Class HudTransformPlacement

Turns a preview scale, deform or rotate gesture into a new element transform.

Inheritance

object

HudTransformPlacement

Inherited Members

object.ToString()

object.Equals(object)

object.Equals(object, object)

object.ReferenceEquals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

Namespace: Serenity.GameUi.Application.Placement

Assembly: Serenity.GameUi.Application.dll

Syntax

public static class HudTransformPlacement

Remarks

Pure and engine-free, mirroring HudDragPlacement: every gesture is worked out in the element's displayed space and mirrored in and out only at the boundary, so the maths itself never has an opinion about which side of the screen a player is on.

Methods

AngleDeltaDegrees(float, float, float, float)

How far the pointer swept around the fixed point, in counter-clockwise degrees.

Declaration

public static float AngleDeltaDegrees(float startX, float startY, float currentX, float currentY)

Parameters

Type	Name	Description
float	startX	Horizontal component of the vector at gesture start.
float	startY	Vertical component of the vector at gesture start.
float	currentX	Horizontal component of the vector this frame.
float	currentY	Vertical component of the vector this frame.

Returns

Type	Description
float	The angle swept, in degrees; zero when either vector is too short to give a direction.

Remarks

Screen space runs +Y down, so the raw angle difference between the two vectors reads backwards against the canvas's own counter-clockwise convention; negating it is the one sign flip the whole rotate gesture needs.

AxisRatio(float, float, float, float, float, float)

How much bigger the pointer's motion along one axis has become, as a multiple of where it started.

Declaration

public static float AxisRatio(float startX, float startY, float currentX, float currentY, float axisX, float axisY)

Parameters

Type	Name	Description
float	startX	Horizontal component of the vector at gesture start.
float	startY	Vertical component of the vector at gesture start.
float	currentX	Horizontal component of the vector this frame.
float	currentY	Vertical component of the vector this frame.
float	axisX	Horizontal component of the axis to project onto.
float	axisY	Vertical component of the axis to project onto.

Returns

Type	Description
float	The axis ratio; 1 when the start projection is too small to give a direction.

Remarks

Unlike ScaleRatio(float, float, float, float), this projects onto an arbitrary axis rather than the start vector itself, so a deform gesture can grow one of the element's own local axes while ignoring motion along the other entirely. The guard checks the SIGNED projection's magnitude rather than a squared length, since the axis is not required to be normalized and a squared comparison would scale quadratically with however long the caller's axis vector happens to be.

CompensatedOffset(HudOffset, HudElementBasis, HudElementBasis, float, float)

The offset that keeps a fixed point in place while the element's scale, stretch and rotation change around its anchor.

Declaration

public static HudOffset CompensatedOffset(HudOffset displayedOffset, HudElementBasis before, HudElementBasis after, float fixedPointX, float fixedPointY)

Parameters

Type	Name	Description
HudOffset	displayedOffset	The offset before this gesture, in displayed space.
HudElementBasis	before	The element's basis before this gesture.
HudElementBasis	after	The element's basis after this gesture.
float	fixedPointX	Horizontal position of the point to hold still, in container-local units.
float	fixedPointY	Vertical position of the point to hold still, in container-local units.

Returns

Type	Description
HudOffset	The compensated offset, in displayed space.

Remarks

offset' = offset + before.Transform(f) − after.Transform(f) — exact for any affine map, since the fixed point's position relative to the anchor moved by the old basis and will move by the new one, so undoing the old displacement and applying the new one to the offset is what holds the point still on screen.

Deform(IHudPlacedElement, HudTransformGesture, HudDeformGesture)

Applies a deform gesture to an element, stretching it along one or both of its own local axes and compensating its offset around the fixed point.

Declaration

public static HudElementTransform Deform(IHudPlacedElement element, HudTransformGesture gesture, HudDeformGesture deform)

Parameters

Type	Name	Description
IHudPlacedElement	element	The element being deformed.
HudTransformGesture	gesture	The gesture to apply.
HudDeformGesture	deform	Which axes this gesture changes, and their screen-space directions.

Returns

Type	Description
HudElementTransform	The new scale, stretch, rotation and offset.

Remarks

Only StretchX/StretchY change; scale and rotation are echoed back unchanged. Mirrors in and out exactly like Resize(IHudPlacedElement, HudTransformGesture) and Rotate(IHudPlacedElement, HudTransformGesture) — the offset and rotation cross the mirror boundary, but the stretch itself never needs to: mirroring is a horizontal flip of an axis-aligned quantity, and F·R(θ)·S·F equals R(−θ)·S for any stretch, so a mirrored element deforms by the same amount an unmirrored one would for the same drag.

NormalizeDegrees(float)

Folds an angle into the half-open range (-180, 180] degrees.

Declaration

public static float NormalizeDegrees(float degrees)

Parameters

Type	Name	Description
float	degrees	The angle to fold.

Returns

Type	Description
float	The equivalent angle within (-180, 180].

Resize(IHudPlacedElement, HudTransformGesture)

Applies a uniform scale gesture to an element, compensating its offset around the fixed point.

Declaration

public static HudElementTransform Resize(IHudPlacedElement element, HudTransformGesture gesture)

Parameters

Type	Name	Description
IHudPlacedElement	element	The element being scaled.
HudTransformGesture	gesture	The gesture to apply.

Returns

Type	Description
HudElementTransform	The new scale, stretch, rotation and offset.

Remarks

Only Scale changes; the gesture's own stretch is echoed back unchanged.

Rotate(IHudPlacedElement, HudTransformGesture)

Applies a rotate gesture to an element, compensating its offset around the fixed point.

Declaration

public static HudElementTransform Rotate(IHudPlacedElement element, HudTransformGesture gesture)

Parameters

Type	Name	Description
IHudPlacedElement	element	The element being rotated.
HudTransformGesture	gesture	The gesture to apply.

Returns

Type	Description
HudElementTransform	The new scale, stretch, rotation and offset.

Remarks

Only RotationDegrees changes; scale and stretch are echoed back unchanged.

ScaleRatio(float, float, float, float)

How much bigger the pointer's distance from the fixed point has become, as a multiple of where it started.

Declaration

public static float ScaleRatio(float startX, float startY, float currentX, float currentY)

Parameters

Type	Name	Description
float	startX	Horizontal component of the vector at gesture start.
float	startY	Vertical component of the vector at gesture start.
float	currentX	Horizontal component of the vector this frame.
float	currentY	Vertical component of the vector this frame.

Returns

Type	Description
float	The scale ratio; 1 when the start vector is too short to give a direction.

Remarks

The projection of the current vector onto the start vector, rather than a plain length ratio: a length ratio would report the same growth whichever direction the pointer moved, so dragging perpendicular to the starting handle would still "scale" the element. The projection collapses perpendicular motion towards zero instead, which is also why it needs no square root or trig — it is exact and cheap in both axes at once.

Snap(float, float)

Rounds a value to the nearest multiple of a step.

Declaration

public static float Snap(float value, float step)

Parameters

Type	Name	Description
float	value	The value to round.
float	step	The grid step. Zero or less leaves the value untouched.

Returns

Type	Description
float	The snapped value.