Grayscale overlay

steve2 · September 18, 2017, 5:11pm

Hi,

I would like to get a grayscale screenshot (overlay) of the current window and do drawings on it. I mean, the current window and all widgets, etc on it should lose all their colors and I should do drawings on it. Do you know how to do this?

I use

odc = wx.DCOverlay(wx.Overlay, dc)

but its not grayscale.

Tim_Roberts · September 18, 2017, 5:43pm

steve wrote:

I would like to get a grayscale screenshot (overlay) of the current
window and do drawings on it. I mean, the current window and all
widgets, etc on it should lose all their colors and I should do
drawings on it. Do you know how to do this?

Well, an overlay is something that appears over the top of an existing
window, so the controls on the window still show through. Is that
really what you're after? It sounds like you want a separate window
contains a converted copy of your current window, so the existing
controls are not visible.

There is nothing in wx that will convert a color bitmap to a grayscale
bitmap, in part because the definition of "grayscale" is not completely
uniform. You'll have to do that by hand, pixel by pixel, or using
another graphics library. It's not hard.

Perhaps you should describe what you're trying to in a bit more detail.

···

--
Tim Roberts, timr@probo.com
Providenza & Boekelheide, Inc.

Gadget_Steve · September 18, 2017, 5:50pm

Just get the screenshot, (in colour), convert to an image with
ConvertToImage() and then use Pillow or Numpy to convert to greyscale.

···

On 18/09/2017 18:11, steve wrote:

Hi,

I would like to get a grayscale screenshot (overlay) of the current
window and do drawings on it. I mean, the current window and all
widgets, etc on it should lose all their colors and I should do drawings
on it. Do you know how to do this?

I use

odc = wx.DCOverlay(wx.Overlay, dc)

but its not grayscale.

--
Steve (Gadget) Barnes
Any opinions in this message are my personal opinions and do not reflect
those of my employer.

---
This email has been checked for viruses by AVG.

Robin · September 18, 2017, 7:43pm

wx.Image has a ConvertToGreyscale method.

Drawing in a layer on top of other widgets will be tricky however. The overlay classes on OSX use a native implementation that can do that, however the other platforms use a generic overlay based on ClientDC so it can only support drawing on the window performing the overlay which is likely to be the parent of the widgets you want to draw over.

The only approach that comes to mind is to use wx.ScreenDC to blit a snapshot of the window into a bitmap, temporarily replace (or hide) the current contents of the window with one that displays that bitmap and supports drawing like you want. However that won’t work on OSX (DC’s are one-way there, in most cases you can’t easily get their current contents) but you can use the overlay classes there. Also, IIRC the ScreenDC approach may or may not work on Linux, depending on a number of factors.

Robin

···

On Monday, September 18, 2017 at 10:43:15 AM UTC-7, Tim Roberts wrote:

steve wrote:

I would like to get a grayscale screenshot (overlay) of the current

window and do drawings on it. I mean, the current window and all

widgets, etc on it should lose all their colors and I should do

drawings on it. Do you know how to do this?

Well, an overlay is something that appears over the top of an existing

window, so the controls on the window still show through. Is that

really what you’re after? It sounds like you want a separate window

contains a converted copy of your current window, so the existing

controls are not visible.

There is nothing in wx that will convert a color bitmap to a grayscale

bitmap, in part because the definition of “grayscale” is not completely

uniform. You’ll have to do that by hand, pixel by pixel, or using

another graphics library. It’s not hard.

Perhaps you should describe what you’re trying to in a bit more detail.

–
Tim Roberts, timr@probo.com

Providenza & Boekelheide, Inc.

steve2 · September 18, 2017, 8:33pm

Sorry for causing misunderstanding,

I have a panel on my frame, and I do drawings on it (rectangles, shapes etc) with wxpython GDI (using methods like dc.DrawRectangle etc). Rectangles and shapes have colors. There are no widgets on the panel. Just shapes.

When I press a button on the toolbar, I want everything on that panel to turn into grayscale (all shapes will lose their colors), and a colored custom progress bar will appear in the middle of that grayscaled panel (and on top of shapes), and it will run (because a lengthy operation will be executed). When the execution is completed, the progress bar will disappear and the shapes on panel will regain its original colors.

I hope I could explain it.

···

On Monday, September 18, 2017 at 10:43:56 PM UTC+3, Robin Dunn wrote:

wx.Image has a ConvertToGreyscale method.

