I'm a newbie to Blackberry 10 development and the whole qt signal-slot mechanism.
I am trying to register a signal and slot for when a user clicks on a different tab in my Blackberry 10 native application. I have the following code for my UI:
TabbedPane {
id: mainTabbedPane
showTabsOnActionBar: true
peekEnabled: true
sidebarState: SidebarState.VisibleFull
Tab {
...
} //End of first tab
Tab {
...
} //End of second tab
...
applicationui.cpp
AbstractPane *appPane = qmlDocument->createRootObject<AbstractPane>();
if (appPane) {
// Set the main application scene to NavigationPane.
Application::instance()->setScene(appPane);
}
TabbedPane* tabbedPane = appPane->findChild<TabbedPane*>("mainTabbedPane");
qDebug("Pane: %p", tabbedPane);
QObject::connect(tabbedPane, SIGNAL(activeTabChanged(bb::cascades::Tab*)), SLOT(sectionTriggered(bb::cascades::Tab*)));
My issue is that it seems the TabbedPane is not being found despite being in the UI. What I'm I doing wrong? Also, I'm I implementing the signal-slot correctly?
Thank you in advance.
You could also use onTriggered in QML, so you can get that this way. Depends on what you want
Tab {
title: "Tab name"
onTriggered: {
}
},
BUT to fix your problem directly, you're missing objectName
TabbedPane {
id: mainTabbedPane
objectName: "mainTabbedPane"
showTabsOnActionBar: true
peekEnabled: true
sidebarState: SidebarState.VisibleFull
Tab {
...
} //End of first tab
Tab {
...
} //End of second tab
Related
I have a component/delegate declared in qml and I would like to connect one o its actions to a signal in another qml or C++ class. So, the Component looks like this:
Component
{
id: mainButtonDelegate
Button {
id: buttonOperation
text: qsTr(buttonText)
buttonEnabled: false
onIsEnableChanged:
{
buttonEnabled = cppRegisteredClass.isButtonEnabled(text)
}
}
}
Can I create connection for the component (so for every button), like the following expressed in Qt?
connect(loginForm, SIGNAL(loginChanged()), this, SLOT(onIsEnableChanged()))
My model is a ListModel expressed in a qml file.
Edit
If this is not the correct approach could somebody suggest me another way to do sth like this?
You can use the Connections-object.
You expression would be translated to:
Connections {
target: loginForm
onLoginChanged: whatIsThis.onIsEnabledChanged()
}
Alternatively you can use the JS connect syntax:
http://doc.qt.io/qt-5/qtqml-syntax-signals.html#connecting-signals-to-methods-and-signals
You expression would translate to:
loginForm.loginChanged.connect(this.onIsEnabledChanged)
I am posting how I have done what I wanted, just if anyone else need this.
I have added a function in the model and used set property.
function action()
{
for(var i= 0; i<count; ++i)
{
if(backend.disable())
{
setProperty(i, "enable", false)
setProperty(i, "opac", 0.3)
}
else
{
setProperty(i, "enable", true)
setProperty(i, "opac", 1)
}
}
}
In the component (inside an Item parent), I have added:
LoginForm{
id: loginForm
onLoginIdentityChanged: {
mymodel.action()
}
I have a Window containing what I called a Page - a Rectangle the size of the main window:
LoginWindow {
id: loginWindow
}
SelectionWindow {
id: selectionWindow
}
ServiceWindow {
id: serviceWindow
}
ConfirmWindow {
id: confirmWindow
}
IssueWindow {
id: issueWindow
}
Each *Window here is an element inheriting from Page.
Now I can jump between different Page elements setting their visibility. Only one Page can be visible at a time. The last Page is IssueWindow and from there I want to switch back to LoginWindow and logout the user.
From C++ I emit a signal issueFinished and in MainWindow I have this code:
onIssueFinished: {
// This line won't hide the Page
issueWindow.visible = false;
loginHandle.logout();
}
As noted in the comment, the Page element just won't hide, while other elements will change their visibility. I am using GammaRay to see the changes and everything works, just hiding the issueWindow doesn't. Also when printing the issueWindow.visible to console, it's false.
