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Zooming in VisualWorks

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Michael Meyer-6
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Zooming in VisualWorks

Michael Meyer-6
Hi
In my application I paint geometric shapes like Rectangles. Now my application should support zooming.
The simplest solution till now was to put a wrapper around the GraphicsContext.

graphicsContext := (ExamplesBrowser prepareScratchWindow) graphicsContext.
myGraphicsContext := GraphicsContextWrapper on: graphicsContext zoom: 1.7. "1.7 stands for 170%"
(Rectangle origin: 6@6 corner: 60@30) displayFilledOn: myGraphicsContext.

In the GraphicsContextWrapper I have methods like this:

GraphicsContextWrapper >> displayRectangle: aRectangle
     graphicsContext displayRectangle: (aRectangle * self zoom)

Unfortunaelty this approach does not work for text. Im using instances of ComposedText. ComposedText
calls the method "displayMappedString: aString from: startIndex to: endIndex at: aPoint withMap: map"
in the GraphicsContext. There are two problems:

1. Replacing "aPoint" with "aPoint * self zoom" returns the wrong y coordinate.
2. I can no longer scale the text at this point (I think).

Has anybody got a simple solution for zooming text? A solution that only needs changes in the GraphicsContext
would be nice.

Cheers,
michael

Michael Lucas-Smith
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Re: Zooming in VisualWorks

Michael Lucas-Smith
Hi,

I've done a similar thing called ScalingGraphicsContext and it's in the Public Store repository. It includes zooming of text. The only thing it doesn't zoom is pixmap's, but it does zoom Mask's, Image's, etc.

I went for the 'dumpest thing that could work' and tried to see if it was fast enough - thus far it has been fast enough.

Cheers,
Michael

> Hi
> In my application I paint geometric shapes like Rectangles. Now my
> application should support zooming.
> The simplest solution till now was to put a wrapper around the GraphicsContext.

> graphicsContext := (ExamplesBrowser prepareScratchWindow) graphicsContext.
> myGraphicsContext := GraphicsContextWrapper on: graphicsContext zoom: 1.7. "1.7 stands for 170%"
> (Rectangle origin: 6@6 corner: 60@30) displayFilledOn: myGraphicsContext.

> In the GraphicsContextWrapper I have methods like this:

> GraphicsContextWrapper >> displayRectangle: aRectangle
>      graphicsContext displayRectangle: (aRectangle * self zoom)

> Unfortunaelty this approach does not work for text. Im using
> instances of ComposedText. ComposedText
> calls the method "displayMappedString: aString from: startIndex to: endIndex at: aPoint withMap: map"
> in the GraphicsContext. There are two problems:

> 1. Replacing "aPoint" with "aPoint * self zoom" returns the wrong y coordinate.
> 2. I can no longer scale the text at this point (I think).

> Has anybody got a simple solution for zooming text? A solution that
> only needs changes in the GraphicsContext
> would be nice.

> Cheers,
> michael

Michael Meyer-6
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Re: Zooming in VisualWorks

Michael Meyer-6
Hi michael,
that ScalingScreenGraphicsContext of yours is really nice :-)
Thanks a lot.

michael

Michael Lucas-Smith schrieb:

> Hi,
>
> I've done a similar thing called ScalingGraphicsContext and it's in the Public Store repository. It includes zooming of text. The only thing it doesn't zoom is pixmap's, but it does zoom Mask's, Image's, etc.
>
> I went for the 'dumpest thing that could work' and tried to see if it was fast enough - thus far it has been fast enough.
>
> Cheers,
> Michael
>
>> Hi
>> In my application I paint geometric shapes like Rectangles. Now my
>> application should support zooming.
>> The simplest solution till now was to put a wrapper around the GraphicsContext.
>
>> graphicsContext := (ExamplesBrowser prepareScratchWindow) graphicsContext.
>> myGraphicsContext := GraphicsContextWrapper on: graphicsContext zoom: 1.7. "1.7 stands for 170%"
>> (Rectangle origin: 6@6 corner: 60@30) displayFilledOn: myGraphicsContext.
>
>> In the GraphicsContextWrapper I have methods like this:
>
>> GraphicsContextWrapper >> displayRectangle: aRectangle
>>      graphicsContext displayRectangle: (aRectangle * self zoom)
>
>> Unfortunaelty this approach does not work for text. Im using
>> instances of ComposedText. ComposedText
>> calls the method "displayMappedString: aString from: startIndex to: endIndex at: aPoint withMap: map"
>> in the GraphicsContext. There are two problems:
>
>> 1. Replacing "aPoint" with "aPoint * self zoom" returns the wrong y coordinate.
>> 2. I can no longer scale the text at this point (I think).
>
>> Has anybody got a simple solution for zooming text? A solution that
>> only needs changes in the GraphicsContext
>> would be nice.
>
>> Cheers,
>> michael
>
>

Steven Kelly
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RE: Zooming in VisualWorks

Steven Kelly
In reply to this post by Michael Meyer-6
Michael,

If Rectangles are just the start of more involved graphics, you might
want to look at GF/ST (in goodies\parc\GFST or contrib\GFST). It
implements a similar scaling graphics context to Michael Lucas-Smith's,
but is faster, includes the option of double buffering, direct
manipulation of the graphics, and linking graphics to domain objects.

All the best,
Steve

> -----Original Message-----
> From: Michael Meyer [mailto:[hidden email]]
> Sent: 23 April 2006 14:14
> To: [hidden email]
> Subject: Zooming in VisualWorks
>
> Hi
> In my application I paint geometric shapes like Rectangles. Now my
> application should support zooming.
> The simplest solution till now was to put a wrapper around the
> GraphicsContext.
>
> graphicsContext := (ExamplesBrowser prepareScratchWindow)
graphicsContext.
> myGraphicsContext := GraphicsContextWrapper on: graphicsContext zoom:
1.7.
> "1.7 stands for 170%"
> (Rectangle origin: 6@6 corner: 60@30) displayFilledOn:
myGraphicsContext.
>
> In the GraphicsContextWrapper I have methods like this:
>
> GraphicsContextWrapper >> displayRectangle: aRectangle
>      graphicsContext displayRectangle: (aRectangle * self zoom)
>
> Unfortunaelty this approach does not work for text. Im using instances
of

> ComposedText. ComposedText
> calls the method "displayMappedString: aString from: startIndex to:
> endIndex at: aPoint withMap: map"
> in the GraphicsContext. There are two problems:
>
> 1. Replacing "aPoint" with "aPoint * self zoom" returns the wrong y
> coordinate.
> 2. I can no longer scale the text at this point (I think).
>
> Has anybody got a simple solution for zooming text? A solution that
only
> needs changes in the GraphicsContext
> would be nice.
>
> Cheers,
> michael

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