David Alm: Automated Syncronization with Documentation

2012-10-18T17:19:06Z

Automated Syncronization with Documentation

New page

This is a Beta Read Only version of this page.
Please review and send recommendations to [mailto:mitov@mitov.com mitov@mitov.com].
We will enable the editing as soon as we are happy with the overall Wiki site.


'''Class:''' [[Interface IGDIPlus.IGPGraphics|IGPGraphics]]

== Syntax ==
=== Delphi: ===
<code>
'''function''' Save() : TGPGraphicsState;
</code>

=== C++ Builder: ===
<code>
TGPGraphicsState '''__fastcall''' Save();
</code>

=== Visual C++ (MFC): ===
<code>
Save();
</code>

== Summary ==
Saves the current state (transformations, clipping region, and quality settings) of this [[Class IGDIPlus.TGPGraphics|TGPGraphics]] object.

== Description ==
Call this method to save the current state (transformations,
clipping region, and quality settings) of this [[Class IGDIPlus.TGPGraphics|TGPGraphics]]
object. You can restore the state later by calling the
[[Class IGDIPlus.TGPGraphics|TGPGraphics]].[[Method function IGDIPlus.IGPGraphics.Restore(TGPGraphicsState) : TGPGraphics|Restore]] method.

Examples:

The following examples show two ways to use the Save method.
The first example shows how to restore nested saved states,
and the second example shows how to restore only the first of
two nested saved states.

Restoring Nested Saved States

The following example sets the world transformation of a
Graphics object to a rotation and then saves the state of the
Graphics object. Next, the code calls [[Method function IGDIPlus.IGPGraphics.TranslateTransform(Single;Single;TGPMatrixOrder) : TGPGraphics|TranslateTransform]], and
saves the state again. Then the code calls [[Method function IGDIPlus.IGPGraphics.ScaleTransform(Single;Single;TGPMatrixOrder) : TGPGraphics|ScaleTransform]]. At
that point, the world transformation of the Graphics object
is a composite transformation: first rotate, then translate,
then scale. The code uses a red pen to draw an ellipse that
is transformed by that composite transformation.

The code passes state2, which was returned by the second call
to Save, to the [[Method function IGDIPlus.IGPGraphics.Restore(TGPGraphicsState) : TGPGraphics|Restore]] method, and draws the ellipse again
using a green pen. The green ellipse is rotated and
translated but not scaled. Finally the code passes state1,
which was returned by the first call to Save, to the [[Method function IGDIPlus.IGPGraphics.Restore(TGPGraphicsState) : TGPGraphics|Restore]]
method, and draws the ellipse again using a blue pen. The
blue ellipse is rotated but not translated or scaled.

<code>
var
AGraphics : [[Interface IGDIPlus.IGPGraphics|IGPGraphics]];
AState1, AState2 : IGPGraphicsState;

begin
AGraphics := [[Class IGDIPlus.TGPGraphics|TGPGraphics]].Create( ACanvas );

</code>
<code lang="delphi">
AGraphics.[[Method function IGDIPlus.IGPGraphics.RotateTransform(Single;TGPMatrixOrder) : TGPGraphics|RotateTransform]](30.0);
AState1 = graphics.Save();
AGraphics.[[Method function IGDIPlus.IGPGraphics.TranslateTransform(Single;Single;TGPMatrixOrder) : TGPGraphics|TranslateTransform]](100.0, 0.0, [[Enum item IGDIPlus.TGPMatrixOrder.MatrixOrderAppend|MatrixOrderAppend]]);
AState2 = graphics.Save();
AGraphics.[[Method function IGDIPlus.IGPGraphics.ScaleTransform(Single;Single;TGPMatrixOrder) : TGPGraphics|ScaleTransform]](1.0, 3.0, [[Enum item IGDIPlus.TGPMatrixOrder.MatrixOrderAppend|MatrixOrderAppend]]);

// Draw an ellipse.
// Three transformations apply: rotate, then translate, then scale.
AGraphics.[[Method function IGDIPlus.IGPGraphics.DrawEllipse(IGPPen;TGPRect) : TGPGraphics|DrawEllipse]]([[Class IGDIPlus.TGPPen|TGPPen]].Create( aclRed ), 0, 0, 100, 20);

