, Intent)按预期工作，并将图像设置为 ImageView - R.id.imageView。单击按钮时，视图将更改为 B 面。再次单击按钮时，视图将更改为 A 面，但用户选择的图像不存在。
您可以在里面做的一件事onActivityResult(int, int, Intent)是：将图像的路径保存在 SharedPreferences 中。
SharedPreferences preferences;
final String PREFS = "your.application.name.prefs";
// Keyword to find the path
final String IMAGE_SELECTED_BY_USER = "image_selected_by_user";
// Use a default image when the user starts the app for the first time
// or if the retrieved path points to a deleted image etc.
final String PATH_TO_A_DEFAULT_IMAGE = "path_to_a_default_image"
@Override
protected void onCreate(Bundle savedInstanceState) {
....
....
preferences = getActivity().getSharedPreferences(PREFS, 0);
imagePath = preferences.getString(IMAGE_SELECTED_BY_USER, PATH_TO_A_DEFAULT_IMAGE);
frontImageView = (ImageView) findViewById(R.id.imageView);
Drawable drawable = null;
if (new File(imagePath).exists()) {
drawable = Drawable.createFromPath(imagePath);
} else {
drawable = Drawable.createFromPath(PATH_TO_A_DEFAULT_IMAGE);
}
frontImageView.setImageDrawable(drawable);
getFragmentManager()
.beginTransaction()
.add(R.id.postcardFrame, new CardFrontFragment())
.commit();
....
....
}
在 中onActivityResult(int, int, Intent)，保存图片路径：
if(file.exists()){
Log.d(tag, "File Exists");
Drawable d = Drawable.createFromPath(newPath);
setImage.setImageDrawable(d);
Editor editor = preferences.edit();
editor.putString(IMAGE_SELECTED_BY_USER, newPath);
editor.commit();
} else{
try{
Log.d(tag,"File didnt exist");
FileOutputStream out = new FileOutputStream(file);
frontImage.compress(Bitmap.CompressFormat.PNG, 90, out);
if (file.exists()) {
Log.d(tag, "file exists now");
newPath = file.getAbsolutePath();
Drawable b = Drawable.createFromPath(newPath);
setImage.setImageDrawable(b);
Editor editor = preferences.edit();
editor.putString(IMAGE_SELECTED_BY_USER, newPath);
editor.commit();
}
} catch (Exception e) {
e.printStackTrace();
}
}
这样，当用户启动应用程序时，他/她将看到默认图像或之前选择的图像。
哪里savedInstanceState有用：假设您为用户提供了在 B 面编写短信的选项。现在，如果在编写消息时，用户将设备从横向旋转为纵向（或反之亦然），则该消息/她写道将会消失，因为该活动将被销毁并重新创建。要保存消息，您可以使用onSaveInstanceState(Bundle)：
@Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putString("Text_To_Save", someEditText.getText().toString());
}
轮换时，活动的onCreate(Bundle)' will be called. The bundle passed is the same one fromonSaveInstanceState(Bundle)`。要检索文本：
String savedString = "";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (savedInstanceState != null) {
if (savedInstanceState.contains("Text_To_Save")) {
savedString = savedInstanceState.getString("Text_To_Save");
}
}
someEditText.setText(savedString);
}