I'm a little bit lost in an App I'm trying to write. I'd like to display either an image, or an Video - depending on an entry in a list.
So, if the entry in the list I'm currently displaying has a video I want to use the Chewie Player in the UI
child = Chewie(
controller: _chewieController,
)
if the entry in the list I'm currently displaying has an image I want to use CachedNetworkImage:
CachedNetworkImage(imageUrl: _questions[widget.questionno].getSourceUrl(),)
as you probably noticed, I am a programming beginner. How can I solve this problem?
Right now the code I'm trying to use in the UI looks like this:
Container(
if (_questions[widget.questionno].getVideo()=="Ja") {
child = Chewie(
controller: _chewieController,
)
} else {
child = CachedNetworkImage(imageUrl: _questions[widget.questionno].getSourceUrl(),)
}
),
Try something like this:
bool video = false
if(entryInList is Video){ //Replace Video with whatever type you would have
//for Videos
video = true
}
And in your Widget tree
child: video ? VideoWidget() : FotoWidget()
Or all in one line:
child: entryInList is Video ? VideoWidget() : FotoWidget()
finally got it working, it's probably not the best way, but whatever, it works and I'm super happy :D
child: Builder(
builder: (context) {
if (_questions[widget.questionno].getVideo()=='Ja') {
return
Container(child: Chewie(controller: _chewieController,));
} else {
return
Container(child: CachedNetworkImage(imageUrl: _questions[widget.questionno].getSourceUrl(),));
}
}
)
additionally I also had to put the whole definition of the chewie controller (which is in initState) into an if thingie.
Related
I am using edit method on a form Check box control in a Grid and data source is a view. The parameter in _set boolean is not setting to true when we clicked on the check box. The code in the edit method is as follows.
edit NoYes markNow(
boolean _set,
VendInvoiceProdReceiptNotInvoicedView _vendInvoiceProdReceiptNotInvoicedViewLocal,
NoYes _markNow)
{
if (_set)
{
if (_markNow)
{
matchedReceipts.insert(_vendInvoiceProdReceiptNotInvoicedViewLocal.VendPackingSlipJourRecId, _vendInvoiceProdReceiptNotInvoicedViewLocal.PackingSlipId);
}
else
{
if (matchedReceipts.exists(_vendInvoiceProdReceiptNotInvoicedViewLocal.VendPackingSlipJourRecId))
{
matchedReceipts.remove(_vendInvoiceProdReceiptNotInvoicedViewLocal.VendPackingSlipJourRecId);
}
}
this.refresh();
}
return matchedReceipts.exists(_vendInvoiceProdReceiptNotInvoicedViewLocal.VendPackingSlipJourRecId) ? NoYes::Yes : NoYes::No;
}
Could you please help me with this.
Edit methods cannot be used on top of Views as data source, Use regular table as data source.
So, I have come across a solution for this problem using Get_storage thanks to a couple of great explanations about the topic. I managed to work with getx and the Provider package to save data when adding new stuff and reading it when starting the application (thats the behavior i'm going for here). Said that, i'm having a hard time trying to remove data from memory.
Context
The project is a to-do list app, the front end is working perfectly, but when it comes to storage it gets more complicated. The thing is that i'm very new to flutter and mobile development, i recieved some help but this kind of stuff is still foggy in my brain, i could not remove data using the same logic. When i called box.Remove('key') like the docs say, my ENTIRE list got removed. I don't have a single clue why that happaned.
And so i wonder if i could understand it more by reading through some more explanations, i know Shared Preferences is a great deal do work with this kind of situation, but i would also be confortable with a solution using get_storage since i'm more familiar with it.
the code:\
I'm calling these lists inside a listView on a different file with the help of Provider - -
List<Task> _tasks = [
Task(
name: "Title",
description: "Description",
),
];
Adding tasks to my ListView - -
void add(String newTitle, newDesc) {
final task = Task(name: newTitle, description: newDesc);
_tasks.add(task);
notifyListeners();
}
Here is the removal of a task from the ListView - -
void removeTasks(Task task) {
_tasks.remove(task);
notifyListeners();
}
I tried to implement a logic to write and read data, it worked. But i also tried to use this removeTasks method to remove from storage as well by calling box.Remove('tasks'); ('tasks' was the key passed to the writing and reading methods). It removed everything from memory since my listview got empty.
