[Gambas-user] Gambas2 Grab in Gambas3

[Richard Welch]

Fabien, right on the button.

Cached now seems to work for me - when the code was first written in G2 
some years ago, minimising the window blanked the DrawingArea to 
background and overlaying it with a window from another application 
blanked the hidden part of the DrawingArea (I can't now remember if this 
always happened or if it was intermittent, depending on some factor 
which I never identified).  Turning on cached did not help. Hence the 
workaround of the use of an invisible PictureBox to backup the image, 
allowing its restoration to be a neat single operation independent of 
the original drawing process.

So I'm happy.  What was for you, no doubt, a simple observation has 
saved me a lot of hassle.  Thank you.

Richard


On 09/11/16 17:53, Fabien Bodard wrote:
> 2016-11-09 17:45 GMT+01:00 Richard Welch <richardpa608 at ...626...>:
>> Fabien, thank you for your reply.
>>
>> There are snags with each of these...
>>
>> First approach:
>>
>> Although the DrawingArea is often fully visible on screen, sometimes it
>> will be too big.
>> I can think of a way round this but it is not very elegant!
>>
>> Second approach:
>>
>> The image is sometimes highly complex and can comprise hundreds of
>> rectangles and lines as well as text.  I already do use generic
>> functions as you describe, with variable-driven adjustments to cope with
>> the differences between printing and screen display.  There are many
>> places in the code which may build a display.
>>
>> I found in G2 that there were times when the image in a DrawingArea was
>> not restored if it was partially covered by a window from another
>> application and then exposed once more.  This mechanism enabled it to be
>> restored easily without having to rebuild it from scratch.  Maybe the
>> DrawingArea in G3 is more robust?
> And why not using cached mode ?
>> Richard
>>
>>
>> On 08/11/16 17:31, Fabien Bodard wrote:
>>> Well... there is two answers.
>>>
>>> First :
>>>
>>> Use the Desktop.ScreenShot Function
>>> (http://gambaswiki.org/wiki/comp/gb.qt4/desktop/screenshot).
>>> But your widget must be visible on the screen... This is why it is a
>>> SCREEN shot.
>>>
>>>
>>> Second :
>>>
>>> When you are drawing something in a drawingarea you use a generic
>>> drawing function.
>>>
>>> Exemple :
>>>
>>>
>>> Public sub DrawingArea_Draw()
>>>
>>> DrawARect()
>>>
>>> End
>>>
>>>
>>> Private Sub DrawARect()
>>>
>>>     Paint.Brush = Brush.Color(Color.Yellow)
>>>     Paint.Rectangle(10,10,Paint.Width - 20, Paint.Height - 20)
>>>     Paint.Fill
>>>
>>> End
>>>
>>>
>>> Public Function MakeImage(iWidth as integer, iHeight as integer) as Image
>>>
>>>     Dim hImage a new Image(iWidth, iHeight, Color.White)
>>>
>>>     Paint.Begin(hImage)
>>>        DrawARect()
>>>     Paint.End
>>>
>>> End
>>>
>>>
>>> With that you have only one drawing function (DrawARect) able to draw
>>> every where ... even on a printer. This is the way used in most of the
>>> components too
>>>
>>> 2016-11-08 12:52 GMT+01:00 Richard Welch <richardpa608 at ...626...>:
>>>> I need a simple way to copy the current image in a visible DrawingArea
>>>> to a hidden PictureBox.
>>>>
>>>> The project was written in Gambas2, where a simple Grab method did the
>>>> trick, but in G3 this does something different so the converted code
>>>> does not function fully.
>>>>
>>>> FMain.pbxPicture.W = FMain.drwRep.W
>>>> FMain.pbxPicture.H = FMain.drwRep.H
>>>> FMain.pbxPicture.Background = FMain.drwRep.Background
>>>> FMain.pbxPicture.Picture = FMain.drwRep.Grab()
>>>>
>>>> With what do I replace the Grab method?
>>>>
>>>> (The DrawingArea is painted in many different pieces of code, depending
>>>> on context, so I want to make the change which will have the smallest
>>>> impact possible on the source code)
>>>>
>>>> There is a gambas-user thread started around 19 April 2012.
>>>> Is this fully relevant?
>>>> Is this the /simplest/ answer?
>>>> It would need some very tedious testing in my context.....
>>>>
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>>
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