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Docs: LCL/controls. Updates topics to specify how Height/ClientHeight and Width/ClientWidth differ from VCL.

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* TControl.ClientHeight
* TControl.ClientWidth
* TControl.Height
* TControl.Width
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dsiders 2024-10-15 17:14:14 +01:00
parent 4937c042e2
commit 49b437e2e5
1 changed files with 82 additions and 17 deletions
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99
docs/xml/lcl/controls.xml
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@ -2634,7 +2634,7 @@ the values for internal members in the class instance.
<var>GetHotSpot</var> is an overridden <var>TPoint</var> function which gets
the <var>HotSpot</var> for the image list resolution. GetHotSpot uses the
value from the <var>DragHotspot</var> property. It contains the screen
coordinates where the Drag and Drop operation was started. X is is the
coordinates where the Drag and Drop operation was started. X is the
horizontal position, and Y is the vertical position in the <var>TPoint</var>
type.
</p>
@ -17886,10 +17886,10 @@ WMLButtonTripleClk, WMLButtonQuadClk, et. al.
<descr>
<p>
<var>ClientHeight</var> is an <var>Integer</var> property with the number of
pixels needed for client area on the control. The property contains the value
from the Bottom member in ClientRect. Changing the value for ClientHeight
causes SetClientSize to be called to apply the existing ClientWidth and the
new value for the property.
pixels needed for the vertical client area on the control. The property
contains the value from the Bottom member in ClientRect. Changing the value for
ClientHeight causes SetClientSize to be called to apply the existing
ClientWidth and the new value for the property.
</p>
<p>
The value for ClientHeight is not stored or used to set the Height for the
@ -17898,10 +17898,29 @@ is restored and when auto-layout policies using Anchors are applied to the
control. For example, when Anchors is set to [akBottom] the value in
ClientHeight is needed / used.
</p>
<remark>
In the LCL, ClientHeight has the same value as Height. Derived classes (like
TCustomForm or TForm) may implement a ClientHeight property that differs from
Height - but in the current LCL version, they do not. This differs from the
behavior in the Delphi VCL where a TForm instance adjusts the value in
ClientHeight to remove pixels used in non-client areas like the title bar,
borders, frames, and scroll bars. LCL uses this approach because there is no
reliable way to determine the sizes for all of the non-client areas on all of
the platforms where LCL is supported. Without a reliable way, the LCL would
needlessly move the forms around on the screen or resize them endlessly. In the
LCL, neither Height nor ClientHeight include the non-client area on a form
instance. The height of a TMainMenu instance is omitted from both values as
well.
</remark>
<p>
Use ClientWidth to access the number of pixels needed for the horizontal client
area on the control.
</p>
</descr>
<seealso>
<link id="TControl.ClientRect"/>
<link id="TControl.ClientWidth"/>
<link id="TControl.Height"/>
<link id="TControl.AutoSizing"/>
<link id="TControl.EnableAutoSizing"/>
<link id="TControl.AutoAdjustLayout"/>
@ -17970,8 +17989,8 @@ for the control.
<descr>
<p>
<var>ClientWidth</var> is an <var>Integer</var> property with the number of
pixels need for the width of the client area on the control. The property
contains the value from the Right member in ClientRect. Changing the value
pixels need for the horizontal client area on the control. The property
contains the value from the Right member in ClientRect. Changing the value
for ClientWidth causes SetClientSize to be called to apply the new property
value and the existing ClientHeight for the control.
</p>
@ -17982,10 +18001,27 @@ is restored and when auto-layout policies using Anchors are applied to the
control. For example, when Anchors is set to [akRight] the value in
ClientWidth is needed / used.
</p>
<remark>
In the LCL, ClientWidth has the same value as Width. Derived classes (like
TCustomForm or TForm) may implement a ClientWidth property that differs from
Width - but in the current LCL version, they do not. This differs from the
behavior in the Delphi VCL where a TForm instance adjusts the value in
ClientWidth to remove pixels used in non-client areas like the borders, frames,
and scroll bars. LCL uses this approach because there is no reliable way to
determine the sizes for all of the non-client areas on all of the platforms
where LCL is supported. Without a reliable way, the LCL would needlessly move
the forms around on the screen or resize them endlessly. In the LCL, neither
Width nor ClientWidth include the non-client area on a form instance.