Since i'm not that experienced, i went through the documentation and could understand some of the SharedPreferences Explanation (same with got_storage) but i'm having a hard time when trying to apply it to my code.
I would appreciate any help using get_storage OR shared preferences to this problem.
Where i'm calling the deletion:
// bool variables that control the state of the screen
// since i can change it to show done tasks or on goind tasks
// dont mind that, i think its irrelevant to the problem.
//
bool isActiveDoing = true;
bool isActiveDone = false;
List finalArray = []; //it will store the tasks
class TaskList extends StatefulWidget {
#override
_TaskListState createState() => _TaskListState();
}
class _TaskListState extends State<TaskList> {
#override
Widget build(BuildContext context) {
//dont mind the if else as well, its not part of the problem
//just using it to handle the state of the screen
if (isActiveDoing) {
finalArray = Provider.of<TasksFunctions>(context).tasks;
}
//TasksFunctions is a class with methods on regards to the storage
//it contains add tasks, remove, etc... i'm using provider to
//link those to the screens with the notifyListeners
if (isActiveDone) {
finalArray = Provider.of<TasksFunctions>(context).doneTasks;
}
//now here is where i call the class tha has the deletion method
return Consumer<TasksFunctions>(
builder: (context, tasksFunctions, child) {
return ListView.builder(
//list view tha has all the tasks
itemCount: finalArray.length,
itemBuilder: (context, index) {
final task = finalArray[index];
//using the slidableWidget to wrap the deletion method
return SlidableWidget(
onDismissed: (action) {
if (isActiveDoing) {
Provider.of<TasksFunctions>(context, listen: false)
.removeTask(task);
//so here is where i'm deleting those tasks, calling that method
//listed up on this post
}
if (isActiveDone {
Provider.of<TasksFunctions>(context, listen: false)
.removeDone(task);
}
},
);
},
);
},
);
}
}
So i spent some time translating the code, but i think that it does not match any of flutter's good practices principles.
I also tried calling storageList.remove(task); and then rewriting it with the box.write('tasks', storageList); but nothing was removed from the memory (maybe because i didn't loop through the whole storageLists searching for the right index i guess)
Sounds like your code is based on my answer to your original question about this.
If that's the case, then the key tasks is the key to the entire list of maps, not a single map or Task. So it's behaving as expected when it wipes all of your tasks.
In order to persist any changes, you'd have to remove that particular map (Task) from storageList then overwrite the box again with box.write('tasks', storageList); It will save over the same list of maps and persist any deletions you made.
If you share your code where you're trying to delete the task and whats going on around it I can give you a more specific example.
EDIT: Answering question in comments.
If you wanted to go the UniqueKey route you wouldn't need the index at all. You could do something like this.
class Task {
final String name;
final String description;
final String key; // not an actual Key but will take the String value of a UniqueKey
Task({this.key, this.name, this.description});
}
When you add a new Task it would look like this.
final task = Task(
description: 'test description',
name: 'test name',
key: UniqueKey().toString());
Then you could use a Map of maps instead of a list of maps and use the key for both.
Map storageList = {};
void addAndStoreTask(Task task) {
_tasks.add(task);
final Map storageMap = {}; // temporary map that gets added to storage
storageMap['name'] = task.name;
storageMap['description'] = task.description;
storageMap['key'] = task.key;
storageList[task.key] = storageMap; // adding temp map to storageList
box.write('tasks', storageList); // adding map of maps to storage
}
Then your restore function would look like this:
void restoreTasks() {
storageList = box.read('tasks'); // initializing list from storage
storageList.forEach((key, value) { // value here is each individual map that was stored
final task =
Task(name: value['name'], description: value['description'], key: key);
_tasks.add(task);
});
}
Then when you go to delete, you iterate through the list and find the matching key.
