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child: Container(color: red, width: 10, height: 10),
)
<code_end>
You might guess that the Container has to be
between 70 and 150 pixels, but you would be wrong.
The ConstrainedBox only imposes additional constraints
from those it receives from its parent.
Here, the screen forces the ConstrainedBox to be exactly
the same size as the screen, so it tells its child Container
to also assume the size of the screen, thus ignoring its
constraints parameter.
<topic_end>
<topic_start>
Example 10
<code_start>
Center(
child: ConstrainedBox(
constraints: const BoxConstraints(
minWidth: 70,
minHeight: 70,
maxWidth: 150,
maxHeight: 150,
),
child: Container(color: red, width: 10, height: 10),
),
)
<code_end>
Now, Center allows ConstrainedBox to be any size up to
the screen size. The ConstrainedBox imposes additional
constraints from its constraints parameter onto its child.
The Container must be between 70 and 150 pixels.
It wants to have 10 pixels,
so it ends up having 70 (the minimum).
<topic_end>
<topic_start>
Example 11
<code_start>
Center(
child: ConstrainedBox(
constraints: const BoxConstraints(
minWidth: 70,
minHeight: 70,
maxWidth: 150,
maxHeight: 150,
),
child: Container(color: red, width: 1000, height: 1000),
),
)
<code_end>
Center allows ConstrainedBox to be any size up to the
screen size. The ConstrainedBox imposes additional
constraints from its constraints parameter onto its child.
The Container must be between 70 and 150 pixels.
It wants to have 1000 pixels,
so it ends up having 150 (the maximum).
<topic_end>
<topic_start>
Example 12
<code_start>
Center(
child: ConstrainedBox(
constraints: const BoxConstraints(
minWidth: 70,
minHeight: 70,
maxWidth: 150,
maxHeight: 150,
),
child: Container(color: red, width: 100, height: 100),
),
)
<code_end>
Center allows ConstrainedBox to be any size up to the
screen size. The ConstrainedBox imposes additional
constraints from its constraints parameter onto its child.
The Container must be between 70 and 150 pixels.
It wants to have 100 pixels, and that’s the size it has,
since that’s between 70 and 150.
<topic_end>
<topic_start>
Example 13
<code_start>
UnconstrainedBox(
child: Container(color: red, width: 20, height: 50),
)
<code_end>
The screen forces the UnconstrainedBox to be exactly
the same size as the screen. However, the UnconstrainedBox
lets its child Container be any size it wants.
<topic_end>
<topic_start>
Example 14