Use opacity instead of visibility, and bind one method on opacity change which handle the enabled and disabled state like.
onIssueFinished: {
// This line won't hide the Page
issueWindow.opacity = 0.0;
loginHandle.logout();
}
IssueWindow {
id: issueWindow
onOpacityChanged: {
enabled = ( opacity === 1.0)
}
}
You need to implement opacity change in all the windows.
And set the opacity for all other windows.
Or you can use stack view or swipe view.
Found out the issue was actually incorrect order of switching visibility and firing signals and responding to them.
To make sure only one Page is visible, you might use an index.
You set the visibility to:
visible: (selected == thisPageIdentifier)
With this you make sure, only the page with the corresponding pageIdentifyer is visible, and you don't have to throw around multiple signals to show and hide.
When a new page shall become visible, just set the selected property to the corresponding identifier (int or string or what ever) and the other pages turn invisible.
This should increase scalability as you do not have new signals to handle in all the other pages, if you decide to add a new page once. You only need to make sure, the identifier is unique.
Your example code adjusted to this:
Item {
property int selection: 0
LoginWindow {
id: loginWindow
visible: (selection === 0)
}
SelectionWindow {
id: selectionWindow
visible: (selection === 1)
}
ServiceWindow {
id: serviceWindow
visible: (selection === 2)
}
ConfirmWindow {
id: confirmWindow
visible: (selection === 3)
}
IssueWindow {
id: issueWindow
visible: (selection === 4)
}
}
I'm new to Qt, and from what I've read on qt-project.org and other places; QtQuick seems like an attractive option because of its ability to work on both pointer and touch based devices. My problem is getting it to work well with c++.
I decided to write a variant of Conway's Game of Life as a next step after "Hello World". I am thoroughly mystified as to how to get the "board" -- a [height][width][bytes-per-pixel] array of char -- integrated into the scene graph.
Basically, the process is that the "LifeBoard" iterates through its rules and updates the char*/image. I've got this simple QML:
:::QML
ApplicationWindow {
id: life_app_window
visible: true
title: qsTr("Life")
menuBar: MenuBar {
Menu {
title: qsTr("File")
MenuItem {
text: qsTr("Quit")
onTriggered: Qt.quit();
}
}
}
toolBar: ToolBar {
id: lifeToolBar;
ToolButton {
id: toolButtonQuit
text: qsTr("Quit")
onClicked: Qt.quit()
}
ToolButton {
id: toolButtonStop
text: qsTr("Stop")
enabled: false
//onClicked:
}
ToolButton {
id: toolButtonStart
text: qsTr("Start")
enabled: true
//onClicked: //Start life.
}
ToolButton {
id: toolButtonReset
text: qsTr("Stop")
// onClicked: //Reset life.
}
}
Flow {
id: flow1
anchors.fill: parent
//*****
// WHAT GOES HERE
//*****
}
statusBar: StatusBar {
enabled: false
Text {
// Get me from number of iterations
text: qsTr("Iterations.")
}
}
}
I want to image to come from a class with a api kinda like this:
class Life {
public:
QImage getImage() {}
// Or
char* getPixels(int h, int w, QImage::Format_ARGB8888) {}
}
I have no clue, and hours wading through tutorials did not help. How does one link a char* image in c++ to a ??? in QML so that the QML can start/stop the "Life" loop and so that the "Life" loop and update the char array and notify QML to redraw it?
Note: I've looked at subclassing QQuickImageProvider based on the info here. The problem with this approach is that I cannot see how to let c++ "drive" the on screen image. I wish to pass control from QML to c++ and let c++ tell QML when to update the display with the changed image. Is there a solution with this approach? Or another approach entirely.
First way to do that would be creating a Rectangle for each game pixel in QML, which might be fancy for a 8x8 board, but not for a 100x100 board, since you need to write the QML code manually for each pixel.
