How Do I Constrain the Maximum Extent Of an Image?

Hello Daniel,

thanks again. I will have a closer look at constraints.

Mane

Hello Daniel,

I had a closer look at IViewportConstraint. What I miss is a possibility to limit the viewport to specific bounds on a bitmap, not only on a smaller or taller band around th pic what VisibilityConstraint does.

This has the advantage to slide the bounds of a viewport afterwards and you can also use one bitmap source for more implementations with different viewport extents.

This would advance the Constaintsettings. I imagine this like following lines:

//bitmap extents: e.g. 2000x1000

var rect:Rectangle = new Rectangle(100, 100, 200, 200);

var boundConstraint:BoundConstraint = new BoundConstraint()
boundConstraint.bounds = rect;

//with this constraint the viewport is limited to 100x100 px.

mapper always want to set boundaries :-)

Cheers,
Mane

Hi,

I just implemented my own BoundConstraint. It is working if your Viewport Rect is inside of the Bound Rect, but I think this is how it schould work, because bounds have no sense if viewport is bigger than the bounds.

This is my BoundConstraint:


package org.openzoom.flash.viewport.constraints
{

import flash.geom.Rectangle;
import org.openzoom.flash.core.openzoom_internal;
import org.openzoom.flash.viewport.IViewportConstraint;
import org.openzoom.flash.viewport.IViewportTransform;

use namespace openzoom_internal;

/**
* Makes Bound to the IViewport
*/
public final class BoundConstraint implements IViewportConstraint
{
include "../../core/Version.as"

//--------------------------------------------------------------------------
//
// Class constants
//
//--------------------------------------------------------------------------

private static const DEFAULT_BOUNDS:Rectangle = new Rectangle(0, 0, 1, 1)

//--------------------------------------------------------------------------
//
// Constructor
//
//--------------------------------------------------------------------------

/**
* Constructor.
*/
public function BoundConstraint()
{
}

//----------------------------------
// Bounds
//----------------------------------

private var _bounds:Rectangle = DEFAULT_BOUNDS

/**
* Maximum bounds the Viewport can reach.
*/

public function get bounds():Rectangle
{
return _bounds
}

public function set bounds(value:Rectangle):void
{
_bounds = value
}

//--------------------------------------------------------------------------
//
// Methods: IViewportConstraint
//
//--------------------------------------------------------------------------

/**
* @inheritDoc
*/
public function validate(transform:IViewportTransform,
target:IViewportTransform):IViewportTransform
{

var viewportBounds:Rectangle = transform.getBounds()

var x:Number = viewportBounds.x // 0 //transform.x
var y:Number = viewportBounds.y //transform.y

//outside of bound

if (!bounds.containsRect(viewportBounds)) {

if (viewportBounds.left < bounds.left) {
// left bound
x = bounds.left
}

if (viewportBounds.top < bounds.top) {
// top bound
y = bounds.top
}

if (viewportBounds.right > bounds.right) {
// right bound
x = bounds.right - viewportBounds.width
}

if (viewportBounds.bottom > bounds.bottom) {
// bottom bound
y = bounds.bottom - viewportBounds.height
}
}

//inside of bounds
//if (bounds.containsRect(viewportBounds)) {
//trace("innen");
//
//x = viewportBounds.x
//y = viewportBounds.y
//}

// validate bounds
transform.panTo(x, y)

return transform
}
}
}



You have only to intit the bounds in the CompositeConstraint:


var constraint:CompositeConstraint = new CompositeConstraint();
var boundConstraint:BoundConstraint = new BoundConstraint();
bounds = new Rectangle(0.5312538146972657, 0.3466752370198569, 0.0026041666666666665, 0.001953125);
boundConstraint.bounds = bounds;

constraint.constraints = [zoomConstraint, scaleConstraint, centerConstraint, boundConstraint];



Cheers,
Mane