Roassal should export PNG

[seandenigris]

Originally reported on Google Code with ID 1089

We have a first draft of RTPNGExporter, but the problem is that it provides only the
visible part of the morph.

The problem is here:
exportToFile
    PNGReadWriter 
        putForm: view view canvas morph imageForm
        onFileNamed: self fileName 

Reported by tudor@tudorgirba.com on 2014-10-09 05:05:32

[seandenigris]

Ideally, we should delegate to the AthensCairoCanvas, but somehow the athens canvas
instance from the TRCanvas is empty.

We certainly do not want to re-render the scene because some picture can be expensive
to produce.

Reported by tudor@tudorgirba.com on 2014-10-09 05:10:55

[seandenigris]

Yes, somehow your canvas in TRCanvas is only used for shape creations
(computePath). Drawing is done with TRMorphs cairo-surface.

AthensCairoSurface has a writeToPng: method for writing the current surface data
as a png file.

Reported by nicolaihess on 2014-10-09 07:33:48

[seandenigris]

Indeed. However, we probably have to redraw everything again given that the canvas in
the TRMorph is only the visible one

Reported by tudor@tudorgirba.com on 2014-10-09 07:56:07

[seandenigris]

I tried this, but somehow it does not work:

exportToFile
     | completeMorph |
     completeMorph := view view canvas morphClass new
          canvas: view view canvas;
          extent: view view canvas encompassingRectangle extent.
     PNGReadWriter
          putForm: completeMorph imageForm
          onFileNamed: self fileName

Any idea why?

Reported by tudor@tudorgirba.com on 2014-10-12 22:09:02

[seandenigris]

How do I render an existing trachel shape on an Athens surface?

Reported by tudor@tudorgirba.com on 2014-10-12 22:09:44

[seandenigris]

Here is a script that Alex put together. It almost work, but we still need to extract
the logic from TRMorph. Also, there still is a problem with the logic as the picture
is shifted to the right.

b := RTMondrianViewBuilder new.
b shape rectangle 
   withBorder;
   width: [ :cls | cls numberOfVariables * 5];
   height: #numberOfMethods;
   linearFillColor: #numberOfLinesOfCode within: RTObject withAllSubclasses.
b nodes: RTObject withAllSubclasses.
b edgesFrom: #superclass.
b treeLayout.
b build.

form := FormCanvas extent: (b view canvas encompassingRectangle) extent.
m := TRMorph new.
m canvas: b view canvas.
m extent: (b view canvas encompassingRectangle) extent.
m createSurface.
m drawOn: form.
m surface writeToPng: 'foo.png'

Reported by tudor@tudorgirba.com on 2014-11-12 13:06:59

[seandenigris]

Can anyone else look at this?

Reported by tudor@tudorgirba.com on 2014-11-12 13:07:14

[seandenigris]

Here is a standalone script that seems to almost works. There is still seems to be a
problem with one pixel at the bottom and to the right that gets cut.

b := RTMondrianViewBuilder new.
b shape rectangle 
   withBorder;
   width: [ :cls | cls numberOfVariables * 5];
   height: #numberOfMethods;
   linearFillColor: #numberOfLinesOfCode within: RTObject withAllSubclasses.
b nodes: RTObject withAllSubclasses.
b edgesFrom: #superclass.
b treeLayout.
b build.

trachelCanvas := b view canvas.
form := FormCanvas extent: (trachelCanvas encompassingRectangle) extent.
session := Smalltalk session.
surface := AthensCairoSurface extent: (trachelCanvas encompassingRectangle extent)
asIntegerPoint.
form fillRectangle: trachelCanvas encompassingRectangle color: trachelCanvas color.
"The drawing has to be done when a change in the shapes occured or when there is an
animation."
surface drawDuring: [:cs |
    surface clear.
    "We display the elements that are subject to the camera"
    trachelCanvas shapes do: [ :trachelShape |
        trachelShape drawOn: cs.
    ].
    "We display the elements that are _NOT_ subject to the camera"
    trachelCanvas fixedShapes do: [ :trachelShape |
        trachelShape drawOn: cs.
    ].
].
"aCanvas translucentImage: surface asForm at: self bounds origin."
"asForm creates a new Form, which is likely to be expensive. This can be cached"
form image: surface asForm at: trachelCanvas encompassingRectangle origin sourceRect:
(0 @ 0 extent: surface extent) rule: 34.
surface writeToPng: 'foo.png'

Reported by tudor@tudorgirba.com on 2014-11-12 13:27:05

[seandenigris]

I integrated this in RTPNGExporter, but we still have the one pixel problem.

Reported by tudor@tudorgirba.com on 2014-11-12 13:52:51

[seandenigris]

I've tried this and it looks okay (simply adding 10 @ 10 to the extent):

b := RTMondrianViewBuilder new.
b shape rectangle
  withBorder;
  width: [ :cls | cls numberOfVariables * 5];
  height: #numberOfMethods;
  linearFillColor: #numberOfLinesOfCode within: RTObject withAllSubclasses.
b nodes: RTObject withAllSubclasses.
b edgesFrom: #superclass.
b treeLayout.
b build.

trachelCanvas := b view canvas.
form := FormCanvas extent: (trachelCanvas encompassingRectangle) extent.
session := Smalltalk session.
surface := AthensCairoSurface extent: (trachelCanvas encompassingRectangle extent +
(10 @ 10)) asIntegerPoint.
form fillRectangle: (trachelCanvas encompassingRectangle expandBy: 10 @ 10) color:
trachelCanvas color.
"The drawing has to be done when a change in the shapes occured or when there is an
animation."
surface drawDuring: [:cs |
    surface clear.
    "We display the elements that are subject to the camera"
    trachelCanvas shapes do: [ :trachelShape |
        trachelShape drawOn: cs.
    ].
    "We display the elements that are _NOT_ subject to the camera"
    trachelCanvas fixedShapes do: [ :trachelShape |
        trachelShape drawOn: cs.
    ].
].
"aCanvas translucentImage: surface asForm at: self bounds origin."
"asForm creates a new Form, which is likely to be expensive. This can be cached"
form image: surface asForm at: trachelCanvas encompassingRectangle origin sourceRect:
(0 @ 0 extent: surface extent) rule: 34.
surface writeToPng: '/tmp/foo.png'

Reported by alexandre.bergel on 2014-11-12 14:02:33

[seandenigris]

How is adding 10@10 a solution?

1. asIntegerPoint rounds down.
2. encompassingRectangle does not take the strokewidth into account.

Reported by nicolaihess on 2014-11-12 22:46:07

[seandenigris]

Other observiations:

- file chooser dialog has "Your title here" as title.
- cancel file chooser dialog -> MessageNotUnderstood: receiver of ""fullName"" is nil

Reported by nicolaihess on 2014-11-13 11:25:55

[seandenigris]

@Nicolai: Thanks for finding the issues. They are fixed now.

@Alex: Looks great. Thanks!

Reported by tudor@tudorgirba.com on 2014-11-13 21:09:59

• Status changed: Fixed