// [[Method function IGDIPlus.IGPGraphics.Restore(TGPGraphicsState) : TGPGraphics|Restore]] to AState2 and draw the ellipse again.
// Two transformations apply: rotate then translate.
AGraphics.[[Method function IGDIPlus.IGPGraphics.Restore(TGPGraphicsState) : TGPGraphics|Restore]](AState2);
AGraphics.[[Method function IGDIPlus.IGPGraphics.DrawEllipse(IGPPen;TGPRect) : TGPGraphics|DrawEllipse]]([[Class IGDIPlus.TGPPen|TGPPen]].Create( aclGreen ), 0, 0, 100, 20);

// [[Method function IGDIPlus.IGPGraphics.Restore(TGPGraphicsState) : TGPGraphics|Restore]] to AState1 and draw the ellipse again.
// Only the rotation transformation applies.
AGraphics.[[Method function IGDIPlus.IGPGraphics.Restore(TGPGraphicsState) : TGPGraphics|Restore]](AState1);
AGraphics.[[Method function IGDIPlus.IGPGraphics.DrawEllipse(IGPPen;TGPRect) : TGPGraphics|DrawEllipse]]( [[Class IGDIPlus.TGPPen|TGPPen]].Create( aclBlue ), 0, 0, 100, 20);
end;
</code>

Restoring Only the First of Two Nested Saved States

The following example sets the world transformation of a
Graphics object to a rotation and then saves the state of the
Graphics object. Next, the code calls [[Method function IGDIPlus.IGPGraphics.TranslateTransform(Single;Single;TGPMatrixOrder) : TGPGraphics|TranslateTransform]], and
saves the state again. Then the code calls [[Method function IGDIPlus.IGPGraphics.ScaleTransform(Single;Single;TGPMatrixOrder) : TGPGraphics|ScaleTransform]]. At
that point, the world transformation of the Graphics object
is a composite transformation: first rotate, then translate,
then scale. The code uses a red pen to draw an ellipse that
is transformed by that composite transformation.

The code passes state1, which was returned by the first call
to Save, to the [[Method function IGDIPlus.IGPGraphics.Restore(TGPGraphicsState) : TGPGraphics|Restore]] method, and draws the ellipse again
using a green pen. The green ellipse is rotated but not
translated or scaled.

Next the code attempts to restore the state identified by
state2. The attempt fails because the call [[Method function IGDIPlus.IGPGraphics.Restore(TGPGraphicsState) : TGPGraphics|Restore]](state1)
removed the information blocks identified by both state1 and
state2 from the stack.

<code>
var
AGraphics : [[Interface IGDIPlus.IGPGraphics|IGPGraphics]];
AState1, AState2 : IGPGraphicsState;

begin
AGraphics := [[Class IGDIPlus.TGPGraphics|TGPGraphics]].Create( ACanvas );

AGraphics.[[Method function IGDIPlus.IGPGraphics.RotateTransform(Single;TGPMatrixOrder) : TGPGraphics|RotateTransform]](30.0);
AState1 = graphics.Save();
AGraphics.[[Method function IGDIPlus.IGPGraphics.TranslateTransform(Single;Single;TGPMatrixOrder) : TGPGraphics|TranslateTransform]](100.0, 0.0, [[Enum item IGDIPlus.TGPMatrixOrder.MatrixOrderAppend|MatrixOrderAppend]]);
AState2 = graphics.Save();
AGraphics.[[Method function IGDIPlus.IGPGraphics.ScaleTransform(Single;Single;TGPMatrixOrder) : TGPGraphics|ScaleTransform]](1.0, 3.0, [[Enum item IGDIPlus.TGPMatrixOrder.MatrixOrderAppend|MatrixOrderAppend]]);

</code>
<code lang="delphi">
// Draw an ellipse.
// Three transformations apply: rotate, then translate, then scale.
</code>

<code>
AGraphics.[[Method function IGDIPlus.IGPGraphics.DrawEllipse(IGPPen;TGPRect) : TGPGraphics|DrawEllipse]]([[Class IGDIPlus.TGPPen|TGPPen]].Create( aclRed ), 0, 0, 100, 20 );

</code>
<code lang="delphi">
// [[Method function IGDIPlus.IGPGraphics.Restore(TGPGraphicsState) : TGPGraphics|Restore]] to AState1 and draw the ellipse again.
// Only the rotation transformation applies.
AGraphics.[[Method function IGDIPlus.IGPGraphics.Restore(TGPGraphicsState) : TGPGraphics|Restore]](AState1);
</code>

