Android's Compass (compass) detailed

Compass (Compass) is a custom view that inherits the view class, overriding the bounds (onmeasure) and content (OnDraw) of the views;

As shown in figure:

The following is the specific design of the compass:

1. Create Compassview class, compass view

Location: Java->package->compassview

Package Mzx.spike.compass.app;  
Import Android.content.Context;  
Import android.content.res.Resources;  
Import Android.graphics.Canvas;  
Import Android.graphics.Paint;  
Import Android.util.AttributeSet;  
Import Android.view.View;  
      
Import android.view.accessibility.AccessibilityEvent; 
 /** * Created by C.l.wang on 14-3-16. * * public class Compassview extends View {private float bearing;//azimuth public void setbearing FL  
        Oat _bearing) {bearing = _bearing;  
    Sendaccessibilityevent (accessibilityevent.type_view_text_changed);  
    public float getbearing () {return bearing;  
    Private Paint Markerpaint;  
    Private Paint Textpaint;  
    Private Paint Circlepaint;  
    Private String northstring;  
    Private String eaststring;  
    Private String southstring;  
    Private String weststring;  
      
    private int textHeight;  
Public Compassview {        Super (context);  
    Initcompassview ();  
        Public Compassview (context, AttributeSet attrs) {Super (context, attrs);  
    Initcompassview ();  Public Compassview (context, AttributeSet attrs, int defaultstyle) {Super (context, attrs,  
        DefaultStyle);  
    Initcompassview ();  
      
        private void Initcompassview () {setfocusable (true);  
      
        Resources R = This.getresources ();  
        Circlepaint = new Paint (Paint.anti_alias_flag);  
        Circlepaint.setcolor (R.getcolor (R.color.background_color)); Circlepaint.setstrokewidth (1);  
      
        Stroke width Circlepaint.setstyle (Paint.Style.FILL_AND_STROKE);  
        northstring = r.getstring (R.string.cardinal_north);  
        eaststring = r.getstring (r.string.cardinal_east);  
        southstring = r.getstring (R.string.cardinal_south);  
weststring = r.getstring (r.string.cardinal_west);      
        Textpaint = new Paint (Paint.anti_alias_flag);  
      
        Textpaint.setcolor (R.getcolor (R.color.text_color));  
      
        TextHeight = (int) textpaint.measuretext ("YY");  
        Markerpaint = new Paint (Paint.anti_alias_flag);  
    Markerpaint.setcolor (R.getcolor (R.color.marker_color)); @Override protected void onmeasure (int widthmeasurespec, int heightmeasurespec) {int measure  
        dwidth = measure (Widthmeasurespec);  
      
        int measuredheight = measure (Heightmeasurespec);  
      
        int d = math.min (Measuredwidth, measuredheight);  
    Setmeasureddimension (d, D);  
      
        protected int measure (int measurespec) {int result;  
        int specmode = Measurespec.getmode (Measurespec);  
      
        int specsize = measurespec.getsize (Measurespec);  
        if (Specmode = = measurespec.unspecified) {result = 200; else {result = Specsize;  
        return result;  
        } @Override protected void OnDraw (Canvas Canvas) {int mmeasuredwidth = Getmeasuredwidth ();  
      
        int mmeasuredheight = Getmeasuredheight ();  
        int px = MMEASUREDWIDTH/2;  
      
        int py = MMEASUREDHEIGHT/2;  
      
        int radius = math.min (px, py);  
      
        Canvas.drawcircle (px, py, radius, circlepaint);  
        Canvas.save (); Canvas.rotate (-bearing, px, py);  
        The opposite direction rotates int textWidth = (int) textpaint.measuretext ("W");  
        int cardinalx = PX-TEXTWIDTH/2;  
      
        int cardinaly = Py-radius+textheight;  
      
            for (int i=0; i<24; i++) {canvas.drawline (px, Py-radius, px, py-radius+10, markerpaint);  
            Canvas.save ();  
      
            Canvas.translate (0, textHeight);  
                if (i%6 = = 0) {String dirstring = ""; switch (i) {case (0): {dirstring = northstring;  
                        int arrowy = 2*textheight;  
                        Canvas.drawline (px, arrowy, px-5, 3*textheight, Markerpaint);  
                        Canvas.drawline (px, arrowy, px+5, 3*textheight, Markerpaint);  
                    Break Case (6): dirstring = eaststring;  
                    Break Case (a): Dirstring = southstring;  
                    Break Case (a): Dirstring = weststring;  
                Break  
            } canvas.drawtext (Dirstring, Cardinalx, Cardinaly, Textpaint);  
                else if (i%3 = = 0) {String angle = string.valueof (i*15);  
      
                float angletextwidth = textpaint.measuretext (angle);  
                int angletextx = (int) (PX-ANGLETEXTWIDTH/2);  
                int angletexty = Py-radius+textheight; Canvas.drawtext (ANgle, Angletextx, Angletexty, Textpaint);  
      
            } canvas.restore ();  
        Canvas.rotate (px, py);  
    } canvas.restore ();  
        @Override public boolean dispatchpopulateaccessibilityevent (final Accessibilityevent event) {  
      
        Super.dispatchpopulateaccessibilityevent (event);  
      
            if (Isshown ()) {String bearingstr = string.valueof (bearing);  
      
            Event.gettext (). Add (BEARINGSTR);  
        return true;  
    else return false; }  
}

This class of code more, detailed:

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