overviewmap.js

用来在地图上做操作GIS,在地图上做标记

        }
    },

    /**
     * Method: rectMouseUp
     * Handle browser events
     *
     * Parameters:
     * evt - {<OpenLayers.Event>} evt
     */
    rectMouseUp: function(evt) {
        if(!OpenLayers.Event.isLeftClick(evt)) return;
        if(this.performedRectDrag) {
            this.updateMapToRect();
            OpenLayers.Event.stop(evt);
        }        
        document.onselectstart = null;
        this.rectDragStart = null;
    },
    
    /**
     * Method: rectDblClick
     * Handle browser events
     *
     * Parameters:
     * evt - {<OpenLayers.Event>} evt
     */
    rectDblClick: function(evt) {
        this.performedRectDrag = false;
        OpenLayers.Event.stop(evt);
        this.updateOverview();
    },

    /**
     * Method: mapDivClick
     * Handle browser events
     *
     * Parameters:
     * evt - {<OpenLayers.Event>} evt
     */
    mapDivClick: function(evt) {
        var pxBounds = this.getRectPxBounds();
        var pxCenter = pxBounds.getCenterPixel();
        var deltaX = evt.xy.x - pxCenter.x;
        var deltaY = evt.xy.y - pxCenter.y;
        var top = pxBounds.top;
        var left = pxBounds.left;
        var height = Math.abs(pxBounds.getHeight());
        var width = pxBounds.getWidth();
        var newTop = Math.max(0, (top + deltaY));
        newTop = Math.min(newTop, this.ovmap.size.h - height);
        var newLeft = Math.max(0, (left + deltaX));
        newLeft = Math.min(newLeft, this.ovmap.size.w - width);
        this.setRectPxBounds(new OpenLayers.Bounds(newLeft,
                                                   newTop + height,
                                                   newLeft + width,
                                                   newTop));
        this.updateMapToRect();
        OpenLayers.Event.stop(evt);
    },

    /**
     * Method: maximizeControl
     * Unhide the control.  Called when the control is in the map viewport.
     *
     * Parameters:
     * e - {<OpenLayers.Event>}
     */
    maximizeControl: function(e) {
        this.element.style.display = '';
        this.showToggle(false);
        if (e != null) {
            OpenLayers.Event.stop(e);                                            
        }
    },

    /**
     * Method: minimizeControl
     * Hide all the contents of the control, shrink the size, 
     * add the maximize icon
     * 
     * Parameters:
     * e - {<OpenLayers.Event>}
     */
    minimizeControl: function(e) {
        this.element.style.display = 'none';
        this.showToggle(true);
        if (e != null) {
            OpenLayers.Event.stop(e);                                            
        }
    },

    /**
     * Method: showToggle
     * Hide/Show the toggle depending on whether the control is minimized
     *
     * Parameters:
     * minimize - {Boolean} 
     */
    showToggle: function(minimize) {
        this.maximizeDiv.style.display = minimize ? '' : 'none';
        this.minimizeDiv.style.display = minimize ? 'none' : '';
    },

    /**
     * Method: update
     * Update the overview map after layers move.
     */
    update: function() {
        if(this.ovmap == null) {
            this.createMap();
        }
        
        if(!this.isSuitableOverview()) {
            this.updateOverview();
        }
        
        // update extent rectangle
        this.updateRectToMap();
    },
    
    /**
     * Method: isSuitableOverview
     * Determines if the overview map is suitable given the extent and
     * resolution of the main map.
     */
    isSuitableOverview: function() {
        var mapExtent = this.map.getExtent();
        var maxExtent = this.map.maxExtent;
        var testExtent = new OpenLayers.Bounds(
                                Math.max(mapExtent.left, maxExtent.left),
                                Math.max(mapExtent.bottom, maxExtent.bottom),
                                Math.min(mapExtent.right, maxExtent.right),
                                Math.min(mapExtent.top, maxExtent.top));        
        var resRatio = this.ovmap.getResolution() / this.map.getResolution();
        return ((resRatio > this.minRatio) &&
                (resRatio <= this.maxRatio) &&
                (this.ovmap.getExtent().containsBounds(testExtent)));
    },
    
