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An Android library to display OpenStreetMap views.
package org.osmdroid.views.overlay;
/**
* ScaleBarOverlay.java
*
* Puts a scale bar in the top-left corner of the screen, offset by a configurable
* number of pixels. The bar is scaled to 1-inch length by querying for the physical
* DPI of the screen. The size of the bar is printed between the tick marks. A
* vertical (longitude) scale can be enabled. Scale is printed in metric (kilometers,
* meters), imperial (miles, feet) and nautical (nautical miles, feet).
*
* Author: Erik Burrows, Griffin Systems LLC
* [email protected]
*
* Change Log:
* 2010-10-08: Inclusion to osmdroid trunk
*
* License:
* LGPL version 3
* http://www.gnu.org/licenses/lgpl.html
*
* Usage:
*
* MapView map = new MapView(...);
* ScaleBarOverlay scaleBar = new ScaleBarOverlay(this.getBaseContext(), map);
*
* scaleBar.setImperial(); // Metric by default
*
* map.getOverlays().add(scaleBar);
*
*
* To Do List:
* 1. Allow for top, bottom, left or right placement.
* 2. Scale bar to precise displayed scale text after rounding.
*
*/
import java.lang.reflect.Field;
import org.osmdroid.DefaultResourceProxyImpl;
import org.osmdroid.ResourceProxy;
import org.osmdroid.api.IGeoPoint;
import org.osmdroid.util.GeoPoint;
import org.osmdroid.util.constants.GeoConstants;
import org.osmdroid.views.MapView;
import org.osmdroid.views.MapView.Projection;
import org.osmdroid.views.safecanvas.ISafeCanvas;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.Paint.Style;
import android.graphics.Picture;
import android.graphics.Rect;
import android.view.WindowManager;
public class ScaleBarOverlay extends SafeDrawOverlay implements GeoConstants {
// ===========================================================
// Fields
// ===========================================================
// Defaults
float xOffset = 10;
float yOffset = 10;
float lineWidth = 2;
final int textSize = 12;
int minZoom = 0;
boolean imperial = false;
boolean nautical = false;
boolean latitudeBar = true;
boolean longitudeBar = false;
// Internal
private final Context context;
protected final Picture scaleBarPicture = new Picture();
private int lastZoomLevel = -1;
private float lastLatitude = 0;
public float xdpi;
public float ydpi;
public int screenWidth;
public int screenHeight;
private final ResourceProxy resourceProxy;
private Paint barPaint;
private Paint bgPaint;
private Paint textPaint;
private Projection projection;
final private Rect mBounds = new Rect();
final private Matrix mIdentityMatrix = new Matrix();
private boolean centred = false;
private boolean adjustLength = false;
private float maxLength;
// ===========================================================
// Constructors
// ===========================================================
public ScaleBarOverlay(final Context context) {
this(context, new DefaultResourceProxyImpl(context));
}
public ScaleBarOverlay(final Context context, final ResourceProxy pResourceProxy) {
super(pResourceProxy);
this.resourceProxy = pResourceProxy;
this.context = context;
this.barPaint = new Paint();
this.barPaint.setColor(Color.BLACK);
this.barPaint.setAntiAlias(true);
this.barPaint.setStyle(Style.FILL);
this.barPaint.setAlpha(255);
this.bgPaint = null;
this.textPaint = new Paint();
this.textPaint.setColor(Color.BLACK);
this.textPaint.setAntiAlias(true);
this.textPaint.setStyle(Style.FILL);
this.textPaint.setAlpha(255);
this.textPaint.setTextSize(textSize);
this.xdpi = this.context.getResources().getDisplayMetrics().xdpi;
this.ydpi = this.context.getResources().getDisplayMetrics().ydpi;
this.screenWidth = this.context.getResources().getDisplayMetrics().widthPixels;
this.screenHeight = this.context.getResources().getDisplayMetrics().heightPixels;
// DPI corrections for specific models
String manufacturer = null;
try {
final Field field = android.os.Build.class.getField("MANUFACTURER");
manufacturer = (String) field.get(null);
} catch (final Exception ignore) {
}
if ("motorola".equals(manufacturer) && "DROIDX".equals(android.os.Build.MODEL)) {
// If the screen is rotated, flip the x and y dpi values
WindowManager windowManager = (WindowManager) this.context
.getSystemService(Context.WINDOW_SERVICE);
if (windowManager.getDefaultDisplay().getOrientation() > 0) {
this.xdpi = (float) (this.screenWidth / 3.75);
this.ydpi = (float) (this.screenHeight / 2.1);
} else {
this.xdpi = (float) (this.screenWidth / 2.1);
this.ydpi = (float) (this.screenHeight / 3.75);
}
} else if ("motorola".equals(manufacturer) && "Droid".equals(android.os.Build.MODEL)) {
// http://www.mail-archive.com/[email protected]/msg109497.html
this.xdpi = 264;
this.ydpi = 264;
}
// set default max length to 1 inch
maxLength = 2.54f;
}
// ===========================================================
// Getter & Setter
// ===========================================================
/**
* Sets the minimum zoom level for the scale bar to be drawn.