Drawing in a layer on top of other widgets will be tricky however. The overlay classes on OSX use a native implementation that can do that, however the other platforms use a generic overlay based on ClientDC so it can only support drawing on the window performing the overlay which is likely to be the parent of the widgets you want to draw over.

The only approach that comes to mind is to use wx.ScreenDC to blit a snapshot of the window into a bitmap, temporarily replace (or hide) the current contents of the window with one that displays that bitmap and supports drawing like you want. However that won’t work on OSX (DC’s are one-way there, in most cases you can’t easily get their current contents) but you can use the overlay classes there. Also, IIRC the ScreenDC approach may or may not work on Linux, depending on a number of factors.

Robin

On Monday, September 18, 2017 at 10:43:15 AM UTC-7, Tim Roberts wrote:

steve wrote:

I would like to get a grayscale screenshot (overlay) of the current

window and do drawings on it. I mean, the current window and all

widgets, etc on it should lose all their colors and I should do

drawings on it. Do you know how to do this?

Well, an overlay is something that appears over the top of an existing

window, so the controls on the window still show through. Is that

really what you’re after? It sounds like you want a separate window

contains a converted copy of your current window, so the existing

controls are not visible.

There is nothing in wx that will convert a color bitmap to a grayscale

bitmap, in part because the definition of “grayscale” is not completely

uniform. You’ll have to do that by hand, pixel by pixel, or using

another graphics library. It’s not hard.

Perhaps you should describe what you’re trying to in a bit more detail.

–
Tim Roberts, ti...@probo.com

Providenza & Boekelheide, Inc.

Gadget_Steve · September 19, 2017, 7:44am

Simply hide the existing panel and replace it with one displaying a grey
scale version of the current bitmap or image for the duration.

···

On 18/09/2017 21:33, steve wrote:

Sorry for causing misunderstanding,

I have a panel on my frame, and I do drawings on it (rectangles, shapes
etc) with wxpython GDI (using methods like dc.DrawRectangle etc).
Rectangles and shapes have colors. There are no widgets on the panel.
Just shapes.

When I press a button on the toolbar, I want everything on that panel to
turn into grayscale (all shapes will lose their colors), and a colored
custom progress bar will appear in the middle of that grayscaled panel
(and on top of shapes), and it will run (because a lengthy operation
will be executed). When the execution is completed, the progress bar
will disappear and the shapes on panel will regain its original colors.

I hope I could explain it.

On Monday, September 18, 2017 at 10:43:56 PM UTC+3, Robin Dunn wrote:

    wx.Image has a ConvertToGreyscale method.

    Drawing in a layer on top of other widgets will be tricky however.
      The overlay classes on OSX use a native implementation that can do
    that, however the other platforms use a generic overlay based on
    ClientDC so it can only support drawing on the window performing the
    overlay which is likely to be the parent of the widgets you want to
    draw over.

    The only approach that comes to mind is to use wx.ScreenDC to blit a
    snapshot of the window into a bitmap, temporarily replace (or hide)
    the current contents of the window with one that displays that
    bitmap and supports drawing like you want. However that won't work
    on OSX (DC's are one-way there, in most cases you can't easily get
    their current contents) but you can use the overlay classes there.
    Also, IIRC the ScreenDC approach may or may not work on Linux,
    depending on a number of factors.

    Robin

    On Monday, September 18, 2017 at 10:43:15 AM UTC-7, Tim Roberts wrote:

        steve wrote:
         >
         > I would like to get a grayscale screenshot (overlay) of the
        current
         > window and do drawings on it. I mean, the current window and all
         > widgets, etc on it should lose all their colors and I should do
         > drawings on it. Do you know how to do this?

        Well, an overlay is something that appears over the top of an
        existing
        window, so the controls on the window still show through. Is that
        really what you're after? It sounds like you want a separate
        window
        contains a converted copy of your current window, so the existing
        controls are not visible.

        There is nothing in wx that will convert a color bitmap to a
        grayscale
        bitmap, in part because the definition of "grayscale" is not
        completely
        uniform. You'll have to do that by hand, pixel by pixel, or using
        another graphics library. It's not hard.

        Perhaps you should describe what you're trying to in a bit more
        detail.

        --
        Tim Roberts, ti...@probo.com <javascript:>
        Providenza & Boekelheide, Inc.

--
Steve (Gadget) Barnes
Any opinions in this message are my personal opinions and do not reflect
those of my employer.

---
This email has been checked for viruses by AVG.