    /**
     * Method updateOverview
     * Called by <update> if <isSuitableOverview> returns true
     */
    updateOverview: function() {
        var mapRes = this.map.getResolution();
        var targetRes = this.ovmap.getResolution();
        var resRatio = targetRes / mapRes;
        if(resRatio > this.maxRatio) {
            // zoom in overview map
            targetRes = this.minRatio * mapRes;            
        } else if(resRatio <= this.minRatio) {
            // zoom out overview map
            targetRes = this.maxRatio * mapRes;
        }
        this.ovmap.setCenter(this.map.center,
                            this.ovmap.getZoomForResolution(targetRes));
        this.updateRectToMap();
    },
    
    /**
     * Method: createMap
     * Construct the map that this control contains
     */
    createMap: function() {
        // create the overview map
        var options = OpenLayers.Util.extend(
                        {controls: [], maxResolution: 'auto'}, this.mapOptions);
        this.ovmap = new OpenLayers.Map(this.mapDiv, options);
        this.ovmap.addLayers(this.layers);
        this.ovmap.zoomToMaxExtent();
        // check extent rectangle border width
        this.wComp = parseInt(OpenLayers.Element.getStyle(this.extentRectangle,
                                               'border-left-width')) +
                     parseInt(OpenLayers.Element.getStyle(this.extentRectangle,
                                               'border-right-width'));
        this.wComp = (this.wComp) ? this.wComp : 2;
        this.hComp = parseInt(OpenLayers.Element.getStyle(this.extentRectangle,
                                               'border-top-width')) +
                     parseInt(OpenLayers.Element.getStyle(this.extentRectangle,
                                               'border-bottom-width'));
        this.hComp = (this.hComp) ? this.hComp : 2;
    },
        
    /**
     * Method: updateRectToMap
     * Updates the extent rectangle position and size to match the map extent
     */
    updateRectToMap: function() {
        // The base layer for overview map needs to be in the same projection
        // as the base layer for the main map.  This should be made more robust.
        if(this.map.units != 'degrees') {
            if(this.ovmap.getProjection() && (this.map.getProjection() != this.ovmap.getProjection())) {
                alert('The overview map only works when it is in the same projection as the main map');
            }
        }
        var pxBounds = this.getRectBoundsFromMapBounds(this.map.getExtent());
        if (pxBounds) {
          this.setRectPxBounds(pxBounds);
        }
    },
    
    /**
     * Method: updateMapToRect
     * Updates the map extent to match the extent rectangle position and size
     */
    updateMapToRect: function() {
        var pxBounds = this.getRectPxBounds();
        var lonLatBounds = this.getMapBoundsFromRectBounds(pxBounds);
        this.map.setCenter(lonLatBounds.getCenterLonLat(), this.map.zoom);
    },
    
    /**
     * Method: getRectPxBounds
     * Get extent rectangle pixel bounds
     *
     * Returns:
     * {<OpenLayers.Bounds>} A bounds which is the extent rectangle's pixel
     * bounds (relative to the parent element)
     */
    getRectPxBounds: function() {
        var top = parseInt(this.extentRectangle.style.top);
        var left = parseInt(this.extentRectangle.style.left);
        var height = parseInt(this.extentRectangle.style.height);
        var width = parseInt(this.extentRectangle.style.width);
        return new OpenLayers.Bounds(left, top + height, left + width, top);
    },

    /**
     * Method: setRectPxBounds
     * Set extent rectangle pixel bounds.
     *
     * Parameters:
     * pxBounds - {<OpenLayers.Bounds>}
     */
    setRectPxBounds: function(pxBounds) {
        var top = Math.max(pxBounds.top, 0);
        var left = Math.max(pxBounds.left, 0);
        var bottom = Math.min(pxBounds.top + Math.abs(pxBounds.getHeight()),
                              this.ovmap.size.h - this.hComp);
        var right = Math.min(pxBounds.left + pxBounds.getWidth(),
                             this.ovmap.size.w - this.wComp);
        this.extentRectangle.style.top = parseInt(top) + 'px';
        this.extentRectangle.style.left = parseInt(left) + 'px';
        this.extentRectangle.style.height = parseInt(Math.max(bottom - top, 0))+ 'px';
        this.extentRectangle.style.width = parseInt(Math.max(right - left, 0)) + 'px';
    },