* @param minimum zoom level
*/
public void setMinZoom(final int zoom) {
this.minZoom = zoom;
}
/**
* Sets the scale bar screen offset for the bar. Note: if the bar is set to be drawn centered, this will be the middle of the bar, otherwise the top left corner.
* @param x x screen offset
* @param y z screen offset
*/
public void setScaleBarOffset(final float x, final float y) {
xOffset = x;
yOffset = y;
}
/**
* Sets the bar's line width. (the default is 2)
* @param width the new line width
*/
public void setLineWidth(final float width) {
this.lineWidth = width;
}
/**
* Sets the text size. (the default is 12)
* @param size the new text size
*/
public void setTextSize(final float size) {
this.textPaint.setTextSize(size);
}
/**
* Sets the length to be shown in imperial units (mi/ft)
*/
public void setImperial() {
this.imperial = true;
this.nautical = false;
lastZoomLevel = -1; // Force redraw of scalebar
}
/**
* Sets the length to be shown in nautical units (nm/ft)
*/
public void setNautical() {
this.nautical = true;
this.imperial = false;
lastZoomLevel = -1; // Force redraw of scalebar
}
/**
* Sets the length to be shown in metric units (km/m)
*/
public void setMetric() {
this.nautical = false;
this.imperial = false;
lastZoomLevel = -1; // Force redraw of scalebar
}
/**
* Latitudinal / horizontal scale bar flag
* @param latitude
*/
public void drawLatitudeScale(final boolean latitude) {
this.latitudeBar = latitude;
lastZoomLevel = -1; // Force redraw of scalebar
}
/**
* Longitudinal / vertical scale bar flag
* @param longitude
*/
public void drawLongitudeScale(final boolean longitude) {
this.longitudeBar = longitude;
lastZoomLevel = -1; // Force redraw of scalebar
}
/**
* Flag to draw the bar centered around the set offset coordinates or to the right/bottom of the coordinates (default)
* @param centred set true to centre the bar around the given screen coordinates
*/
public void setCentred(final boolean centred) {
this.centred = centred;
lastZoomLevel = -1; // Force redraw of scalebar
}
/**
* Return's the paint used to draw the bar
* @return the paint used to draw the bar
*/
public Paint getBarPaint() {
return barPaint;
}
/**
* Sets the paint for drawing the bar
* @param pBarPaint bar drawing paint
*/
public void setBarPaint(final Paint pBarPaint) {
if (pBarPaint == null) {
throw new IllegalArgumentException("pBarPaint argument cannot be null");
}
barPaint = pBarPaint;
lastZoomLevel = -1; // Force redraw of scalebar
}
/**
* Returns the paint used to draw the text
* @return the paint used to draw the text
*/
public Paint getTextPaint() {
return textPaint;
}
/**
* Sets the paint for drawing the text
* @param pTextPaint text drawing paint
*/
public void setTextPaint(final Paint pTextPaint) {
if (pTextPaint == null) {
throw new IllegalArgumentException("pTextPaint argument cannot be null");
}
textPaint = pTextPaint;
lastZoomLevel = -1; // Force redraw of scalebar
}
/**
* Sets the background paint. Set to null to disable drawing of background (default)
* @param pBgPaint the paint for colouring the bar background
*/
public void setBackgroundPaint(final Paint pBgPaint) {
bgPaint = pBgPaint;
lastZoomLevel = -1; // Force redraw of scalebar
}
/**
* If enabled, the bar will automatically adjust the length to reflect a round number (starting
* with 1, 2 or 5). If disabled, the bar will always be drawn in full length representing a
* fractional distance.
*/
public void setEnableAdjustLength(boolean adjustLength) {
this.adjustLength = adjustLength;
lastZoomLevel = -1; // Force redraw of scalebar
}
/**
* Sets the maximum bar length. If adjustLength is disabled this will match exactly the length of the bar.
* If adjustLength is enabled, the bar will be shortened to reflect a round number in length.