Thus I'd go for images created in C++ and exposed to QML. You call them via an image provider to allow asynchronous loading. Let Life do the logic only.
The image is called from QML like this:
Image {
id: board
source: "image://gameoflife/board"
height: 400
width: 400
}
Now gameoflife is the name of the image provider and board the so-called id you can use later.
Register gameoflife in you main.cpp
LifeImageProvider *lifeIP = new LifeImageProvider(life);
engine.addImageProvider("gameoflife", lifeIP);
where engine is your main QQmlApplicationEngine and life an instance of your Life game engine.
LifeImageProvider is your class to create pixeldata. Starts somehow like
class LifeImageProvider : public QQuickImageProvider
{
public:
LifeImageProvider(Life *myLifeEngine);
QPixmap requestPixmap(const QString &id, QSize *size, const QSize &requestedSize);
private:
Life *myLifeEngine_;
};
The important method is requestPixmap, which is called from QML. You need to implement it.
To refresh the game board when Life sends a stateChanged() signal, expose life as a global object to QML:
context->setContextProperty("life", &life);
You can bind the signal to QML
Image {
id: board
source: "image://gameoflife/board"
height: 400
width: 400
}
Connections {
target: life
onStateChanged: {
board.source = "image://gameoflife/board?" + Math.random()
// change URL to refresh image. Add random URL part to avoid caching
}
}
Just for fun, and at the risk of downvotes for a completely tangential answer, here's a GameOfLife implemented entirely in QML, just put it in a .qml file and run it with qmlscene. Works on Qt 5.3.0, and runs surprisingly (to me) fast on an old Core 2 Duo lappy. I'm sure it'll never be as fast/efficient as a C++ QQuickImageProvider based solution though, but it does make the point it's possible to do quite a lot in QML without resorting to C++.
import QtQuick 2.2
Rectangle {
id: main
width: 640
height: 640
color: '#000088'
Timer {
interval: 1000/60
running: true
repeat: true
onTriggered: {advance();display();}
}
Component {
id: cellComponent
Rectangle {
objectName: 'cell'
property int row: 0
property int col: 0
x: main.width/2+width*col
y: main.height/2+height*row
width: 5
height: 5
radius: 2
smooth: true
color: '#ffcc00'
}
}
property var cells: null
Component.onCompleted: {
cells=[[-1, 0],[-1, 1],[ 0,-1],[ 0, 0],[ 1, 0]];
display();
}
function display() {
// Just completely regenerate display field each frame
// TODO: might be nicer to do differential updates, would allow birth/death animations
// Nuke all previously displayed cells
for (var i=0;i<children.length;i++) {
if (children[i].objectName=='cell') {
children[i].destroy();
}
}
// Show current set of cells
for (var i=0;i<cells.length;i++) {
var c=cellComponent.createObject(
main,
{'row':cells[i][0],'col':cells[i][1]}
);
}
}
function advance() {
// Build a hash of the currently alive cells and a neighbour count (includes self)
var a=new Object;
var n=new Object;
for (var i=0;i<cells.length;i++) {
var p=cells[i]
var r=p[0];
var c=p[1];
if (!(r in a)) a[r]=new Object;
a[r][c]=1;
for (var dr=r-1;dr<=r+1;dr++) {
for (var dc=c-1;dc<=c+1;dc++) {
if (!(dr in n)) n[dr]=new Object;
if (!(dc in n[dr])) n[dr][dc]=0;
n[dr][dc]+=1;
}
}
}
// For all live cells, assess viability
var kill=[];
var stay=[];
for (var r in a) {
for (var c in a[r]) {
if (n[r][c]-1<2 || n[r][c]-1>3)
kill.push([Number(r),Number(c)]);
else
stay.push([Number(r),Number(c)]);
}
}
// For neighbours of live cells, assess potential for births
var born=[];
for (var r in n) {
for (var c in n[r]) {
if (!((r in a) && (c in a[r]))) {
if (n[r][c]==3)
born.push([Number(r),Number(c)]);
}
}
}
cells=stay.concat(born)
}
}
And for a pure QML version using GLSL (via a recursive QML ShaderEffect) to compute the Game of Life rules on GPU see here.
