B4J Question Canvas "World view" and Movable Window View

maleche · Oct 9, 2023

When drawing MANY items on a Canvas, I would like to keep the plotted lines and objects that are moving.
The canvas should contain a "World View" having 9000 x 9000. The targets move per speed and course vector every second and encompass the entire World (9000 x 9000).
i would like to only show the "View port" or a window about 100 x 100. as i move the "Window/View Port", it shows the objects.
To clarify, the "World" dimensions are beyond the view and the window only displays the current or previous plotted targets.
Moreover, i have tried to scale the canvas, but rely on redrawing everything using 100dip/100 as i read in this forum.
any chance of a function/method to accomplish this scaling and window?
see attached example
Keep up the outstanding work!
Doyle

drgottjr · Oct 9, 2023

not sure i fully understand what you want, but it sounds like a transparent (movable) pane on top of a fixed base. technically, you could also move the base when the movable pane gets to the edge of the screen. for the demo i chose 4 buttons to move the pane around. obviously there are other ways to handle it

maleche · Oct 9, 2023

Thank your for the quick response.
I think i was unclear in my initial description.
The Portal is the entire screen, while the "World" view is extend beyond the portal. The user can move the world view in range of the view port. the 100x100 is really the screen resolution (view).
sorry if i wasn't clear.

Here is a better example picture

stevel05 · Oct 9, 2023

I would think that a ScrollPane would be the way to go for this.

PaulMeuris · Oct 10, 2023

Have a look at my Kanban cards application
In this application the grid is larger than the form dimensions.
You can scroll up and down to go to the cards vertically and you can use the slidebar to scroll left to right to go to the cards horizontally.
And there is also an Android version available.

William Lancee · Oct 10, 2023

@stevel05 is, as usual, perfect in his solution. I wasn't too familiar with ScrollPane, so I made a little test.
Note the handles of the scroll bars. The image generated by a B4XCanvas on a designer layout pane is 9000 x 9000 pixels.
The view screen = the form is 1024 x 768. The complete code (.zip attached):

B4X:

Sub Class_Globals
    Type SortPair(key As Object, value As Object)
    Private Root As B4XView
    Private xui As XUI
    
    Dim cv As B4XCanvas
    Private Pane1 As B4XView
End Sub

Private Sub B4XPage_Created (Root1 As B4XView)
    Root = Root1
    Dim windowz As ScrollPane
    windowz.Initialize("move")
    windowz.SetHScrollVisibility("ALWAYS")
    windowz.SetVScrollVisibility("ALWAYS")

    Dim windowx As B4XView = windowz
    Root.AddView(windowx, 0, 0, Root.Width, Root.height)
    windowx.ScrollViewInnerPanel.LoadLayout("bigPane")
    
    cv.Initialize(Pane1)
    For r = 4000 To 100 Step -100
        cv.DrawCircle(4500, 4500, r, xui.Color_RGB(Rnd(100, 255), Rnd(100, 255), Rnd(100, 255)), True, 0)
    Next

    windowz.HPosition = .5
    windowz.VPosition = .5
End Sub

Magma · Oct 10, 2023

maleche said:
When drawing MANY items on a Canvas, I would like to keep the plotted lines and objects that are moving.
The canvas should contain a "World View" having 9000 x 9000. The targets move per speed and course vector every second and encompass the entire World (9000 x 9000).
i would like to only show the "View port" or a window about 100 x 100. as i move the "Window/View Port", it shows the objects.
To clarify, the "World" dimensions are beyond the view and the window only displays the current or previous plotted targets.
Moreover, i have tried to scale the canvas, but rely on redrawing everything using 100dip/100 as i read in this forum.
any chance of a function/method to accomplish this scaling and window?
see attached example
Keep up the outstanding work!
Doyle

...I think stevel05 was right... my question... is why you need that?...

* if it is for "Game" reason... you may need some limits, IFs, etc (for showing objects moving only if showing in viewport) - or may be use some game library...
* if it is just for drawing - it is great !

William Lancee · Oct 10, 2023

And @PaulMeuris is right too.
https://www.b4x.com/android/forum/threads/b4j-kanban-cards-application.149795/post-949711

maleche · Oct 14, 2023

WOW!
Thank you so much for the help!

B4J Question Canvas "World view" and Movable Window View

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