xiaoyan159/vtm
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

add docs

Browse Source
This commit is contained in:
Hannes Janetzek 2013-09-20 13:55:47 +02:00
parent f049673412
commit 4fadd929ee
1 changed files with 25 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

39
vtm/src/org/oscim/utils/ScanBox.java
View File

@ -18,24 +18,31 @@ package org.oscim.utils;
import org.oscim.core.Tile; import org.oscim.core.Tile;
/** /**
* Scan-line fill algorithm to retrieve tile-coordinates. * Scan-line fill algorithm to retrieve tile-coordinates from
* Viewport.
* <p>
* ScanBox is used to calculate tile coordinates that intersect the box (or
* trapezoid) which is the projection of screen bounds to the map. Usage:
* *
* ScanBox is used to calculate tile coordinates that intersect * <pre>
* the box (or trapezoid) which is the projection of screen
* bounds to the map.
*
* use:
* Viewport.getMapViewProjection(box) * Viewport.getMapViewProjection(box)
* yourScanBox.scan(pos.x, pos.y, pos.scale, zoomLevel, coords); * ScanBox sb = new ScanBox(){
* @Override
* protected void setVisible(int y, int x1, int x2) {
* }
* };
* sb.scan(pos.x, pos.y, pos.scale, * zoomLevel, coords);
* *
* where zoomLevel is the zoom-level for which tile coordinates * </pre>
* should be calculated. *
* */ * where zoomLevel is the zoom-level for which tile coordinates should be
* calculated.
*/
public abstract class ScanBox { public abstract class ScanBox {
private final float[] mBox = new float[8]; private final float[] mBox = new float[8];
private float[] transScale(double x, double y, double scale, int zoom, float[] box){ private float[] transScale(double x, double y, double scale, int zoom, float[] box) {
scale *= Tile.SIZE; scale *= Tile.SIZE;
//double curScale = Tile.SIZE * scale; //double curScale = Tile.SIZE * scale;
@ -95,7 +102,7 @@ public abstract class ScanBox {
float max = Float.MIN_VALUE; float max = Float.MIN_VALUE;
float min = Float.MAX_VALUE; float min = Float.MAX_VALUE;
for(int i = 0; i < 8; i += 2){ for (int i = 0; i < 8; i += 2) {
float xx = box[i]; float xx = box[i];
if (xx > max) if (xx > max)
max = xx; max = xx;
@ -103,8 +110,8 @@ public abstract class ScanBox {
min = xx; min = xx;
} }
max = (float)Math.ceil(max); max = (float) Math.ceil(max);
min = (float)Math.floor(min); min = (float) Math.floor(min);
if (min == max) if (min == max)
max++; max++;
@ -197,13 +204,13 @@ public abstract class ScanBox {
if (dy > e0.dy) if (dy > e0.dy)
dy = e0.dy; dy = e0.dy;
int x0 = (int)Math.ceil(e0.x0 + m0 * dy); int x0 = (int) Math.ceil(e0.x0 + m0 * dy);
dy = d1 + y - e1.y0; dy = d1 + y - e1.y0;
if (dy > e1.dy) if (dy > e1.dy)
dy = e1.dy; dy = e1.dy;
int x1 = (int)Math.floor(e1.x0 + m1 * dy); int x1 = (int) Math.floor(e1.x0 + m1 * dy);
if (x1 < minX) if (x1 < minX)
x1 = minX; x1 = minX;