<code>
AGraphics.[[Method function IGDIPlus.IGPGraphics.DrawEllipse(IGPPen;TGPRect) : TGPGraphics|DrawEllipse]]([[Class IGDIPlus.TGPPen|TGPPen]].Create( aclGreen ), 0, 0, 100, 20 );

</code>
<code lang="delphi">
// The information block identified by AState2 has been lost.
// The following call to [[Method function IGDIPlus.IGPGraphics.Restore(TGPGraphicsState) : TGPGraphics|Restore]] has no effect because
// [[Method function IGDIPlus.IGPGraphics.Restore(TGPGraphicsState) : TGPGraphics|Restore]](AState1) removed from the stack the
// information blocks identified by AState1 and AState2.
AGraphics.[[Method function IGDIPlus.IGPGraphics.Restore(TGPGraphicsState) : TGPGraphics|Restore]](AState2);

// The Graphics object is still in the state identified by state1.
// The following code draws a blue ellipse on top of the previously
// drawn green ellipse.
</code>

<code>
AGraphics.[[Method function IGDIPlus.IGPGraphics.DrawEllipse(IGPPen;TGPRect) : TGPGraphics|DrawEllipse]]([[Class IGDIPlus.TGPPen|TGPPen]].Create( aclBlue ), 0, 0, 100, 20 );
</code>
Note
When you call the Save method of a Graphics object, an
information block that holds the state of the Graphics object
is put on a stack. The Save method returns a value that
identifies that information block. When you pass the
identifying value to the Graphics::[[Method function IGDIPlus.IGPGraphics.Restore(TGPGraphicsState) : TGPGraphics|Restore]] method, the
information block is removed from the stack and is used to
restore the Graphics object to the state it was in at the
time of the Save call. Note that the identifier returned by a
given call to the Save method can be passed only once to the
Graphics::[[Method function IGDIPlus.IGPGraphics.Restore(TGPGraphicsState) : TGPGraphics|Restore]] method.

Calls to the Save method can be nested; that is, you can call
the Save method several times before you call the [[Method function IGDIPlus.IGPGraphics.Restore(TGPGraphicsState) : TGPGraphics|Restore]]
method. Each time you call the Save method, an information
block is put on the stack, and you receive an identifier for
the information block. When you pass one of those identifiers
to the [[Method function IGDIPlus.IGPGraphics.Restore(TGPGraphicsState) : TGPGraphics|Restore]] method, the Graphics object is returned to the
state it was in at the time of the Save call that returned
that particular identifier. The information block placed on
the stack by that Save call is removed from the stack, and
all information blocks placed on that stack after that Save
call are also removed.

Calls to the [[Method function IGDIPlus.IGPGraphics.BeginContainer(TGPRect;TGPRect;TGPUnit) : TGPGraphicsContainer|BeginContainer]] method place information blocks
on the same stack as calls to the Save method. Just as a
Graphics::[[Method function IGDIPlus.IGPGraphics.Restore(TGPGraphicsState) : TGPGraphics|Restore]] call is paired with a Save call, an
[[Method function IGDIPlus.IGPGraphics.EndContainer(TGPGraphicsContainer) : TGPGraphics|EndContainer]] call is paired with a [[Method function IGDIPlus.IGPGraphics.BeginContainer(TGPRect;TGPRect;TGPUnit) : TGPGraphicsContainer|BeginContainer]] call.

Note When you call [[Method function IGDIPlus.IGPGraphics.Restore(TGPGraphicsState) : TGPGraphics|Restore]], all information blocks placed on
the stack (by Save or by [[Method function IGDIPlus.IGPGraphics.BeginContainer(TGPRect;TGPRect;TGPUnit) : TGPGraphicsContainer|BeginContainer]]) after the
corresponding call to Save are removed from the stack.
Likewise, When you call [[Method function IGDIPlus.IGPGraphics.EndContainer(TGPGraphicsContainer) : TGPGraphics|EndContainer]], all information blocks
placed on the stack (by Save or by [[Method function IGDIPlus.IGPGraphics.BeginContainer(TGPRect;TGPRect;TGPUnit) : TGPGraphicsContainer|BeginContainer]]) after the
corresponding call to [[Method function IGDIPlus.IGPGraphics.BeginContainer(TGPRect;TGPRect;TGPUnit) : TGPGraphicsContainer|BeginContainer]] are removed from the
stack.

Method function IGDIPlus.IGPGraphics.Save() : TGPGraphicsState - Revision history

David Alm: Automated Syncronization with Documentation