This class implements the variation where we draw more of the page at low resolution while panning. More...

Inheritance diagram for org.mozilla.gecko.gfx.DisplayPortCalculator.DynamicResolutionStrategy:

Collaboration diagram for org.mozilla.gecko.gfx.DisplayPortCalculator.DynamicResolutionStrategy:

Public Member Functions
DisplayPortMetrics	calculate (ImmutableViewportMetrics metrics, PointF velocity)
	Calculates a displayport given a viewport and panning velocity. More...

boolean	aboutToCheckerboard (ImmutableViewportMetrics metrics, PointF velocity, DisplayPortMetrics displayPort)
	Returns true if a checkerboard is about to be visible and we should not throttle drawing. More...

String	toString ()

Public Member Functions inherited from org.mozilla.gecko.gfx.DisplayPortCalculator.DisplayPortStrategy
abstract DisplayPortMetrics	calculate (ImmutableViewportMetrics metrics, PointF velocity)
	Calculates a displayport given a viewport and panning velocity. More...

abstract boolean	aboutToCheckerboard (ImmutableViewportMetrics metrics, PointF velocity, DisplayPortMetrics displayPort)
	Returns true if a checkerboard is about to be visible and we should not throttle drawing. More...

boolean	drawTimeUpdate (long millis, int pixels)
	Notify the strategy of a new recorded draw time. More...

void	resetPageState ()
	Reset any page-specific state stored, as the page being displayed has changed. More...

Private Member Functions
float	splitBufferByVelocity (float amount, float velocity)
	Split the given buffer amount into two based on the velocity. More...

Private Attributes
final float	VELOCITY_EXPANSION_THRESHOLD

final float	VELOCITY_FAST_THRESHOLD

Static Private Attributes
static final float	SIZE_MULTIPLIER = 1.5f

static final float	VELOCITY_MULTIPLIER = 60.0f

static final float	FAST_SPLIT_FACTOR = 0.95f

static final float	SLOW_SPLIT_FACTOR = 0.8f

static final float	PREDICTION_VELOCITY_MULTIPLIER = 30.0f

static final float	DANGER_ZONE_MULTIPLIER = 0.20f

Detailed Description

This class implements the variation where we draw more of the page at low resolution while panning.

In this variation, as we pan faster, we increase the page area we are drawing, but reduce the draw resolution to compensate. This results in the same device-pixel area drawn; the compositor then scales this up to the viewport zoom level. This results in a large area of the page drawn but it looks blurry. The assumption is that drawing extra that we never display is better than checkerboarding, where we draw less but never even show it on the screen.

Definition at line 455 of file DisplayPortCalculator.java.

Member Function Documentation

◆ aboutToCheckerboard()

boolean org.mozilla.gecko.gfx.DisplayPortCalculator.DynamicResolutionStrategy.aboutToCheckerboard	(	ImmutableViewportMetrics	metrics,
		PointF	velocity,
		DisplayPortMetrics	displayPort
	)

inline

Returns true if a checkerboard is about to be visible and we should not throttle drawing.

Reimplemented from org.mozilla.gecko.gfx.DisplayPortCalculator.DisplayPortStrategy.

Definition at line 613 of file DisplayPortCalculator.java.

References org.mozilla.gecko.gfx.DisplayPortMetrics.contains(), org.mozilla.gecko.gfx.DisplayPortCalculator.DynamicResolutionStrategy.DANGER_ZONE_MULTIPLIER, org.mozilla.gecko.gfx.ImmutableViewportMetrics.getViewport(), and org.mozilla.gecko.gfx.DisplayPortCalculator.DynamicResolutionStrategy.PREDICTION_VELOCITY_MULTIPLIER.

◆ calculate()

DisplayPortMetrics org.mozilla.gecko.gfx.DisplayPortCalculator.DynamicResolutionStrategy.calculate	(	ImmutableViewportMetrics	metrics,
		PointF	velocity
	)

inline

Calculates a displayport given a viewport and panning velocity.

Reimplemented from org.mozilla.gecko.gfx.DisplayPortCalculator.DisplayPortStrategy.

Definition at line 515 of file DisplayPortCalculator.java.

◆ splitBufferByVelocity()

float org.mozilla.gecko.gfx.DisplayPortCalculator.DynamicResolutionStrategy.splitBufferByVelocity	(	float	amount,
		float	velocity
	)

inlineprivate

Split the given buffer amount into two based on the velocity.

Given an amount of total usable buffer on an axis, this will return the amount that should be used on the left/top side of the axis (the side which a negative velocity vector corresponds to).

Definition at line 592 of file DisplayPortCalculator.java.

References org.mozilla.gecko.gfx.DisplayPortCalculator.DynamicResolutionStrategy.FAST_SPLIT_FACTOR, org.mozilla.gecko.util.FloatUtils.fuzzyEquals(), org.mozilla.gecko.gfx.DisplayPortCalculator.DynamicResolutionStrategy.SLOW_SPLIT_FACTOR, and org.mozilla.gecko.gfx.DisplayPortCalculator.DynamicResolutionStrategy.VELOCITY_FAST_THRESHOLD.

Referenced by org.mozilla.gecko.gfx.DisplayPortCalculator.DynamicResolutionStrategy.calculate().