I'm trying to make small platformer game, just in learning purposes. I've tried to animate character with array of SKTextures like this:
let animation: SKAction = SKAction.animate(
with: frames.map {
let texture : SKTexture = SKTexture(imageNamed: $0)
texture.filteringMode = SKTextureFilteringMode.nearest
return texture
},
timePerFrame: 0.15
)
frames variable is array of SKTextures. I've used map to set filtering mode for each texture. This works fine and dandy, but than i've discovered that i can create animations (actions) in ActionEditor in XCode with AnimateWithTextures action. And here lies my problem. This is much more efficient, but i can't change filtering mode for textures in animation in ActionEditor. I've looked into SKTexture class and saw this:
open class SKTexture : NSObject, NSCopying, NSCoding {
...
/**
The filtering mode the texture should use when not drawn at native size. Defaults to SKTextureFilteringLinear.
*/
open var filteringMode: SKTextureFilteringMode
...
}
If i'm not mistaken open means that i can override variable, but i don't know how. I want to set default value of filteringMode to SKTextureFilteringMode.nearest for all SKTextures so ActionEditor will use textures with texture filtering set to nearest neighbor.
Also if you know how to set filtering mode for textures in specific action – i would like to know how to do it too. Thanks
you can create a function to setup the animation for you, and create an extension to SKTexture with your custom init, and when your ready just call it to your node.
extension SKTexture { // Declare this extension outside your class decleration
convenience init(customImageNamed: String) {
self.init(imageNamed: customImageNamed)
self.filteringMode = .nearest
}
}
func setupAnimationWithPrefix(_ prefix: String, start: Int, end: Int, timePerFrame: TimeInterval) -> SKAction{
var textures = [SKTexture]()
for i in start...end{
textures.append(SKTexture(customImageNamed: "\(prefix)\(i)"))
}
return SKAction.animate(with: textures, timePerFrame: timePerFrame)
}
if you have 10 images named image1, image2, image3 ect..then this is how you would use this function
func runAction(){
let action = setupAnimationWithPrefix("image", start: 1, end: 10, timePerFrame: 0.1)
yourNode.run(action)
} // you can change timePerFrame to your liking i find 0.1 sec per frame the best
Unfortunately you can't override a variable without subclassing it, that is to do something like
class MyTexture: SKTexture {
from there, you could override the variable:
override var filteringMode: SKTextureFilteringMode {
get {
return .nearest
}
set {
}
}
That should work, but now you can't change the filtering mode, ever (without going through a bunch of hooplah).
So the more apt way would be to set the default value via the initializer, but SKTexture has no public designated initializers, so that option is out of the window.
So your best bet is going to be the convenience init extension by Arie, or just make a plain function that returns a new texture:
func nearestTexture(imageNamed name: String) -> SKTexture {
let newTex = SKTexture(imageNamed: name)
newTex.filteringMode = .nearest
return newTex
}
let texture: SKTexture = nearestTexture(imageNamed: "lol")
ActionEditor is still very limited in features, you are going to have to write some kind of code behind to allow for texture filtering. If you do not plan on scaling your sprites (Note I said sprite, not scene, these are two different behaviors), then I would not even worry about texture filtering, the time difference would be negligible.
I have a performance issue while displaying large amounts MapItems on a Map provided by the QML Location module. I already asked the question here (https://forum.qt.io/topic/79229/large-amount-of-qml-mapitems), but nobody could help me, so I wanted to try it here once. I also found this question (How to use the QML/QtLocation module for displaying a large amount of offline data on a map?), but before adding another dependency, I wanted to see if my code can be improved so that QML can handle this situation without any help.
I am currently trying to plot a large amount of items onto a QML Map (30,000 - 120,000 points). These items shall be updated dependent of the position of a QSlider. Performance decreases strongly from about 1,000 items upwards, when I use 30,000 it takes several minutes until the QML Map has all the data visualized and is responsive again. I have a machine which is absolutely capable of fulfilling this task in general, so I think the problem is QML. I am using Qt 5.8.
Is there any way to improve this performance or is it just not possible with a QML-map to plot so many MapItems at a time? I tried MapCircles, Polylines, Polygons and MapQuickItems with images, but for me it seems like the performance issue just arises from adding this amount of MapItems, as I could not see a significant difference in processing time between these types.