I have a uitabbarcontroller with 4 tab bar items and each tab bar item has a uinavigationcontroller.
I needed to lock the orientation of one uitabbar item only to Portrait. So i implemented the following code:
Created a custom tab bar controller and added the following code in it:
MainTabBarController.m
-(BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
// You do not need this method if you are not supporting earlier iOS Versions
return [self.selectedViewController shouldAutorotateToInterfaceOrientation:interfaceOrientation];
}
-(NSUInteger)supportedInterfaceOrientations
{
if (self.selectedViewController)
return [self.selectedViewController supportedInterfaceOrientations];
return UIInterfaceOrientationMaskPortrait;
}
-(BOOL)shouldAutorotate
{
return YES;
}
Created a custom navigation controller to use in one of the uitabbaritems and added the following code in it:
-(NSUInteger)supportedInterfaceOrientations
{
return [self.topViewController supportedInterfaceOrientations];
}
-(BOOL)shouldAutorotate
{
return YES;
}
and for the uiviewcontroller in the custom navigation controller i added the following code:
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
return (interfaceOrientation == UIInterfaceOrientationPortrait);
}
- (BOOL)shouldAutorotate
{
return NO;
}
- (NSUInteger)supportedInterfaceOrientations
{
return UIInterfaceOrientationMaskPortrait;
}
The above code works fine. My issue is, if you go to the tabbar item (whose orientation is locked to Protrait) when the device is already in Landscape mode the orientation changes to Landscape. Can anyone please help me how to solve my issue.
Thanks,
Anand.
FYI!!!
I've found a way for my problem. I added the following function to the viewcontroller for which i want the display only in protrait mode:
-(void)viewWillLayoutSubviews
{
[super viewWillLayoutSubviews];
if (UIDeviceOrientationIsLandscape([[UIDevice currentDevice] orientation]))
{
if ([[UIDevice currentDevice] respondsToSelector:#selector(setOrientation:)])
{
int orientationPortrait = UIInterfaceOrientationPortrait;
NSMethodSignature *sig = [[UIDevice currentDevice] methodSignatureForSelector:#selector(setOrientation:)];
NSInvocation* invo = [NSInvocation invocationWithMethodSignature:sig];
[invo setTarget:[UIDevice currentDevice]];
[invo setSelector:#selector(setOrientation:)];
[invo setArgument:&orientationPortrait atIndex:2];
[invo invoke];
}
}
}
i want to add some ui inside camera view blackberry 10
like photobomber samples on github
https://github.com/blackberry/Cascades-Samples/tree/master/photobomber
but i want to overlay the image while the camera is active and save the photo + image inside the photo to memory
can somebody tell me how to do that ?
best regards,
adit
You should opt for DockLayout whenever you want to overlap any controls. Go through the following code, you should get the idea
Page {
content: Container {
gestureHandlers: [
TapHandler {
onTapped: cameraControl.capturePhoto()
}
]
layout: DockLayout {
}
Camera {
id: cameraControl
onCameraOpened: {
cameraControl.startViewfinder();
}
}
Button {
horizontalAlignment: HorizontalAlignment.Center
verticalAlignment: VerticalAlignment.Center
text: "Overlapping button"
}
}
onCreationCompleted: {
if (cameraControl.allCamerasAccessible) {
cameraControl.open(CameraUnit.Rear);
}
}
}
To capture photo you can use capturePhoto method of camera control. Go through the documentation to find more methods.
Do note that Camera control should be declared at the top in the container & other controls should be declared below it to overlap controls over it.
Don't forget to provide Camera acess permission in bar-descriptor, to add LIBS += -lcamapi in pro file & to import bb.cascades.multimedia 1.0 in qml.