* @param pMaxLengthInCm maximum length of the bar in the screen in cm. Default is 2.54 (=1 inch)
*/
public void setMaxLength(final float pMaxLengthInCm) {
this.maxLength = pMaxLengthInCm;
lastZoomLevel = -1; // Force redraw of scalebar
}
// ===========================================================
// Methods from SuperClass/Interfaces
// ===========================================================
@Override
public void drawSafe(final ISafeCanvas c, final MapView mapView, final boolean shadow) {
if (shadow) {
return;
}
// If map view is animating, don't update, scale will be wrong.
if (mapView.isAnimating()) {
return;
}
final int zoomLevel = mapView.getZoomLevel();
if (zoomLevel >= minZoom) {
final Projection projection = mapView.getProjection();
if (projection == null) {
return;
}
final IGeoPoint center = projection.fromPixels((screenWidth / 2), screenHeight / 2);
if (zoomLevel != lastZoomLevel
|| (int) (center.getLatitudeE6() / 1E6) != (int) (lastLatitude / 1E6)) {
lastZoomLevel = zoomLevel;
lastLatitude = center.getLatitudeE6();
createScaleBarPicture(mapView);
}
mBounds.set(0, 0, scaleBarPicture.getWidth(), scaleBarPicture.getHeight());
mBounds.offset((int) xOffset, (int) yOffset);
if (centred && latitudeBar)
mBounds.offset(-scaleBarPicture.getWidth() / 2, 0);
if (centred && longitudeBar)
mBounds.offset(0, -scaleBarPicture.getHeight() / 2);
mBounds.set(mBounds);
c.save();
c.setMatrix(mIdentityMatrix);
c.getWrappedCanvas().drawPicture(scaleBarPicture, mBounds);
c.restore();
}
}
// ===========================================================
// Methods
// ===========================================================
public void disableScaleBar() {
setEnabled(false);
}
public void enableScaleBar() {
setEnabled(true);
}
private void createScaleBarPicture(final MapView mapView) {
// We want the scale bar to be as long as the closest round-number miles/kilometers
// to 1-inch at the latitude at the current center of the screen.
projection = mapView.getProjection();
if (projection == null) {
return;
}
// calculate dots per centimeter
int xdpcm = (int) ((float) xdpi / 2.54);
int ydpcm = (int) ((float) ydpi / 2.54);
// get length in pixel
int xLen = (int) (maxLength * xdpcm);
int yLen = (int) (maxLength * ydpcm);
// Two points, xLen apart, at scale bar screen location
IGeoPoint p1 = projection.fromPixels((screenWidth / 2) - (xLen / 2), yOffset);
IGeoPoint p2 = projection.fromPixels((screenWidth / 2) + (xLen / 2), yOffset);
// get distance in meters between points
final int xMeters = ((GeoPoint) p1).distanceTo(p2);
// get adjusted distance, shortened to the next lower number starting with 1, 2 or 5
final double xMetersAdjusted = this.adjustLength ? adjustScaleBarLength(xMeters) : xMeters;
// get adjusted length in pixels
final int xBarLengthPixels = (int) (xLen * xMetersAdjusted / xMeters);
// Two points, yLen apart, at scale bar screen location
p1 = projection.fromPixels(screenWidth / 2, (screenHeight / 2) - (yLen / 2));
p2 = projection.fromPixels(screenWidth / 2, (screenHeight / 2) + (yLen / 2));
// get distance in meters between points
final int yMeters = ((GeoPoint) p1).distanceTo(p2);
// get adjusted distance, shortened to the next lower number starting with 1, 2 or 5
final double yMetersAdjusted = this.adjustLength ? adjustScaleBarLength(yMeters) : yMeters;
// get adjusted length in pixels
final int yBarLengthPixels = (int) (yLen * yMetersAdjusted / yMeters);
final Canvas canvas = scaleBarPicture.beginRecording(xBarLengthPixels, yBarLengthPixels);
// create text
final String xMsg = scaleBarLengthText((int) xMetersAdjusted, imperial, nautical);
final Rect xTextRect = new Rect();
textPaint.getTextBounds(xMsg, 0, xMsg.length(), xTextRect);
final int xTextSpacing = (int) (xTextRect.height() / 5.0);
final String yMsg = scaleBarLengthText((int) yMetersAdjusted, imperial, nautical);
final Rect yTextRect = new Rect();
textPaint.getTextBounds(yMsg, 0, yMsg.length(), yTextRect);
final int yTextSpacing = (int) (yTextRect.height() / 5.0);
// paint background
if (bgPaint != null) {
canvas.drawRect(0, 0, yTextRect.height() + 2 * lineWidth + yTextSpacing,
xTextRect.height() + 2 * lineWidth + xTextSpacing, bgPaint);
if (latitudeBar)
