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Refactor tile position calculation for readability

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This commit is contained in:
Andreas Hocevar
2016-02-29 21:23:19 +01:00
parent 8256ff60b6
commit 8553da6679
1 changed files with 11 additions and 15 deletions
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26
src/ol/renderer/canvas/canvastilelayerrenderer.js
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@@ -95,9 +95,8 @@ ol.renderer.canvas.TileLayer.prototype.composeFrame = function(
var tileGrid = source.getTileGridForProjection(projection);
var tilesToDraw = this.renderedTiles_;
var clipExtents, clipExtent, currentZ, i, ii, j, jj, insertPoint;
var origin, tile, tileExtent, tileHeight, tileOffsetX, tileOffsetY;
var tilePixelSize, tileWidth;
var clipExtent, clipExtents, currentZ, h, i, ii, j, jj, left, origin, tile;
var tileExtent, tilePixelSize, top, w;
for (i = 0, ii = tilesToDraw.length; i < ii; ++i) {
tile = tilesToDraw[i];
tileExtent = tileGrid.getTileCoordExtent(
@@ -132,22 +131,19 @@ ol.renderer.canvas.TileLayer.prototype.composeFrame = function(
renderContext.clip();
}
currentZ = tile.getTileCoord()[0];
tilePixelSize = source.getTilePixelSize(currentZ, pixelRatio, projection);
insertPoint = ol.extent.getTopLeft(tileExtent);
tileWidth = Math.round(ol.extent.getWidth(tileExtent) * pixelScale);
tileHeight = Math.round(ol.extent.getHeight(tileExtent) * pixelScale);
// Calculate all insert points from a common origin and tile widths to avoid
// Calculate all insert points by tile widths from a common origin to avoid
// gaps caused by rounding
origin = ol.extent.getBottomLeft(tileGrid.getTileCoordExtent(
tileGrid.getTileCoordForCoordAndZ(center, currentZ)));
tileOffsetX = offsetX + Math.round((origin[0] - center[0]) * pixelScale);
tileOffsetY = offsetY + Math.round((center[1] - origin[1]) * pixelScale);
w = Math.round(ol.extent.getWidth(tileExtent) * pixelScale);
h = Math.round(ol.extent.getHeight(tileExtent) * pixelScale);
left = Math.round((tileExtent[0] - origin[0]) * pixelScale / w) * w +
offsetX + Math.round((origin[0] - center[0]) * pixelScale);
top = Math.round((origin[1] - tileExtent[3]) * pixelScale / h) * h +
offsetY + Math.round((center[1] - origin[1]) * pixelScale);
tilePixelSize = source.getTilePixelSize(currentZ, pixelRatio, projection);
renderContext.drawImage(tile.getImage(), tileGutter, tileGutter,
tilePixelSize[0], tilePixelSize[1],
Math.round((insertPoint[0] - origin[0]) * pixelScale / tileWidth) *
tileWidth + tileOffsetX,
Math.round((origin[1] - insertPoint[1]) * pixelScale / tileHeight) *
tileHeight + tileOffsetY, tileWidth, tileHeight);
tilePixelSize[0], tilePixelSize[1], left, top, w, h);
if (clipExtents) {
renderContext.restore();
}