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Refactor backBuffer tile code out of generic Tile base class into Tile.Image to make it nicer when subclassing Tile for other needs. (Closes #1645) r=elemoine.

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git-svn-id: http://svn.openlayers.org/trunk/openlayers@7667 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf
This commit is contained in:
Paul Spencer
2008-08-01 18:25:28 +00:00
parent e7ebdc8aa0
commit 7f38f22d8f
2 changed files with 121 additions and 132 deletions
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132
lib/OpenLayers/Tile.js
View File

@@ -79,38 +79,6 @@ OpenLayers.Tile = OpenLayers.Class({
* {Boolean} Is the tile loading?
*/
isLoading: false,
/**
* Property: isBackBuffer
* {Boolean} Is this tile a back buffer tile?
*/
isBackBuffer: false,
/**
* Property: lastRatio
* {Float} Used in transition code only. This is the previous ratio
* of the back buffer tile resolution to the map resolution. Compared
* with the current ratio to determine if zooming occurred.
*/
lastRatio: 1,
/**
* Property: isFirstDraw
* {Boolean} Is this the first time the tile is being drawn?
* This is used to force resetBackBuffer to synchronize
* the backBufferTile with the foreground tile the first time
* the foreground tile loads so that if the user zooms
* before the layer has fully loaded, the backBufferTile for
* tiles that have been loaded can be used.
*/
isFirstDraw: true,
/**
* Property: backBufferTile
* {<OpenLayers.Tile>} A clone of the tile used to create transition
* effects when the tile is moved or changes resolution.
*/
backBufferTile: null,
/** TBD 3.0 -- remove 'url' from the list of parameters to the constructor.
* there is no need for the base tile class to have a url.
@@ -157,13 +125,6 @@ OpenLayers.Tile = OpenLayers.Class({
* Nullify references to prevent circular references and memory leaks.
*/
destroy:function() {
if (OpenLayers.Util.indexOf(this.layer.SUPPORTED_TRANSITIONS,
this.layer.transitionEffect) != -1) {
this.layer.events.unregister("loadend", this, this.resetBackBuffer);
this.events.unregister('loadend', this, this.resetBackBuffer);
} else {
this.events.unregister('loadend', this, this.showTile);
}
this.layer = null;
this.bounds = null;
this.size = null;
@@ -171,12 +132,6 @@ OpenLayers.Tile = OpenLayers.Class({
this.events.destroy();
this.events = null;
/* clean up the backBufferTile if it exists */
if (this.backBufferTile) {
this.backBufferTile.destroy();
this.backBufferTile = null;
}
},
/**
@@ -221,50 +176,12 @@ OpenLayers.Tile = OpenLayers.Class({
// The only case where we *wouldn't* want to draw the tile is if the
// tile is outside its layer's maxExtent.
var drawTile = (withinMaxExtent || this.layer.displayOutsideMaxExtent);
if (OpenLayers.Util.indexOf(this.layer.SUPPORTED_TRANSITIONS, this.layer.transitionEffect) != -1) {
if (drawTile) {
//we use a clone of this tile to create a double buffer for visual
//continuity. The backBufferTile is used to create transition
//effects while the tile in the grid is repositioned and redrawn
if (!this.backBufferTile) {
this.backBufferTile = this.clone();
this.backBufferTile.hide();
// this is important. It allows the backBuffer to place itself
// appropriately in the DOM. The Image subclass needs to put
// the backBufferTile behind the main tile so the tiles can
// load over top and display as soon as they are loaded.
this.backBufferTile.isBackBuffer = true;
// potentially end any transition effects when the tile loads
this.events.register('loadend', this, this.resetBackBuffer);
// clear transition back buffer tile only after all tiles in
// this layer have loaded to avoid visual glitches
this.layer.events.register("loadend", this, this.resetBackBuffer);
}
// run any transition effects
this.startTransition();
} else {
// if we aren't going to draw the tile, then the backBuffer should
// be hidden too!
if (this.backBufferTile) {
this.backBufferTile.clear();
}
}
} else {
if (drawTile && this.isFirstDraw) {
this.events.register('loadend', this, this.showTile);
this.isFirstDraw = false;
}
}
this.shouldDraw = drawTile;
this.shouldDraw = (withinMaxExtent || this.layer.displayOutsideMaxExtent);
//clear tile's contents and mark as not drawn
this.clear();
return drawTile;
return this.shouldDraw;
},
/**
@@ -335,49 +252,6 @@ OpenLayers.Tile = OpenLayers.Class({
topLeft.lat);
return bounds;
},
/**
* Method: startTransition
* Prepare the tile for a transition effect. To be
* implemented by subclasses.
*/
startTransition: function() {},
/**
* Method: resetBackBuffer
* Triggered by two different events, layer loadend, and tile loadend.
* In any of these cases, we check to see if we can hide the
* backBufferTile yet and update its parameters to match the
* foreground tile.
*
* Basic logic:
* - If the backBufferTile hasn't been drawn yet, reset it
* - If layer is still loading, show foreground tile but don't hide
* the backBufferTile yet
* - If layer is done loading, reset backBuffer tile and show
* foreground tile
*/
resetBackBuffer: function() {
this.showTile();
if (this.backBufferTile &&
(this.isFirstDraw || !this.layer.numLoadingTiles)) {
this.isFirstDraw = false;
// check to see if the backBufferTile is within the max extents
// before rendering it
var maxExtent = this.layer.maxExtent;
var withinMaxExtent = (maxExtent &&
this.bounds.intersectsBounds(maxExtent, false));
if (withinMaxExtent) {
this.backBufferTile.position = this.position;
this.backBufferTile.bounds = this.bounds;
this.backBufferTile.size = this.size;
this.backBufferTile.imageSize = this.layer.imageSize || this.size;
this.backBufferTile.imageOffset = this.layer.imageOffset;
this.backBufferTile.resolution = this.layer.getResolution();
this.backBufferTile.renderTile();
}
}
},
/**
* Method: showTile