</remark>
<p>
Use ClientHeight to access the number of pixels needed for the vertical client
area on the control.
</p>
</descr>
<seealso>
<link id="TControl.ClientRect"/>
<link id="TControl.ClientHeight"/>
<link id="TControl.Width"/>
<link id="TControl.AutoSizing"/>
<link id="TControl.EnableAutoSizing"/>
<link id="TControl.AutoAdjustLayout"/>
@ -18825,11 +18861,13 @@ property along with the existing values in Top, Width, and Height.
</element>
<element name="TControl.Height">
<short>The vertical size for the control.</short>
<short>
The vertical size for the control.
</short>
<descr>
<p>
Height is an Integer property with the vertical size for the control in
pixels.
<var>Height</var> is an <var>Integer</var> property with the vertical size for
the control in pixels.
</p>
<p>
Setting a negative value in Height is not allowed, and the property defaults
@ -18839,9 +18877,8 @@ IDE).
</p>
<p>
Setting a new value for the property causes SetBounds and ChangeBounds to be
called. This ensures that the new value is is the range allowed in
Constraints, and that the control is aligned on its Parent using the Anchors
for the control.
called. This ensures that the new value is in the range allowed in Constraints,
and that the control is aligned on its Parent using the Anchors for the control.
</p>
<p>
A value assigned to Height is ignored when AutoSize is set to <b>True</b>;
@ -18853,8 +18890,22 @@ Values in Top, Left, Width, and Height are used to calculate the display area
for the control in GetClientRect. They determine the clipping rectangle used
when the control is drawn on its Parent.
</p>
<remark>
In the LCL, Height has the same value as ClientHeight. Derived classes (like
TCustomForm or TForm) may implement a ClientHeight property that differs from
Height - but in the current LCL version, they do not. This differs from the
behavior in the Delphi VCL where the value in Height includes pixels used in
non-client areas like the title bar, borders, frames, and scroll bars. LCL
uses this approach because there is no reliable way to determine the sizes for
all of the non-client areas on all of the platforms where LCL is supported.
Without a reliable way, the LCL would needlessly move the forms around on the
screen or resize them endlessly. In the LCL, neither Height nor ClientHeight
include the non-client area on a form instance. The height of a TMainMenu
instance is omitted from both values as well.
</remark>
</descr>
<seealso>
<link id="TControl.ClientHeight"/>
<link id="TControl.Left"/>
<link id="TControl.Top"/>
<link id="TControl.Width"/>
@ -18929,7 +18980,9 @@ property along with the existing values in Left, Width, and Height.
</element>
<element name="TControl.Width">
<short>The horizontal size for the control.</short>
<short>
The horizontal size for the control.
</short>
<descr>
<p>
<var>Width</var> is an <var>Integer</var> property with the horizontal size
@ -18942,9 +18995,8 @@ to <b>0</b> (zero). At design-time, setting Width to a value not in the range
</p>
<p>
Setting a new value for the property causes SetBounds and ChangeBounds to be
called. This ensures that the new value is is the range allowed in
Constraints, and that the control is aligned on its Parent using the Anchors
for the control.
called. This ensures that the new value is in the range allowed in Constraints,
and that the control is aligned on its Parent using the Anchors for the control.
</p>
<p>
A value assigned to Width is ignored when AutoSize is set to <b>True</b>; the
@ -18955,8 +19007,21 @@ Values in Top, Left, Width, and Height are used to calculate the display area
for the control in GetClientRect. They determine the clipping rectangle used
when the control is drawn on its Parent.
</p>
<remark>
In the LCL, Width has the same value as ClientWidth. Derived classes (like
TCustomForm or TForm) may implement a ClientWidth property that differs from
Width - but in the current LCL version, they do not. This differs from the
behavior in the Delphi VCL where the value in Width includes pixels used in
non-client areas like the borders, frames, and scroll bars. LCL uses this
approach because there is no reliable way to determine the sizes for all of the
non-client areas on all of the platforms where LCL is supported. Without a
reliable way, the LCL would needlessly move the forms around on the screen or
resize them endlessly. In the LCL, neither Width nor ClientWidth include the
non-client area on a form instance.
</remark>
</descr>
<seealso>
<link id="TControl.ClientWidth"/>
<link id="TControl.Height"/>
<link id="TControl.Left"/>
<link id="TControl.Top"/>