Tim_Roberts · September 19, 2017, 5:52pm

steve wrote:

I have a panel on my frame, and I do drawings on it (rectangles,
shapes etc) with wxpython GDI (using methods like dc.DrawRectangle
etc). Rectangles and shapes have colors. There are no widgets on the
panel. Just shapes.

That's very different from what you first described.

When I press a button on the toolbar, I want everything on that panel
to turn into grayscale (all shapes will lose their colors), and a
colored custom progress bar will appear in the middle of that
grayscaled panel (and on top of shapes), and it will run (because a
lengthy operation will be executed). When the execution is completed,
the progress bar will disappear and the shapes on panel will regain
its original colors.

It seems to me that the easy way to do this is to have all of your color
selections go through a filter:

m\_Shape\-&gt;SetBackgroundColor\( ChooseColor\( 255,128,64 \) \);

...
wxColour MyWindow::ChooseColor( int r, int g, int b )
{
if( m_NeedGrayscale )
{
// This is a cheap but acceptable RGB->grayscale conversion.
int gray = (2 * r + 4 * g + b) / 7;
return wxColour( gray, gray, gray );
}
else
return wxColour( r, g, b );
}

Now, to draw in grayscale, you just set the flag and call "Refresh();."

···

--
Tim Roberts, timr@probo.com
Providenza & Boekelheide, Inc.

Tim_Roberts · September 19, 2017, 5:54pm

Tim Roberts wrote:

steve wrote:

I have a panel on my frame, and I do drawings on it (rectangles,
shapes etc) with wxpython GDI (using methods like dc.DrawRectangle
etc). Rectangles and shapes have colors. There are no widgets on the
panel. Just shapes.

That's very different from what you first described.

When I press a button on the toolbar, I want everything on that panel
to turn into grayscale (all shapes will lose their colors), and a
colored custom progress bar will appear in the middle of that
grayscaled panel (and on top of shapes), and it will run (because a
lengthy operation will be executed). When the execution is completed,
the progress bar will disappear and the shapes on panel will regain
its original colors.

It seems to me that the easy way to do this is to have all of your color
selections go through a filter:

Holy cripes, I totally spaced that I was on the wxPython list.

def ChooseColor\( self, r, g, b \):
    if self\.NeedGrayScale:
        gray = \(2 \* r \+ 4 \* g \+ b\) / 7
        return wx\.Colour\( gray, gray, gray \)
    else:
        return wx\.Colour\( r, g, b \)

\.\.\.\.
    self\.widget\.SetBackgroundColor\( self\.ChooseColor\( 255, 128, 64 \) \)

···

--
Tim Roberts, timr@probo.com
Providenza & Boekelheide, Inc.

Chris_Barker1 · September 20, 2017, 12:25am

Holy cripes, I totally spaced that I was on the wxPython list.

Makes you appreciate Python, eh?

Another option:

Rather than greyscale, draw a semi-transparent white or black
rectangle over the whole thing -- that will make it look all muted.

Also - you should probably have your window double/buffered-- so you
can grab the buffet, make it an image, convert to grayscale, and the
put it back.

-CHB

···

    def ChooseColor( self, r, g, b ):
        if self.NeedGrayScale:
            gray = (2 * r + 4 * g + b) / 7
            return wx.Colour( gray, gray, gray )
        else:
            return wx.Colour( r, g, b )

    ....
        self.widget.SetBackgroundColor( self.ChooseColor( 255, 128, 64 ) )

--
Tim Roberts, timr@probo.com
Providenza & Boekelheide, Inc.

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steve2 · September 20, 2017, 10:08pm

Great answer Chris, it doesn’t exactly do what I want, bu still it is very handy. Thanks.

···

On Wednesday, September 20, 2017 at 3:25:37 AM UTC+3, Chris Barker - NOAA Federal wrote:

Holy cripes, I totally spaced that I was on the wxPython list.

Makes you appreciate Python, eh?

Another option:

Rather than greyscale, draw a semi-transparent white or black

rectangle over the whole thing – that will make it look all muted.

Also - you should probably have your window double/buffered-- so you

can grab the buffet, make it an image, convert to grayscale, and the

put it back.

-CHB
def ChooseColor( self, r, g, b ):
    if self.NeedGrayScale:
        gray = (2 * r + 4 * g + b) / 7
        return wx.Colour( gray, gray, gray )
    else:
        return wx.Colour( r, g, b )
....
    self.widget.SetBackgroundColor( self.ChooseColor( 255, 128, 64 ) )
–

Tim Roberts, ti...@probo.com

Providenza & Boekelheide, Inc.

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