I'm playing around with Rebol, and Can't figure out how I can add components from the user back to my layout.
I have a layout that has images, taken from image-urls, linked to articles/videos online. I want to add more images linked to their corresponding articles/videos online, taken from the user as 2 urls (one for the image and one for the article/video).
Do I use a list, add the two links to the list and call the view again using show as the button event? Is there a way to add it without refreshing my whole layout?
You can use a list, but it's a tricky beast. I'll include an example here so that you can evaluate the way it works and if it's right for you.
With a list, you define a layout, then modify the layout dynamically based on some data or other. To illustrate, here's some icons:
icons: [
http://reb4.me/r/html-document.png
http://reb4.me/r/pdf-document.png
http://reb4.me/r/excel-document.png
http://reb4.me/r/word-document.png
http://reb4.me/r/zip-document.png
]
The list style consists of a size, layout and a supply function (and I'm going to zap the edge):
view center-face layout [
across
lst: list 48x240 edge none [image 48x48] supply [
face/image: all [
img: pick icons count
load-image img
]
]
btn "Random" [
icons: random icons
show lst
]
]
Included at the bottom is a button that modifies our data, then redisplays only the list.
Size is 48x240 — list works vertically, calling the supply function (list height / iterative layout height) times. I have five icons, so multiplied the icon height by five.
The [image 48x48] is our iterative layout. Note that we only define one face in this example. Unlike generic layouts, a list layout is created using the layout/tight refinement—you need to be specific if you want alternate spacing.
The supply [...] part is our supply function. This is shorthand for a function that will be created and called to update the list. That function is func [face count index][...] where face is the operative face; count is the position in the list; and index is the face's offset in the iterative layout.
It's key to remember that iterative layout is only created once. As the count increases, you are merely changing the attributes of the faces within that layout.
You only need show the list, not the whole layout.
So from here, you can see the relationship between the data source and the display.
Related
I need to get the indices of all data items that are currently in view in a Kivy RecycleView widget. I want to display many Image widgets for which I render a texture and apply it to them. To save memory I need to delete these textures if they are not in view any more. I tried using the Kivy RecycleView example and modify it for my needs:
class SelectableImage(RecycleDataViewBehavior, Image):
def refresh_view_attrs(self, rv, index, data):
#Catch and handle the view changes
#print in view
print(index)
#call initial function of image class
return super(SelectableImage, self).refresh_view_attrs(rv, index, data)
The problem here is that refresh_view_attrs() only fires when a new Image widget gets added to the view. Thus I can only know what that last Image is, but not if there are any other in view. For this I'd also need to know which widget disappeared from the view. Is there any function in the RecycleView widget that I can use to obtain such information? Maybe there is a function that gets called whenever the view changes?
Okay, I found three possible solutions for my issue:
1. Solution
Calculate the position of all the Image widgets yourself and compare it with the position of the scrollbar to get the widgets that are currently displayed.
This is quite hacky and the RecycleView already does this internally. Thus I'd save the unnecessary computing and avoid this approach.
2. Solution
Use the get_visible_view(index) function of the view_adapter property of a RecycleView. This returns the currently visible view associated with index. If it return None, the view associated with index is not visible right now. This is how it's called for example:
self.myRecycleView.view_adapter.get_visible_view(index)
You could loop through the entire length of your data list and check for each item (the index in the list) if it is currently displayed or not.
3. Solution
My favourite approach: Use get_view_index_at(pos) of the layout_manager property to check what view index is at the given coordinates. This way you could check which item is at the top of the RecycleLayout widget and which one is at the bottom. You need to use coordinate transformation though. Example:
#get position at top center of RecycleView (upper limit)
pos = self.myRecycleView.to_local(self.myRecycleView.center_x, self.myRecycleView.height)
#check which items collides with the given position
print(self.myRecycleView.layout_manager.get_view_index_at(pos))
I hope this clears some things up!
I'm developing a custom table component for very large and very custom content. Therefore I decided not to go with TableView, but start from scratch (i.e. Control). I adopted the idea of the VirtualFlow to create and manage only the visible part of the table and reuse cells that have become invisible. However I needed virtual rows and columns.
My CustomVirtualFlow implements layoutChildren(). From the component's size and scrollbar positions I know which cells are visible. If necessary, I add cells to the VirtualFlow. I then update the content and css pseudo class states (selected, focused, ...).
This works almost fine ... currently, my only problem is that the css styles are sometimes lagging: newly created cells are shown with e.g. wrong backgrounds for a moment and then get correcteted with the next pulse.
My explanation for this is that JavaFX performs layout in two passes:
first a css pass and secondly the layout pass that calls layoutChildren().
The css of newly added children (during layoutChildren) is therefore not processes correctly.
