draw:image vs draw:fill-image & multiple copies

[Regina Henschel]

Hi David,

Dr. David Alan Gilbert schrieb am 18.07.2024 um 19:37:
> Hi,
>    (Context: PDF importing a weird document with thousands of identical
> images https://bugs.documentfoundation.org/show_bug.cgi?id=88914 )
> 
> If you insert an image into a Draw document you get a
>    draw:frame with a draw:image inside, with the image data

The picture itself is only inside the draw:image element, if you use the 
flat format (.fodp). Otherwise there is only a link to the image that is 
in a separate folder.

> 
> If you duplicate that image (copy/paste), you get a second
> draw:frame and second draw:image with the data again.

The image itself is only onetime in the folder. All copies have a link 
to the same image.

> 
> Is there any way with draw:image not to copy the data?

That would be only relevant for a document in flat format.

> I wondered if it was doable with a
>    draw:image xlink:href=hmmsomething
> but couldn't figure out if it was possible to link back to your
> own images?

The links are set automatically all to the same image. Nothing to do for 
you.

> 
> But the other route is a
>    draw:custom-shape
>     to a style with a draw:fill-image-name
>       to a draw:fill-image
> 
> and then you can have multiple draw:custom-shape's sharing the
> draw:fill-image - and hopefully the style.
> Is there any downside to that?

It depends on the kind of image, what you will do with the image and in 
which module you use the image.

The <draw:frame> element can contains more than one <draw:image> child 
element. That is used for example for a svg-image. These child elements 
have different mime-types, so that a consumer can take that one it is 
able to render. If a consumer is not able to render the vector graphic, 
it can take the bitmap, for example. That is not possible with a style 
with image-fill.

Compared to shapes, images have specialized features:
* You can adjust color/contrast/brightness/gamma/transparency without 
actually changing the image.

* The image need not be in the document itself, but can be an external 
resource.

* You can define an "Image Map".

* You can define a "Contour Wrap".

* Images have events to trigger macros.

On the other hand, a custom-shape with bitmap fill can be used in 
3D-mode. That allows perspective and 3-dimensional rotation.

Kind regards,
Regina