当我使用MapController.setZoom(x)时,例如从级别5缩放到15,缩放非常快,新级别的地图瓦片经常没有加载完成。这对用户来说不是很好。有没有Maps内置函数可以将缩放变慢以便瓦片可以在达到15级之前被加载,或者至少几乎加载完成呢?最好的问候。P
一种更简单的方法是利用MapController.zoomIn()方法,该方法提供了一些简单的动画来缩放一个级别。
下面是一些代码:
// a Quick runnable to zoom in
int zoomLevel = mapView.getZoomLevel();
int targetZoomLevel = 18;
long delay = 0;
while (zoomLevel++ < targetZoomLevel) {
handler.postDelayed(new Runnable() {
@Override
public void run() {
mapController.zoomIn();
}
}, delay);
delay += 350; // Change this to whatever is good on the device
}
这个没有简单的方式。但是,我可以帮助你。
首先,这里有一个我个人实用类的免费礼物,Tween.java:
import android.os.Handler;
public class Tween {
public static interface TweenCallback {
public void onTick(float time, long duration);
public void onFinished();
}
long start;
long duration;
Handler handler;
TweenCallback callback;
public Tween(TweenCallback callback) {
handler = new Handler();
this.callback = callback;
}
public void start(final int duration) {
start = android.os.SystemClock.uptimeMillis();
this.duration = duration;
tickRunnable.run();
}
public void stop() {
handler.removeCallbacks(tickRunnable);
}
Runnable tickRunnable= new Runnable() {
public void run() {
long now = android.os.SystemClock.uptimeMillis();
float time = now - start;
boolean finished = (time >= duration);
if (finished) {
time = duration;
}
callback.onTick(time, duration);
if (!finished) {
handler.post(tickRunnable);
}
else {
callback.onFinished();
}
}
};
//
// Tweening functions. The 4 parameters are :
//
// t - time, ranges from 0 to d
// b - begin, i.e. the initial value for the quantity being changed over time
// c - change, the amount b will be changed by at the end
// d - duration, of the transition, normally in milliseconds.
//
// All were adapted from http://jstween.sourceforge.net/Tween.js
//
public static float strongEaseInOut(float t, float b, float c, float d) {
t/=d/2;
if (t < 1) return c/2*t*t*t*t*t + b;
return c/2*((t-=2)*t*t*t*t + 2) + b;
}
public static float regularEaseIn(float t, float b, float c, float d) {
return c*(t/=d)*t + b;
}
public static float strongEaseIn(float t, float b, float c, float d) {
return c*(t/=d)*t*t*t*t + b;
}
}
MapController.zoomToSpan()
与Tween结合使用...这里是一些完全未经测试的代码,应该可以工作,也许需要微调,您只需传递目标纬度和经度跨度即可。public void slowZoom(int latE6spanTarget, int lonE6spanTarget) {
final float initialLatE6span = mapView.getLatitudeSpan();
final float initialLonE6span = mapView.getLongitudeSpan();
final float latSpanChange = (float)(latE6spanTarget - initialLatE6span);
final float lonSpanChange = (float)(lonE6spanTarget - initialLonE6span);
Tween tween = new Tween(new Tween.TweenCallback() {
public void onTick(float time, long duration) {
float latSpan = Tween.strongEaseIn(time, initialLatE6span, latSpanChange, duration);
float lonSpan = Tween.strongEaseIn(time, initialLonE6span, lonSpanChange, duration);
mapView.getController().zoomToSpan((int)latSpan, (int)lonSpan);
}
public void onFinished() {
}
});
tween.start(5000);
}