    /**
     * Method: getRectBoundsFromMapBounds
     * Get the rect bounds from the map bounds.
     *
     * Parameters:
     * lonLatBounds - {<OpenLayers.Bounds>}
     *
     * Returns:
     * {<OpenLayers.Bounds>}A bounds which is the passed-in map lon/lat extent
     * translated into pixel bounds for the overview map
     */
    getRectBoundsFromMapBounds: function(lonLatBounds) {
        var leftBottomLonLat = new OpenLayers.LonLat(lonLatBounds.left,
                                                     lonLatBounds.bottom);
        var rightTopLonLat = new OpenLayers.LonLat(lonLatBounds.right,
                                                   lonLatBounds.top);
        var leftBottomPx = this.getOverviewPxFromLonLat(leftBottomLonLat);
        var rightTopPx = this.getOverviewPxFromLonLat(rightTopLonLat);
        var bounds = null;
        if (leftBottomPx && rightTopPx) {
            bounds = new OpenLayers.Bounds(leftBottomPx.x, leftBottomPx.y,
                                           rightTopPx.x, rightTopPx.y);
        }
        return bounds;
    },

    /**
     * Method: getMapBoundsFromRectBounds
     * Get the map bounds from the rect bounds.
     *
     * Parameters:
     * pxBounds - {<OpenLayers.Bounds>}
     *
     * Returns:
     * {<OpenLayers.Bounds>} Bounds which is the passed-in overview rect bounds
     * translated into lon/lat bounds for the overview map
     */
    getMapBoundsFromRectBounds: function(pxBounds) {
        var leftBottomPx = new OpenLayers.Pixel(pxBounds.left,
                                                pxBounds.bottom);
        var rightTopPx = new OpenLayers.Pixel(pxBounds.right,
                                              pxBounds.top);
        var leftBottomLonLat = this.getLonLatFromOverviewPx(leftBottomPx);
        var rightTopLonLat = this.getLonLatFromOverviewPx(rightTopPx);
        return new OpenLayers.Bounds(leftBottomLonLat.lon, leftBottomLonLat.lat,
                                     rightTopLonLat.lon, rightTopLonLat.lat);
    },

    /**
     * Method: getLonLatFromOverviewPx
     * Get a map location from a pixel location
     *
     * Parameters:
     * overviewMapPx - {<OpenLayers.Pixel>}
     *
     * Returns:
     * {<OpenLayers.LonLat>} Location which is the passed-in overview map
     * OpenLayers.Pixel, translated into lon/lat by the overview map
     */
    getLonLatFromOverviewPx: function(overviewMapPx) {
        var size = this.ovmap.size;
        var res  = this.ovmap.getResolution();
        var center = this.ovmap.getExtent().getCenterLonLat();
    
        var delta_x = overviewMapPx.x - (size.w / 2);
        var delta_y = overviewMapPx.y - (size.h / 2);
        
        return new OpenLayers.LonLat(center.lon + delta_x * res ,
                                     center.lat - delta_y * res); 
    },

    /**
     * Method: getOverviewPxFromLonLat
     * Get a pixel location from a map location
     *
     * Parameters:
     * lonlat - {<OpenLayers.LonLat>}
     *
     * Returns:
     * {<OpenLayers.Pixel>} Location which is the passed-in OpenLayers.LonLat, 
     * translated into overview map pixels
     */
    getOverviewPxFromLonLat: function(lonlat) {
        var res  = this.ovmap.getResolution();
        var extent = this.ovmap.getExtent();
        var px = null;
        if (extent) {
            px = new OpenLayers.Pixel(
                        Math.round(1/res * (lonlat.lon - extent.left)),
                        Math.round(1/res * (extent.top - lonlat.lat)));
        } 
        return px;
    },

    CLASS_NAME: 'OpenLayers.Control.OverviewMap'
});