Simple. Drag & Drop, and Draw

Lar_123 · **Posted:** November 17th, 2007, 1:02 am

Simple but am stuck. Is in Advanced section, since uses Scripts for drawing.

in the example a user drags an object, Opus Draws a line from starting point to place where user Drops an object. Great, that works. Can change to different drop zone.

Need help for condition when User drags object out of valid Drop Zone. Want the line to disappear when object returns to its 'home'.

Thanks.
p.s. I will have 12 objects to drag... so looking for streamlining coding.

sandyn · **Posted:** November 17th, 2007, 2:22 pm

a very simple way is to add a left mouse trigger which clears the drawing frame before the drop trigger.
When you click on the object, any previous line is cleared first, if it's a valid drop the line is re-drawn. If it's not a valid drop, the line isn't re-drawn.

Sandy

Lar_123 · **Posted:** November 18th, 2007, 8:04 am

I think you mean add that trigger to the Dragged object. I'll try that. Previously I had trouble putting a xx.ClearDraw() action that could get called before a real Draw action.

sandyn · **Posted:** November 18th, 2007, 11:02 am

Yes

. Sorry I wasn't clearer. I tried it and it works fine, but there is probably several other ways of doing it.

A screen refresh can be forced by using a wait(0) this may be required between the ClearDraw and Draw statements
Sandy

Lar_123 · **Posted:** November 19th, 2007, 11:53 am

Putting a ClearDraw() under a mouseclick trigger prevented any lines from being drawn as part of the Drop action. So that does not appear to be a solution.

BTW, I did not use a 'wait' in the example .imp... and lines did erase and redraw correctly as long as another valid drop was achieved.

Here's the script used with 'This Object Dropped' trigger under Button_1. Works well to move line when Button moved to different drop zone. Fails to remove line when "not dropped".

Code:

frame1.ClearDraw();
var ToPos = Button_1.GetPosition();
var FromPos =  Vector_1.GetPosition()
frame1.DrawLine( FromPos, ToPos );

Quote:

but there is probably several other ways of doing it.

Open to other suggestions.

sandyn · **Posted:** November 19th, 2007, 12:14 pm

I have two triggers attached to the draggable object.
first:- "This object dropped all objects"

Code:

dframe1.SetLineColour("red");
var FromPos =  Vector_27.GetPosition()
var ToPos = Vector_28.GetPosition();
wait()
dframe1.DrawLine( FromPos, ToPos );

Add the "wait(0)"

then:-"Left Mouse Click"
with a script attached and

Code:

dframe1.ClearDraw();

Works perfect---I can drag and drop the object and the line is drawn.

If I move the object off the target, the line is cleared. If I drag it to another valid drop the line is drawn, if I drag it to another drop zone the first line clears and the new line is drawn.

Sandy

sandyn · **Posted:** November 19th, 2007, 5:35 pm

the modified IMP
I have modified the actions of both stars to work correctly...I hope :-)

Lar_123 · **Posted:** November 19th, 2007, 10:28 pm

Sandyn, thanks... wait(), applause! :lol:

Works perfect.
Now if I could just understand 'why' that little wait command makes all the difference?

I guess impatience is highly overrated.

thanks.

mackavi · **Posted:** November 19th, 2007, 10:35 pm

...because certain events happen faster than others such as a screen update. The wait simply gives these events the chance to 'catch up'

Lar_123 · **Posted:** November 20th, 2007, 12:21 am

thanks, Mac.

So in this case, are we waiting for the ClearDraw from the MouseClick before going on to the DrawLine under the drop trigger?

I ask, as there's not much 'code' going on above the wait() command. Also, I tried putting a wait() under the MClk action (after the ClearDraw there)... and that did not work.

sandyn · **Posted:** November 20th, 2007, 1:38 am

I think there's an element of serendipity with my design :-)

When you click on the drag-able object, it triggers a ClearDraw(), but it seems the screen isn't updated until the wait(0). See the help on "wait()"

from help file:-

Quote:

Example 2: Refreshing the screen

The wait function can be set to zero, which is often used to update the screen. For example, if you do this

for(..;..;..)
{
Image_1.Show()
Image_1.Hide()
}

You may expect the image to flicker, however, the screen is not updated between the Show and Hide. To update the screen, use wait(0):

for(..;..;..)
{
Image_1.Show()
Wait(0)
Image_1.Hide()
}

there is a problem with my method :-(

if you have dragged the star to the square--it's OK. If you move the star within the square---it's OK, but if you click on the star in the square, but not move it, the line is cleared.
this can be overcome by doing the following
add the following to the script in the mouse click trigger after the ClearDraw()

Code:

if(Vector_28.IsObjectIntersecting(Vector_29))
{
   wait(0)
   dframe1.DrawLine( FromPos, ToPos );
}

(Vector_28 is the star and Vector_29 is the rectangle)

You also need to 'OR' this with the other vectors in the IF statement so that this method can be expanded to work when the red star is dragged to any rectangle. I haven't tried the 'OR' bit, but I think it should work???
If you have problems, I'll post an IMP tomorrow---it's past my bedtime.
PS I could have used:
if(this.IsObjectIntersecting(Vector_29))

Sandy

Lar_123 · **Posted:** November 20th, 2007, 8:28 am

Sandy,

Thanks for further refining. Should prove useful to others here too.

Quote:

there is a problem....if you have dragged the star to the square-- but if you click on the star in the square, but not move it, the line is cleared.

Very true.

Quote:

You also need to 'OR' this with the other vectors... so that this method can be expanded to work when the red star is dragged to any rectangle. I haven't tried the 'OR' bit, but I think it should work???

I might try something with a test for "dropped" as a property of the Star object. Otherwise I am concerned with the IF statement and coding all the combinations of drag-objs and dropzones. One page I plan will have 8 draggable onto 5 dropzones. Also will look to move some code to 'functions' if that makes sense.

Lar_123 · **Posted:** November 20th, 2007, 8:33 am

Oh, on the 'wait' thing. I didn't expect screen refresh was entering here. As you saw, having ClearDraw and then DrawLine in one script was operating well (except for the object returning condition).

I guess because a separate trigger event was used, this action of drop and draw needed the time (wait).

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Simple. Drag & Drop, and Draw

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