ScaleTransform Class

Use a ScaleTransform to stretch or shrink an object horizontally or vertically. The ScaleX property specifies by how much to stretch or shrink an object along the x-axis, and the ScaleY property specifies by how much to stretch or shrink an object along the y-axis. Scale operations are centered on the point specified by the CenterX and CenterY properties.

Freezable Features: Because it inherits from the Freezable class, the ScaleTransform class provides several special features: ScaleTransform objects can be declared as resources, shared among multiple objects, made read-only to improve performance, cloned, and made thread-safe. For more information about the different features provided by Freezable objects, see Freezable Objects Overview.

This example shows how to use a ScaleTransform to scale an element.

Use the ScaleX and ScaleY properties to resize the element by the factor you specify. For example, a ScaleX value of 1.5 stretches the element to 150 percent of its original width. A ScaleY value of 0.5 shrinks the height of an element by 50 percent.

Use the CenterX and CenterY properties to specify the point that is the center of the scale operation. By default, a ScaleTransform is centered at the point (0,0), which corresponds to the upper-left corner of the rectangle. This has the effect of moving the element and also of making it appear larger, because when you apply a Transform, you change the coordinate space in which the object resides.

The following example uses a ScaleTransform to double the size of a 50-by-50 Rectangle. The ScaleTransform has a value of 0 (the default) for both CenterX and CenterY.

<!-- Scales a rectangle by 200% from a center of (0,0).-->
<Rectangle Height="50" Width="50" Fill="#CCCCCCFF" 
  Stroke="Blue" StrokeThickness="2"
  Canvas.Left="100" Canvas.Top="100">
  <Rectangle.RenderTransform>
    <ScaleTransform CenterX="0" CenterY="0" ScaleX="2" ScaleY="2" />
  </Rectangle.RenderTransform>
</Rectangle>

Typically, you set CenterX and CenterY to the center of the object that is scaled: (Width/2, Height/2).

The following example shows another Rectangle that is doubled in size; however, this ScaleTransform has a value of 25 for both CenterX and CenterY, which corresponds to the center of the rectangle.

<!-- Scales a rectangle by 200% from a center of (25,25).-->
<Rectangle Height="50" Width="50" Fill="#CCCCCCFF"
  Canvas.Left="100" Canvas.Top="100" Stroke="Blue" StrokeThickness="2">
  <Rectangle.RenderTransform>
    <ScaleTransform CenterX="25" CenterY="25" ScaleX="2" ScaleY="2" />
  </Rectangle.RenderTransform>
</Rectangle>

The following illustration shows the difference between the two ScaleTransform operations. The dotted line shows the size and position of the rectangle before scaling.

For the complete sample, see 2-D Transforms Sample.

More Code

.NET Framework

.NET Framework Client Profile

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

Reference

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