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<p>Il 22/04/2018 13:22, Michael Van Canneyt via Lazarus ha scritto:<br>
</p>
<blockquote type="cite"
cite="mid:alpine.DEB.2.20.1804221321180.26933@home.telenet.be">This
is how all properties that are TPersistent descendents work, so
this
<br>
behaviour should not come as a surprise.
</blockquote>
<br>
I wouldn't say so.<br>
<br>
E.g. TCanvas is a TPersistent descendent, but the Canvas property of
a TCustomControl is declared like that:<br>
<blockquote type="cite">
<pre> property Canvas: TCanvas read FCanvas write FCanvas; </pre>
</blockquote>
This means that after a <br>
<pre>SomeControl.Canvas := MyCanvas;</pre>
or<br>
<pre>MyCanvas := SomeControl.Canvas;</pre>
SomeControl.Canvas and MyCanvas will be the same object. Only a
pointer is copied.<br>
<br>
On the contrary, the property Bitmap of a TPicture is declare like
that:<br>
<br>
<blockquote type="cite">
<pre> property Bitmap: TBitmap read GetBitmap write SetBitmap;</pre>
</blockquote>
<br>
where GetBitmap actually returns the TPicture.Bitmap Object, while
SetBitmap creates a different Bitmap Object, and assigns it the
content of the supplied bitmap (see TPicture.SetGraphic, called by
TPicture.SetBitmap).<br>
<br>
This means that after a<br>
<pre>MyBitmap := SomePicture.Bitmap;</pre>
MyBitmap and SomePicture.Bitmap will represent the same Object,
while after a<br>
<pre>SomePicture.Bitmap := MyBitmap;</pre>
MyBitmap and SomePicture.Bitmap will represent different Objects.<br>
<br>
This is IMHO a TPicture specific inconsistency. <br>
<br>
Giuliano<br>
<br>
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