121
lib/OpenLayers/Tile/Image.js
View File

@@ -37,13 +37,44 @@ OpenLayers.Tile.Image = OpenLayers.Class(OpenLayers.Tile, {
* the image will be hidden behind the frame.
*/
frame: null,
/**
* Property: layerAlphaHack
* {Boolean} True if the png alpha hack needs to be applied on the layer's div.
*/
layerAlphaHack: null,
/**
* Property: isBackBuffer
* {Boolean} Is this tile a back buffer tile?
*/
isBackBuffer: false,
/**
* Property: lastRatio
* {Float} Used in transition code only. This is the previous ratio
* of the back buffer tile resolution to the map resolution. Compared
* with the current ratio to determine if zooming occurred.
*/
lastRatio: 1,
/**
* Property: isFirstDraw
* {Boolean} Is this the first time the tile is being drawn?
* This is used to force resetBackBuffer to synchronize
* the backBufferTile with the foreground tile the first time
* the foreground tile loads so that if the user zooms
* before the layer has fully loaded, the backBufferTile for
* tiles that have been loaded can be used.
*/
isFirstDraw: true,
/**
* Property: backBufferTile
* {<OpenLayers.Tile>} A clone of the tile used to create transition
* effects when the tile is moved or changes resolution.
*/
backBufferTile: null,
/** TBD 3.0 - reorder the parameters to the init function to remove
* URL. the getUrl() function on the layer gets called on
@@ -93,6 +124,15 @@ OpenLayers.Tile.Image = OpenLayers.Class(OpenLayers.Tile, {
this.layer.div.removeChild(this.frame);
}
this.frame = null;
/* clean up the backBufferTile if it exists */
if (this.backBufferTile) {
this.backBufferTile.destroy();
this.backBufferTile = null;
}
this.layer.events.unregister("loadend", this, this.resetBackBuffer);
OpenLayers.Tile.prototype.destroy.apply(this, arguments);
},
@@ -135,8 +175,47 @@ OpenLayers.Tile.Image = OpenLayers.Class(OpenLayers.Tile, {
if (this.layer != this.layer.map.baseLayer && this.layer.reproject) {
this.bounds = this.getBoundsFromBaseLayer(this.position);
}
if (!OpenLayers.Tile.prototype.draw.apply(this, arguments)) {
return false;
var drawTile = OpenLayers.Tile.prototype.draw.apply(this, arguments);
if (OpenLayers.Util.indexOf(this.layer.SUPPORTED_TRANSITIONS, this.layer.transitionEffect) != -1) {
if (drawTile) {
//we use a clone of this tile to create a double buffer for visual
//continuity. The backBufferTile is used to create transition
//effects while the tile in the grid is repositioned and redrawn
if (!this.backBufferTile) {
this.backBufferTile = this.clone();
this.backBufferTile.hide();
// this is important. It allows the backBuffer to place itself
// appropriately in the DOM. The Image subclass needs to put
// the backBufferTile behind the main tile so the tiles can
// load over top and display as soon as they are loaded.
this.backBufferTile.isBackBuffer = true;
// potentially end any transition effects when the tile loads
this.events.register('loadend', this, this.resetBackBuffer);
// clear transition back buffer tile only after all tiles in
// this layer have loaded to avoid visual glitches
this.layer.events.register("loadend", this, this.resetBackBuffer);
}
// run any transition effects
this.startTransition();
} else {
// if we aren't going to draw the tile, then the backBuffer should
// be hidden too!
if (this.backBufferTile) {
this.backBufferTile.clear();
}
}
} else {
if (drawTile && this.isFirstDraw) {
this.events.register('loadend', this, this.showTile);
this.isFirstDraw = false;
}
}
if (!drawTile) {
return false;
}
if (this.isLoading) {
@@ -150,6 +229,42 @@ OpenLayers.Tile.Image = OpenLayers.Class(OpenLayers.Tile, {
return this.renderTile();
},
/**
* Method: resetBackBuffer
* Triggered by two different events, layer loadend, and tile loadend.
* In any of these cases, we check to see if we can hide the
* backBufferTile yet and update its parameters to match the
* foreground tile.
*
* Basic logic:
* - If the backBufferTile hasn't been drawn yet, reset it
* - If layer is still loading, show foreground tile but don't hide
* the backBufferTile yet
* - If layer is done loading, reset backBuffer tile and show
* foreground tile
*/
resetBackBuffer: function() {
this.showTile();
if (this.backBufferTile &&
(this.isFirstDraw || !this.layer.numLoadingTiles)) {
this.isFirstDraw = false;
// check to see if the backBufferTile is within the max extents
// before rendering it
var maxExtent = this.layer.maxExtent;
var withinMaxExtent = (maxExtent &&
this.bounds.intersectsBounds(maxExtent, false));
if (withinMaxExtent) {
this.backBufferTile.position = this.position;
this.backBufferTile.bounds = this.bounds;
this.backBufferTile.size = this.size;
this.backBufferTile.imageSize = this.layer.imageSize || this.size;
this.backBufferTile.imageOffset = this.layer.imageOffset;
this.backBufferTile.resolution = this.layer.getResolution();
this.backBufferTile.renderTile();
}
}
},
/**
* Method: renderTile
* Internal function to actually initialize the image tile,