I have more data on the map visualized, which should not be refreshed every time the QSlider is moved. Even though I tried just to clear all MapItems and add the new ones for performance tests, but even this did not improve the performance.
My code (a bit abstracted) looks like this:
///-------------- Widget.cpp-----------------///
void ProcessInput(int qslider_pos) {
QVariantList lat_vec;
QVariantList lon_vec;
// Fill vectors with lateral and longitudinal positions
// ...
// Clean current points on map and draw new ones
SendToQmlFuncRemovePoints();
SendToQmlFuncAddPoints(lat_vec, lon_vec);
}
void QmlConnector::SendToQmlFuncRemovePoints()
{
QVariant returnedValue;
QMetaObject::invokeMethod(QmlMapSingleton::instance()->GetRoot(), "remove_points",
Q_RETURN_ARG(QVariant, returnedValue));
}
void QmlConnector::SendToQmlFuncAddPoints(QVariantList input_one, QVariantList input_two)
{
QVariant returnedValue;
QMetaObject::invokeMethod(QmlMapSingleton::instance()->GetRoot(), "add_points",
Q_RETURN_ARG(QVariant, returnedValue),
Q_ARG(QVariant, QVariant::fromValue(input_one)), Q_ARG(QVariant, QVariant::fromValue(input_two)));
}
.
///-------------- Map.qml -----------------///
Map {
anchors.fill: parent
property variant points: ({})
property int pointCounter: 0
Plugin
{
id: osmplugin
name: "osm"
PluginParameter { name: "osm.mapping.highdpi_tiles"; value: true }
}
Component.onCompleted: {
points = new Array();
}
id: map
plugin: osmplugin
//Javascript functions
function add_points(array_lat, array_lon) {
var myArray = new Array()
var component = Qt.createComponent("mapcircle.qml");
for (var i=0; i<array_lat.length; i++)
{
var object = component.createObject(map, { "center": QtPositioning.coordinate(array_lat[i], array_lon[i]})
map.addMapItem(object)
myArray.push(object)
}
map.points = myArray
}
function remove_points() {
var count = map.points.length
for (var i = 0; i<count; i++){
map.removeMapItem(map.points[i])
map.points[i].destroy()
}
map.points = []
}
}
.
///-------------- mapcircle.qml -----------------///
import QtQuick 2.0
import QtLocation 5.6
MapCircle {
radius: 1
border.width: 0
color: 'green'
}
Qt says that the performance decreases with the number of elements added to the map. Do you need all the points to be visible on the map in the same time, if not you can play around with visibility.
Can't you use QQuickPaintedItem to paint the points in C++ and wrap it into an MapQuickItem, if you have multiple polygonsfor e.g? But also there are some limitation, you cannot have to big images displayed.
If you need all the points maybe you can have different points based on the map zoom level and reduce the number of points added to the map at small zoom level, as was recommended on the other group ...
I have a TMS layer that looks something like this:
var v = 1;
my_tms = new OpenLayers.Layer.TMS(
"My TMS",
"my_mapserver.php?v="+my_var+"&",
{ transparent: 'true', type:'png', getURL:get_my_url }
);
Where my_mapserver.php returns map tiles according to the value of v.
The app allows users to change v, and I simply want to refresh the my_tms layer, however, so far the only way I can get it to refresh is by destroying the map and recreating it.
I thought I could just do something like this:
v = 2;
my_tms = new OpenLayers.Layer.TMS(
"My TMS",
"my_mapserver.php?v="+my_var+"&",
{ transparent: 'true', type:'png', getURL:get_my_url }
);
my_tms.redraw();
However, these tiles are not getting requested when I redraw().
Any help is appreciated.
As TMS layers inherits from Grid layer you could try to call clearGrid() method to remove all existing tiles and then spiralTileLoad() to load new ones.
layer.redraw();, OpenLayers.Strategy.Refresh and clearGrid() didn't help me in reloading tiles of OpenLayers.Layer.TMS layer in OpenLayers 2.13.1, but helped:
layer.mergeNewParams({});