canvas.drawRect(yTextRect.height() + 2 * lineWidth + yTextSpacing, 0,
xBarLengthPixels + lineWidth, xTextRect.height() + 2 * lineWidth
+ xTextSpacing, bgPaint);
if (longitudeBar)
canvas.drawRect(0, xTextRect.height() + 2 * lineWidth + xTextSpacing,
yTextRect.height() + 2 * lineWidth + yTextSpacing, yBarLengthPixels
+ lineWidth, bgPaint);
}
// draw latitude bar
if (latitudeBar) {
canvas.drawRect(0, 0, xBarLengthPixels, lineWidth, barPaint);
canvas.drawRect(xBarLengthPixels, 0, xBarLengthPixels + lineWidth, xTextRect.height()
+ lineWidth + xTextSpacing, barPaint);
if (!longitudeBar) {
canvas.drawRect(0, 0, lineWidth, xTextRect.height() + lineWidth + xTextSpacing,
barPaint);
}
canvas.drawText(xMsg, xBarLengthPixels / 2 - xTextRect.width() / 2, xTextRect.height()
+ lineWidth + xTextSpacing, textPaint);
}
// draw longitude bar
if (longitudeBar) {
canvas.drawRect(0, 0, lineWidth, yBarLengthPixels, barPaint);
canvas.drawRect(0, yBarLengthPixels, yTextRect.height() + lineWidth + yTextSpacing,
yBarLengthPixels + lineWidth, barPaint);
if (!latitudeBar) {
canvas.drawRect(0, 0, yTextRect.height() + lineWidth + yTextSpacing, lineWidth,
barPaint);
}
final float x = yTextRect.height() + lineWidth + yTextSpacing;
final float y = yBarLengthPixels / 2 + yTextRect.width() / 2;
canvas.rotate(-90, x, y);
canvas.drawText(yMsg, x, y, textPaint);
}
scaleBarPicture.endRecording();
}
/**
* Returns a reduced length that starts with 1, 2 or 5 and trailing zeros. If set to nautical or imperial the
* input will be transformed before and after the reduction so that the result holds in that respective unit.
* @param length length to round
* @return reduced, rounded (in m, nm or mi depending on setting) result
*/
private double adjustScaleBarLength(double length) {
long pow = 0;
boolean feet = false;
if (this.imperial) {
if (length >= GeoConstants.METERS_PER_STATUTE_MILE / 5)
length = length / GeoConstants.METERS_PER_STATUTE_MILE;
else {
length = length * GeoConstants.FEET_PER_METER;
feet = true;
}
} else if (this.nautical) {
if (length >= GeoConstants.METERS_PER_NAUTICAL_MILE / 5)
length = length / GeoConstants.METERS_PER_NAUTICAL_MILE;
else {
length = length * GeoConstants.FEET_PER_METER;
feet = true;
}
}
while (length >= 10) {
pow++;
length /= 10;
}
while (length < 1 && length > 0) {
pow--;
length *= 10;
}
if (length < 2) {
length = 1;
} else if (length < 5) {
length = 2;
} else {
length = 5;
}
if (feet)
length = length / GeoConstants.FEET_PER_METER;
else if (this.imperial)
length = length * GeoConstants.METERS_PER_STATUTE_MILE;
else if (this.nautical)
length = length * GeoConstants.METERS_PER_NAUTICAL_MILE;
length *= Math.pow(10, pow);
return length;
}
protected String scaleBarLengthText(final int meters, final boolean imperial,
final boolean nautical) {
if (this.imperial) {
if (meters >= METERS_PER_STATUTE_MILE * 5) {
return resourceProxy.getString(ResourceProxy.string.format_distance_miles,
(int) (meters / METERS_PER_STATUTE_MILE));
} else if (meters >= METERS_PER_STATUTE_MILE / 5) {
return resourceProxy.getString(ResourceProxy.string.format_distance_miles,
((int) (meters / (METERS_PER_STATUTE_MILE / 10.0))) / 10.0);
} else {
return resourceProxy.getString(ResourceProxy.string.format_distance_feet,
(int) (meters * FEET_PER_METER));
}
} else if (this.nautical) {
if (meters >= METERS_PER_NAUTICAL_MILE * 5) {
return resourceProxy.getString(ResourceProxy.string.format_distance_nautical_miles,
((int) (meters / METERS_PER_NAUTICAL_MILE)));
} else if (meters >= METERS_PER_NAUTICAL_MILE / 5) {
return resourceProxy.getString(ResourceProxy.string.format_distance_nautical_miles,
(((int) (meters / (METERS_PER_NAUTICAL_MILE / 10.0))) / 10.0));
} else {
return resourceProxy.getString(ResourceProxy.string.format_distance_feet,
((int) (meters * FEET_PER_METER)));
}
} else {
if (meters >= 1000 * 5) {
return resourceProxy.getString(ResourceProxy.string.format_distance_kilometers,
(meters / 1000));
} else if (meters >= 1000 / 5) {
return resourceProxy.getString(ResourceProxy.string.format_distance_kilometers,
(int) (meters / 100.0) / 10.0);
} else {
return resourceProxy.getString(ResourceProxy.string.format_distance_meters, meters);
}
}
}
}
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