Group2D questions

Getting Started
1

Hello,

I am writing a desktop application which need vectorial graphics with zoom an pan.
Forum readings show that Group2D is a handy way to do that.

So I have :

  • a windows with a canvas named Canvas1
  • a picture PictGraph
  • a Group2d VectGraph

Into Canvas1.paint I have

g.DrawPicture PictGraph, 0, 0

In windows.opening :

Var VectGraph as new Group2D
Var PictGraph as new Picture (1000,1000,32)

// Add a rectangle to VectGraph

Var a as new RectShape
a.Height = 50
a.Width = 20
a.X = 100
a.Y = 50
a.FillColor = color.rgb(255, 0, 0)
VectGraph.AddObject(a)

// Add the Group2D to PictGraph
PictGraph.Graphics.DrawObject VectGraph, 0, 0

// Update Canvas1
Canvas1.Invalidate

The app is running but I expect to get a rectangle into the canvas and… nothing displayed !

For sure I do something wrong but I dont understand what.

Any help appreciated.
Regards
Philippe

2

Is your Canvas width/heigh > 1000,1000 ?

3

No it is around 400x300 pixels.

4

You dont need PictGraph
To draw the Group2d , your canvas code can be


dim VectGraph = new Group2D
// Add a rectangle to VectGraph
Var a as new RectShape
a.Height = 50
a.Width = 20
a.X = 100
a.Y = 50
a.FillColor = color.rgb(255, 0, 0)
VectGraph.AddObject(a)

g.drawobject(VectGraph,0,0)

You could make VectGraph a property of the window, set the contents in the window opening event, and just use
if VectGraph <> nil then g.drawobject(VectGraph,0,0)
in the canvas’ Paint event

5

You are right the code works without PictGraph and using drawobject instead of drawpicture into Canvas1 paint event.

But always no rectangle on screen !

6

Have-you tried to change the X,Y values ?

7

I found the problem

Should use

VectGraph = new Group2D

and not

Var VectGraph as new Group2D