Table of Contents

Class Canvas

Namespace
GHIElectronics.Endpoint.UI.Controls
Assembly
GHIElectronics.Endpoint.UI.dll
public class Canvas : Panel
Inheritance
Canvas
Derived
Inherited Members

Constructors

Canvas() 

public Canvas()

Methods

ArrangeOverride(int, int)

ArrangeOverride allows for the customization of the final sizing and positioning of children.

protected override void ArrangeOverride(int arrangeWidth, int arrangeHeight)

Parameters

arrangeWidth int

Final width

arrangeHeight int

Final height

Remarks

UIElement authors should override this method, call Arrange on each visible child UIElement, to size and position each child UIElement by passing a rectangle reserved for the child within parent space. Note: It is required that a parent UIElement calls Arrange on each child or they won't be rendered. Typical override follows a pattern roughly like this (pseudo-code): 

protected override void ArrangeOverride(int arrangeWidth, int arrangeHeight)
{

         foreach (UIElement child in VisualChildren)
         {
             child.Arrange(new Rect(childX, childY, childWidth, childHeight);
         }
     }</code></pre></example>

GetBottom(UIElement) 

public static int GetBottom(UIElement e)

Parameters

e UIElement

Returns

int

GetLeft(UIElement) 

public static int GetLeft(UIElement e)

Parameters

e UIElement

Returns

int

GetRight(UIElement) 

public static int GetRight(UIElement e)

Parameters

e UIElement

Returns

int

GetTop(UIElement) 

public static int GetTop(UIElement e)

Parameters

e UIElement

Returns

int

MeasureOverride(int, int, out int, out int)

Measurement override. Implement your size-to-content logic here.

protected override void MeasureOverride(int availableWidth, int availableHeight, out int desiredWidth, out int desiredHeight)

Parameters

availableWidth int

Available size that parent can give to the child. May be MaxValue(when parent wants to measure to content). This is soft constraint. Child can return bigger size to indicate that it wants bigger space and hope that parent can throw in scrolling...

availableHeight int
desiredWidth int
desiredHeight int

Remarks

MeasureOverride is designed to be the main customizability point for size control of layout. UIElement authors should override this method, call Measure on each child UIElement, and compute their desired size based upon the measurement of the children. The return value should be the desired size.

Note: It is required that a parent UIElement calls Measure on each child or they won't be sized/arranged. Typical override follows a pattern roughly like this (pseudo-code): 
protected override void MeasureOverride(int avialableWidth, int availableHeight, out int desiredWidth, out int desiredHeight)
{
foreach (UIElement child in VisualChildren)
{
child.Measure(availableSize);
availableSize.Deflate(child.DesiredSize);
_cache.StoreInfoAboutChild(child);
}

         Size desired = CalculateBasedOnCache(_cache);
         return desired;
     }</code></pre></example>



The key aspects of this snippet are:

  • You must call Measure on each child UIElement
  • It is common to cache measurement information between the MeasureOverride and ArrangeOverride method calls
  • Calling base.MeasureOverride is not required.
  • Calls to Measure on children are passing either the same availableSize as the parent, or a subset of the area depending
on the type of layout the parent will perform (for example, it would be valid to remove the area
for some border or padding).

SetBottom(UIElement, int) 

public static void SetBottom(UIElement e, int bottom)

Parameters

e UIElement
bottom int

SetLeft(UIElement, int) 

public static void SetLeft(UIElement e, int left)

Parameters

e UIElement
left int

SetRight(UIElement, int) 

public static void SetRight(UIElement e, int right)

Parameters

e UIElement
right int

SetTop(UIElement, int) 

public static void SetTop(UIElement e, int top)

Parameters

e UIElement
top int
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