Revise shapePhoto() to not use TkPhotoGetValidRegion()
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Requiring post-8.3 is trivial these days. Anyone using a version of Tk that doesn't have an alpha channel in photo images is also quite able to use the old versions of this code. |
shape.c:404:47: error: cannot take the address of an rvalue of type 'void *'
404 | imageName = Tcl_GetStringFromObj(objv[0], &NULL);
| ^~~~~
Remove unneeded includes, macros, and configure checks
chrstphrchvz
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shapePhoto()currently works by obtaining a region fromTkPhotoGetValidRegion()and passing it toShape_CombineRegion()(and in turnXShapeCombineRegion()on X11). However,TkPhotoGetValidRegion()is not a public Tk C API. And as discussed at https://core.tcl-lang.org/tk/info/919066 it takes a very long time to compute the region for some images, and I am not aware of an instance in core Tk or an extension where using this region is strictly necessary. Tk could draw photo image instances using a clip mask rather than a region (as attempted in chrstphrchvz/tk#4). I propose thatshapePhoto()follow a similar approach: use the public APITk_PhotoGetImage()to access alpha channel data and create a bitmap (pixmap with depth of 1) for use a clip mask to be passed toShape_CombineBitmap()(and in turnXShapeCombineMask()on X11).Note that this would leave
Shape_CombineRegion()unused within the shape extension.If Tk 8.3 or later can be required, then this approach allows photo shape source support to be enabled unconditionally. That should also make it okay for demos to use a photo shape source. As an example, I propose revising the dragger.tcl demo: instead of using doc-mask.xbm as a bitmap shape source, make doc-img.gif have a transparent background and use it as a photo shape source; the demo should look the same as before.
I have tested this using recent Tk core-8-6-branch on XQuartz (macOS), after applying demo and build fixes/workarounds (some from #7, some not reported). Some build fixes are currently included in this pull request, but can be moved to another pull request if desirable.