I tried to call applyCss() directly, which helps, but seems to do too much because it takes a lot of time.
My question is:
How is the correct way to add nodes during layout, i.e. if the size of the component makes it neccessary to use further nodes?
If it is not during layoutChildren(), where else should I do it?
I have a read-only diagram to visualize some data. My end users would like to "filter" the data such that only a subset of the data may be shown at one time. I realize that I can redraw the whole diagram each time I apply a filter omitting the elements that are not to be shown but I am wondering if there is a way that I can simply "hide" some existing elements dynamically and then subsequently re-show them.
To try and make crystal clear, if this were a web page instead of a diagram, I would draw the analogy of applying the CSS of display: none to elements of my choosing.
You can actually do the same with a JointJS diagram elements/links. For example:
myElement.attr('./display', 'none')
hides the whole SVG group element in which the element is rendered. Note the '.' is a special selector that points to the whole group. If you want to hide only a certain SVG subelement, you can do it similarly, e.g. for the joint.shapes.basic.Rect element, you'd do:
myRect.attr('rect/display', 'none')
This hides only the rectangle (the SVG <rect> element referenced by the tag name rect in the attrs object - that we modify via the attr() method.
I've a layer with multiple markers with rather big icons, so they overlap. Via the list on the side of the map users can select a marker and the map will pan (and zoom) to it. But it will still be behind some other makers.
How do I get a individual makers z-index and set it? I would be useful to get the highest used z-index and just add one. (another solution is to add the total number of markers to the z-index)
The markers (or features) are in a myLib.features array. The console doesn't show any z-index type functions.
I can't find a appropriate example or api function for this.
EDIT:
I found this example: http://dev.openlayers.org/examples/ordering.html
I don't really understand it. Somehow the created feature takes the next z-index given by the layer via somekind of symbolizer. I have no idea how to work this static sort into a dynamic one.
Try this:
First of all, make sure you are using a OpenLayers.Layer.Vector layer, not a OpenLayers.Layer.Markers layer. Apparently the Markers layer is old news and all new development is done in the Vector layer. It has more features. (I wasted a pile of time with the Markers layer myself).
Then, each of your markers needs to be a OpenLayers.Feature.Vector object. The constructor takes three arguments, the third of which is called the style. The style is where you set your image attributes, the background shadow, the mouse-over text, and the z-index, which has the property name "graphicZIndex". I think that's what you're looking for.
http://dev.openlayers.org/releases/OpenLayers-2.12/doc/apidocs/files/OpenLayers/Feature/Vector-js.html#OpenLayers.Feature.Vector.OpenLayers.Feature.Vector.style
Add your "markers" (which are Vector's) to your Vector layer with the addFeatures function. And just ignore the "options" argument.
http://dev.openlayers.org/releases/OpenLayers-2.12/doc/apidocs/files/OpenLayers/Layer/Vector-js.html#OpenLayers.Layer.Vector.addFeatures
I found that example page too, and I found it confusing too. It was setting all the markers' styles in the Vector layer's constructor (as default values to be used if the marker style was omitted) instead of the marker's constructor. I think it makes more sense to set the marker style in the marker constructor.
To change the style in real-time, take one of your OpenLayers.Feature.Vector markers, called "marker" and do this. And let's call the Vector Layer "layer".
marker.style.graphicZIndex = 13;
layer.redraw();
I want to place the components A and B over component with List. I need that would text of list will be to visible. I can not find which layout can do it.
How this behavior is in lwuit? What solutions exist?
The question is somewhat unclear, jmunoz answer is correct if you want component's A and B to reside at the bottom of the screen and the list to scroll above. However from the drawing it seems you want an "always on top" effect which you can achieve either via a glass pane (for non-interactive components) or via the LayeredLayout class.
This is actually quite simple using the following:
myForm.setLayout(new LayeredLayout());
myForm.setScrollable(false);
// will occupy the entire area of the form but should be scrollable
myForm.addComponent(componentUnderneath);
Container south = new Container(new BorderLayout());
myForm.addComponent(south);
south.addComponent(BorderLayout.SOUTH, whateverYouWantToPlaceOnTopInTheSouth);
You must do the following:
The Form must not do scroll. Use Form.setScrollable(false). Set the layout of the ´Form´ to BORDER_LAYOUT, myForm.setLayout(new BorderLayout()) . Ok in BorderLayoutyou can put the components in the Form as you want.
Put the Listcomponent in the center of the BorderLayout with myForm.addComponent(BorderLayout.CENTER, List) and the other two elements in the south of the layout using
Container southContainer = new Container();
southContainer.addComponent(A);
southContainer.addComponent(B);
myForm.addComponent(BorderLayout.SOUTH, southContainer)
With this you can get a scrollable Listand two elements always visible.