How to draw on screen with finger?

ozgureffe · Aug 2, 2011

Hi,
I am looking for a solution to draw something on a panel? I found some samples in multitouch Using Agraham's Gestures library here -> Actually that sample is very similar to what i am looking for but is complicated for me as i am a beginner and my point is not related with multi touch... I am not related with multi touching functions...

Is there any simple way for this without using multi gesture? Single touch is enough for me for this project ?

And is it possible to save my drawings as image files ?

Thank You..

Kamac · Aug 2, 2011

without using multi gesture?

Means you don't want multi-touch?

Only multi gesture library allows you to use multi-touch with b4a.

And is it possible to save my drawings as image files?

Here's how you save ImageView as .png

Dim Out As OutputStream
Out = File.OpenOutput(File.DirRootExternal, "Test.png", False)
Bitmap1.WriteToStream(out, 100, "PNG")
Out.Close

Instead of Bitmap1 you have to give your ImageView name.

Edit@

Here's some very basic drawing:

B4X:

Sub Globals
    Dim Canvas1 As Canvas
End Sub

Sub Activity_Create(FirstTime As Boolean)
    Canvas1.Initialize(Activity) 'Initialize the canvas (drawer) and makes it draw on the activity (form).
End Sub

Sub Activity_Touch(Action As Int, tx As Float, ty As Float)
    Canvas1.DrawCircle(tx, ty, 5dip, Colors.Red, False, 2dip)
    Activity.Invalidate3(tx - 7dip, ty - 7dip, tx + 7dip, ty + 7dip)
End Sub

i hope it'll work, didn't test it.

Edit2@

Repaired and tested. It works.

ozgureffe · Aug 2, 2011

Yes! I mean I don't want and I don't need multi-touch...
I am looking something simpler with only basic logic about drawing.

And is it possible to save my drawing as an image file?

Kamac · Aug 2, 2011

And is it possible to save my drawing as an image file?

Sure, give me a sec' to complete that example for you

Kamac · Aug 2, 2011

Done

See the attachments.

PS.

The image will be saved on your sdcard root folder.

ozgureffe · Aug 2, 2011

Thak you so much
I am just tested your code it is working if draw in slow speed but if i move my finger faster it becomes dotty

ozgureffe · Aug 2, 2011

Thank you so much Kamac everything is working flawless now.
Only problem which is left is dots without connection if i draw a little bit faster.

Kamac · Aug 2, 2011

Hm, yeah.

I gotta look on fixing this

Give me some time.

Edit@

It could be fixed using line, but it's too late for me to do that now.

kickaha · Aug 3, 2011

I assume you are doing several circles to fill it. If so, instead of

B4X:

Sub Activity_Touch(Action As Int, tx As Float, ty As Float)
    Canvas1.DrawCircle(tx, ty, 5dip, Colors.Red, False, 2dip)
   Canvas1.DrawCircle(tx, ty, 4dip, Colors.Red, False, 2dip)
   Canvas1.DrawCircle(tx, ty, 3dip, Colors.Red, False, 2dip)
   Canvas1.DrawCircle(tx, ty, 2dip, Colors.Red, False, 2dip)
   Canvas1.DrawCircle(tx, ty, 1dip, Colors.Red, False, 2dip)
   Activity.Invalidate3(tx - 7dip, ty - 7dip, tx + 7dip, ty + 7dip)
End Sub

Why not

B4X:

Sub Activity_Touch(Action As Int, tx As Float, ty As Float)
    Canvas1.DrawCircle(tx, ty, 5dip, Colors.Red, True, 2dip)
   Activity.Invalidate3(tx - 7dip, ty - 7dip, tx + 7dip, ty + 7dip)
End Sub

As the flag after the colour is for filled or not filled.

How to draw on screen with finger?

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