-function drawMap(aPixels, aOverdraw) {
- // aPixels is an object with left/right/top/bottom members telling how many
- // pixels on the borders should actually be drawn.
- // aOverdraw is a bool that tells if we should draw placeholders or draw
- // straight over the existing content.
- if (!aPixels)
- aPixels = {left: gMapCanvas.width, right: gMapCanvas.width,
- top: gMapCanvas.height, bottom: gMapCanvas.height};
- if (!aOverdraw)
- aOverdraw = false;
-
- document.getElementById("zoomLevel").textContent = gPos.z;
- gZoomFactor = Math.pow(2, gMaxZoom - gPos.z);
- var wid = gMapCanvas.width * gZoomFactor; // Width in level 18 pixels.
- var ht = gMapCanvas.height * gZoomFactor; // Height in level 18 pixels.
- var size = gTileSize * gZoomFactor; // Tile size in level 18 pixels.
-
- var xMin = gPos.x - wid / 2; // Corners of the window in level 18 pixels.
- var yMin = gPos.y - ht / 2;
- var xMax = gPos.x + wid / 2;
- var yMax = gPos.y + ht / 2;
-
- if (gMapPrefsLoaded && mainDB)
- gPrefs.set("position", gPos);
-
- var tiles = {left: Math.ceil((xMin + aPixels.left * gZoomFactor) / size) -
- (aPixels.left ? 0 : 1),
- right: Math.floor((xMax - aPixels.right * gZoomFactor) / size) -
- (aPixels.right ? 1 : 0),
- top: Math.ceil((yMin + aPixels.top * gZoomFactor) / size) -
- (aPixels.top ? 0 : 1),
- bottom: Math.floor((yMax - aPixels.bottom * gZoomFactor) / size) -
- (aPixels.bottom ? 1 : 0)};
-
- // Go through all the tiles in the map, find out if to draw them and do so.
- for (var x = Math.floor(xMin / size); x < Math.ceil(xMax / size); x++) {
- for (var y = Math.floor(yMin / size); y < Math.ceil(yMax / size); y++) { // slow script warnings on the tablet appear here!
- // Only go to the drawing step if we need to draw this tile.
- if (x < tiles.left || x > tiles.right ||
- y < tiles.top || y > tiles.bottom) {
- // Round here is **CRUCIAL** otherwise the images are filtered
- // and the performance sucks (more than expected).
- var xoff = Math.round((x * size - xMin) / gZoomFactor);
- var yoff = Math.round((y * size - yMin) / gZoomFactor);
- // Draw placeholder tile unless we overdraw.
- if (!aOverdraw &&
- (x < tiles.left -1 || x > tiles.right + 1 ||
- y < tiles.top -1 || y > tiles.bottom + 1))
- gMapContext.drawImage(gLoadingTile, xoff, yoff);
-
- // Initiate loading/drawing of the actual tile.
- gTileService.get(gActiveMap, {x: x, y: y, z: gPos.z},
- function(aImage, aStyle, aCoords) {
- // Only draw if this applies for the current view.
- if ((aStyle == gActiveMap) && (aCoords.z == gPos.z)) {
- var ixMin = gPos.x - wid / 2;
- var iyMin = gPos.y - ht / 2;
- var ixoff = Math.round((aCoords.x * size - ixMin) / gZoomFactor);
- var iyoff = Math.round((aCoords.y * size - iyMin) / gZoomFactor);
- var URL = window.URL;
- var imgURL = URL.createObjectURL(aImage);
- var imgObj = new Image();
- imgObj.src = imgURL;
- imgObj.onload = function() {
- gMapContext.drawImage(imgObj, ixoff, iyoff);
- URL.revokeObjectURL(imgURL);
- }
- }
- });
- }
- }
- }
- drawTrack();
-}
-